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RUSVM Pharmacology > Excretion > Flashcards

Flashcards in Excretion Deck (23):
1

Routes of drug excretion

Renal Hepatic Other

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Important processes of renal excretion to pharmacology

Glomerular Filtration

Active Tubular Secretion

Tubular Reabsorption

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Glomerular filtration is an (active/passive) process

Passive

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Glomerular filtration rate (GFR) depends on

arterial blood pressure and renal blood flow

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Factors that affect glomerular filtration

GFR

Molecular size

Electric charge

Plasma protein binding

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Freely Filtered

Molecules charged or uncharged that are able to pass through the membrane freely

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Active tubular secretion occurs at the

Proximal convoluted tubule

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Organic Cation Transporters (OCTs)

In the proximal tubule, responsible for secretion of organic bases

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Endogenous Substances and Drugs secreted by organic cation transporters (OCTs)

Endogenous : Choline, Dopamine

Drugs: Cimetidine, Procainamide, Nicotine

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Organic Anion Transporters (OATs)

Proximal tubule transporter responsible for secretion of organic acids

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Endogenous Substances and Drugs secreted by organic anion transporters (OAT)

Endogenous : Uric acid

Drugs: penicillin, thaizide diuretics, loop diuretics

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Tubular reabsorption occurs in

Proximal and distal convoluted tubules

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Tubular reabsorption is (active/passive) in the distal tubule

Passive

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Acidification

Ammonium chloride / Methionine - enhances excretion of weak basic drugs

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Alkalinization

Sodium bicarbonate - enhances excretion of weak acidic drugs

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Factors the affect renal excretion

Age

Heart/Liver/Kidney disease

Size of drug

Protein binding

Dose-drug concentration

Lipid solubility

pKa of drug

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Total renal excretion of a drug =

Filtration Rate + Secretion + Reabsorption

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Hepatic drug excretion

Active transport of parent drugs and/or conjugates from hepatic sinusoids to bile canaliculi

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Types of drugs likely excreted in bile

Lipid soluble with MW >300 with polar group Steroid hormones

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Enterohepatic Circulation

Conjugates excreted in bile can be hydrolyzed in the intestine and the free drug can be reabsorbed

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Enterohepatic Circulation allows the drug

to remain in the body for longer

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Other routes of excretion

Feces

Milk/Eggs

Expired Air

Sweat

Saliva

Hair/Feathers

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Excretion

Removal of the drug and metabolites out of the body