Formulation and evaluation of lyophilized wafers of rizatriptan benzoate
Migraine is a headache of varying intensity often accompanied by nausea and sensitivity to light and sun. The present investigation deals with the formulation and evaluation of oral wafer of rizatriptan benzoate which is used for the treatment of migraine. The wafer formulation was prepared by freeze-drying an aqueous solution of rizatriptan benzoate containing various hydrophilic polymers like hydroxypropyl methylcellulose E3, hydroxypropyl cellulose EF, maltodextrin and polyvinyl alcohol as matrix formers. The formulations were evaluated for parameters like physicochemical properties, compatibility, glass-transition temperature, in vitro release, and stability. The physicochemical compatibility of the drug and the polymers was studied by infrared spectroscopy and differential scanning calorimetry. The results revealed no physical and chemical incompatibility between the drug and the excipients employed. The prepared formulations were evaluated for different physicochemical properties like appearance, thickness, weight variation, friability, loss on drying, drug content, disintegration time and wetting volume. Scanning electron microscopy studies were carried out on the optimized formulations to study the internal structure of the lyophilized wafer systems. In vitro release data showed that more than 90% of the drug dissolved within 5 min. All formulations were found to be stable after doing one-month stability studies under accelerated conditions (40°C and 75% relative humidity) without significant alteration in physical appearance and drug content. It was concluded that formulations containing hydroxypropyl methylcellulose E3 produced optimized results.