The climatic condition changes as we move across the globe, which means that the climatic condition is different in a different part of the world. The stability of pharmaceutical product is influenced by climatic conditions. Hence, the stability study of the pharmaceutical product needs to be studied keeping in mind the climatic conditions of the country. As per ICH guidelines for stability studies, the climate of the world is divided into four different zones (Zone I, II, III, IV.). Zone IV is further divided into two, zone IV A and zone IV B.
ICH stability zones:
| Stability Zones | Climatic Condition |
| Zone I | Temperate Zone |
| Zone II | Mediterranean /Sub-tropical Zone |
| Zone III | Hot Dry Zone |
| Zone IV A | Hot Humid Tropical Zone |
| Zone IV B | Hot/Higher Humidity |
As the climatic zones are differentiated based on the temperature and humidity of different part of the world. ICH has defined different stability condition for studies as per the Stability zone. The stability study condition for Drug Product is mentioned below:
| Long Term Stability Testing Conditions | |||
| Stability Zone | Temperature | Humidity | Minimum Duration |
| Zone I | 21°C ± 2°C | 45 %RH ± 5 % RH | 12 Months |
| Zone II | 25°C ± 2°C | 60 %RH ± 5 % RH | 12 Months |
| Zone III | 30°C ± 2°C | 35 %RH ± 5 % RH | 12 Months |
| Zone IV A | 30°C ± 2°C | 65 %RH ± 5 % RH | 12 Months |
| Zone IV B | 30°C ± 2°C | 75 %RH ± 5 % RH | 12 Months |
Intermediate and Accelerated Stability Testing Condition:
| Study | Storage condition | Minimum Duration |
|---|---|---|
| Intermediate | 30°C ± 2°C/65% RH ± 5% RH | 6 Months |
| Accelerated | 40°C ± 2°C/75% RH ± 5% RH | 6 months |
For the Drug Productintended for storage in a refrigerator:
| Study | Storage Condition | Minimum Duration |
|---|---|---|
| Long Term | 5°C ± 3°C | 12 months |
| Accelerated | 25°C ± 2°C/60% RH ± 5% RH | 6 months |
For the Drug Product intended for storage in a freezer:
| Study | Storage Condition | Minimum Duration |
|---|---|---|
| Long Term | -15°C ± 5°C/ No Humidity | 12 months |
| Accelerated | 5°C ± 3°C/No Humidity | 6 months |
A successful stability study establishes the shelf-life of the drug product, the retest period of a drug substance, and appropriate storage conditions. A successful stability study must also ensure that patients receive safe and effective medicine.