Stability of Clonazepam Suspension in HSC Vehicle

The stability of clonazepam as an extemporaneous suspension compounded from tablets was studied. The clonazepam suspension (0.1 mg/mL) was prepared by incorporating pulverized 0.5-mg clonazepam tablets into the suspending Hospital for Sick children (HSC) Vehicle containing simple syrup and methylcellulose. This vehicle is also prepared extemporaneously. A clonazepam suspension and a clonazepam solution, both prepared in HSC Vehicle, were analyzed at various times during the 60-day study period against a clonazepam standard acetonitrile solutions stored in glass. These preparations using HSC Vehicle were stored at 4*C in a polyvinyl chloride (PVC) amber-colored plastic bottle. At various times during the 60 day study period, three samples from each bottle were removed and the concentration of clonazepam determined by a high-performance liquid chromatography assay procedure. This stability study demonstrates that storage of clonazepam suspension is safe for at least 60 days in a PVC bottle at 4*C, while the HSC solution rapidly loses the active ingredient by adsorption onto the plastic matrix due to the immediate availability towards the PVC.