Melting point and softening time of suppositories containing nonsteroidal anti-inflammatory drugs

Abstract

The melting point of lipophilic base mixtures for suppositories comprising confectionary fats with various surfactants including emulsifying cetostearyl alcohol type B (1 -10%), emulsifier T-2 (1 -5%), sodium lauryl sulfate (0.2 -5%), and phospholipid concentrate (0.1 -1%) has been investigated. It is established that these surfactants added in the indicated concentrations lead to depression of the melting point of confectionary fat. Introduction of suspended nonsteroidal anti-inflammatory drugs (NSAIDs) such as diclofenac sodium, analgin, paracetamol, naproxen, acetylsalicylic acid, and sodium salicylate to the aforementioned mixtures changed their melting points within 0.5 -3°C depending on the nature of the drug and excipient. The melting points of all investigated suppositories fell within 31.0 -36.3°C, thus obeying pharmacopoeial requirements. The softening time of all anti-inflammatory suppositories varied within 2 -11 min depending on the particular types of components and was within the pharmacopoeial limits. A comparative analysis of the variation of melting point and softening time of the NSAID suppositories showed no clear correlation between the two parameters in the indicated limits. The reported data can be used for selecting the optimum bases for suppositories and developing a common approach to the evaluation of the quality and performance characteristics of suppositories.