Basic Principles of Pharmacology

Study Notes

This presentation covers drug naming and classification.
Previous knowledge of drug sources and types is assumed.
Drugs are named and grouped based on their chemical structures or therapeutic effects.
Learning outcomes include explaining drug nomenclature, generic substitution, and bioequivalence, along with describing anatomical and therapeutic chemical classification of medicines.

Chemical name: Detailed description of the drug's chemical structure. Example: Acetylsalicylic acid for aspirin. Frequently complex and not used for prescription.
International Non-proprietary Name (INN): A single, unique, globally recognized name for a drug. It is the generic name. Example: Aspirin.
Proprietary Name/Trade Name/Brand Name: A name given to a drug by the manufacturer. Example: Bayer Aspirin. Numerous companies can market the same drug under different trade names.

The INN program (WHO, 1950) aimed to create a universally accepted unique name.
Drug nomenclature has improved with better analytical techniques for identification and purity.
Originally, chemical modifications of existing chemical names were used to create INNs, yet this became less useful as more drugs become similar in structure. This approach was replaced using mode of action instead.
Nowadays, mode of action of drugs is used as part of the naming.

Originator: The first pharmaceutical company to develop a drug product and often holds patent to prevent other companies from producing the same medicine for a certain time period. Example: Pfizer for Viagra.
Generic: When other companies develop a drug containing the same active pharmaceutical ingredient (API) as the originator. Example: Dynafil and Zeldina are generics for Viagra.
Generic substitution is the practice of using a generic version of a drug.

Both have the same active ingredient, strength, dosage form, and route of administration.
Safety, and efficacy of generic drugs are tested thoroughly (bioequivalence test).
The cost of generic drugs are often less than the originator.

Two drugs are bioequivalent if they have similar rates and extents of absorption in the body.
Bioequivalence is assessed by comparing plasma concentration curves through comparing Cmax (maximum plasma concentration) and AUC (Area under the curve).
It ensures that the generic drug is similar in effectiveness to the branded drug.
Used to determine if a generic drug is interchangeable with the originator.
There should not be more than a 20% difference in plasma concentrations.