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92 Cards in this Set
- Front
- Back
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What is pharmacology?
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The study of the history, source, physical and chemical properties, compounding, biochemical and physiological effect, mechanisms of action, absorption, distribution, elimination, and therapeutic use of drugs
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What is pharmacotherapeutics?
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The use of drugs in the prevention and treatment of disease
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What are pharmacokinetics?
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drug absorption, distribution, biotransformation, and elimination
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What are pharmacodynamics?
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The relationship b/t drug concentration and phamacologic effect. Includes mechanism of action, effects, interaction / receptors and w/ drugs
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Describe the two compartment model
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1) peripheral and central compartment 2) Tissue may be target tissue or resiviors 3) Free drug passes b/t compartments 4) absorbed drug passes into the central compartment
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What is absorption?
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The rate at which drug leaves its site of administration
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What is bioavailability?
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The extent to which drug reaches its site of action
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What are the characteristics of the cell membrane?
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Fluidity, flexibility, high electrical resistance, impermiable to polar molecules
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What size limits are there on drugs?
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Most need to be >100 gmw to bind to receptors, and < 1000 gmw to move accross membranes. Li+ is an exception (acts like sodium)
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Large molecular weight drugs need to be administered...
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IV
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What is a chiral molecule?
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One that has a center of 3d asymetry - fx of unique tetrahedral binding pattern of carbon
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What are enantiomers?
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asymetric molecules identical in atomic construction and bonding but differ in 3-d arrangement of attoms. Mirror images, but not superimposable
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hat are optical isomers?
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Chemically identical, distringuished by direction they rotate polarized light when disolved in solution
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What are racemic mixtures?
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Contain equal amounts of both isomers. Dose not rotate light
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What are geometirc isomers?
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Describe the orientation of functional groups at the end of a molecule, no rotation possible (cis/trans)
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Administration of a racemic mixture is...
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Administration of two different drugs / distinct pharmacokinetic/dynamics properties [1/3 of drugs!]
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Describe simple diffusion
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Large, nonpolar drugs pass through lipid protein channels. Rate of transfer proportional to concentration gradient, lipid solubility of drug, molecular size of drug, and surface area
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Describe filtration
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The continuous bulk flow of water across membrane carries small size water soluble drug molecules [ionized and non-inionized]. Drugs must be < 200 GMW to pass through.
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What is fick's law
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flux = (c1-c2) x area x permeability coefficient /thickness
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What is pinocytosis
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cell membrane engulfs small droplets of ECF that contain proteins, large drug molecules, etc. [e.g. B12, Fe; neurotransmitters exocytosed]
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What is carrier mediated transport?
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Carriers carry large or lipid insoluble molecules across membrane - drugs, AAs, peptides, cellular metabolites
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What characterizes active transport?
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selectability, saturabilit, competitive inhibitionenergy requirement, movement against a gradient
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Is facilitated diffusion saturatable?
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yes
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At a steady state accross a membrane, is [drug] equal?
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No, dependent on Ph differences, degree of ionization/ion trapping.
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Describe oral administration
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1) most economical, conventient, common, safest 2) absorption limited mainly to nonionized, lipid-soluble drugs 3) greatest absorption in SI 4) subject to 1st pass metabolism by liver, intestinal enzymes and bacteria
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Describe sublingual/buccal administration
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1) rapid, no first-pass metabolism
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Describe rectal administration
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1) variable, often incomplete 2) proximal rectum - absorbed into superior hemrrhoidal veins, subject to 1st pass met. 3) Low rectal administration - no 1st pass.
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Describe SQ administration
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1) fast absorption, dependent on blood flow to area
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Describe IM administration
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1) fast absoption w/ aqueus solutions
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Describe IV administration
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Immediate effect
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Describe IA administration
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Used only for local effects (e.g. contrast)
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Describe Intrathecal administration
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drugs injected into CSF
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Describe pulmonary administration
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1) very fast absorption of gasses, volitle afents, aerosols [large SA] 2) particles > 60 micrometers deposited in trachea, > 20 in brochi, 2-6 reach alveoli, and 1-2 are retained in alveoli. <0.6 are exhaled.
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Describe intranasal absorption
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fast absorption
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Describe transdermal administration
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1) absorption increased w/ oily vehicle 2) GMW should be < 1000, pH 5-9, daily dose requirements < 10mg 3) Inital absoption is via sweat ducts and hair folicles 4) skin 10-20 mcs on back and abd, 400-600 mcs on palms. Thin in postauricular area. 4) stratum corneum - regenerates every 7 days, limits duration of transdermal administration
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Describe intraperitoneal administration
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Large absorbing surface area, exposed to 1st pass metabolism. Infrequently used.
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Which are more readily absorbed, aqueus solns or oily ones?
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Aqueous solutions -> more soluble
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The non-ionized/ionized ration is dependent upon
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1) pKa of drug 2) pH 3) acid/base
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What is pKa
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pH at which a substance is 50% ionized
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Acidic drugs are highly ionized at ...
