Drug products moisture sensitivity

The storage conditions and the length of the studies should be sufficient to cover storage, shipment, and subsequent use. Both drug substances and products should be evaluated under storage conditions that test for thermal stability (temperature effect) and moisture sensitivity (humidity tolerance). 

Badway, S. I. F., Gawronski, A. J., and Alvarez, F. J. (2001), Application of sorption-desorption moisture transfer modeling to the study of chemical stability of a moisture sensitive drug product in different packaging configurations, Int. J. Pharm., 223(1-2), 1-13. 

Sensitivity to moisture or potential for solvent loss is not a concern for drug products packaged in impermeable containers that provide a permanent barrier to passage of moisture or solvent. Thus, stability studies for products stored in impermeable containers can be conducted under any controlled or ambient humidity condition. 

Not every drug product is susceptible to degradation by all of these factors not all drug products are fight sensitive. Not all tablets are subject to loss of quality caused by absorption of moisture. Sensitivity to oxygen is most commonly found with liquid-based dosage forms. Laboratory studies can be used to determine which of these factors actually have an influence on a particular drug product. 

Some excipients contain a certain amount of amorphous form such as spray-dried lactose,27 and others are hygroscopic, such as microcrystalline cellulose.28 These excipients will adsorb water, which causes a change in the micro-environment of the formulation. If the drug substance is moisture-sensitive, degradation may occur quickly. Therefore, consider both drug-excipient compatibility and excipient impurity profile in selecting excipients for low-dose drug products. 

An alternative to Plan A is to conduct two side-by-side studies by simultaneously placing samples from the same batch of drug product under the ICH conditions as well as the previously approved storage condition. The protocol containing the ICH storage conditions is considered an alternative to the approved protocol. This plan may prove to be particularly useful if the drug product is believed to be sensitive to moisture. 

As mentioned in the preceding section, moisture can affect the performance of the drug product and therefore a test for water may be required if the product demonstrates sensitivity to moisture. 

Dry compaction technique like roller compaction is experiencing renewed interest in the industry. There are a number of drug substances which are moisture sensitive and cannot be directly compressed. The roller compaction provides suitable alternative technology for processing these products. 

A good understanding of physicochemical properties of the active is required. An awareness of the drug and product stability profile (sensitivity to moisture, oxygen, light). 

Freeze-drying is one of the low-temperature drying techniques suitable for drying of highly heat-sensitive materials such as drugs, pharmaceutical, biological, and food products. Freeze-drying removes moisture captured inside the solids by sublimation of moisture from solid state (ice) to vapor state. 

---