Pharmaceutical product shelf-life temperature effects

Finally, as for any pharmaceutical product, ophthalmic products have to be designed to be stable. Ideally, the product should be stable at room temperature over a shelf-life period of 2-3 years. Multidose products must also be stable, after opening the pack, over the period of use. If antimicrobial preservatives are included to maintain sterility over this period, the effectiveness of the chosen preservative has to be demonstrated. There must be a discard statement on the label of multidose products indicating that the contents must not be used after a stated period. Normally, this does not exceed 28 days after opening the pack, unless there is a good justification. 

From Equation (6.11), it can be seen that reaction rates increase exponentially with the ERH. The values for B typically range from 0 to 0.09. This means that in going from dry conditions (10% RH) to moist conditions (75% RH) at a fixed temperature, the degradation rate will range from equal (B = 0) to 347 times faster (B = 0.09) at the damp conditions compared to the dry conditions. To put another perspective on this, in the latter case, a pharmaceutical product with a shelf-life of only 1 week at 75% RH would increase to 6.7 years with effective desiecant. 

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