Stability of drug substances

Stability studies :

Define stability  :

To study on how the product quality changes with time under the influence of temperature, humidity and light ti establish its shelf life or retest.

Why stability  ?

• To provide storage condition
• To provide retest or expiry.

How to establish retest/expiry date :

Pack the material into tiny packs simulated to marketing conditions and keep in stability chamber.

withdraw as per the scheduled intervals and test it. Compare the results against initial results and draw trend chart.

what is long-term or real time storage condition :

The condition at which the material is stored.

 what is Accelerated storage condition :

The condition at which the material is stored about 15 degrees above to the long term storage temperature to know the potential degradation of the substance.

For every real time storage condition, one accelerated storage condition study for a period of 6 months is essential to extrapolate the retest or expiry.

Product intended to store at 25°C:

Retest/Expiry= available long term study period + 12 months

OR 

available long term study period X 2

apply both the formula and report whichever is  lower value, as the retest.

In short we can remember in more way:

1. If the available long term data is more than 1 year, then the retest is +12 month to the long term period. 

2. If the available long term data is less than 1 year, then the retest is twice to the  long term period. 

Product intended to store at 5°C:

Retest/Expiry= available long term study period + 6 months

OR 

available long term study period X 1.5

apply both the formula and report whichever is  lower value, as the retest.

In shout we can remember in more way:

1. If the available long term data is more than 1 year, then the retest is +6 month to the long term period. 

2. If the available long term data is less than 1 year, then the retest is 1.5 times to the  long term period. 

ICH Q1(A) and Q1(E) guidance are  more useful for stability studies.

Tips to remember :

1. The stability chambers are calibrated once in year.
2. frequent preventive maintenance shall be done the chamber, specially heater tanks maintenance.
3. Standby chamber shall be in place.
4. Within 24 hours, the samples shall be shifted to standby chamber when the current chamber is failed to run.
5. Excursions in the chamber shall be monitored and acknowledged once in a day minimum.
6. Prefer purified water as a source of  water supply to the stability chamber heater tank.
7. yearly once the  chamber uniform distribution of temp and humidity shall be verified .
8. if the accelerated condition study has no variance during, there is no extrapolation study required to establish retest or expiry. use the formulas as given above.
9. if there are changes or variance in the accelerated condition, the retst and expiry shall be less the proposed extension period.
10. Forced degradation study shall be done as a part of stability indicative nature of analytical method and to know the degradation pathways.

Regards,

Bujji Reddy Kanchi.

Quality-Pharmaceuticals

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