Bioavailability of drugs (Distribution)

It is the fraction of a drug that reaches the systemic circulation from a given dose. The intravenous route of drug administration gives 100% bioavailability, as it directly enters the circulation.

Sources of drugs

They are natural, semisynthetic, and synthetic. Natural resources are plants, animals, minerals, microorganisms, etc. Semisynthetic drugs are obtained from natural sources and are chemically modified later. Synthetic drugs are produced artificially. The different sources of drugs are:

Route of Drug Administration

Local Routes:
It is the simplest mode of administration of a drug at the site where the desired action is required.
Systemic side effects are minimal.

Nomenclature of Drugs

Chemical name: It denotes the chemical structure of the drug, e.g. acetylsalicylic acid is the chemical name of aspirin and N-acetyl-p-aminophenol for paracetamol. It is not suitable for use in a prescription.

Introduction to general pharmacology

World Health Organisation (WHO) defines drug as ‘any substance or product that is used or intended to be used to modify or explore physiological systems or pathological states for the benefit of the recipient’.

Antitubercular drugs: Introduction, classification and mode of action

Tuberculosis (TB) is a chronic infectious disease caused by M. tuberculosis, an acid-fast bacillus (AFB).
Mycobacterial infections require prolonged treatment. Since TB is a chronic infection, it consists of excessive fibrous tissue with central necrosis. So vascularity of the lesion is poor; hence, the penetration of the drug into the lesion is decreased.