Page 77 - Quality control of pharmaceuticals (07-PA 704)

Impurities in Pharmaceuticals

Impurities in pharmaceuticals are the unwanted chemicals that remain with the
active pharmaceutical ingredients (APIS) or develop during formulation or upon
aging of API.
The presence of these unwanted chemical even in small amounts may influence the
efficacy and safety of the pharmaceutical products.
Impurity profiling is the common name of a group of analytical activities, the aim of
which is the detection, identification and quantitative determination of organic and
inorganic impurities as well as residual solvents in bulk drugs and pharmaceutical
formations.
Different pharmacopoeias are incorporating limits to allowable levels of impurities
in APIS and formulations.
Types of impurities:

I. Impurities associated in with APIs
1. Organic impurities
2. Inorganic impurities
3. Residual solvent

II. Impurities forms during formulation
1. Method related
2. Environmental related
3. Dosage form related

III. Formation of impurities on aging
1. Mutual interaction amongst ingredients
2. Functional group related typical degradation

IV. Other impurities
1. Isomeric / Enantiomeric impurities