Physicochemical and Microbiological Stability of Compounded Bethanechol Chloride Oral Suspensions in PCCA Base, SuspendIt®.

Abstract

Bethanechol chloride is a cholinergic agent used to treat acute postoperative and postpartum nonobstructive (functional) urinary retention and for neurogenic atony of the urinary bladder with retention. It is available in the United States as tablets for oral administration in four dosage strengths: 5 mg, 10 mg, 25 mg, and 50 mg. A review of the therapeutic uses of bethanechol chloride reveals the need for flexibility in dosing. This flexibility is readily achieved using an oral liquid dosage form. However, no commercial liquid dosage form of bethanechol chloride currently exists. An extemporaneously compounded suspension from pure drug powder or commercial tablets would provide a flexible, customizable option to meet unique patient needs with convenient and accurate dosing options. The purpose of this study was to determine the physicochemical and microbiological stability of extemporaneously compounded bethanechol chloride suspensions using two brands of commercially available tablets (Amneal and Upsher-Smith) in the PCCA Base, SuspendIt. This base is a sugar-free, paraben-free, dye-free, and gluten-free thixotropic vehicle containing a natural sweetener obtained from the monk fruit. The study design included two bethanechol chloride concentrations to provide stability documentation over a bracketed concentration range for eventual use by compounding pharmacists. A robust stability-indicating ultra-high-performance liquid chromatographic assay for the determination of the chemical stability of bethanechol chloride in PCCA SuspendIt was validated. Suspensions of bethanechol chloride were prepared from the tablets in PCCA SuspendIt at 1-mg/mL and 5-mg/mL concentrations, selected to represent a range within which the drug is commonly dosed. Samples were stored in amber plastic prescription bottles at room temperature (25°C). Samples were assayed initially, and on the following time points (days): 14, 30, 60, 90, and 180. Physical data such as pH and appearance were also noted. Microbiological stability was tested. A stable extemporaneous product is defined as one that retains at least 90% of the initial drug concentration throughout the sampling period and is protected against microbial growth. Using this criterion, no significant degradation of the bethanechol chloride was observed over the 180-day test period for either concentration at room temperature. Drug concentrations were at, or above 93% of initial values for both brands of commercially available tablets. No microbial growth was observed. pH values remained fairly constant. This study demonstrates that bethanechol chloride tablets are physically, chemically, and microbiologically stable in PCCA SuspendIt for 180 days at room temperature at both concentrations studied, thus providing a viable, compounded alternative for bethanechol chloride in a liquid dosage form, with an extended BUD to meet patient needs.