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392 Cards in this Set

  • Front
  • Back
What is Sublingual
ventral surface of the tongue
What is Buccal
lining of the cheek
What are the two general purposes for administering drugs to the oral cavity:
To achieve systemic or local effects
In the oral cavity, what is the principle barrier for drug absorption
Epithelium
What makes the oral cavity good for systemic delivery
Highly vascularized
What does Keratinization help form
it helps to form a tough barrier
Are the Buccal and sublingual membranes keratinized
No
Which is thicker, buccal or sublingual epithelial layer?
Buccal > sublingual; buccal epithel is thicker
Which is more permeable, buccal or sublingual epithelial layer?
Sublingual > buccal
What is the pH of Saliva
about 7
How is saliva critical for drug delivery?
it can dissolve the drug but it can also wash it away
What are the advantages of Sublingual/Buccal Delivery
1. Avoidance of GI acid degradation, GI enzymatic degradation, and the hepatic first pass effect (drainage is to the jugular vein), 2. Can achieve rapid onset of action and high blood levels (for some drugs), 3. Can also be used for prolonged action (can be several hours for buccal)
What are the disadvantages of Sublingual/Buccal Delivery
1. Relatively low permeability for most drugs because of skin like barrier properties (e.g., Small, lipophilic drugs are best absorbed), 2. The drug can be washed away (e.g., by saliva, eating, and drinking), 3. Sometimes unpredictable bioavailability (e.g., due to mucosal variations)
In dosage form design, Sublingual vs. buccal, which should be designed for rapid release over a short period of time?
Sublingual products
Why are sublingual products designed for rapid drug release over a short period of time
drug dissolve in sublingual pool of saliva, must be quickly absorbed before being washed away
Why are buccal products generally designed for slower drug release over a sustained period of time?
has lower permeability; relatively easy to keep dosage forms in place (*but some buccal products work faster (fentanyl))
Why should buccal/sublingual drugs and excipients should be bland and non-irritating
so as not to stimulated saliva flow
What type of sublingual administration is designed to disintegrate rapidly and leave little residue
Tablets
Why are compressed tablets usually lightly compressed
to facilitate disintegration, i.e., Nitroglycerin
Besides serving as a diluent, what other purpose does lactose have SL NTG tablets
NTG adsorbed to lactose to reduce explosive risk and help stabilize it
Are sublingual lyophilized tablets slow or fast dissolving
Fast-dissolving tablets; Example: Asenapine; peak plasma conc. with in 0.5-1.5 hours (reduced if water is drank within 10 mins)
How are molded tablets prepared
Prepared by forcing a moistened blend of drug and excipients into a mold, followed by forcing the wet mass out of the mold and allowing to dry; tend to be softer than compressed tablets. Tablet molds are also available for extemporaneous compounding.
How should sublingual NTG tablets be stored
Must be dispensed in the original glass container that is airtight; NTG interacts with and passes though plastic;NTG is volatile thus may evaporate rapidly
How is sublingual Nitrolingual Spray applied?
sprayed on or under tongue
How are sublingual films prepared
Drug is uniformly mixed with a fast-dissolving polymer (e.g., cellulose-based), plus a plasticizer, flavors, colorants, etc. The technology is also used for some products intended for GI absorption
Describe buccal chewing gum
A gum base with several excipients for flavor, texture, stickiness, etc.
Why is nicotine produced in a chewing gum
high hepatic first-pass, good buccal absorption
How is nicotine gum prepared
Nicotine is bound to a cation exchange resin; nicotine exchanges with saliva (chewing is critical). It's formulated with buffer to raise the pH to 8.5 which increases the nonionized form thus better absorption
What does the systemic bioavailability of nicotine in gum depend on
the time the saliva is held in the mouth**if swallowed, nicotine hepatically metabolized
Describe buccal lozenges
Hard tablets, typically prepared like hard candy that dissolves slowly in the mouth; e.g., Commit: Similar to Nicorette, the nicotine is bound to a cation exchange resin; cation exchange as the lozenge dissolves
What are buccal lollipops
Essentially a lozenge-on-a-stick. e.g., fentanyl citrate lollipop - Actiq (very lipophilic, high hepatic and intestinal first pass) used for pain associated with cancer
Describe the usage of buccal lollipops
placed between cheek and gums, then sucked for about 15 mins. Rapid absorption followed by prolonged absorption (rapid from absorption in the mouth, prolonged - from GI absorption)
Why is the goal of buccal mucoadhesive tablets
To keep the dosage form in place; Designed to slowly disintegrate/dissolve
What is an example of mucoadhesive excipients
cellulose derivatives; Striant (testosterone buccal system)-testosterone (high hepatic 1st pass and lipophilic) stays between cheek and gums until removes (12hrs)
How are Orally Disintegrating Tablets (for Buccal Drug Delivery) prepared
Prepared by lyophilization ; e.g. Zelaper (selegiline hydrochlloride)
How is Zelapar (selegiline hydrochloride) Orally Disintegrating Tablets (for Buccal Drug Delivery) used
Placed on the tongue where it rapidly dissolves; absorption is buccal, avoid food/liquid 5 minutes before and after
(2) Fentora (fentanyl citrate) Buccal Tablet (compressed)
Placed between the cheek and gums where disintegration occurs rapidly; uses Oravescent technology
Describe oravescent technology
Oravescent technology involves release of CO2, with pH changes that favor dissolution, then absorption. 1) pH decrease, thus ionized form and dissolution 2) pH then increase favoring unionized form and absorption
What are some general guidelines for administering buccal or sublingual tablets
Avoid eating, drinking, chewing, smoking, and talking (if practical) ---do not disturb
What are the most local common purposes of vaginal dosage forms
vaginal infection, lubricant, and contraception
Liquid Dosage form for the vaginal route
Douche
Semisolid Dosage forms for the vaginal route
Creams, gels, ointments, and foams
Solid Dosage forms for the vaginal route
Suppositories or compressed tablets shaped like Suppositories
What are other names for solid vaginal dosage forms
Other names include pessary, ovule, and insert
Film Dosage forms for the vaginal route
similar to oral films, the drug is uniformly dispersed or dissolved in a thin, rapidly disintegrating polymer sheet
Describe the gross anatomy of the vagina
The vagina is a fibromuscular tube, about 6 - 10 cm long (adult), extending from the cervix
Describe the vaginal mucosa
A mucous membrane composed of a stratified squamous epithelium
What are the key features of the vaginal mucosa
Contains rugae and a natural microflora
What are rugae
folds in the wall - increase surface area, can help retain the product
What is the importance of a natural microflora
important for healthy vaginal mucosa; aerobes and anaerobes
Describe Vaginal epithelium
not keratinized; A stratified squamous epithelium composed of 5 strata
Describe the Mucous layer (vaginal fluid)
There is a limited amount of vaginal fluid, but it is fairly complex (transudates, exfoliated epithelial cells, leukocytes)
What is the Source of vaginal secretions
Vaginal fluid consists mainly of cervical secretions, which flow continuously to the vagina
How does the vaginal environment maintain an acidic environment that is bacteriostatic
Lactobacillus acidophilus produces lactic acid from glycogen in the vaginal epithelial cells
What type of Enzymes are in the vaginal secretions
peptidases
Is Venous drainage from the vagina hepatic?
