The prime objective of conducting stability studies on pharmaceutical dosage forms is to define the shelf life under recommended storage conditions. In the interest of patient safety the dosage form should be guaranteed for its quality, safety and efficacy throughout its shelf life under prescribed storage conditions. The shelf life should be decided taking into consideration the climatic zones in which the product is expected to be marketed.
A mix of factors contribute to the stability of the pharmaceutical formulation
Environmental Factors – temperature, humidity and exposure to light
Ingredients – chemical and physical nature of active pharmaceutical substance as well as excipients
Manufacturing Process – the conditions to which the ingredients are exposed during manufacturing can have significant influence on formulation stability
Packaging Material – nature and compatibility of packaging materials and container closure systems. Possibility of interaction of packaging material in which the drug is delivered, transported and stored throughout the shelf life needs proper investigation.
Stability studies are based on application of validated methods of analysis for evaluation of physical, chemical, biological and microbiological characteristics. Commonly evaluated parameters are assay or potency, concentration of decomposition products, hardness, disintegration, dissolution rate, etc. Efficacy of additives and antimicrobial agents is also determined to ascertain that there is no loss during the shelf life period.
Types of Studies
Stability testing is necessary at different stages of manufacture and release of pharmaceutical products
Accelerated stability tests are designed to increase the physicochemical degradation of the pharmaceutical formulation. Such tests help evaluate alternate formulations, packaging materials and manufacturing processes. Such studies also help predict the shelf life. Accelerated studies data should also be supported by simultaneous real-time studies
Drug regulatory authorities require manufacturer to submit information on the product stability of the final dosage form in its container and packing. The data should be based on both accelerated and real-time studies. Submitted data should also be supplemented with published data if available on the product or its ingredients.
Data submitted to registration body on the expiry date by the manufacturer is required to be substantiated by real-time stability studies Results of ongoing stability studies are verified in the course of GMP inspections
Post-registration additional data are required to be submitted to the regulating authorities whenever major modifications are adopted in the formulation’s manufacturing process or packaging.
We have seen that the quality and stability of pharmaceutical formulations is of prime concern for the well-being of entire human population. Food and cosmetics are other important segments and subsequent articles will cover aspects concerning the stability of these products.
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