Pharmacology Synopses 1 Flashcards by X x

ideal for lipid soluble drugs that would otherwise be metabolized in the gut or liver

sublingual route

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route reserved for nitrates or certain hormones

sublingual route

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rate and completeness of absorption

factors comprising bioavailability

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bioavailability of drug types, most to least

solution> suspension >capsule >tablet >coated tablet

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route commonly used in children, slow absorption

rectal (no villi in rectum)

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route for rapid clinical response, precise plasma concentrations, no issues of bioavailability

intravenous injection

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route to deliver high concentrations of drugs to a particular tissue

intraarterial injection

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route to bypass blood-brain barrier

intrathecal, via lumbar puncture to subarachnoid space

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intramuscular absorption rates, high to low

arm> thigh> buttocks

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subcutaneous injections absorb ____ than intramuscular

slower than

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heat, massage, vasodilators

increase rate of subcutaneous absorption

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coadministration of vasoconstrictors, as with local anesthetics

slows rate of subcutaneous absorption

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route for volatile anesthetics or drugs for pulmonary function, not subject to first-pass liver metabolism

inhalation

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drug patches enter system via

zero order kinetics (amount constant per unit time)

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occurs only for molecules less than 150-200 MW

passive aqueous diffusion

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allows molecules of 20-30,000 MW to pass through via aqueous diffusion

endothelial capillary lining (but not in brain)

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occurs for drugs that are analogs of endogenous compounds

carrier mediated facilitated transport

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may reduce the amount of drug reaching target tissue, or metabolically activate an inert pro-drug

first pass effect (via liver)

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will increase rate of passive absorption by maintaining concentration gradient of free drug

drug binding to plasma protein

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gastrointenstinal absorption rate, but not extent of absorption

reduced by the presence of food in the gut

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equation for Ka

[H+][A-]/[HA]

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equation for pH of acids

pKa + log [A-]/[HA]

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equation for pH of bases

pKa + long [B]/[BH+]

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more rapid than elimination, accomplished via circulation, influenced by regional blood flow

distribution

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peripheral compartments

adipose and skeletal, less well perfused, drug equilibrates more slowly

special compartments

CNS, CSF, pericardial fluid, bronchial secretions, middle ear fluid (difficult to treat infections)

weak acids and neutral drugs bind particularly to

albumin

basic drugs tend to bind

alpha-1-acid glycoprotein (orosomucoid)

protein binding ____ the net transfer of drugs across membrane

decreases

at equilibrium, the total drug concentration in plasma is usually ____ than in extravascular fluid

higher (due to protein-drug in plasma)

for drugs secreted renally, protein binding

decreases the rate of elimination

for drugs eliminated hepatically, protein binding

may promote drug elimination

apparent blood volume

amount of drug injected/blood concentration at time zero

if plasma binding is marker, apparent volume will be

small

if there is extracellular binding, storage in fat or other tissues, apparent volume will be

large

generally bind plasma proteins and have small Vd

acidic drugs

generally bind extravascular sites and have large Vd

basic drugs

capable of eliminating drugs with low molecular weight or polar and fully ionized at body pH

the kidneys

most important extrahepatic site of drug metabolism

GI tract

sites of drug metabolizing action

Liver, Gi tract, intestines, skin, placenta, lungs

most enzymes involved in drug metabolism are located within

the lipophilic membranes of the smooth endoplasmic reticulum

the enzymes that carry out metabolism on the SER are called

the MFO system (microsomal mixed-function oxidase system)

phase I reactions convert a drug to a more polar compound by adding or unmasking

polar functional groups: OH, NH2, SH

phase II reactions conjugate the compound with wndogenous compounds such as

glucuronic acid, sulfuric acid, acetic acid, or amino acids (glycine!)