Venous drainage is not to the hepatic portal system thus no hepatic-first pass
What three components have significant variations in the vaginal mucosa
The amount and composition of vaginal fluid, pH, and the epithelium
How can the amount and composition of vaginal fluid vary
The amount and consistency varies during the menstrual cycle which can affect drug dissolution and residence time
Increase in pH between about 4 weeks of age and puberty, and upon menopause means increase risk of what
infection
What can be effected by the thickness changes throughout the menstrual cycle
drug absorption. The epithelium becomes thinner upon menopause
What is the percentage of systemic absorption Through the Vaginal Epithelium for most current products**often between 1-10%
often between 1-10%
Why is there significant interpatient variability for absorption through the vaginal epithelium
because of variation in vaginal mucosa
Explain the Possibility of a first uterine pass effect
There are reports that some intravaginally administered drugs accumulate in uterine tissue which means the uterus could be treated with intervaginal product
At what pH should products be formulated to match vaginal pH
keep product pH around 4 to maintain infection resistance; pH is also important for drug solubility and stability
What are the product attributes after administration
Retention, liquefaction, distribution
What characteristics of the product effect the retention so that it is long enough for the drug to distribute adequately
rheology and level of insertion can be important
How quickly should the product dissolve or melt
ideally should be within minutes
What can happen if the product leaks too quickly or excessively
can lead to reduced effect and compliance problems
Explain mucoadhesive (bioadhesive) drugs
product will stick, wont be as messy, may prolong drug release
Why are Applicators are usually required for intravaginal delivery
to help the product to be placed high in the vagina
How to Use Pessaries or Vaginal Cream
1. Wash your hands., 2. Remove any foil or plastic covering from the pessary or applicator. 3. If an applicator is supplied, load it with the pessary or cream. 4. Whilst laying down, knees bent and spread apart, gently insert the applicator (or pessary) into the vagina as far as it will comfortably go. 5. Press the plunger to deposit the pessary or cream in the vagina and withdraw the applicator. 6. Wash your hands again.
What ocular conditions can be treated by topical products
Glaucoma, Infections, Inflammation, Dry eyes
The eye wall consists of what three concentric layers:
Outermost - conjunctiva/sclera and the cornea, Middle - Uveal tract (choroid, ciliary body, and iris), Innermost - retina
What divides the inside of the eye
the lens divides the eye into aqueous and vitreous humors (aka anterior and posterial SEGMENTS/REGENS - not chambers)
What is the aqueous humor divided by
iris; into anterior and posterior chambers.
What makes the aqueous humor
It is continuously generated by the ciliary bodies
How does the aqueous humor flow
from the posterior chamber through the pupil
How does the aqueous humor exit into systemic circulation
mainly though Schlemms canals
What are the Surrounding Structures of the eye
Conjunctiva, Lacrimal Gland, Puncta, Nasolacrimal Apparatus
Describe the Conjunctiva
A thin, transparent, vascularized mucous membrane that extends from the edge of the cornea, across a portion of the sclera, then extends to the internal surface of the eyelids to form the conjunctival sacs (cul-de-sacs)
What is the Lacrimal Gland
One of the glands responsible for tear production.
What is one function of tears
removal of foreign material through the puncta.
What is the Puncta
The small openings to the lacrimal canaliculi.
What is the drainage system for lacrimal fluid
Nasolacrimal Apparatus
How do tears drain through the Nasolacrimal Apparatus
Tears drain through the canaliculi to the lacrimal sac then to the nasal cavity via the lacrimal duct from the nasal cavity they are moved toward the nasopharynx. Tear drainage occurs by gravity and through an active process employing a pumping mechanism. **blinking (15-50x per min)
What are the 4 mojor Potential Ophthalmic Drug Target Areas
Pre-ocular structures (e.g., conjunctiva and eyelid (nfections and inflammation)), Cornea (infections and pain), Tissues in the anterior segment, and Tissues in the posterior segment (NOT likely target for topicals)
What are the Tissues in the anterior segment
(1) Iris muscles -alpha-1 (2) Ciliary epithelium - alpha-2, beta-2, (3) Ciliary muscle - beta-2
Im transcorneal Absorption, what are the major pathways for a topical ophthalmic to reach intraocular tissues
through the cornea and sclera (passage though the cornea dominates)
What covers the cornea
Tear film
What are the three layers of the tear film and what is the function of each layer
(1) Mucoid layer (Involved in adhesion of the aqueous tear fluid; keeps the cornea wettable), (2) Tear fluid (Aqueous solution of inorganic electrolytes, proteins including enzymes and immunoglobins and glucose), (3) Lipid film; A layer of wax and cholesterol esters adsorbed to the tear fluid. (reduced evaporation of the tear fluid)
What provides the driving force for passive diffusion through the cornea
concentration of drug in the tear film (passive diffusion dominates corneal permeation)
What are the layers of the Cornea
Epithelium, Stroma, Endothelium
What are the most important layers for drug absorption
epithelium, stroma, and endothelium ** lipophilc, hydrophilic, lipophilic
Describe the Corneal epithelium
Continuous with the conjunctiva, but with a different thickness, A stratified epithelium, The epithelium is the main barrier for drug passage through the cornea
What structures increase the surface area or the corneal squamous cells
surrounded by tight junctions and have microvilli
What is the main barrier for drug passage through the cornea
epithelium: It is primarily a lipophilic barrier (lipophilic drugs permeate well); The drug's ionization state can be important (unionized = more lipophilic thus permeated epithelium better)
What layer of the cornea is a barrier for lipophilic drugs
Stroma
Which layer of the cornea provides metabolic exchange between the cornea and the aqueous humor.
