Present invention discloses an improved and commercially viable process for the preparation of rizatriptan benzoate of formula-I. According to the present process the hydrazone intermediate derived from the phenylhydrazine of formula-Ill and 4-dimethylaminobutyraldehyde diethyl acetal is gradually heated to 60-70°C in aqueous sulfuric acid medium and maintained for 3-4hr to get rizatriptan with less dimeric impurity of formula-X. The resultant rizatriptan is isolated and converted into the pharmaceutical^ acceptable benzoate salt. Present process produces less percentage of dimeric (less than 3%) or polymeric impurities compared to the prior art process and more yield of rizatriptan. Rizatriptan benzoate produced according to the present process has more than 99.5% purity with less than 0.1% dimeric impurity of formula-X by HPLC. Rizatriptan benzoate is useful for the treatment of migraine.
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