STABILIZATION OF AQUEOUS THYMOXAMINE USING DIMETHYL-BETA-CYCLODEXTRIN

Moxisylyte (or thymoxamine) is an alpha-adrenoceptor blocking agent us ed to reverse mydriasis. The drug molecule has an ester moiety which i s vulnerable to acid and base catalyzed hydrolysis. Long-term storage of the drug at room temperature has not been possible because of this hydrolysis. An accelerated, stability-indicating assay was developed t o study the hydrolysis and modify the formulation for room temperature storage (instead of refrigeration). Stability studies with pH variati on and with beta-cyclodextrins resulted in a formulation with dimethyl -beta-cyclodextrin at pH 5.0. All other available beta-cyclodextrins e ither accelerated the hydrolysis or had little effect.