Endothelium
For Transcorneal Drug Absorption, what kind opf drugs are best absorbed
Drugs with a moderate octanol/water partition at physiological pH are best absorbed. i.e. because of diverse barriers
For Transcorneal Drug Absorption, the _________ the tear film, the __________ the penetration
greater, faster
What happens to the rate of absorption through damaged epithelium
increases
Normally, how much of the dose (instilled as drops) will cross the cornea
less than 5 %
What are the possible fates of the drop(s) applied to the eye (before crossing the cornea):
Spillage, Removal by Nasolacrimal Drainage, Enzymatic degradation
Once the drug has crossed the cornea, what fates can be met:
Penetration into deeper intraocular tissues, Binding to proteins, Elimination
Where are the greatest concentrations are usually achieved
within the aqueous humor in the anterior region of the eye. The amount reaching the posterior region is usually insignificant
How can iris color effect the binding to proteins
some lipophilic drugs can bind to melanin in the iris; in dark irides can reduce the drug effect or act as a depot
After eye drops are applied, how can the drug be eliminated
Entry into systemic circulation
How can the drug can enter the systemic circulation from within the eye:
via aqueous humor turnover ; exits through the canal of schlenmm or through uveal blood vessels
Some metabolize drugs and esterases are important for what
some prodrugs
What are the routes of systemic absorption
Absorption through tissues encountered following nasolacrimal drainage; Absorption through blood vessels in the conjunctiva; Absorption from within the eye
Why does the conjunctiva facilitate drug absorption
it's more permeable than the cornea and covers a much greater surface area; the conjunctiva is highly vascularized , most that permeates is absorbs systemically
What is the overall impact of systemic absorption
over 50% of the instilled dose can be systemically absorbed
Why is Pseudomonas aeruginosa of great concern
can invade abraded cornea and cause corneal ulceration and blindness
What antimicrobial preservatives is most widely used against P. aeruginosa
Benzalkonium chloride (BAC) (0.01% or less); Can affect corneal penetration.**can act as a penetration enhancer
What can happen if the concentration of Benzalkonium chloride (BAC) is too high
Can damage the corneal epithelium
What is Polyquad (polyquaternium-1)
antimicrobial preservative; Almost nonsensitizing=alternative to BAC but does not penetrate the cornea well.
What is Thimerosal (0.001-0.01%)
An organic mercurial antimicrobial preservative; Hypersensitivity is a problem
What is the normal pH of tears
between 7 and 7.4
Solutions below a pH of 6.6 and above a pH of 9.0 have been associated with what
irritation, reflex tears, and blinking.**speeds up drop elimination from the eye surface
What are some important buffers for opthalmics
acetate, phosphate, citrate, borate; Chosen based on compatibility with the drug product and on desired pH. (often chosen to help stability or stabilize the drug)
What is used to adjust the pH of opthalmics
Strong acids (e.g., HCl or H2SO4) and strong bases (e.g., NaOH)
What is the aproximate Osmolarity (Tonicity) of tears
about 300 mOsm/kg
Isotonicity is very important for what
comfort; Instilled fluids far outside of the normal range can irritate, leading to a reflex tearing and blinking. This will speed up elimination from the eye surface
What are some common Tonicity modifiers
NaCl, mannitol, and dextrose
Increased viscosity can do what
Increase retention time / reduce the drainage rate (Can increase bioavailablilty); can irritate if too high
What are some Viscosity modifiers
glycerin, cellulose derivatives (e.g. hydroxyethylcellulose), polyvinyl alcohol, PEGs
Why are viscosity modifiers used
Increase viscosity can increase retention/reduce drainage time and they must have a lubricating effect
What type of doseage form are Liquid Ophthalmics (Eyedrops)
Solutions or suspensions
How is the formulation and manufacturing of a solution done
Dissolve drug and part or all of excipients. Sterilize by heat or membrane filtration. If required, add the other sterilized excipients, bring to volume with sterile water.
How is the formulation and manufacturing of a suspension done
Reduce the particle size to less than 10 micrometersl; smaller particles reduce irritation and speeds dissolution. Can't filter-sterilize , so must aseptically add the sterilized solid to the sterilized solution.
What types of drugs are suspension eye drop s used for
Used for poorly water-soluble drugs or to improve stability. They do not provide a drug depot, but they do mix with tears less rapidly thus remain in the cul-de-sac longer
What is an example of an antioxidant
Sodium metabisulfites
What is an example of a chelator
EDTA disodium
Besides its ability to limit oxidation by chelating metals, what other important function does EDTA have
increase the activity of BAC against P aeruginosa
What are some examples of Surfactants
Polysorbate (Tween) 80 and tyloxapol
How are surfactants used in eye drops
Used as wetting agents for suspensions and can facilitate spreading of the drops because they reduce surface tension
How are eye drops packaged
In a sterile Drop-tainer
What is the main advantage of a semisolid Ophthalmic/Ointment
Prolonged contact time
What is the main disadvantage of a semisolid Ophthalmic/Ointment
Can cause blurred vision
How is the formulation and manufacturing of a opthalminc ointment done
The ointment base is usually white petrolatum, with or without mineral oil to reduce viscosity. Sterilize the ointment base by heat, then filter while molten. Add sterilized drug and excipients aseptically.
What is used in preparing ophthalmic Gels
These employ a gel former such as Carbomer or gums (e.g., cellulose derivatives)
After using eye drops, why do you apply gentle pressure against the inner corner of the eye
(nasolacrimal occlusion) to slow drainage as well as limit systemic effects
What does the dissolution test measure
measures the rate and extent of the drug in the tablet to go into solution
When is the dissolution test a particularly important test for drugs with limited water solubility
where dissolution is the rate-limiting step for absorption
Describe the rotating basket method (USP)
The tablet is placed inside a stainless steel wire basket, which is rotated at a fixed speed while immersed in a dissolution medium (at body temperature) contained in a cylindrical vessel.
