PHARMACOLOGY

 PHYSICAL STATE OF THE DRUG ::

Liquids are absorbed better than solids Smaller the particle size greater is the absorption Larger tablets are better absorbed than highly compressed tablets 

Functional state of the gastrointestinai tract ::

Diseased conditions may impair the absorption of drugs e.g. in diarrhoea there is increased peristaltic activity and so the absorption of drug is reduced 

Presence of other substances ::

The presence of food retards the absorption so the drug is given before meals for its rapid absorption However if the drug causes irritation it is administered after meals Calcium forms a complex with tetracycline so it reduces absorption of this drug Hence it is given with water and not with calcium food or milk food enhances the absorption of hydralazine propranolol and metoprolol 

Route of administration ::

The drug plasma concentration is dependent on the route of administration and nature of the drug Peak concentration is achieved with Penicillin G when given per intramuscular injection 

Diseased conditions ::

Normally absorption of drugs is decreased in conditions like coeliac disease e.g. digoxin However it is interesting to note that the absorption of propranolol cotrimoxazole and cephalaxin is increased in

 patients with coeliac disease Iron is absorbed more by anaemic patients via apoferritin carrier than those who are normal more severe is the anaemia greater is the absorption