Effect of isopropyl myristate on the viscoelasticity and drug release of a drug-in-adhesive transdermal patch containing blonanserin

The purpose of this study was to investigate the effect of isopropyl myristate (IPM), a penetration enhancer, on the viscoelasticity and drug release of a drug-in-adhesive transdermal patch containing blonanserin. The patches were prepared with DURO-TAK® 87-2287 as a pressure-sensitive adhesive (PSA) containing 5% (w/w) of blonanserin and different concentrations of IPM. An in vitro release experiment was performed and the adhesive performance of the drug-in-adhesive patches with different concentrations of IPM was evaluated by a rolling ball tack test and a shear-adhesion test. The glass transition temperature (Tg) and rheological parameters of the drug-in-adhesive layers were determined to study the effect of IPM on the mechanical properties of the PSA. The results of the in vitro release experiment showed that the release rate of blonanserin increased with an increasing concentration of IPM. The rolling ball tack test and shear-adhesion test showed decreasing values with increasing IPM concentration. The results were interpreted on the basis of the IPM-induced plasticization of the PSA, as evidenced by a depression of the glass transition temperature and a decrease in the elastic modulus. In conclusion, IPM acted as a plasticizer on DURO-TAK® 87-2287, and it increased the release of blonanserin and affected the adhesive properties of the PSA.

Isopropyl myristate (IPM), a commonly used penetration enhancer, can act as a plasticizer on Duro-TAK® 87-2287. The plasticization effect caused an enhancement of drug release, an increase in the tack and a decrease in the shear-adhesion of the transdermal patch.