Pharma Talk #2

HOW DRUG ACTS IN THE BODY? And, HOW BODY GIVES RESPONSE TO THE DRUG? These two questions are quite familiar with and they are not, yet, complicated to answer, but, mostly, students fail to deliver it while having lots of confusion. So, today, I am going to discuss it one by one,  however, there are various theories available to understand the complicated mechanism, but, at first, we must know the definition of ‘DRUG’; it’s defined as the substance which do not impart new functions to the body, mind it, rather, alter the pace of ongoing activity, for instance, when a drug is administered in the ill-body, then, it, only, alters the pace of the following activity and maintains equilibrium. Not only that, sometimes, it’s used to diagnose certain diseases.
However, drugs produce certain effects in the body, and they are as follows;

1. STIMULATION: it refers to selective enhancement of the level of activity of specialized cells, e.g. adrenaline stimulates heart, pilocarpine stimulates salivary glands etc.

2.DEPRESSION: it means selective diminution of activity of specialized cell, e.g. barbiturates depress CNS, quinidine depresses heart, omeprazole depresses gastric acid secretion etc.

3.IRRITATION: this connotes a non-selective, often noxious effect and is particularly applied to less specialized cells.

4.REPLACEMENT: this refers to the use of natural metabolites, hormones, or their congeners in deficiency states, e.g. levodopa in Parkinsonism, insulin in diabetes mellitus, iron in anaemia.

5.CYTOTOXIC ACTION: selective cytotoxic action on invading parasites or cancer cells, attenuating them without significantly affecting the host cells is utilized for cure/palliation of infections and neoplasms, e.g. penicillin, chloroquine etc.

Majority of drugs act by interacting with a discrete target bimolecule, which usually is a protein. Such mechanism confers selectivity of action to the drug. Functional proteins that are targets of drug action can be grouped into four major categories, such as, enzymes, ion-channels, transporters and receptors etc. The mechanisms will be discussed as in next articles.