Cloud Point Modulation of an Antidepressant Drug Imipramine Hydrochloride with Pharmaceutical Excipients and the Thermodynamics Thereon

This article is focused on the influence of surfactants and polymers (which are used extensively in drug delivery as drug carriers) on the cloud point (CP) of an amphiphilic drug imipramine hydrochloride (IMP). The cloud points of IMP solutions were determined visually. Surfactants and polymers were added to know their effect on the cloud point of the drug prepared in cetyltrimethylammonium bromide (CTAB) and sodium phosphate buffer (pH = 6.7). Anionic surfactants show a peaked behavior, whereas cationic (conventional as well as gemini) and nonionic surfactants show continuous increase. The behavior with polymers is dictated by the number of monomer units present in a particular polymer. The thermodynamic parameters are evaluated: whereas Delta G c degrees is found to be negative, Delta H c degrees and T Delta S c degrees values are negative as well as positive (depending upon type and nature of additive). [Supplement materials are available for this article. Go to the publisher's online edition of the Journal of Dispersion Science and Technology to View the free supplemental file.]