Development of an UPLC-MS/MS micromethod for quantitation of cinitapride in plasma and its application in a pharmacokinetic interaction trial.

AIM: Cinitapride (CIN) is a benzamide-derived molecule used for the treatment of gastroesophageal reflux and dyspepsia. Its pharmacokinetics are controversial due to the use of supratherapeutic doses and the lack of sensitive methodology. Therefore, a sensitive and accurate micromethod was developed for its quantitation in human plasma. RESULTS: CIN was extracted from 300 µl of heparinized plasma by liquid-liquid extraction using cisapride as internal standard, and analyzed with an ultra performance liquid chromatograph employing positive multiple-reaction monitoring-MS. CONCLUSION: The method proved to be rapid, accurate and stable within a range between 50 and 2000 pg/ml and was successfully validated and applied in a pharmacokinetic interaction trial, where it was demonstrated that oral co-administration of simethicone does not modify the bioavailability of CIN.

Ciprofloxacin bioavailability is enhanced by oral co-administration with phenazopyridine: a pharmacokinetic study in a Mexican population.

BACKGROUND: and objective: In Mexico, urinary tract infections (UTIs) constitute the second most frequent type of infections treated at primary-care clinics. Ciprofloxacin has played a major role in the treatment of UTIs because it has a broad spectrum of antibacterial activity. In addition to antimicrobial agents, phenazopyridine has been used to alleviate symptoms that occur during episodes of UTI. Thus, the present study was designed to compare the pharmacokinetic behaviour of ciprofloxacin administered alone versus ciprofloxacin combined with phenazopyridine. PATIENTS AND METHODS: Twenty-four healthy male Mexican volunteers participated in this project. The study was carried out with a single oral dose of ciprofloxacin 500mg. The double-blind, crossover, randomised, balanced trial design comprised two treatments, two periods and two sequences. After administration of the study medication, serial blood samples were collected for a period of 12 hours. The harvested plasma was analysed for ciprofloxacin by high-performance liquid chromatography. The area under the concentration-time curve to last measurable concentration (AUC(t)), area under the concentration-time curve extrapolated to infinity (AUC(infinity)), peak plasma concentration (C(max)), time to reach C(max) (t(max)), mean residence time (MRT), elimination constant (k(e)) and elimination half-life (t(1/2)) were determined from plasma concentrations of both treatments and considered as primary variables for statistical analysis. RESULTS: While there were no differences between the two treatments in terms of C(max) and k(e), AUC(t )and AUC(infinity) were 35% and 29% higher, respectively, in the combined treatment arm. Moreover, a significant delay in t(max )(from 1 to 1.5 hours) and a statistical increase of 29% in MRT were also observed with phenazopyridine co-administration. CONCLUSION: Oral co-administration of phenazopyridine increases ciprofloxacin bioavailability with regard to the amount absorbed (AUC) and permanence in the body (MRT), which could be useful during treatment.

Bioequivalence evaluation of two brands of meloxicam tablets (Promotion and Mobicox): pharmacokinetics in a healthy female Mexican population.

We conducted a randomized, crossover study in 23 healthy young female volunteers to compare the bioavailability of two brands of meloxicam (7.5 mg) tablets and to obtain pharmacokinetic parameters of this molecule in Mexican population not reported previously. Two tablets (15 mg) were administered as a single dose on 2 treatment days separated by a 1-week washout period. After dosing, serial blood samples were collected for a period of 72 h. Plasma harvested was analyzed for meloxicam by a modified and validated high-performance liquid chromatography (HPLC) method previously reported. Pharmacokinetic parameters AUC(0-t), AUC(0-alpha), C(max), T(max), k(e), MRT and t(1/2) were determined from plasma concentrations of both formulations, resulting in a C(max) 120% larger than and a T(max) 65% faster than those reported in other populations. AUC(0-t), AUC(0-alpha), and C(max) were statistically tested for bioequivalence after log transformation data in a non-balanced design, and no significant differences were found either in 90% classical confidence interval (90% CI) or in Schuirmann test (p < 0.05); thus, we concluded that bioequivalence existed between both formulations.

Bioequivalence evaluation of two brands of ketoconazole tablets (Onofin-K and Nizoral) in a healthy female Mexican population.

A randomized, crossover study was conducted in 24 healthy female volunteers to compare the bioavailability of two brands of ketoconazole (200 mg) tablets; Onofin-K (Farmacéuticos Rayere S.A., Mexico) as the test and Nizoral (Janssen-Cilag, Mexico) as the reference products. The study was performed at the Clinical Pharmacology Research Center of the Hospital General de Mexico in Mexico City. Two tablets (400 mg) were administered as a single dose with 250 ml of water after a 12 h overnight fast on two treatment days separated by a 1 week washout period. After dosing, serial blood samples were collected for a period of 12 h. Plasma harvested was analysed for ketoconazole by a modified and validated HPLC method with UV detection in the range 400-14000 ng/ml, using 200 microl of plasma in a full-run time of 2.5 min. The pharmacokinetic parameters AUC(0-t), AUC(0-alpha), Cmax, Tmax and t(1/2) were determined from plasma concentrations of both formulations and the results discussed. AUC(0-t), AUC(0-alpha) and Cmax were tested for bioequivalence after log transformation of data, and no significant differences were found either in 90% classic confidence interval or in the Anderson and Hauck test (p < 0.05). Based on statistical analysis, it is concluded that Onofin-K is bioequivalent to Nizoral.