PHARMACOLOGY

(C) Alteration of the mucosa ::

If the intestinal mucosa is destroyed by toxic doses of an agent like tannic acid the absorption of drug may be as rapid as intramuscular or subcutaneous injection 

(D) Alteration of transport mechanism ::

      Drug interaction may interfere with an active mechanism by competing in the transport cycle Methyldopa will be absorbed slowly from the intestinal tract in presence of certain natural amino acids 

2.Modification of dermatomucosal absorption ::

A topically applied drug that is absorbed through the skin or membranes of the ear eye mouth nose rectum urethra or vagina may interact with drugs administered orally or parenterally Therefore drug interactions that influence rates and sites of dermatomucosal as well as g.i. absorption and function must be anticipated and considered 

3.Modification of distribution of drugs ::

A. Alteration of drug transport ::

The rates and routes of distribution of drug from its site of intake to its site of action biotransformation storage and excretion may be influenced by another drug fluid flow physical and biochemical factors and transmembranal transport influence the distribution of drugs 

B.Alteration of drug binding ::

When drugs are bound to proteins and other constituents of the body these effects may occur in rare instances they combine with specific proteins to initiate hypersensitivity reactions Displacement of a drug from its binding sites in the plasma and the tissues may enhance its activity because it is then free to contact receptor sites The intensity of effects in the patient caused by displacement varies with the ratio between bound drug and released drug