Drug clearance : Once a drug enters into the body, the process of elimination begins. The three major routes of eliminations are: (i) Hepatic metabolism (ii) Biliary elimination (iii) Urinary excreation Excreation is irreversible removal of the drug from the body. It involves BIOTRANSFORMATION & EXCREATION.   •> Metabolism results in products with increase polarity, which allows the drug to be eliminated.  •> Clearance(CL) estimates the vomume of blood from which  the drug is cleared per unit of time.                            CL = 0.693 x V d / t  1/2    - W here T 1/2 is the elimination half life, Vd is apparent volume of distribution and 0.693 is natural log. BIOTRANSFORMATION               • The general principle of biotransformation is the metabolic conversion of drug mollecule to more water soluble metabolites that are more read...