Pharmacokinetics Word Scramble
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| Question | Answer |
| Km | [S] at Vmax, low Km => high affinity |
| Noncompetitive inhibitor | -Does not resemble substrate -Does not bind to active site -Cannot be overcome by increased [S] -Decreases Vmax, no effect on Km -Decreases efficacy of substrate |
| Competitive inhibitor | -Resembles substrate -Binds to active site -Can be overcome by increased [S] -Decreases Km, no effect on Vmax -Decreases potency of substrate |
| Volume of Distribution (Vd) | = (Amount of drug in body)/(Concentration of drug in plasma) Low Vd => distributes in blood Med Vd => distributes in extracellular space/body water High Vd => distributes in tissues |
| Clearance | = (rate of elimination)/(plasma concentration) = Vd x Ke |
| Loading dose | = Cp x Vd/F Not affected by renal/hepatic dysfunction |
| Maintenance dose | = Cp x Cl/F Decreased by renal/hepatic dysfunction |
| Zero-order elimination | Constant amount of drug eliminated over time, regardless of concentration Phenytoin, Ethanol, Aspirin |
| First-order elimination | Elimination rate proportional to concentration, constant fraction of drug eliminated per unit time (exponential decay) |
| Weak acids | Trapped in basic environments, treat overdose w/ bicarb Phenobarbitol, MTX, TCAs, aspirin HB + OH- --> B- + H2O |
| Weak bases | Trapped in acidic environment, treat overdose w/ ammonium chloride Amphetamines BOH + H+ --> B+ + H2O |
| Phase I metabolism | Reduction, oxidation, hydrolysis Yields slightly polar, water-soluble metabolites, often still active CyP450 Lost first by elderly patients |
| Phase II metabolism | Acetylation, glucuronidation, sulfation Yields very polar, inactive metabolites for renal excretion Conjugation, separate from P450 |
| Therapeutic index | = median LD50/median ED50 |
Created by:
zacharykr
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