the most common phase II reaction is

glucuronide formation

terminal oxidizing enzyme in most MFO reactions

cytochrome P450

receptors for exogenous ligands

ion channels, enzymes, ion transporters, carriers and pumps, structural proteins

glomeruli permit the passage of most drug molecules, except

protein bound drugs

can kidney actively transport some protein bound drugs?

yes, though associated protein dissassociates

renal tubules reabsorb

nonionized, lipid-soluble drugs

alkalinized urine promotes excretion of

drugs that are weak acids

acidified urine promotes excretion of

weak bases

drugs and metabolites passed into the small intestine via bile may undergo

enterohepatic cycling

receptor types for endogenous ligands

Ligand-gated ion channels, G-protein receptors, tyrosine kinase receptors

See 7 transmembrane passes, think

G-protein coupled receptor

Adrenergic and muscarinic Ach receptors are in this family

single subunit receptor protein

receptors for insulin and growth factors are in this class

tyrosine kinase

steroid hormone receptors are of this class

intracellular, hormone-receptor complex binds to DNA

for a congerneric series of agonists, lower ED50 means

lower dissociation constant (tighter receptor binding)

the effect of a competitive agonist is

to reduce apparent affinity of D for R

competitive antagonist bind

reversibly with same site on receptor as the agonist

with competitive inhibitor, curve shifts

right

with competitive inhibitor, slope and maximum response

do not change

the effect of the inhibitor may reversible or irreversible, but the agonist has no influence on the extent of antagonism

noncompetitive inhibition

with noncompetitive inhibitor, curve shifts

generally not (kd isn't changing)

with noncompetitive inhibitor, maximum response

is decreased

no drug effect seen until minimum occupancy is achieved

fractional occupancy threshold

effect of fractional occupancy threshold on slope

increases

effect of fractional occupany threshold on curve shift

shifts to the right

with fractional occupancy threshold, the ED50

overestimates the dissociation constant (ED50>Kd)

drug maximal effect achieved without occupying all receptors

spare receptors

in the presence of spare receptors, curve shifts

to the left

in the presence of spare receptors, ED50

is less than (underestimates) Kd

incapable of causing a maximal response at any concentration

partial agonist

describes the binding forces between drug and receptor

affinity

describes the physiological effectiveness of the drug receptor complex

efficacy

partial agonists act as antagonists by

binding receptors but having low intrinsic activity

slope of an LDR curve indicates

how steeply the drug effect varies with dose = one indication of the margin of safety

curve that shows a normal distribution around the average dose patients first respond to

Non-cumulative dose-response frequency curve

dose at which 50% of patients show a toxic response

TD50

equation for therapeutic index

TD50/ED50

rapid decrease in the magnitude of response due to the action of a drug

tachyphylaxis

decrease in response to a given does resulting from prolonged administration

tolerance

what follows zero order kinetics?

constant IV infusion

more rapid absorption will ____ peak plasma concentration, ____latency, and ____duration

increase, decrease, decrease

increase in dose will ____ latency, ____ peak plasma concentration, and ____ duration of effect

decrease, increase, increase

more rapid elimination will ____ peak plasma concentration and duration of effect

decrease

when repeated doses of a drug are given at short intervals and elimination is a first order process, plasma concentration will

plateau

when a drug is administered at a constant rate IV, and eliminated first order, plasma concentration will

plateau

approximate total body storage equals

1.44 times the amount administered per half life

avoiding toxicity and maintaining steady state is easier when drugs have

a long half life

in zero order elimination, k=

in first order elimination, k=

.693/halflife

typically, absorption follows

first order kinetics

equation for bioavailability

F=AUCoral/AUCiv

equation for relative bioavialability

AUCgeneric/AUCtradename

triphasic curve, rapid peak and decline, slow decline

Single-dose IV, long decline=Ke

level of drug in blood rises slowly until elimination = absorption. Bioavailability=1

subcutaneous or intramuscular single dose

blood level rises until equal to elimination, Cmax is slower, tmax is later

oral, single dose

Pharmacology Synopses 1 Flashcards

(99 cards)