Nifedipine (1), a drug practically insoluble in water, has been solubilized employing sodium benzoate (2) and sodium salicylate (3) as hydrotropes. In 30% w/v 2 solution the solubility of 1 increased 85 and 76 fold at 25 +/- 1 degree C and at 37 +/- 1 degree C respectively. The corresponding increase in solubility of 1 in 30% w/v 3 solution was 135 and 107 fold respectively. To study the mechanism of hydrotropic solubilization of 1, the solution properties of 2 and 3 over a concentration range of 1 to 30% w/v were undertaken. The probable mechanism involves a complexation type of interaction at a low concentration of hydrotrope, aggregation of the hydrotropic molecules and inclusion of 1 in these aggregates at high concentration; and structural changes in water caused by hydrotropes.

Benzoates↗

PubMed1988

Formulation and evaluation of nifedipine injection.

An attempt has been made to formulate a stable, aqueous injection of nifedipine (1) using the technique of hydrotropic solubilization. Sodium benzoate (2; 30% w/v) and sodium salicylate (3; 30% w/v) have been employed as the vehicle to prepare the injection of 1 in 1 mg/5 ml and 1 mg/2 ml concentration in either case. An accelerated stability study for 4 weeks at 8 degrees C, room temperature, 40 and 50 degrees C indicates maximum stability at 8 degrees C, suggesting the need of storage with refrigeration. Light stability study in the specially designed chamber indicates that covering the ampoules with black chart paper affords adequate stability to the 1 injection. The injections are also stable to autoclaving. Preliminary in vivo study in rats shows that the injection is effective.

Animals↗

PubMed1987

Salmonella typhi meningitis.

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Child, Preschool↗