Sources of Impurities in
Medicinal agent

The origin of impurities in drugs is from various sources and phases of
the synthetic process and
preparation of pharmaceutical
dosage forms.

Majority of the impurities are characteristics
of the synthetic route of
the manufacturing process.

There are
several possibilities of
synthesizing a drug; it is possible that the same product of different sources may
give
rise to different impurities.

Organic  impurities  

may  arise  from
 starting materials, by products,
synthetic intermediates
and degradation products.

Inorganic impurities may be derived from the manufacturing process and
are
normally known and identified as
reagents, ligands, inorganic salts, heavy metals, catalysts, filter aids and charcoal etc. 

Sources of organic
impurities:

• Impurities
  originating from drug
  substance synthetic processes
• Starting materials
  and intermediates
•  Impurities
  in the starting materials
•  Reagents, ligands
  and catalysts
•  By–products of the synthesis
•  Products of over–reaction
•  Products of side reactions
•  Impurities
  originating from degradation of the
  drug substance.