Compositions for nasal drug delivery, methods of making same, and methods of removing residual solvent from pharmaceutical preparations

A process for making an intranasal drug delivery system comprising gelatin microspheres in combination with a drug intended for intranasal delivery, said process comprising:

• a) preparing a low-salt or salt-free aqueous solution of gelatin and the drug to be delivered, at a temperature above the gelation temperature of the gelatin;
• b) preparing a solution of a suitable oil and a suitable surfactant;
• c) emulsifying a mixture of the solution of step (a) and the solution of step (b) to generate a water-in-oil emulsion wherein the volume ratio of (a):(b) is between 1:2 and 1:10;
• d) continuing emulsification until the target droplet size is achieved;
• e) reducing the temperature of said emulsion to below the gelation temperature of the gelatin at a controlled rapid rate to achieve gelation before droplet coalescence, thus allowing the formation of gelatin microspheres associated with drug at the desired particle size;
• the emulsion in steps (c, d) and (e) above being mixed at the maximum rate consistent with a low-vortex or vortex-free circulation pattern;
• f) separating the drug-containing microspheres from the oil/surfactant phase;
• and
• g) dehydrating the drug-containing microspheres to produce a dry powder.