Sources of Impurities in Medicinal agent

 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, heavmetals, catalysts, filter aids and charcoaetc. 

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.

 Limit Test

Limit test is defined as quantitative or semi quantitative test designed to identifand 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.

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