Describe the paddle method (USP)
Allow the dosage to sink to the bottom of the vessel. Agitate the dissolution medium. Dissolution medium is specified
In dissolution tests, how humch of the drug should be disolved in 45 minutes
75%
What is an example of dissolution medium for basic drugs
0.1N HCl; Protonation/dissolution in stomach
What is an example of dissolution medium for acidic drugs
Buffer at pH of 7; Deprotonation/dissolution area in small intestine
What is an example of dissolution medium for neutral drugs
Water
In order to maintain dissolution, how should tablets be stored
store tablets under proper conditions so they maintain the ability to dissolve (tightly sealed, away from high humidity and high temperatures)
How does the lumen increase the risk of esophageal adhesions
It is narrow and coated with mucus; there is little water
What can result following Esophageal Adhesion
following adhesion, the drug will dissolve, possible irritation, inflammation and ulceration; e.g., aspirin, NSAIDs, tetracycline, ferrous sulfate, KCl
What factors cause a predisposition to adhesions
shape (flat vs round), size, surface properties (sticky if wet), patient position (e.g. supine position increases the risk), volume of water (if none, increase risk), and disease
What is the recommended method for taking tablets to avoid adhesions
take the tablet while standing with a glass full of water at least 1 hour before bed
Describe the tablet form: Lozenges
prepared and formulated like hard candy
Describe the tablet form: Troches
compressed into a hard disc
Describe the tablet form: Chewable tablets
Prepared by wet granulation, sometimes without a disintegrant (chewing takes place of disintegrant). Often have a high mannitol or xylitol content and flavorants to give cooling sensation in the mouth
How are Lozenges and Troches administered
Intended to dissolve slowly (e.g., 30 minutes) in the mouth, usually for a local effect.(eg for thrush)
How are Chewable tablets administered
Pleasant tasting tablets designed to disintegrate smoothly in the mouth; Examples: vitamins, antacids, antibiotics
Describe the tablet form: Effervescent tablets
Prepared by compressing the drug with effervescent salt mixtures (e.g., sodium bicarbonate and citric acid)
How are Effervescent tablets administered
Generally designed to be dissolved in liquid prior to ingestion;effervescent KCl tablets
How are Fast-dissolving tablets administered
Designed to disintegrate rapidly in the mouth before swallowing; less than 1 min
What are some claims for fast-dissolving tablets
Easier to take and swallow (typically you don’t need water (though following with water may be recommended)). Possible faster onset of action , but often not true (faster because of disintegration before swallowing; BUT drug dissolution can be rate limiting, drug particles might be coated)
What methods of formulation and manufacture (in the U.S.) are used to prepare fast-dissolving tablets
Lyophilization (freeze-drying) - Leaves a very porous product (sponge like, tablet usually brittle thus special packaging and handling). Direct compression with special disintegrants (ex:superdisintegrants - very hydrophilic cellulose deriv and effervescent disintegrants; these tablets must be well protected)
How are suppositories used
for insertion into the rectum, vagina or the urethra
What happens after suppositories are inserted
after insertion, suppositories soften, melt or dissolve in the cavity fluids (due to body temp)
What are the weights of rectal, vaginal, and urethral suppositories
rectal-2 g, vaginal-5 g, urethral-2 g female, 4 g male
What uses are suppositories are indicated for
administering drugs to infants and small children, severely debilitated patients, those who cannot take medications orally; for either systemic or local application
What are the advantages of suppositories over oral therapy
Avoid loss of the drug (Acidic pH of stomach or enzymes destroy drug), drugs can irritate stomach, and some drugs can be destroyed by first liver passage
What are the disadvantages of Suppository
un-comfortable, Variation of absorption (physiological), Irritation for mucous caused by some drugs or bases
Describe the anorectal physiology
~10” long (20-30 cm), Nonmotile, 2-3 ml inert mucous fluid, No villi/microvilli, has blood and lymphatic vessels, and pH: 7 to 8
What are some treatment uses of suppositories
Hemorrhoid (astringent, local anesthetic, vasoconstrictor, antipruritic, antiseptic); Fungal infection; Bacterial infection; Chronic inflammation; Constipation (Glycerin S.)
After Rectal Insertion, how much of the drug is absorbed into blood circulation?
50-70%
What is the anorectal Main Blood Circulation
1. Inferior haemorrhoidal vein (HV), 2. Middle HV, 3. Superior (upper) HV.
What types of drugs can be used in suppositories
anti-emetic, tranquilizer, vasodilator, analgesic, hypnotic, antipyretic, antiasthmatic
What Physicochemical Factors Affect Rectal Absorption
Lipid solubility (melt and release from base), Particle size (dissolution rate, absorption-diffuse), Suppository vehicle
The ideal suppository base should:
be nontoxic, nonirritating, and easily formed by compression or molding; dissolve or disintegrate in the presence of mucous secretions (pH 7-8); melt at body temperature to allow for the release of the medication; be stable on storage, not bind or otherwise interfere with release and absorption of drug substances.
How are suppository bases classified?
according to their composition and physical properties
What are the types of suppository bases (according to their composition and physical properties)
Oleaginous (fatty) bases, Water soluble or miscible bases
Why are pharmaceutical additives added to suppositories
To Improve Quality
What are some common pharmaceutical additives added to suppositories
plasticizer - Cetylalcohol, Propylene glycol antioxidant, dispersant – Surfactant, Absorbance enhancer
What are used as a Oil-Soluble suppository bases
Theobroma Oil or cocoa butter and Synthetic Triglycerides
Describe the triglycerides of Cocoa Butter
All the acids are bonded to glycerin, forming an important number of triglycerides. Of these acids, 80% are disaturated triglycerides, of which 20% are of the SOS type, 55% POS, and the remaining 5% are POP (Stearic Acid, Palmitic Acid, Oleic Acid)
What gives Cocoa Butter its physical and chemical behavior, mainly in its fusion and solidification properties
Its triglyceride composition (mixture of liquid triglycerides entrapped in a network of crystalline, solid triglycerides)
What happens if cocoa butter is heated above 35°C (95°F)?
it melts to a bland, nonirritating oil.
What happens to Cocoa butter if it's overheated?
Cocoa butter is a polymorphic compound and if overheated will convert to a metastable structure that melts in the 25° to 30°C (77° to 86°F) range.
What are the 4 forms of cocoa butter crystals
1. beta crystal (mp 34-36 °C) -what you want, 2. beta’ crystal* (mp 27 °C), 3. alpha crystal* (mp 22 °C), 4. gamma crystal* (mp 18 °C) (liquid)
Describe Synthetic Triglycerides used are suppository bases
Consists of hydrogenated vegetable oil, Do not exhibit polymorphism, More expansive
What is an example of a synthetic triglycerides used as suppository base
Fattybase: triglycerides derived from palm, palm kernel and coconut oils, stable with a low irritation profile, needs no special storage conditions, exhibits excellent mold release characteristics, solid with a melting point of 35-37°C
What are used as Water Soluble/Water Miscible suppository bases
Glycerinated Gelatin and Polyethylene Glycol (PEG) polymers
What are Glycerinated Gelatin suppositories composed of
70% glycerin, 20% gelatin and 10% water [translucent]
How should Glycerinated Gelatin suppositories be packaged
in tight containers, as they are hygroscopic
What isn't Glycerinated Gelatin recommended as a rectal suppository base
may exert an osmotic effect and a defecation reflex; useful suppository base, particularly for vaginal suppositories
Describe the physical state in terms of polymers for Polyethylene Glycol (PEG) polymers
<1000=liquid >1000=solid
Describe Polyethylene Glycol (PEG) polymers for use as a suppository base
are chemically stable, miscible with water and mucous secretions, can be formulated, either by molding or compression
What aren't Polyethylene Glycol (PEG) polymers stored in polystyrene prescription vials
the polyethylene glycol will adversely interact with polystyrene (use glass containers)
What is the major disadvantage of Polyethylene Glycol (PEG) polymers
incompatibility with a large number of drugs; e.g. silver tannins, aspirin, quinine, indomethacin; Sodium barbital, salicylic acid, camphor will crystallize out of PEG suppositories
What three methods can be used to prepare suppositories
Rolled (Hand-Shaped) Suppositories– Only possible with cocoa butter base; Compression-Molded (Fused) Suppositories– no heat, mold under pressure; Fusion or Melt Molding (most common)
Explain why density calculations and mold calibrations are required to provide accurate doses of suppositories
measured by weight but compounded by volume: Suppositories are generally made from solid ingredients and drugs which are measured by weight. When they are mixed, melted, and poured into suppository mold cavities, they occupy a volume –the volume of the mold cavity.
