Excretion of Drugs - Exam 3 Flashcards
definition of the excretion of drugs
the removal or clearance of drugs from the body
route of drug excretion in order of importance (most to least)
renal, hepatic & biliary, feces, milk, semen, sweat, saliva, hair/feathers, expired air
renal excretion dependent on 3 factors
glomerlular filtration rate + active tubular secretion + passive tubular secretion = total renal excretion
factors affecting glomerular filtration
GFR, molecular size, molecular charge, plasma protein binding
T/F only unbound drugs are freely filtered
T
GFR
glomerlular filtration rate, arterial blood pressure, blood flow -> capillaries -> Bowman’s capsule -> ultrafiltrate
factors affecting active tubular secretion
proximal convoluted tubule, organic cation transporters, organic anion transporters
PCT
proximal convoluted tubule, require energy
OTC
organic cation transporters; basic
OAT
organic anion transporters; acidic
factors affecting passive tubular secretion
proximal & distal convoluted tubules (nonionized), physiological properties (H2O soluble, ionized, polar), degree of ionization, acidification of the urine pH enhances renal excretion of weak basic drugs, alkalinization of the urine pH enhances renal excretion of weak acidic drugs, fluid therapy & diuretics
factors affecting total renal excretion
liver, kidney, or cardiac disease, age, urine pH modifiers, fluid therapy/diuretics, plasma protein binding, the dose and rate of drug absorption
what is the 2nd most important organ for excretion of drugs
liver
enterohepatic recirculation
lipophilic compounds excreted in bile can be hydrolyzed in the intestines, converts them back to lipid soluble free drugs, reabsorbed
importance of enterohepatic recirculation
prolongs the 1/2 life of a drug
