Characterization, stability, and pharmacokinetics of sibutramine/β-cyclodextrin inclusion complex

β-Cyclodextrin (β-CD) is widely used to increase the stability, solubility, and bioavailability of poorly soluble drugs because of the appropriate size of its cavity. Sibutramine is a neurotransmitter reuptake inhibitor that has been investigated as an oral anorexiant. Here we report the complexation of sibutramine base with β-CD and the stability, dissolution, and pharmacokinetic properties of the sibutramine/CD complex. The formation of sibutramine/β-CD inclusion complexes is confirmed using differential scanning calorimetry, X-ray diffractometry, and 1H nuclear magnetic resonance. The thermal and photochemical stability of sibutramine is significantly improved by the complexation with β-CD, and the pharmacokinetic parameters (e.g., the plasma concentration, area under the curve, and maximum concentration of two active metabolites) for humans are comparable with those of the commercialized standard product (Reductil®). Our study suggests that sibutramine/β-CD complexation can be of great use to increase the stability and biological efficacy of sibutramine base.