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114 Cards in this Set
- Front
- Back
Polymers do not have _______ phase
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Vapor
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Addition Polymerization includes these 3 steps
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Initiation
Propagation Termination |
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Degree of Polymerization
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number of mers
monomer (1) dimer (2) Trimer (3) etc. |
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Mono-dispersed
vs Poly-dispersed |
same size chains
different size chains smaller chains dissolve quickest |
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Topology
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Linear
Branched Crosslinked |
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Stereoisomerism:
Isotactic Syndiotactic Atactic |
same direction
alternating direction randome direction |
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Order of repeating units:
Homopolymer Random Copolymer Alternate Copolymer Block Copolymer Graft Copolymer |
Homopolymer: ------------------
Random Copolymer -=-----=--=- Alternate Copolymer -=-=-=-=- Block Copolymer --------=====I Graft Copolymer -------- ===== |
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Temperature at which a glassy polymer softens into a viscous liquid or rubbery phase
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Glass transition Temperature (Tg)
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Temperature at which the ordered regions of crustalline polymer melt
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Melting Temperature (Tm)
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Temperature above which ploymer degrades
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Decomposition Temperature (Td)
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Thermal Transitions of Polymers
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Td> Tm> Tg
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Thermal transitions DeltaH
Shift in base line endothermic exothermic |
Tg
Tm Td |
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1st and 2nd order transitions
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1st order- volume change is sudden/significant
2nd order- volume change is not sudden/significant |
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which has more crystal or more amorphous
temp 70-115 temp 220 |
temp 70-115= amouphous
temp 220= crystal |
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Tg and crosslinking
Linear Polymer Lightly-crosslinked polymer Highly-crosslinked polymer |
Linear Polymer= low Tg
Lightly-crosslinked polymer= highTg Highly-crosslinked polymer= no Tg |
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Number Average
vs. Weight Average |
deals with number of molecules
deals with size of molecules |
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Polydispersity
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Mw/Mn >1
the closer the pulydispersity is to 1, the more similar each measurement is |
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Elastic Properties of Polymers
Fibers Tough Plastics AUC=? |
Fibers= high modulus (strength)
Tough Plastics= low modulus (strength) AUC= toughness Rubbers |
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Drug Degrations includes
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1. Reducing bioavailability and therapeutic effect
2. Producing toxics 3. Changing the physical form of a drug 4. Excipient degradation |
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The expected potency of a drug usually should not fall below _____
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90%
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Problem with Rotigotine( Neupro)
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active ingredients may crystallize in the patch
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Stability Triangle Includes
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Purity
Identity Potency |
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Hydrolysis:
Ester Lactone Amide Lactam Anhydride |
Ester= -OH with COOH
Lactone=-OH with COOH in ring Amide= COOH with NH2 Lactam= COOH with NH2 ring Anhydride= two COOH |
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Hydrolysis Facts
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-Anhydrides are more reactive than acids
-ester hydrolysis to acid and alcohol is reversible under acidic condition -Amides are more stable than esters -rate of OH catalyzed hydrolysis of amides is greater than H-catalyzed hydrolysis of amides |
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De-amination occurs in:
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asparagine
glutamine insulin recombinant human growth |
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Hydrolysis degradation is affected by:
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pH
buffer salts and ionic stregth temperature moisture co-solvents complexing agents surfactants |
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Specific acid-base catalysis
general acid-base catalysis |
catalysis by H+ or OH
catalysis by buffer ions like acetate or citrate |
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Antioxidants:
-Primary -Secondary -Tertiary |
Primary= Free radical scavengers provide electrons to free radicals
Secondary= oxygen scavengers under auto oxidation by consuming oxygen Tertiary= ion scavengers ; chelating agens react with ions responsible for initiating oxidation reactions |
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Drugs with absorption greater than ______ nm may decompose in sunlight
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280 nm
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Light degradation in dilute solution is _____ order
more concentrated solutions show a _______ order reaction |
first
pseudo-zero |
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Photostability Test
stable vs. unstable constant intense light source pH 7.4 room temperature |
stable if half-life is >5 hrs
unstable if half life is <5 hrs |
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undergoes spontaneus racemization
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chlorthalidone
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_______ degrades faster than ________
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solutions
suspensions |
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Have high vapor pressure
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ketones
aldehydes esters low molecular weight alcohols |
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crystals are generally more stable than amourphous except with_______
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Insulin is more stable in amorphous form, not crystal form
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Expiration Date became law in
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1979
date may range over 12 months to 60 months |
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Factors affecting Reaction Rate
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Temperature
Catalyst Reactant Concentration Surface area Pressure |
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Maxwell-Boltzmann Distribution
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For a reaction to happen, particles must collide with energies > or = to Ea for the reaction
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Effect of Temperature
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Ea remains same
Number of molecules with energy > or = Ea increases |
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Assumptions of Arrhenius
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calculates rate constants at different temperatures
Ea is always positive Ea is constant over a given temperature Ea is reduced by catalyst Ea is increase by inhibitors |
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The Arrhenius equation
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this equation is valid as long as the reaction mechanism does not change over the temperature range studies. If not linear, reaction mechanism changes with heat.
