Drugs

Definition of Drug

• The word “Drug” is derived from the Old French word “drogue”, which originally meant herb.
• Broad Definition:

A drug is any chemical agent (other than food) that affects the physiological or biochemical processes of living organisms and is used in the prevention, diagnosis, or treatment of diseases in humans and animals.

Characteristics of a Drug

• A drug can exert both:
  • Beneficial (therapeutic) effects
  • Harmful (adverse/toxic) effects
• No drug is entirely safe unless it is pharmacologically inert, meaning it has no biological activity at all.

Nomenclature of Drugs

Drugs are commonly known by three types of names:

1. Chemical Name

• Represents the precise chemical structure and molecular composition of the drug.
• Difficult to remember, not user-friendly, and not used in prescribing.
• Example:
  • Chemical Name: N-acetyl-p-aminophenol
  • Corresponding Common Name: Paracetamol

2. Common Name or Generic Name

• Assigned by official agencies (such as WHO).
• When accepted and included in a pharmacopoeia, it becomes the official name.
• Universally recognized and used in prescribing drugs.
• Example:
  • Generic Name: Paracetamol

3. Trade Name or Proprietary Name

• Brand names given by manufacturers or pharmaceutical companies.
• A single drug can have multiple trade names, depending on the company marketing it.
• Written with an uppercase letter and often with a ® symbol.
• Examples of Paracetamol trade names:
  • CROCIN®
  • CALPOL®
  • METALGIN®

Orphan Drugs

• Orphan drugs are medications developed specifically to treat rare diseases or conditions.
• These diseases are often referred to as “orphan diseases” due to their low prevalence in the population.
• Because of the small number of affected individuals, the commercial potential is limited, making drug development financially unattractive for pharmaceutical companies.

Essential Drugs

• According to the World Health Organization (WHO):

Essential drugs are those that satisfy the healthcare needs of the majority of the population.
They should be:

• Available at all times
• In adequate amounts
• In appropriate dosage forms
• Of assured quality, and
• At a price the community can afford