What is the Archimedes Principle
The weight of the displaced fluid can be found mathematically: Density = mass / volume
How do you determine the amount of base required in compounding suppositories
Density Factor = weight of drug / weight of base displaced: When a drug is placed in a suppository base, it will displace an amount of base as a function of its density. The density factor is used to determine how much of a base will be displaced by a drug.
How are suppositories compounded when the density factor is not known
Density Factor is experimentally determined by the double casting technique. Double melt technique used (heat exposure)
Why using the topical route
Hydration, Protection, Systemic effect (transdermal drug delivery), Local effects = drug action
What are the Skins functions
Protective barrier on body surface to physical, chemical and biological intrusions, Homeostasis (temperature & water), Sensory, Secretory (vitamin D production), Excretory (via sweat glands)
What are the epidermis' 5 sublayers of keratinocytes (strata)
Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale/Germinativum
How thick is the epidermis
Thickness varies: 75-150 μm in thin skin; 400-600 μm in thick skin
What are the mechanical functions of the epidermis
Provides mechanical protection, Prevents fluid loss, Keeps microorganisms from invading the body
Are there vessels in the epidermis
No vessels in epidermis
Describe the Stratum Corneum
Horned layer: Dead cells, 15‐20 layers in thick skin, 3‐4 layers in thin skin, Flattened non‐nucleated cells filled with keratin filaments (these cells can also absorb water), surface cells constantly sloughed off
Where is the Stratum Corneum found
This layer is only found on the soles of the feet and the palms of the hands; More common in thick skin
Describe the Stratum Lucidum
Thin, translucent lightly stained layer of non‐nucleated cells; Different arrangement of filaments
Describe the Stratum Granulosum
3‐5 layers of polygonal cells with central nuclei and many basophilic granules; Keratohyalin granules contain proteins that bind keratin filaments together; Membrane coating granules also present; secrete to extracellular matrix to make it more waterproof
What is the is the highest layer in the epidermis where living cells are found
Stratum Granulosum
Describe the Stratum Spinosum
Multilayer arrangement of cuboidal, polygonal or squamous cells, extensions with desmosomes, link proteins that attach the cell surface adhesion proteins to intracellular keratin cytoskeletal filaments
What are cytokeratins
Intermediate filaments which are composed of keratin. Synthesized in the Stratum Spinosum
Describe the Stratum Basale/Germinativum
layer of keratinocytes that lies at the base of the epidermis immediately above the dermis. It consists of a single layer of tall, simple columnar epithelial cells lying on a basement membrane. These cells undergo rapid cell division, mitosis
What are some Epidermal characteristics
Cells accumulate keratin and eventually are shed (continuously renewing, 0.06 0.1 mm thick), Epidermal ridges are interlocked with dermal papillae (Fingerprints, Improve gripping ability)
What are Langerhans cells for and what layer of the epidermis are they found
Fro immunity in s. spinosum
What are Merkel cells for and what layer of the epidermis are they found
For sensitivity in s. germinativum
What gives skin its color
melanin amount, carotene content in subcutaneous fat and vascularization
What produces Melanin and where is it produced
by melanocytes in stratum basale; melanin forms from tyrosine
What is melanin
Melanin is any of the oxyacetylene, polyaniline, and polypyrrole blacks and browns or their mixed copolymers.
What do Epidermal cells synthesize when exposed to UV
vitamin D3 (cholecalciferol)
What does epidermal growth factor effect
Growth, Division, Repair, Secretion
The dermis is structurally divided into what two areas
a superficial area adjacent to the epidermis, called the papillary region and a deep thicker area known as the reticular region.
describe the papillary region of the dermis
composed of loose connective tissue; named for its fingerlike projections called papillae, that extend toward the epidermis. The papillae provide the dermis with a bumpy surface that interdigitates with the epidermis, strengthening the connection between the two layers of skin.
What are the features of the dermis
Network of elastic fibers (elasticity decreases with age), Many blood and lymph vessels, Papillary layer vessels supply epidermis, Arteriovenous shunts for blood pressure and temperature regulation, all epidermal structures (hair follicles, sweat and sebaceous glands) penetrate into the dermis, Many sensory nerves in skin (touch, pain, temperature sensation), Sympathetic vasoconstrictor fibers, piloerector fibers and sudomotor fibers
What is the Hypodermis (Subcutaneous layer)
Adipose connective tissue. The hypodermis is not part of the skin, and lies below the dermis.
What is the purpose of the hypodermis
Loose connective tissue attaches skin to subjacent organs and tissues; this loose flexible attachment is so skin can slide over organs (the hypodermis contains 50% of body fat). Fat serves as padding and insulation for the body.
What are the Skin Appendages (accessories)
sweat & sebaceous glands, hair follicles & hairs, nails, nerves & nervous receptors
Topical dosage forms generally contain the following ingredients:
Base or body of the dosage form, Medicinal agent (not always the case), Preservative (espicially if water is added)
Ointments are used topically for several purposes:
Protectants, Antiseptics, Emollients (soften), Antipruritics (for dry/itchy), Kerotolytics (soften by loosening), Astringents (to shrink tissues)
What types of ointments are there
medicated or nonmedicated
Ointments are defined as what
are semisolid preparations intended for external uses
Describe Non-medicated ointments
emollient or lubricant , vehicle for the preparation of medicated ointments
Why is the vehicle or base of an ointment is of prime importance
In the case of a protective ointment, it serves to protect the skin against moisture, air, sun rays and other external factors.