k=Ae ^ (Ea/RT) |
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Effect of catalyst
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Ea is reduced
number of particles with sufficient energy is the same |
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Homogeneous catalysis
Heterogeneous catalysis Autocatalysis |
Catalyst and reactant are in a same phase; everything will be in a gas or in a single liquid phase
Catalyst and reactants are in different phases; a solid catalyst with the reactants as either liquid or gases Reaction is catalyzed by one of its products |
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pH effect
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Kobs= k1 [H+] +k2 + k3[OH-]
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would increase the rate of reaction between similarly charged ions
would decrease the rate of reaction between oppositely charged ions |
Increased Ionic strength
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Studies mechanism by which a chemical process or reaction reaches to its final state from its initial state and the rate at which this process or reaction proceeds
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chemical kinetics
used to know the stabalization of drug products and predicting shelf life |
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Thermodynamics
vs Kinetics |
if a reaction takes place
speed a reaction takes place |
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Different 1st order reactions
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Reversible
Parallel Consecutive |
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A0-A1=kt
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Zero Order
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A0/2k
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Zero order half life
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A0/10k
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Zero order t 0.90
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linear with negative slop
half lives are decreasing |
Zero Order
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At=A0 e^-kt
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First Order
straight line on when using Y=ln At X= time |
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t1/2= 0.693/k
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No concentration involved
First order half life |
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t0.9= 0.105/k
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no concentration involved
First order shelf life |
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Half lives are constant
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independent of [A]
first order |
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1/At=1/A0 + kt
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Second order
positive slope Y=1/At X=time |
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t1/2=1/kA0
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Second order t1/2
t 1/2 are increasing |
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0.11/kA0
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t 0.9 second order
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observed when a reactant reacts with itself or when the reaction rate depends on the concentration of more than one component
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Second order kinetics
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most compounds that degrade in solution follow ________ order reaction
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pseudo-first order reaction
since water in excess, rate of drug decomposition dependent on drug concentration and not water |
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Rate constant Units
zero first second |
zero= Mt-1
first= t-1 Second= M-1t-1 |
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Rate
k kA KA2 |
zero
first second |
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At=A0-kt
At=A0e^(e-kt) 1/At=1/A0 + kt |
Zero
First Second |
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________ is matter resistance to flow
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Viscosity
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______ is the science studying the flow properties of a matter
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Rheology
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When ever a fluid is physically moved or disturbed, as in pouring, spreading, spraying, mixing, etc
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Shear
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Shear Stress =
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Shear Stress = Force/ Area
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Poise
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shear stress of one dyne per square centimeter per second
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Fluidity
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reciprocal of viscosity
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Factors affecting viscosity
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Temperature
Shear Rate Measuring Condition time Pressure Composition and Additives |
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Viscosity of Newtonian fluids _____ sharply with increasing temperature
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decrease
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Most fluids lose their viscosity or their resistance to flow if temperature increases
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Thermo-thinning
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Some fluids will be more reluctant to flow as temperature rises
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Thermo-thickening
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At a given temperature, the viscosity is ________ of the shear rate
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independent
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Non-Newtonian Fluids
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-Shear rate varies, viscosity varies
-Shear rate varies, but shear stress is not proportional -Viscosity is called apparent viscosity -it depends on temperature, speed, spindle, rate of mixing, rate of spraying, rate of pumping |
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Viscosity decreases as shear rate increases (Shear thinning)
ex. ketchup |
Pseudoplastics
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Viscosity increases as shear rate increases (Shear thickening)
ex. whipping cream |
Dilatant
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Viscosity decreases with time under constant shear rate
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Thixotropy
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Viscosity increases with time under constant shear rate
