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Download PHARMACOLOGY AND PRINCIPLES OF DRUG ACTION
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The main branches of pharmacology The interactions of chemicals are divided into two categories:- • Pharmacodynamics • Pharmacokinetics PHARMACODYNAMICS • the effects of the drug on the body • how the effects of a drug are generated Pharmacokinetics • The way the body affects the drug with time considering absorption, distribution, metabolism, excretion. DRUG ABSORPTION, DISTRIBUTION, EXCRETION Absorption Most drugs are given orally passing through the gut wall to enter the bloodstream Absorption… Depends on:- Formulation Stability to acid and enzymes Food in stomach Lipid solubility Routes of administration • enterally ( via gastrointestinal route) or parenterally ( non-gastrointestinal route) ORAL…. Convenient but Some drugs are destroyed by acid or enzymes in gut Parenterally:Intravenous injection… Drugs enter circulation and bypass the absorption barriers Intramuscular/ subcutaneous injection Other routes:Topical - substance is applied directly where needed -Inhalation (asthma inhalers) (lotions, ointments)transdermal Enterally: Sublingual , oral rectal DISTRIBUTION • When drug reaches the circulation and penetrates tissues EXCRETION • Renal Most drugs are eliminated via kidneys • Biliary Some drugs concentrated in bile excreted into intestine may be reabsorbed