What are the 5 types of ointment bases
Hydrocarbon bases, Absorption bases, Emulsion bases water‐in‐oil type, Emulsion bases oil‐in‐water type, Water‐miscible bases
In general, how are ointment bases classified
classified according to their interaction with water
Synonym of Hydrocarbon bases is?
Oleaginous Bases
Characteristics of hydrocarbon bases
Will not absorb water, Not water washable, Insoluble in water, Emollient, Occlusive, Greasy
Describe Occlusive bases
applied to the skin and stays on the skin; a film so water won't evaporate. It will soften the skin and loosen the skin tissues.
What are 4 examples of hydrocarbon bases
Petrolatum, White petrolatum, Yellow ointment, Yellow wax
Describe Petrolatum
purified mixture of semisolid hydrocarbons, melting point 38‐68 oC, yellow to light amber, commercial product: Vaseline)
Describe White petrolatum
Bleached petrolatum; not water washable, commercial product: white vaseline)
Describe Yellow ointment
95 % petrolatum + 5 % yellow wax, synonym: simple ointment
Where is Yellow wax obtained from
obtained from honeycomb of the bee
Describe how Petroleum jelly or petrolatum is made
Petroleum jelly or petrolatum is a byproduct of the refining of petroleum, made from the residue of petroleum distillation left in the still after all the oil has been vaporized.
What are the Important properties of hydrocarbon bases
Therapeutic and Patient Acceptance
What are Therapeutic Advantages of topical delivery
Upon application to the skin, a hydrocarbon base will form an adherent, continuous, greasy, water repellant film; Good occlusiveness: This can have an emollient effect (hydrates skin) and can enhance drug permeation; Prolonged contact with the skin; Good protection
What are the twp types of Absorption bases
1. Permit the incorporation of aqueous solutions; Form W/O emulsions ; Single phase e.g. Hydrophilic petrolatum 2. Are W/O emulsions; Two phase system e.g. Lanolin
What are the general characteristics of absorption bases
Insoluble in water, Not water washable, Anhydrous, Can absorb water, Emollient, Occlusive, Greasy
Describe absorption properties of Anhydrous absorption bases
Contain agents that confer an ability to absorb water. They can also absorb alcohol, but to a lesser degree.
What are two Examples of W/O emulsions
Hydrophilic petrolatum, USP, Aquaphor - petrolatum, mineral oil, mineral wax, woolwax alcohol
Describe the absorption properties of W/O absorption bases
Similar to anhydrous absorption bases, except that these already contain varying amounts of water.
What are two examples of W/O absorption bases Examples
Lanolin, USP, Cold Cream
Where is Lanolin obtained from
Obtained from sheep wool, purified
How much water can lanolin absorb
Can absorb up to 30% of water
What are Emulsion Bases, O/W Type
Water removable ointment bases
What are the Characteristics of emulsion bases, O/W types:
Insoluble in water, Water washable, Will absorb water, Contains water, Emollient, Non ‐ Occlusive, Non ‐ Greasy
What is an Example of emulsion bases, O/W types
Hydrophilic ointment
What is the purpose of stearyl alcohol and white petrolatum in emulsion bases
oily phase
What is the purpose of water and propylene glycol in emulsion bases
aqueous phase
What is the purpose of sodium laurylsulfate
emulsifying agent
What are the characteristics of Water-Soluble Bases
Water soluble, Water washable, Will absorb water, Non - Occlusive, Non - Greasy
What are some Examples of water-soluble bases
Polyethylene glycol (PEG) ointment, Glyceryl Monostearate, Cellulose derivatives, carbopol 934
Explain the density of different Polyethylene glycol (PEG) ointments
Polyethylene Glycol 3350 (solid) High#; Polyethylene Glycol 400 (liquid) Low #
What is Carbopol used for
Thickening agent
What are the criteria for the Selection of Appropriate Base type
Desired release rate, Desirability topical or percutaneous drug absorption, Desirability of occlusion, Stability of drug in vehicle, Influence of drug on consistency or other features of ointment base, Patient factor ‐ dry or weeping (oozing) skin
Define Water Number
Ability of an ointment base to incorporate water without loosing its consistency.
What is the Water Number equivalent
the number of grams of water that can be incorporated into 100 grams of the base.
What is the water number of hydrocarbon bases
0 to 5
What is the water number of Absorption bases
100 to 800
What are the two methods of Preparation of Ointments
Incorporation and fusion
Describe the incorporation process of preparing ointments
" mix together (mortar & pestle, spatula & slab – levigating the powder mechanical incorporation, reduction of particle size in suspending agent compatible with the ointment base)
Describe the fusion method of preparing ointments
components of an ointment melted together and cooled with constant stirring until congealed
About how much ointment Is lost in the compounding process
Between 2 and 4 grams of an ointment may be lost in the compounding process.
How much excess of ointment should be prepared to compensate for loss
General rule: add 10% excess to the prescribed amount.
What must be considered when choosing Levigating Agents
Must be compatible with base – External phase of 2-phase systems, Mustn’t unduly influence product viscosity -Mineral oil & glycerin (Main agents), - Propylene glycol PEG 400, cottonseed oil, caster oil, Surfactants , e.g. polysorbate 80 (Tween 80), Chose Powders over crystalline drugs - less gritty
What are Post Failure Fixes when preparing ointments
Very difficult to fix once you have problems, Keep triturating; Start over
In fusion, what is Incorporated into the ointment
Wax & hard fusible bodies into soft oleaginous materials
In Preparation of ointments, how do you avoid excess heat
Melt on water bath
How do you add ingredients to an ointment
In order of decreasing melting points, Heat to fusion point, Add liquid ingredients. Mix phases by stirring to homogeneous preparation, Powder added after base congeals
When to Use the fusion process ?
For Solids that cant’ be easily triturated: Beeswax, Cetyl alcohol, Paraffin, Stearic acid, Any fusible solid
What can happen if you over heat a ointments during compounding
Lanolin, oleic acid, fatty acids, etc. can oxidize; may be discolored. Heat labile components can degrade (Methylparaben & Propylparaben, drugs)
In fusion what are the Post Failure Fixes for phase separation
i.e. cold mixed, reheat heat and stir vigorously
In fusion what are the Post Failure Fixes for low viscosity
add more high η / melting point ingredients; e.g. Beeswax, paraffin, stearic acid
In fusion what are the Post Failure Fixes for poor dispersion
reheat & add more surfactant; lanolin, etc.
At what temperature will most ingredients used in ointment bases liquefy
around 70°C.
What is helpful in order to mix oil and aqueous phases together :
heat the aqueous phase a few degrees higher than the oil phase prior to mixing. The aqueous phase tends to cool faster than the oil phase and may cause premature solidification of some ingredients.
