Pharmacoat 615

Glimepiride (Actavis, Leskovac, Serbia, chemical structure shown in Figure 1), was used as a poorly soluble drug. Two grades of hydroxypropyl cellulose-HPC-SL and HPC-L (Nisso HPC, Nippon Soda Co., Tokyo, Japan) and hypromellose (HPMC)-Pharmacoat^® 603 and Pharmacoat^® 615 (Shin-Etsu Chemical Co., Ltd., Tokyo, Japan), differing in viscosity, poloxamer 188 (Kolliphor™ P 188 micro, BASF, Ludwigshafen, Germany), polyvinylpyrrolidone K25 (PVP K25-Kollidon^® 25, BASF, Ludwigshafen, Germany) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus^®, BASF, Ludwigshafen, Germany) were tested as potential nanosuspension stabilizers. Mannitol (Pearlitol^® 160 C, Roquette Frères, Lestrem, France) was used as a matrix former for spray drying of the nanosuspension in order to prevent aggregation of glimepiride nanocrystals during solidification process.

For preparation of the inks, metoprolol tartrate (MPT, Microsin, Bucharest, Romania) was weighed and dissolved in the appropriate volume of the water under stirring at ambient temperature. In case of drug-free inks, this step was skipped. Poloxamer 407 (P407, Lutrol^® F 127, BASF, Ludwigshafen, Germany), hypromellose (HPMC, Pharmacoat^® 615, Shin-Etsu Chemical, Tokyo, Japan) and glycerol 85% (Caesar & Loretz, Hilden, Germany) were added in various combinations, modifying the fluid’s properties (Table 1).