Pharm principles random Flashcards
Irreversible Comp. inhibitors effect on Km
Unchanged
Pharmacokinetics vs Pharmacodynamics
PK - what body does to drug
PD - what drug does to body
Vd =
amount of drug in body / plasma drug concentration
Decreased protein binding of drug…
Increases Vd (less trapped in plasma)
Clearance (CL) =
rate of elimination of drug / plasma drug concentration
= Vd x Ke (elimination constant)
t(1/2) =
0.693 x Vd / CL
Half-lives vs. SS%
1 - 50% 2 - 25% 3 - 12.5% 3.3 - 10% 4 - 6.25%
Loading does =
Cp x Vd / F
Maintenance dose =
Cp x CL x dosage interval (time b/t dose) / F
Does time to SS change with DOSE or DOSING FREQ?
NO (but concentration at SS may change)
Intramuscular or subcutaneous have greater absorption rate?
Intramuscular - d/t high vascularity
Zero order elimination drugs?
Phenytoin, Ethanol, Aspirin (high concentrations)
Weak acids and OD Rx
Phenobarbital, methotrexate, aspirin, TCAs
Rx Bicarbonate
Weak bases and OD Rx
Amphetamines
Rx ammonium chloride, VitC/Cranberry juice
Phase 1 metabolism
@ ER: reduction, oxidation, hydrolysis w/ cytochrome P-450
Phase 2 metabolism
@ cytosol: conjugation (Glucuronidation, Acetylation, Sulfation)
Location of CYP450 drug metabolism
Liver AND Gut
Therapeutic index =
Median toxic dose (TD50) / Median effective dose (ED50)
Low TI Drugs
Digoxin, Lithium, Theophylline, Warfarin
High TI indicates…
Selectivity
Jimson Weed (Datura)
Atropine-like (gardener’s pupil)
Atropine flush
High dose antimuscarinic causes cutaneous VD (unknown mechanism)
Tetrodotoxin
bind fast voltage-gated Na+ channels in cardiac and nerve tissue (blocks AP w/out changing RMP)
Ciguatoxin
Opens Na channels causing depolarization
- Temp-related dysesthesia
Scombroid
Bacterial histidine decarboxylase converts histidine to histamine (not degraded by cooking)
Saxitoxin
From dinoflagellates in “red tide”
- VG-Na channel blocker