In mixing aqueous and oil phases, why do you use the lowest temperature possible and keep the time of heating as short as possible.
This will minimize the quantity of water lost through evaporation.
What ingredients of ointments should be melted first
Melt the ingredient with the highest melting point first. Reduce the heat to melt the ingredient with the next lowest melting point. Continue this process until all ingredients have been added. This will ensure that the ingredients were exposed to the lowest possible temperature and thus enhance the stability of the final product.
What happens if you rush the cooling of ointments
Change the consistency of the final product! I.e. makes it more stiff
When are volatile ingredients such as oils, flavors, or drugs, added to the topical drug
when the product is cool to the back of the hand. or it will evaporate
How are ointments filled into jars
fill from the bottom while turning the jar; stab the ointment from time to time to release air pockets
How are ointments filled into tubes
Roll the glassine paper into a tube and insert into the tube, with the cap off, press down on the bottom and pull the paper from the tube OR use a Ziploc bag with a urethra tip and inject the ointment into the tube
What is the Quality Control for ointments
Check the final product for the following characteristics
What are the quality control parameters for ointments
Final product weight, Visual appearance, Color, Odor, Viscosity, Homogeneity/phase separation
What are some Chemical antimicrobial preservatives
phydroxybenzoates, phenols, benzoic acid, sorbic acid, quaternary ammonium salts, organic mercury compounds, formaldehyde
What is the purpose of Absorption Enhancers
Facilitate the absorption of drugs through the skin; Changing the solvent properties of the stratum corneum
What are some examples of absorption enhancers
dimethylsulfoxide, urea, citric acids
Why are Co-Solvents added to ointments
In addition to helping to solubilize drugs, they can help keep drugs in solution after application of the dosage form.
What are some examples of co-solvents used in ointements
glycerin, propylene glycol, ethanol Propylene glycol: used in O/W creams to prevent precipitation of the drug as the cream dries to a thin film.
Compare the hydrocarbon bases of creams and ointments
creams less than 50% hydrocarbon bases, ointments more than 50 % hydrocarbon bases
Describe creams
opaque solids, or thick liquids intended for external application, Are emulsions (O/W), Usually the internal phase ranges from 15 - 40% w/w. They can absorb varying amounts of water. Under optimal conditions, the drug concentrates without crystallizing out.
Describe “Vanishing Creams”
O/W emulsion: After application: water evaporates, leaving a thin residue film of stearic acid
What are Important therapeutic properties of o/w creams
The high concentration in the drug film can be good for drug delivery. The thin film is not continuous and not oleaginous, so it will be less occlusive than oily ointments. Since they are less occlusive, o/w creams will generally be less protective and less emollient than the oily ointments. Most acceptable topical dosage form!
Describe Pastes
Intended for application to the skin, Applied to area that requires protection, Contain a larger proportion of solid material than ointments, Stiffer than ointments; high concentration of powders
What is the definition of powders
dry, finely divided drugs and / or chemicals intended for internal or external use (dusting powders)
What Therapeutic properties do powder have
They can promote drying (absorb liquids); They can reduce friction
What are some Examples of powders and their therapeutic properties
Talc is more lubricating, but doesn't absorb water; Corn starch is less lubricating, but absorbs water; Zinc oxide falls in between
What is a gel?
Are semisolid systems. The movement of the dispersing medium is restricted by an interlacing 3D-network of particles
What causes the viscosity of a gel
Viscosity is caused by the interlacing
What are the applications of gels
Oral, Topical, Intranasal, Vaginal, Rectal
Two-phase system (e.g. Aluminum hydroxide) of a gel is defined as:
If the gel mass consists of a network of small inorganic discrete particles:
Single-phase system (e.g. Carbomer) of a gel is defined as:
If the gel mass consists of a network of large organic particles
What are the three types of Hydrogen gels
"Inorganic (Silica, bentonite,
aluminum); Natural and synthetic gums (Pectin, sodium
alginate); Organic (Methylcellulose)"
What are the three types of Organogels
Hydrocabon type (Mineral oil, PEG); Soap base (Aluminum stearate); Hydrophillic organogles (Carbowax bases)
What are the Characteristics of Gels
Can be clear or turbid, To appeal to the consumer, gels should have clarity and sparkle, Most gels are water washable, greaseless
Why use a gel?
Gels are useful as liquid formulations in oral, topical, intranasally, vaginal, and rectal administration. They have a cooling effect and they can moisturize
What are the Disadvantage of a Gel
bacterial / mold growth due to high content of water
Define Imbibition
Soaking up liquid without a marked increase in volume
Define Swelling
Soaking up liquid with an increase in volume
Define Syneresis
Gel exudes fluid - causing shrinkage; Elastic contraction of the polymer
Define Thixotropy
viscous during storage but loses consistency and become fluid upon shaking. (i.e. ketchup)
Define Xerogel
Liquid is removed from a gel, only the framework remains
Where is Alginic Acid obtained from
Obtained from seaweed
What are the characteristics of Alginic Acid
Tasteless, odorless. Swells in water ~ 200 – 300 times its own weight
What is the most common Alginic Acid
Most common alginate: calcium alginate gel
What industry is Alginic Acid used it
Used in food industry (ice cream, yoghurt)
What are Carbomers (Carbopol)
acrylic acid based polymers
What does the viscosity of Carbomer (Carbopol) depend on
gel viscosity is pH dependent
Describe the form of Carbomer (Carbopol) at low and high pHs
form acidic aqueous solutions (pH ~ 3), thicken at a higher pH (5-6) (NaOH, KOH)
What is the maximum electrolytes that can be added to Carbomer (Carbopol) before a rubbery mass forms
3%
What happens when alcohol is added to Carbomer (Carbopol)
Addition of alcohol: viscosity decreases
What is Carbomer (Carbopol) used in
Used for: oral suspensions, topical gels
What are some examples of cellulose derivatives
Methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose (CMC)
Describe the viscosity characteristics of cellulose derivatives
Viscosity of all derivatives is maintained over a wide pH range (3-11), except CMC
What are cellulose derivatives compatible with
Compatible with water and alcohol
Esxplain the stability of Carboxymethyl Cellulose CMC
Soluble in water at all temperatures; Sensitive to pH, viscosity < pH5; Stable between pH 7-9
How is Carboxymethyl Cellulose CMC used in food
very broad usage; salad dressings, ice cream
Describe the structure of Gum Arabic (Acacia senegal)
Highly branched with b-Galactose backbone
What are the physiochemical properties of Gum Arabic (Acacia senegal)
Water soluble, fat insoluble; Low viscosity gum; Viscosity affected by pH and salts
What are the Food uses of Gum Arabic (Acacia senegal)
Stabilizer for flavor emulsions; Encapsulated flavors; Water binding; Inhibit sugar crystallization
Where is Gum Tragacanth (Astragalus gummifer) derived from
sap of several species of Middle Eastern legumes
Describe the Polymer of Gum Tragacanth
Polymer of Galacturonic Acid + Galactose + Galactose + Arabinose + xylose; Viscosity (varies with grade) 600 - 4,000 CPS at 1%; Acid stable at pH 4-8
Where is Gelatine derived from
Gelatin is a protein produced by partial hydrolysis of collagen extracted from the bones and connective tissues of animals
Describe the viscosity characteristics of gelatine
Forms a solution of high viscosity in hot water, which sets to a gel on cooling
What is Plastibase
Mixture of 5% low-molecular weight polyethylene and 95% mineral oil.
