Oral sustained-release suspension based on a lauryl sulfate salt/complex.

The objective of this study was to evaluate the feasibility of lauryl sulfate (LS) salt/complex as a novel carrier in oral sustained-release suspensions. Mirabegron, which has a pH-dependent solubility, was selected as the model drug. Sodium lauryl sulfate (SLS) was bound to mirabegron in a stoichiometric manner to form an LS salt/complex. LS salt/complex formulation significantly reduced the solubility of mirabegron and helped mirabegron achieve sustained-release over a wide range of pH conditions. Microparticles containing the LS salt/complex were prepared by spray drying with the aqueous dispersion of ethylcellulose (Aquacoat(®) ECD). The diameter of the microparticles was less than 200μm, which will help avoid a gritty taste. In vitro results indicated the microparticles had slower dissolution profiles than the LS salt/complex. The dissolution rate could be controlled flexibly by changing the amount of Aquacoat(®) ECD. The microparticle suspension retained the desired sustained-release property and dissolution profile after being stored for 30days at 40°C. In addition, the suspension displayed sustained-release behavior in dogs without a pronounced Cmax peak, which will help prevent side effects. These results suggest that microparticles containing LS salt/complex may be useful as a novel sustained-release suspension for oral delivery.