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high pH
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Basic drugs are highly ionized at ...
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low pH
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What is the henderson-hasselback equation?
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pH = pKa + log [base/acid]
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How can the H-H equation be rewritten to determine relative ratios of ionized/unionized at a particular pH?
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10^(pH-pKa)=base/acid [=X/HX]
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When a mix of ionized/nonionized drug is is solution at a certain pH ...
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pH changes may cause an increase in the non-ionized variant of the drug, causing it to precipitate out.
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Since local anesthetics are bases, acidosis at the site causes...
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ion trapping, decreased effect of local anesthics
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Since fetal blood is more acidic than maternal blood, and local anesthetics are bases ...
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local anesthetics can become trapped/concentrated in the fetus, particularly w/ fetal distress [i.e. acidosis]
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The ionized form of an acid/base is its
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congugate base/acid
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How do weak acidic drugs absorb in the ECF vs. ICF?
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ECF>ICF
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How do weak basic drugs absorb in the ECF vs. ICF?
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ICF > ECF
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What may happen to basic drugs given IV?
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They may precipitate out in the stomach and be reabsorbed [hence renarcitization]
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What increases amount of change of ionization when pH is changed?
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The closer the pKa to the pH, the greater the change in degree of ionization with small pH changes
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Plasma pH = ...
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pKa + log [base/acid] = 6.1 {pKa of carbonic acid} + log [ionized acid/nonionized acid]
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A 10 torr decrease in PCO2 =
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pH increased by 0.1
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A 20 torr increase in PCO2 =
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pH decreases by 0.1
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Weak acids and bases are packaged for solution as
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salts
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Weak acids are salts w/
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Ca, Mg, Na
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Weak bases are salts w/
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Cl- and SO4
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Distribution involves
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transfer across membranes
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Distribution is unequal d/t
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different CO, regional blood flow, lipid solubility, protein binding, pH gradients
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The organs with the greatest percentage of CO will receive
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The greatest percentage of the drug /in the first few minutes following absorption into the central compartment
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What % of CO does the liver have?
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28
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What % of CO does the kidneys have?
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23
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What % of CO does the muscle have?
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15
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What % of CO does the brain have?
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14
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What % of CO does the skin have?
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9
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What % of CO does the heart have?
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5
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What are the four types of tissues?
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vessel-rich, vessel-poor, fat and muscle
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Vessel-rich tissue is what % of body weight, and what % of CO does it receive?
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10, 75
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Muscle tissue is what % of body weight, and what % of CO does it receive?
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50, 19
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Fat tissue is what % of body weight, and what % of CO does it receive?
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20, 6
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Vessel-poor tissue is what % of body weight, and what % of CO does it receive?
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20, <1
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What limits distribution to the peripheral compartment?
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Protein binding
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Very lipid soluble drugs tend to be
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highly protein bound
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Water soluble drugs tend to be ___ protein bound
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less
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Plasma proteins act as a ...
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resivoir, releasing drug as plasma concentration of the free drug increases
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What binds acidic drugs?
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Albumin (50% of protein)
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What binds basic drugs?
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Alpha-1-acidglycoprotein (AAG)
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What other proteins bind drugs?
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Globulins, lipoproteins, and RBCs
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What else to drugs bind?
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Some cellular proteins (phosphoproteins, nucleoproteins) -> accumulation in certain tissues
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Protein binding ____ the t1/2 of the drug
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increases - it is unable to leave the central compartment to undergo biotransformation/elimination
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Protein binding shows _____ and is ______
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saturation; reversible
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What determines the amount of bound drug?
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1) drug concentration 2) affinity for binding sites 3) # of available binding sites
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The greater the protein binding, the greater the __________
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effect of change (Esp. a decrease) in plasma proteins.
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What increases AAG? [BIT of a CRaMP]
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burns, infection, trauma, chrons, colitis, rental tx, rheumatoid arth, MI, malignancy, Post-op period, chronic Pain
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What decreases albumin? [NICE MR PHaN needs a BMP]
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Neonates, Inflamatory ds, Cardiac failure, Elderly, Malnutrition, Renal Ds, Post-Op period, Hepatic Ds. Nephrotic syndrome, Burns, Malignancy, Pregnancy
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What decreases AAG [NOPE]
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Neonates, Oral contraceptives, Pregnancy, Estrogens
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Elderly tend to have low
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albumin -> increased plasma levels of acidic drugs
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Neonates tend to have low
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AAG -> increased plasma levels of basic drugs
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Drugs w/ high % protein bound
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May cause increased free levels when a second drug w/ a high binding affinity for the plasma proteins is administered
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Uptake of a drug by tissues is dependent on
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1) tissue blood flow 2) tissue capacity (solubility of drug in tissue and mass of tissue)
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The pulmonary system is a resevoir for
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first pass uptake of basic amines
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Bone is a reservoir for
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lead, radium, tetracycline
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