The main branches of pharmacology The interactions of chemicals are divided into two categories:- Pharmacodynamics Pharmacokinetics

the effects of the drug on the body 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

Stability to acid and enzymes 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

When drug reaches the circulation and penetrates tissues DISTRIBUTION When drug reaches the circulation and penetrates tissues

Most drugs are eliminated EXCRETION Renal Most drugs are eliminated via kidneys Biliary Some drugs concentrated in bile excreted into intestine may be reabsorbed