Wednesday, 10 July 2013

FAQ on stability studies

FAQ on stability studies
1.What is stability?
The term “stability” with respect to a drug dosage form, refers the physical and chemical integrity of dosage unit. When appropriate, the ability of the dosage unit to maintain protection against microbial contamination.
2.What are the factors, which affect stability of a drug?
Stability parameters of a drug dosage form can be influenced by environmental conditions of storage (temperature, light, air & humidity) as well as packaging components.
3. What is  shelf life/expiration period?
The time period during which a drug substance or drug product is expected to remain within the approved shelf-life specification, provided that it is stored under the conditions defined on the container label.            
4. What is the purpose of stability study? 
a.          Provide evidence, to how the quality of the drug product varies with time.
b.          Establish shelf life for the product.
c.          To recommend storage conditions
d.          To determine container suitability.
 5.What is accelerated stability testing?
Studies designed to increase the rate of chemical degradation or physical change of a drug substance or drug product by using exaggerated storage conditions as part of the formal stability studies. Data from these studies, in addition to long term stability studies, can be used to assess longer term chemical effects at non-accelerated conditions and to evaluate the effect of short term excursions outside the label storage conditions such as might occur during shipping.
6.What are climatic zones in stability testing?
The four zones in the world that are distinguished by their characteristic prevalent annual climatic conditions. This is based on the concept described by W. Grimm.
 Type of Climate Zone
Zone I
Temperate zone
Zone II
Mediterranean/subtropical zone
Zone III
Hot dry zone
Zone IVa
Hot humid/tropical zone
Zone IVb
Hot/very humid (ASEAN testing conditions)                
 7.What is the testing frequency for accelerated stability study?
At the accelerated storage condition, a minimum of three time points, including the initial and final time points (e.g., 0, 3, and 6 months), from a 6-month study is recommended. Where an expectation (based on development experience) exists that results from accelerated studies are likely to approach significant change criteria, increased testing should be conducted either by adding samples at the final time point or by including a fourth time point in the study design.
 8.What is the testing frequency for long term (drug product) stability study?
The  recommended frequency of testing at the long term storage condition is normally every 3 months over the first year, every 6 months over the second year, and annually thereafter through the proposed shelf life.
 9.What is bracketing & matrixing in stability study?
Bracketing & matrixing are reduced designs, where the testing frequency is reduced or certain factor combinations are not tested at all.
10.What is “significant change” for drug product
In general, “significant change” for a drug product is defined as:
1. A 5% change in assay from its initial value; or failure to meet the acceptance criteria for potency when using biological or immunological procedures;
2. Any degradation product’s exceeding its acceptance criterion;
3. Failure to meet the acceptance criteria for appearance, physical attributes, and functionality test (e.g., color, phase separation, resuspendibility, caking, hardness, dose delivery per actuation)
4. Failure to meet the acceptance criterion for pH; or
5. Failure to meet the acceptance criteria for dissolution for 12 dosage units.


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