10-10-2014, 03:29 PM
IMPURITIES AND ITS IMPORTANCE IN PHARMACY
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ABSTRACT
The current practice of characterization and control of impurities in pharmaceutical substances and products are reviewed with emphasis
on issues specific to the active pharmaceutical ingredient and pharmaceutical formulations. The control of pharmaceutical impurities in
the pharmaceutical industry is an important task to the formulator. The International Conference on Harmonization (ICH) has formulated
a workable guideline regarding the control of impurities in pharmaceutical drug substance as well as formulations. In this review article,
impurities, its different types and origin of impurities have been discussed briefly
INTRODUCTION
An impurity in a drug substance as defined by the
International Conference on Harmonisation (ICH)
Guidelines1
is any component of the drug substance that is
not the chemical entity defined as the drug substance and
affects the purity of active ingredient or drug substances.
Similarly, an impurity in a drug product is any component
of the drug product that is not the chemical entity defined
as the drug substance or an excipient in the drug product2
.
Therefore any extraneous material present in the drug
substance has to be considered an impurity even if it is
totally inert or has superior pharmacological properties.
The impurity profile of pharmaceuticals is of increasing
importance as drug safety receives more and more
attention from the public and from the media. Several
recent books3,4 and journal reviews5,6 address this topic
and guidelines are available from US and international
authorities7
.
Most active pharmaceutical ingredients (API) are
produced by organic chemical synthesis. Various
components, including residual solvents, trace amounts of
inorganic, and organic components can be generated
during such a process. Those components remaining in the
final API are considered as impurities.
Organic impurities
This type of impurities in bulk pharmaceutical chemicals
those are innocuous by virtue of having no significant
undesirable biological activity in the amounts present.
Organic impurities can arise during the manufacturing
process and/or storage of the drug substance. They can be
identified or unidentified, volatile or nonvolatile, and
include:
Starting materials or intermediates
These are the most common impurities found in every API
unless a proper care is taken in every step involved
throughout the multi-step synthesis. Although the end
products are always washed with solvents, there are
always chances of having the residual unreacted starting
materials may remain unless the manufacturers are very
careful about the impurities.
CONCLUSION
This review provides a perspective on impurities in drug
substance and drug product. Impurity profile of
pharmaceuticals is an increasing importance and drug
safety receives more and more attention from the public
and from the media. This article provides the valuable
information about the impurities types and its
classification, various techniques of isolation and
characterization, analytical techniques for the
determination, qualification of impurities and critical
factors to be considered while preparation of the bulk
drugs