Pharmacokinetic study of the prokinetic compounds meranzin hydrate and ferulic acid following oral administration of Chaihu-Shugan-San to patients with functional dyspepsia

Aim of the study: The prokinetic activity of ferulic acid derived from Ligusticum chuanxiong hort in the Chaihu-Shugan-San formula has been shown to be similar to Chaihu-Shugan-San, a popular traditional Chinese medicine for treating functional dyspepsia. The effects of meranzin hydrate, a compound isolated from Fructus aurantii in the Chaihu-Shugan-San formula, are unclear, as the pharmacokinetics have never been studied in patients with functional dyspepsia. This study aimed to describe the pharmacokinetics of ferulic acid and merazin hydrate by evaluating the prokinetics induced by Chaihu-Shugan-San and meranzin hydrate. Materials and methods: Gastric emptying and intestinal transit were measured after oral administration of a single dose of Chaihu-Shugan-San or meranzin hydrate in rats. The tone of rat ileum was selected as direct evidence of the prokinetic activity of meranzin hydrate. Patients with functional dyspepsia were recruited, and meranzin hydrate and ferulic acid were identified by ultra performance liquid chromatography with tandem mass spectrometry in the plasma of patients following a single oral administration of Chaihu-Shugan-San. The resulting pharmacokinetic properties were determined by ultra performance liquid chromatography coupled to photo diode array. Results: In rats, single doses of Chaihu-Shugan-San (20 g/kg) and meranzin hydrate (28 mg/kg) significantly accelerated gastric emptying and intestinal transit (Chaihu-Shugan-San: 68.9 +/- 5.6% and 72.3 +/- 4.7%, meranzin hydrate: 72.9 +/- 3.8% and 75.2 +/- 3.1%) compared with the control (55.45 +/- 3.7% and 63.51 +/- 5.1%, P < 0.05), showing similar results as cisapride (69.6 +/- 4.8% and 71.6 +/- 6.3%). Meranzin hydrate (30, 100 mu mol/L) directly increased the amplitude of rat ileum compared with the control (P < 0.01). The pharmacokinetics profiles of meranzin hydrate and ferulic acid in patient plasma was fitted with a two-compartment model detected by a simple, rapid and accurate UPLC method. Time to reach peak concentration of meranzin hydrate (0.371 mg/L) and ferulic acid (0.199 mg/L) was 23.57 min and 27.50 min, respectively. The elimination half-life and area under the concentration-time curve from t = 0 to the last time of meranzin hydrate and ferulic acid were 139.53 min and 31.445 mu g min/mL and 131.27 min and 14.835 mu g min/mL, respectively. The absorption constant and volume of distribution of meranzin hydrate and ferulic acid were 0.185 +/- 0.065 min(-1) and 3782.89 +/- 2686.72 L/kg and 0.524 +/- 0.157 min(-1) and 11713 +/- 7618.68 L/kg, respectively. The experimental results of the pharmacokinetic parameters of meranzin hydrate and ferulic acid indicate that they were absorbed and distributed rapidly. The pharmacodynamics and pharmacokinetics of prokinetic Chaihu-Shugan-San and its compounds are useful for monitoring Chaihu-Shugan-San formulas in clinical practice and for understanding therapeutic mechanisms. (C) 2011 Elsevier Ireland Ltd. All rights reserved.