Criteria for the selection of switch OTC drugs based on patient benefits, efficacy, and safety [II]: Comparing the physicochemical and pharmaceutical properties of brand-name and switch OTC terbinafine hydrochloride cream.

The physicochemical properties (pH, yield value, and squeeze force) of a drug for dermatomycosis, a terbinafine hydrochloride-containing cream (a brand-name product), and 12 over-the-counter drugs (OTCs) were measured and compared to ascertain the characteristics of each product. The pH of the brand-name product, Lamisil, was 4.1, and that of the OTC products ranged from 4.2 to 7.6; Lamisil Plus (7.6) had a significantly higher pH. Moreover, the yield value for Lamisil, as an index of cream ductility, was 128 dyn/cm, and that for the OTC products ranged from 110 to 887 dyn/cm. In particular, the OTC products Damalin (887 dyn/cm), Barriact (512 dyn/cm), and Exiv Deep (663 dyn/cm) had a significantly higher yield value. In addition, the squeeze force was measured by attaching a HapLog to the thumb and second finger. The squeeze force for Lamisil was 12.9 N, and that for the OTC products ranged from 1.8 to 14.6 N. The OTC product Bilumon (1.8 N) had a significantly lower squeeze force. These results indicated that there were marked differences in the pharmaceutical properties of brand-name and OTC products. External preparations are characterized by their feel during use. Based on the current results, the pharmaceutical characteristics of drugs resulted in differences in their feel during use, suggesting that products appropriate for individual patients can be recommended.