Sources of Impurities in
The origin of impurities in drugs is from various sources and phases of
the synthetic process and
preparation of pharmaceutical
Majority of the impurities are characteristics
of the synthetic route of
the manufacturing process.
several possibilities of
synthesizing a drug; it is possible that the same product of different sources may
rise to different impurities.
may arise from
starting materials, by products,
and degradation products.
Inorganic impurities may be derived from the manufacturing process and
normally known and identified as
reagents, ligands, inorganic salts, heavy metals, catalysts, filter aids and charcoal etc.
Sources of organic
originating from drug
substance synthetic processes
- Starting materials
in the starting materials
- Reagents, ligands
- By–products of the synthesis
- Products of over–reaction
- Products of side reactions
originating from degradation of the
Limit test is defined as quantitative or semi quantitative test designed to identify and control small quantities of impurity which is likely to be present in the substance.
Limit test is generally carried out to determine the inorganic impurities present in compound.