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huron.oh.pharm.quiz1
| Question | Answer |
|---|---|
| pharmacokinetics | movement of drugs through body -"kinetics" movement through body |
| path of enteral drug | stomach to small intestines; absorbed through portal vein; to liver; biotransformation in liver; systematic circulation; target tissue; target cell |
| processes of pharmacokinetics | 1. absorption 2. distribution 3. metabolism 4. excretion |
| what must most drugs penetrate to produce effects? | plasma membrane-the lipid bilayer |
| diffusion | passive transport - chemical moves from area of high concentration to lower concentration |
| what drugs pass easily through plasma membrane: | small, non-ionized and lipophilic |
| large molecules pass into cells | need transport proteins-they are selective and only carry certain molecules |
| absorption | process of moving a drug from site of administration to bloodstream - determines 1. onset of drug action 2. intensity of drug action |
| routes of administration | 1. IV - fastest 2. inhalation (also rapid response)3. subcutaneous and IM 4. tablets & capsules relatively slow 5. topical drugs - absorbed slowly |
| drug concentration & dose | higher dose produces greater concentration gradient for diffusion |
| GI tract environment | 1 fatty foods slow absorption 2. absorption more complete between meals |
| blood flow | must be adequate; during heart failure or shock blood flow is slowed |
| drug ionization | drugs can be "charged" or "uncharged" depending on pH of surrounding fluid - Acids are absorbed in acids because they are nonionized - bases are absorbed in bases because they are nonionized |
| surface area | drugs are absorbed in small intestines & lungs becuase there is more surface area to these organs |
| distribution | transport of pharmacologic agents throughout the body |
| distribution is affected by: | 1. blood flow to tissues; 2. drug solubility 3 tissue storage (lipid-soluble vitamins in adipose tissue); 4. drug-protein binding (drug-protein complexes)5. special barriers (blood-brain and placenta) |
| metabolism | biotransformation-process used by body to chemically change a drug molecule - liver is primary site - but kidneys and intestinal traact cells also have high metabolic rates |
| how do metabolic reactions change structure of drug? | in most cases - it is more easily excreted by body - often changes from lipid soluble (cell can absorb) to water soluble (kidneys can excrete) |
| hepatic microsomal enzymes | P-450 system - named after cytochrome P450 (CYP) an enzyme that metabolizes drugs |
| drugs as substrates | when drug is metabolized by CYP, it is a SUBSTRATE - and drugs often compete for binding sites on the CYP isozymes-therefore DRUG INTERACTIONS are frequent |
| drugs as enzyme inhibitors | some drugs inhibit hepatic CYP isozyems-makes it dangerous to give certain drugs together - liver will not break down properly |
| enzyme induction | some drugs cause liver to Increase metabolic activity - ex. phenobarbital |
| first-pass effect | many drugs are rendered inactive by hepatic metabolic reactions - after going through stomach, portal veins deliver to liver, which inactivates drug |
| Excretion (4) | renal; pulmonary; glandular; fecal & biliary |
| renal excretion | kidneys major excretion of drugs; impairment of kidney function can dramatically affect pharmacokinetics-kidney function must be monitored carefully |
| pulmonary excretion | lungs excrete most drugs in their original unmetabolized form - gaseious or volatile liquid forms can be excreted through drugs |
| glandular secretion | saliva, sweat and breast milk can excrete Ex. garlic |
| fecal or biliary excretion | certain oral drugs travel through GI tract without being absorbed; some go through biliary tract & may be recirculate |
| what determines the therapeutic response of most drugs? | depends on their concentration in plasma-serum plasma is therefore measured to make sure levels are safe ex. lithium |
| minimum effective concentration | minimum amount of drug to have therapeutic effect - Ex. oral route - 2 hours to reach minimum effect |
| therapeutic range | plasma drug concentration (mcg/mL) drug produces its desired therapeutic action |
| toxic concentration | high dose creates adverse effects |
| Drug half-life - plasma half-life (t 1/2) | estimate of duration of action for most medications - most common way is to measure plasma Ex. novocain - half-life of 8 minutes - most dental procedures are not long |
| plateau drug plasma level | multiple doses allow therapeutic level to be maintained in plasma |
| peak and trough | plasma drug levels are not smooth-there will be peaks and throughs - peak must not go above toxic range - troughs should not fall below therapeutic range |
| loading dose | higher amount of drug to "prime" bloodstream to quickly produce therapeutic level |
| maintenance dose | intermittent drugs to keep plasma in therapeutic range (so that excretion does not reduce levels) |
| receptor theory | most drugs produce their actions by activating or inhibitin specific cellular receptors |
| receptor | a cellular molecule to which a medicaiton binds to produce its effects |
| agonist, partial agonists, and antagonists compete for cellular receptors | they modify drug acftion |
| agonist/partial agonist | when drug binds to receptor, it may mimic the effect of the endogenous regulatory molecule |
| antagonist | drug will occupy receptor and prevent endogenous chemical from binding - ex. secretion of stomach acid - antagonist will bind to sites & prevent acid from being produced |
| relationships between agonists and antagonists | explain drug-drug and drug-food interactions |
Created by:
walterina4327
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