Basic Knowledge Regarding Drug

BASIC KNOWLEDGE REGARDING DRUG

The Nature of a Drug

The drug molecule interacts as an agonist (activator) or antagonist (inhibitor) with a specific molecule in the biologic system that plays a regulatory role. This molecule is called a receptor. Drugs may be synthesized within the body like hormones or may be chemicals not synthesized in the body like xenobiotics.

Poisons are also drugs that have exclusively harmful effects. Toxins are usually defined as poisons of biologic origin, i.e., synthesized by plants or animals. A drug is often administered at a location distant from its intended site of action. Therefore, a useful drug must have necessary properties to be transported from its site of administration to its site of action.

The Physical Nature of a Drug

Drugs may be solid at room temperature (e.g, aspirin, atropine), liquid (e.g, nicotine, ethanol), or gaseous (e.g, nitrous oxide). These factors often determine the best route of administration.

Drug Size

The molecular size of the drug varies from very small to larger one. If the molecular size of the drug is very small it easily diffuses the cellular compartments, in case of larger, the drug is administered directly into the vascular compartment by intravenous or intra-arterial infusion.

Drug reactivity and Drug-receptor bonds

Drugs interact with receptors by means of chemical forces or bonds. There are three major types like Covalent, Electrostatic, and Hydrophobic.

Drug Shape

The Shape of a drug molecule must be such as to permit binding to its receptor site via the bonds.