Evaluation between the Usability and Physicochemical Property of Acyclovir Ointments

A lot of prescription medicines have become switch over-the-counter (OTC) medicines. However, additives in brand-name drugs, generic drugs, and switch OTC drugs differ; therefore, the feelings associated with the use of these medicines vary for patients. The aim of this study was to compare the physicochemical properties and the feeling of use (assuming skin as an index of usability) of acyclovir (ACV) ointments. Five ACV ointments were used: ACV-A, a brand-name drug, ACV-B and ACV-C, generic drugs, and ACV-D and ACV-E, switch OTC drugs. The physicochemical properties were evaluated by determining the content uniformity, water content, flattening, viscosity and viscoelasticity, and near-infrared (NIR) absorption spectroscopy. Skin friction was measured to evaluate the feeling associated with use. Results of the content uniformity test indicated that the ACV content was uniform, and equivalence was observed. Measurement of moisture content indicated that this parameter differed in each ointment preparation. The yield value, which was calculated by measuring flattening, was 4416.7 dyne/cm² for ACV-A, 1175.7 dyne/cm² for ACV-B, 2114.9 dyne/cm² for ACV-C, 4234.5 dyne/cm² for ACV-D, and 3620.7 dyne/cm² for ACV-E. Measurement of viscosity and viscoelasticity revealed that viscosity increased with time and the viscoelasticity of each ointment. The second derivative of the NIR spectrum revealed that ACV-B and ACV-C had a wider spectrum of absorption than the other ointments. ACV-B had lesser friction than other ointments. These findings suggest that differences in the type and content of additives (macrogol) result in differences in the physicochemical properties of individual ointments.