Pharm Flashcards by Amanda Krauss

What are the properties of drugs that contribute to activity?

molecular size
solubility
charge

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What is the partition coefficient?

determined by overall polarity of drug
[lipid]/[water]
>1 lipophilic, easier to distribute

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What is significant about quaternary ammonium salts?

permanent cations

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What are the factors that govern filtration?

size of pore

pressure gradient

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How are neutral drugs absorbed?

uncharged-pores, passive diffusion

charged-pores, active transport

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How are acidic drugs absorbed?

HA-pores, passive diffusion

A-pores, active transport

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How are basic drugs absorbed?

B-pores, passive diffusion

HB-pores, active transport

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What is enteral administration?

placing the drug into some portion of the GI

oral, sublingual, rectal

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What are the advantages of oral administration?

passive diffusion
most in small intestine due to time and size
carried to liver via portal

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What is first pass elimination?

extensive hepatic clearance via biotransformations

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What are the advantages of sublingual administration?

enter general circulation by passive diffusion

useful for drugs that do not survive oral administration (nitroglycerin)

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What are the advantages of rectal administration?

dissolves and absorbed by passive diffusion
enters general circulation
good for unconscious, vomiting, or uncooperative patients

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What is parenteral administration?

drug in some portion of body other than GI (subcutaneous, intramuscular, intravenous, intraarterial, inhalation, intrathecal)

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What are the advantages of subcutaneous administration?

absorption by passive diffusion
small and large hydrophilic
rate depends on blood flow

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What are the advantages of intramuscular administration?

can use large volumes and more irritating drugs

good for orally labile, depot preparations

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What are the advantages of intravenous administration?

no absorption

rapid onset but cannot redraw or retard absorption

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What are the advantages of intraarterial administration?

no absorption

achieves high localized drug concentration

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What are the advantages of inhalation administration?

must dissolve in pulmonary fluids before absorption by passive diffusion

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What are the advantages of intrathecal?

directly into subarachnoid space

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What is the first barrier for drug distribution?

capillary endothelium

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How do drugs enter the CNS?

passive at ventricles
active at choroid plexus
movement mainly out of CSF and into blood

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What is significant about the prostate?

highly acidic

basic drugs are protonated and build up

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What is biotransformation and where does it occur?

mainly in the liver
Phase I-oxidation, reduction, hydrolysis
Phase II-conjugation

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What are microsomal enzymes?

located in smooth ER
cytochrome P450-terminal oxidase
substrates must be lipophilic
activity is inducible
CYP3A4/5 is most important

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Where does acetylation occur?

omega-1 or para on aromatic ring

What are nonmicrosomal enzymes?

in cytosol and mitochondria also in blood as esterases not inducible perform all hydrolysis reactions

What are the conjugation reactions that occur?

sulfate is more common but cofactor is limited | gluconuration becomes more important

What are the two primary routes of drug excretion?

biliary and renal

How does a drug get excreted in bile?

Portal vein from absorption Hepatic artery from circulation if greater than 300-->biliary excretion can undergo enterohepatic recycling (reabsorbed into portal) to increase half life

How does a drug get excreted in urine?

filtration if less than albumin and not bound to protein can be secreted by OCT or OAT back flow can occur in distal convoluted tubule

What is the difference between pharmacokinetics and pharmacodynamics?

kinetics-system on drug | dynamics-drug on system

What is affinity?

ability with which the drug binds to the specific receptors

What is intrinsic activity?

property of drug to impart a cellular response

What is an agonist?

stimulates-affinity and intrinsic activity

What is an antagonist?

affinity but no intrinsic activity

What is an inverse agonist?

turns off a constitutively activated receptor

What is specificity?

single receptor type

What is selectivity?

single effect

What are the different mechanisms?

``` intracellular membrane spanning enzymes intracellular tyrosine kinase membrane ion channels G proteins ```

What is supersensitization?

sustained antagonist increase the number of receptors

What is desensitization?

sustained agonist decrease number of receptors

What is tachyphylaxis?

loss of response on repeated administration-slower dissociation

What actions are not receptor mediated?

neutralization of gastric acid osmotic diuretics cholesterol binding resins antibiotics

What is the one compartment model?

equilibriates between plasma and tissues relative to elimination proportional changes not necessarily distributed to all tissue semi log plot is linear

What is the two compartment model?

``` drug takes longer time to equilbriate two slopes (distribtuion and elimination) ```

What is first order elimination?

constant rate of elimination independent of dose linear on semi log enzymes are not saturated

What is zero order elimination?

constant amount of elimination linear on linear scale enzymes are saturated

What is bioavailability? How is it calculated?

amount that reaches circulation F=1 for iv compare area under curve for route compared to iv important in preparation of generic drugs

What is half life? What is the formula?

time to remove half of drug | 0.693/Ke

What is the volume of distribution? What is the significance of high/low Vd? What is the formula?

apparent volume that a drug is distributed within the body high=lipophilic, low=bound to protein Vd=dose/concentration

What is clearance? How is it calculated?

volume of blood from which a drug is completely removed in a given time Cl=Ke(Vd)

What is the steady state concentration?

first order kinetics will eventually reach equilibrium in 4 half lives (balance between intake and elimination) Css=MD/Cl

What is the maintenance dose?

drug given at constant interval | MD=[dose(F)]/interval

What is a loading dose?

iv administration to get to Css quickly | loading dose=[Css(Vd)]/F

What is the median effective dose?

dose required to produce therapy in 50%

What is the median lethal dose?

dose required to produce death in 50%

What is the therapeutic ratio?

LD50/ED50 | larger is safer

What is the certain safety factor?

LD1/ED99 | greater than 1 means little overlap

What is the standard safety margin?

(LD1-ED99)/ED99

What is pharmacogenetics?

genetic basis for variation in drug response

What can polymorphisms do to Km and Vmax?

change increase Km decrease affinity decrease Vmax decrease rate

What happens with Asians flushing?

loss of aldehyde dehydrogenase

What happens with NAT2 acetylators?

isoniazid Inuit and Japanses are fast Scandanavians are slow

What is the significance of CYP3A5?

variation metabolism faster in African population

What is significant about vitamin K oxidoreduction?

variant requires higher dosing

What is significant about CYP2C9?

variant requires lower dose because not metabolized as well

What is significant about 2B6?

cannot make prodrug of cyclophosphamide

What is significant about GST?

increased toxicity of alkylating agents | decrease response in breast cancer

What is signficant about G6PD deficiency?

methemoglobinemia when given Dapsone (oxidized)

How does the dose response curve shift with an antagonist?

shift to the right

What does potentiation do to the graph?

shift to the left-increases the effect | example-cocaine keeping norepinephrine in synaptic cleft longer due to decrease in reuptake