Spatial separation of different drug substances in one microneedle array patch by combining inkjet printing and micromolding technology

Transdermal drug delivery using microneedle array patches has been investigated using a wide range of drug substances. Inkjet printing and micromolding are established methods for the production of microneedle array patches and both were used to combine lisinopril embedded in povidone and ibuprofen in Eudragit® RS / RL in a single patch. Dissolution studies, visual inspection, mechanical strength and insertion into an artificial skin membrane model were investigated. A clear spatial separation of the polymers / drugs was observed. Microneedle array patches containing povidone and Eudragit® RS / RL showed a height reduction below 10 %. 97.14 ± 3.76 % of the microneedles made of povidone and Eudragit® RS and 97.50 ± 2.13 % made of povidone and Eudragit® RL pierced the second layer of Parafilm® M. This indicated a sufficient insertion into the membrane model. 132.14 ± 47.47 µg (Eudragit® RS) and 135.02 ± 3.34 µg (Eudragit® RL) lisinopril has been dissolved after 9 min. It was possible to vary the dissolution of ibuprofen using both types of Eudragit®. 211.80 ± 22.98 µg ibuprofen were dissolved after 24 h (Eudragit® RS) and 445.16 ± 9.98 µg after 6 h (Eudragit® RL). The microneedles successfully pierced human skin and both drug substances permeated across it. This could lead to an interesting approach to combining incompatible drugs in one patch.