Pharmacokinetics and Bioequivalence Study of Hydroxychloroquine Sulfate Tablets in Chinese Healthy Volunteers by LC-MS/MS.

INTRODUCTION: Hydroxychloroquine (HCQ), 4-aminoquinoline, is an antimalarial drug and has become a basic therapy for rheumatic disease treatment. It can stabilize the condition of SLE patients and reduce the chances of patient relapse through its immunosuppressive function and antiinflammatory effects. This drug was absorbed completely and rapidly by oral administration, but has a prolonged half-life for elimination. The objective of this study was to evaluate the pharmacokinetic parameters and relative bioequivalence of a new generic (test) formulation with the branded (reference) formulation of HCQ in healthy Chinese male volunteers. This study was designed to acquire regulatory approval for the test formulation. METHODS: This study was conducted with a randomized, single-dose, two-period, and crossover design. The male subjects were randomly assigned to two groups at a 1:1 ratio to receive 0.2 g hydroxychloroquine sulfate tablets (0.1 g/piece) of the two formulations after a 3-month washout period then administered the alternate formulation. Study drugs were administered after overnight fasting (over 10 h). Plasma concentrations of hydroxychloroquine were measured by a validated LC-MS/MS method. The following pharmacokinetic properties were determined by a noncompartmental pharmacokinetic method: C max, T max, AUC0-t , AUC0-∝, and t 1/2. The bioequivalence between the test and reference products was assessed based on the following parameters: C max, AUC0-60d, and AUC0-∝ using the ANOVA method. If the 90% CI for AUC0-t was within 80-125% and for C max was within 70-143% of the statistical interval proposed by the SFDA, the two formulations were assumed bioequivalent. Concerning the main pharmacokinetic charateristics of hydroxychloroquine, a long half-life drug, the pharmacokinetic parameters of 0-72 h were determined according to the FDA. Furthermore, a comparison was made between the parameters at 0-60 days and 0-72 h to evaluate whether a truncated AUC method can be applied to estimate the relative bioavailability of HCQ. Tolerability was assessed by monitoring vital signs and laboratory tests and by questioning subjects about adverse events. RESULTS: The 90% CI of C max for HCQ is 103.8-142.3%; the AUC0-60 is 100-114.2% and AUC0-∝ 100-115.5%. Both met the criteria according to the SFDA's guidelines for bioequivalence. The relative bioavailability was 109.5% (according to AUC0-60d) and 110.7% (according to AUC0-∝). No serious or unexpected adverse events were observed. CONCLUSIONS: In this study, the pharmacokinetic studies and results were conducted so that the test and reference formulations of HCQ met the Chinese criteria for assuming bioequivalence. Both formulations were well tolerated in the population studies.

Modulation of pharmacokinetics of theophylline by antofloxacin, a novel 8-amino-fluoroquinolone, in humans.

AIM: To evaluate the pharmacokinetic interactions between theophylline and antofloxacin in vivo and in vitro. METHODS: A randomized, 5-day treatment and 3-way crossover design was documented in 12 healthy subjects. The subjects were orally administered with antofloxacin (400 mg on d 1 and 200 mg on d 2 to 5), theophylline (100 mg twice a day and morning dose 200 mg on d 1 and 5), or theophylline plus antofloxacin. The plasma and urinary pharmacokinetics of antofloxacin and theophylline were characterized after the first and last dose. The effect of antofloxacin on theophylline metabolism was also investigated in pooled human liver microsomes. RESULTS: The 5-day treatment with antofloxacin significantly increased the area of the plasma concentration-time curve and peak plasma concentration of theophylline, accompanied by a decrease in the excretion of theophylline metabolites. On the contrary, theophylline did not affect the pharmacokinetics of antofloxacin. In vitro studies using pooled human hepatic microsomes demonstrated that antofloxacin was a weak reversible and mechanism-based inhibitor of CYP1A2. The clinical interaction between theophylline and antofloxacin was further validated by the in vitro results. CONCLUSION: The results showed that antofloxacin increases the plasma theophylline concentration, partly by acting as a mechanism-based inhibitor of CYP1A2.

[The protective effects of ginsenoside RG1 and Rb1 against damage of HaCaT cells by ultraviolet B].

AIM: To investigate the survival rate and the level of HaCaT cells damage with ultraviolet B (UVB) radiation at various doses, and observe the protective effects of ginsenoside Rg1 and Rb1 in vitro. METHODS: MTT assay was employed to analyze the cell survival rate after UVB radiation of 30, 60, 90 and 120 mJ x cm(-2). The damage of nucleolus and the protective effects of ginsenoside Rg1 and Rb1 were scanned by Hoechst 33258 staining and single cell gel electrophoresis assay (SCGE). RESULTS: It was found that the cell survival rate decreased gradually and the damage of nucleolus aggravated as the radiation dose increased from 30 mJ x cm(-2) to 120 mJ x cm(-2). At the dose of 20 microg x mL(1-), obvious protective effect of ginsenoside Rg1 and Rb1 can be observed against UVB radiation-induced HaCaT cells growth inhibition and nucleolus damage. CONCLUSION: UVB radiation inhibits HaCaT human keratinocytes growth and ginsenoside Rg1 and Rb1 can relief the damage.