Page 76 - Quality control of pharmaceuticals (07-PA 704)

be avoided). Heat should be avoided as it is considered another variable, but
temperature can be increase if no degradation is observed at room temperature.
The reaction can be stopped by neutralization, cooling and dilution.

2. Oxidation Stress testing:

Drugs that are susceptible to oxidation are: catechals, thials, alcohols, aldelydes.
H2O2 solutions (1-30%) are usually used for oxidative stress testing.

3. Photostability Stress Test:

It is forcing degradation of drug substance over time to primary oxidative
degradation product via UV or visible light.
The function groups that are likely to undergo photo-reactivity are-co-, c=c, -OH, -
N-O, sulphide and polyenes.
Light stress includes photo-degradation by free radical mechanism.

4. Thermal Stress Test:

This evaluate the stability of the drug at elevated temperature. Stress conditions are
selected based on the fact that every 10oc increase in temperature results in doubling
the reaction rate and decreasing the reaction time by factor of two.
Accelerated Stability Studies:
These tests are required for the registration of new drugs to determine the shelf-life
of the drugs in its dosage form. The test is carried out in a special cabinet where the
temperature is adjusted at 40oc and relative humidity at 75 inside the cabinet. The
drug material under test, together with dosage form in the final packaging form are
introduced into the cabinet and stay for 6 months.
Samples form the drug material and form the dosage forms are taken at specific time
– intervals: zero-time, after 3 months and after 6-months. These samples are
subjected to physical and chemical examinations. If the drug material and the drug
in dosage form show no degradation. So the shelf –life for this form will be 2 years.