Describe the characteristics of Plastibase
Mineral oil is immobilized by in the network of entangled insoluble polyethylene chains. Gel can be heated up to 60°C (140°F) without substantial loss of viscosity.
What is the trade name of Poloxamers
Pluronics
Explain the thermoreversible gels of Poloxamers
liquids at cool, gels at room or body temperature.
Describe the polymer structure of poloxamers
nonionic block copolymers: central hydrophobic chain of polyoxypropylene (poly-propylene oxide) flanked by two hydrophilic chains of polyoxyethylene (poly-ethylene oxide)
What is Bentonite
hydrated aluminum silicate
Where is Bentonite derived from
Bentonite usually forms from eathering of volcanic ash, most often in the presence of water.
What kind of gel is Bentonite
thixotropic gel, swells approx. 12 times its volume
How is Bentonite prepared
preparation of 5% bentonite in water
GEL COMPOSITION typically consists of what components
Gelling agent, Water, Cosolvents, Preservatives, Stabilizers
What alters the consistency of a gel
tangling
What happens if the gelling agent is added to the dispersing medium
agent tends to “clump”
How do you fix clumping gelling agent
sieve the agent onto the surface of the medium as medium is stirring
What gels are recommended for oral use
Only Carbopol® 934P, methylcellulose, hydroxypropylmethylcellulose and CMC
When should the drug be added to a gel during preparation
Drug should be added before the gel is formed. Drug should not interfere with gel formation
What temps are Poloxamers, methylcellulose most soluble
COLD water
What temps are gelatine most soluble
HOT
What temps are carbomers, alginic acid most soluble
TEMPID
How are gels PACKGAGED/STORED/LABELED
Tight containers (tubes, jars, squeeze bottles), Room or Refrigerated Temperatures, as appropriate, Prior to use….store in tight containers.
Why using the topical route
Hydration, Protection, Systemic effect (transdermal drug delivery), Local effects = drug action
What are the Skins functions
Protective barrier on body surface to physical, chemical and biological intrusions, Homeostasis (temperature & water), Sensory, Secretory (vitamin D production), Excretory (via sweat glands)
What are the epidermis' 5 sublayers of keratinocytes (strata)
Stratum Corneum, Stratum Lucidum, Stratum Granulosum, Stratum Spinosum, Stratum Basale/Germinativum
How thick is the epidermis
Thickness varies: 75-150 μm in thin skin; 400-600 μm in thick skin
What are the mechanical functions of the epidermis
Provides mechanical protection, Prevents fluid loss, Keeps microorganisms from invading the body
Are there vessels in the epidermis
No vessels in epidermis
Describe the Stratum Corneum
Horned layer: Dead cells, 15‐20 layers in thick skin, 3‐4 layers in thin skin, Flattened non‐nucleated cells filled with keratin filaments (these cells can also absorb water), surface cells constantly sloughed off
Where is the Stratum Corneum found
This layer is only found on the soles of the feet and the palms of the hands; More common in thick skin
Describe the Stratum Lucidum
Thin, translucent lightly stained layer of non‐nucleated cells; Different arrangement of filaments
Describe the Stratum Granulosum
3‐5 layers of polygonal cells with central nuclei and many basophilic granules; Keratohyalin granules contain proteins that bind keratin filaments together; Membrane coating granules also present; secrete to extracellular matrix to make it more waterproof
What is the is the highest layer in the epidermis where living cells are found
Stratum Granulosum
Describe the Stratum Spinosum
Multilayer arrangement of cuboidal, polygonal or squamous cells, extensions with desmosomes, link proteins that attach the cell surface adhesion proteins to intracellular keratin cytoskeletal filaments
What are cytokeratins
Intermediate filaments which are composed of keratin. Synthesized in the Stratum Spinosum
Describe the Stratum Basale/Germinativum
layer of keratinocytes that lies at the base of the epidermis immediately above the dermis. It consists of a single layer of tall, simple columnar epithelial cells lying on a basement membrane. These cells undergo rapid cell division, mitosis
What are some Epidermal characteristics
Cells accumulate keratin and eventually are shed (continuously renewing, 0.06 0.1 mm thick), Epidermal ridges are interlocked with dermal papillae (Fingerprints, Improve gripping ability)
What are Langerhans cells for and what layer of the epidermis are they found
Fro immunity in s. spinosum
What are Merkel cells for and what layer of the epidermis are they found
For sensitivity in s. germinativum
What gives skin its color
melanin amount, carotene content in subcutaneous fat and vascularization
What produces Melanin and where is it produced
by melanocytes in stratum basale; melanin forms from tyrosine
What is melanin
Melanin is any of the oxyacetylene, polyaniline, and polypyrrole blacks and browns or their mixed copolymers.
What do Epidermal cells synthesize when exposed to UV
vitamin D3 (cholecalciferol)
What does epidermal growth factor effect
Growth, Division, Repair, Secretion
The dermis is structurally divided into what two areas
a superficial area adjacent to the epidermis, called the papillary region and a deep thicker area known as the reticular region.
describe the papillary region of the dermis
composed of loose connective tissue; named for its fingerlike projections called papillae, that extend toward the epidermis. The papillae provide the dermis with a bumpy surface that interdigitates with the epidermis, strengthening the connection between the two layers of skin.
What are the features of the dermis
Network of elastic fibers (elasticity decreases with age), Many blood and lymph vessels, Papillary layer vessels supply epidermis, Arteriovenous shunts for blood pressure and temperature regulation, all epidermal structures (hair follicles, sweat and sebaceous glands) penetrate into the dermis, Many sensory nerves in skin (touch, pain, temperature sensation), Sympathetic vasoconstrictor fibers, piloerector fibers and sudomotor fibers