Generic selection criteria for safety and patient benefit [VII]: Comparing the physicochemical and pharmaceutical properties of brand-name and generic terbinafine hydrochloride cream.

Abstract

We measured and compared the physicochemical properties (pH, yield value, and squeeze force) of a drug for dermatomycosis, terbinafine hydrochloride-containing cream (brand-name product), and 12 generic products to clarify the characteristics of each product. On pH measurement, the pH value of the brand-name product, Lamisil, was 4.8, and those of the generic products ranged from 4.3 to 5.5, showing no marked difference. Furthermore, the yield value of Lamisil, as an index of cream ductility, was 122.2 dyn/cm2, and those of the generic products ranged from 42.1 to 1,621.5 dyn/cm2. In particular, the value of a generic product, Taiyo (42.1 dyn/cm2), was significantly lower, whereas that of another one, Viras (1,621.0 dyn/cm2), was significantly higher. In addition, the squeeze force was measured by attaching a HapLog® to the thumb and second finger. The value of Lamisil was 12.9 N, and those of the generic products ranged from 8.0 to 15.4 N. The values of generic products, Mylan (8.6 N), Tebinaceil (9.0 N), and Kelger (8.0 N), were significantly lower, whereas that of another one, Viras (15.4 N), was significantly higher. These results showed that there were marked differences in the pharmaceutical properties between the generic and brand-name products. The above pharmaceutical characteristics of drugs facilitated the presentation of reasons for differences in the sense of use, which characterizes external preparations, suggesting that products appropriate for individual patients can be recommended.