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Rheopexy
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fluids which do not move until certain force is applied on their structure
viscosity decreases as shear rate increases |
Plastic
no flow occurs in response to stress until certain point, slope after yeild is plastic velocity |
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Movement of one layer of fluid past another with no transfer of matter from one to another
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Laminar Flow
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when layers move, matter can also move from one layer to another
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Turbulent Flow
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behave like solid if stress application is short, they behave like liquids if stress application is long
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Viscoelastic
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application of constant stress to monitor deformation with time
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creep
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Deborah Number
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De= tmaterial/tprocess
De<<1 material behaves as viscous liquid De>>1 material behaves as elastic solid |
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immediate recovery after deformation
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elastic solid
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infinite flow of a fluid
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wetting
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Spring
Dashpot Maxwell Voigt |
know grafts for them
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Poiseuille's Law
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Formula for Liquid flow through a pipe (volume of rate flow)
Factors include: Viscosity pipe radius pipe length pressure differences between two ends |
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Capillary Viscometer
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for dilute solutions and suspensions
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_______ is dependent on the flow time and the fluid density
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Viscosity
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A piston forces the test fluid from a reservoir through a capillary at constant rate. Pressure drops as fluid passes the capillary. By measuring pressure drop across the capillaries of different diameters, viscosity will be determined as function of shear rate
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Extrusion Viscometer
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Solution dosage forms are _______
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Newtonian
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Suspensions and emulsions are ____________
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non-newtonian
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Viscosity of blood is ________
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Thixotropic
viscosity decreases with increase in shear rate Plasma is newtonian and pseudoplastic |
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concentration of a solution at saturation
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solubility
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small vs large particles
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reach same solubility
different rates of dissolution |
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measure of the medium influence on the energy needed to seperate two oppositely charged bodies
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Dielectric constant
Polar solvent >15 non-polar <15 |
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delta H<0
delta H>0 |
for soulte to dissolve, heat must be releases. Inceasing temperature of solvent will decrease the solubility
for the solute to dissolve, heat must be given; increasing temperature will increase solubility |
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love to be mixed wtih a liquid because they obtain more freedom and entropy, so increase in temperature will help them to reach their goal
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solids
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they hate to be mixed with a liquid as they have to give up their freedom and entropy, so increase in temperature will decrease their solubility
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gases
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pH <pka
pH > pka |
ion-diopole decreases
ion-dipole increase |
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pH below which a drug precipitates from the solution as an undissociated acid
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pHp
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ph has no effect on solubility of _____ substance
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non-ionizable
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amphipathic having both polar and non-polar groups
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Surfactants
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ratio of concentrations of un-ionized compound between octanol and water
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Particion Coefficient
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ratio of the sume of the concentrations of all forms of the compound (ionized and unionized) in octanol and water
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Distribution Coefficient
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high vs low partition coefficient
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high lipid solubility/ high permeability
high aqueous solubility/ low permeability |
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Partition coefficient formula
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concentration in ether/ concentration in water
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Partition Coefficient of Electrolytes
Log P= 5 Log P= -2 |
5= drug is 100,000 times more soluble in organic solvent
-2= drug is 100 times more soluble in water |
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compounds with P values 1-3
compounds with Pvalues greater than 6 or lower than 3 |
good absorption
poor transport characteristics |
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amount of particles crossing a unit area in a unit time
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Flux
|
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not constant, depends on temperature, pressure, and concentration
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Diffusion coefficient
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