Stability of Compounded Diltiazem Hydrochloride in Cream, Ointment, and Gel Formulations for Topical Use

Abstract

Interest in the topical use of compounded diltiazem has increased. Published information on the stability of such products is scarce. The objective of this study was to investigate the stability of diltiazem hydrochloride compounded in cream (Glaxal Base), ointment (white petrolatum), and hydroxyethyl cellulose-based gel over 90 days at room (23°C), refrigerator (4°C), and elevated (40°C) temperatures, stored in white plastic and glass amber containers. Organoleptic properties, pH changes, and United States Pharmacopeia recommendations were used for assigning beyond-use-dates. The results showed that the currently recommended United States Pharmacopeia beyond-use date of 30 days is acceptable for diltiazem (2%) in Glaxal Base at 4°C and 23°C in either white plastic or glass amber jars. The cream, however, is not recommended for use if exposed to elevated temperatures (40°C) in white plastic jars but may be used within 7 days if stored in glass amber jars. A beyond-use date of 90 days for diltiazem (2%) hydroxyethyl cellulose-based gel, when maintained at 4°C or 23°C, in either white plastic or glass amber jars, is recommended. Gels exposed to elevated temperatures (40°C) should be used within14 and 30 days in glass amber and white plastic jars, respectively. Lastly, a BUD of 90 days for diltiazem (2%) ointment (white petrolatum) at 23°C stored in either jar type is acceptable. Ointment formulations exposed to elevated temperatures (40°C) may be used within 7 days in white plastic jars. Diltiazem (2%) in white petrolatum should not be stored at 4°C.