Novel montelukast sodium-loaded clear oral solution prepared with hydroxypropyl-β-cyclodextrin as a solubilizer and stabilizer: Enhanced stability and bioequivalence to commercial granules in rats

To develop a montelukast sodium-loaded clear oral solution with enhanced stability that was bioequivalent to commercial granules in rats for the treatment of asthma, various montelukast sodium-loaded solutions were prepared with various amounts of solubilizers and stabilizer, and their solubility and stability were investigated. Furthermore, the dissolution and pharmacokinetic studies were carried out in rats with the optimised formulation and the commercial montelukast sodium-loaded granules. Among the solubilizers tested in this study, hydroxypropyl-β-cyclodextrin (HP-β-CD) was selected because it greatly improved the drug solubility and stability. Furthermore, EDTA sodium was used as a stabilizer because it gave excellent stability. In particular, the montelukast-loaded oral solution, an aqueous clear solution containing montelukast sodium, HP-β-CD, methylparaben sodium, propylparaben sodium and EDTA sodium at w/v percentages of 1.04/156/1.8/0.2/1, gave similar dissolution to the commercial granules in 0.5 % (w/v) sodium lauryl sulphate in water, FDA-regulated dissolution medium. This oral solution gave similar plasma concentrations and pharmacokinetic parameters to the commercial granules, suggesting that it was bioequivalent to the commercial granules in rats. Moreover, it was physically and chemically stable at 25 °C/60 % RH and 40 °C/75 % RH for at least 12 months. Thus, this oral solution is strongly recommended as an alternative to the oral montelukast-loaded product for the treatment of asthma.