Comparative bioavailability study of cefuroxime axetil (equivalent to 500 mg cefuroxime/tablet) tablets (Zednad® versus Zinnat®) in healthy male volunteers.

This study was performed to investigate the bioequivalence of cefuroxime axetil tablets between a generic test product (A) Zednad® Tablet (500 mg cefuroxime/ tablet, Diamond Pharma, Syria), and the Reference Product (B) Zinnat® Tablet (500 mg cefuroxime/tablet, GlaxoSmithKline, Saudi Arabia). The bioavailability study was carried out for 24 healthy male volunteers. The subjects received 1 Zednad® Tablet (500 mg/ tablet) and 1 Zinnat® Tablet (500 mg/tablet) in a randomized, two-way crossover design fashion on 2 treatment days, after an overnight fast of at least 10 h, with a washout period of 7 days. 24 volunteers plus 2 alternatives completed the crossover. The bioanalysis of clinical plasma samples was accomplished by HPLC method, which was developed and validated in accordance with international guidelines. Pharmacokinetic parameters, determined by standard non-compartmental methods, and ANOVA statistics were calculated using SAS Statistical Software. The significance of a sequence effect was tested using the subjects nested in sequence as the error term. The 90% confidence intervals for the ratio between the test and reference product pharmacokinetic parameters of AUC0→t, AUC0→∞, and Cmax were calculated and found to be within the confidence limits of 80.00 - 125.00% for AUC0→t, AUC0→∞ and Cmax. The study demonstrated that the test product (A) was found bioequivalent to the reference product (B) following an oral dose of 500 mg tablet. Therefore, the two formulations were considered to be bioequivalent.

Comparative bioavailability study of cefixime (equivalent to 100 mg/5 ml) suspension (Winex vs Suprax) in healthy male volunteers.

This investigation was carried out to evaluate the bioavailability of a new suspension formulation of cefixime (100 mg/5 ml), Winex, relative to the reference product, Suprax (100 mg/5 ml) suspension. The bio-availability study was carried out in 24 healthy male volunteers who received a single oral dose (200 mg) of the test (A) and the reference (B) products on 2 treatment days after an overnight fast of at least 10 hours. The treatment periods were separated by a one-week washout period. A randomized, balanced two-way crossover design was used. After dosing, serial blood samples were collected over a period of 16 hours. Plasma concentrations of cefixime were analyzed using a sensitive high-performance liquid chromatographic assay. The pharmacokinetic parameters for cefixime were determined using standard non-compartmental method. The parameters AUC(0-t), AUC(0-infinity), Cmax, Kel, t1/2 and Cmax/AUC(0-infinity) were analyzed statistically using raw and log-transformed data. The time to maximum concentration (tmax) was analyzed using raw data. The parametric 90% confidence intervals of the mean values of the pnfinity harmacokinetic parameters: AUC(0-t), AUC(0-infinity) Cmax, and Cmax/AUC(0-infinity) were within the range 80 - 125% which is acceptable for bioequivalence (using log-transformed data). The calculated 90% confidence intervals based on the ANOVA analysis for the mean test/reference ratios of AUC(0-t), AUC(0-infinity), Cmax, and Cmax/AUC(0-infinity) were 88.93 - 107.10%, 89.09 - 107.11%, 89.63 - 108.58% and 96.85 - 105.29%, respectively. The test formulation was found bioequivalent to the reference formulation with regard to AUC(0-t), AUC(0-infinity), and Cmax using the Schuirmann's two one-sided t-tests. Therefore, the two formulations were considered to be bioequivalent.

In vivo evaluation of hydrochlorothiazide liquisolid tablets in beagle dogs.

This study was carried out to evaluate the absorption characteristics of experimentally developed hydrochlorothiazide liquisolid tablets using six male beagle dogs. Comparison with reference commercial tablets was made. As no bibliographic data were found for the pharmacokinetic parameters of the drug in dogs, an intravenous drug administration was included in the study. The drug was administered orally as a single 25 mg dose of commercial and liquisolid tablets on two occasions in a randomized two-way crossover design. The pharmacokinetic parameters of the drug post intravenous dosing were reported for the first time. The results of the oral administration revealed statistically significant differences between the liquisolid and the commercial tablets in the area under the plasma concentration-time curve, the peak plasma concentration, and the absolute bioavailability. On the other hand, no significant differences were observed between the two formulations with regard to the mean residence time, the mean absorption time, and the rate of absorption. The absolute bioavailability of the drug from the liquisolid tablets was 15% higher than that from the commercial one. The parametric 90% confidence intervals for the different parameters were higher than the commonly expected intervals for bioequivalency, indicating greater bioavailability of the liquisolid tablets.

Thymoquinone-induced relaxation of guinea-pig isolated trachea.

The effect of thymoquinone (TQ), the main constituent of the volatile oil of black seed (Nigella sativa), on the guinea-pig isolated tracheal zig-zag preparation was investigated. TQ caused a concentration-dependent decrease in the tension of the tracheal smooth muscle precontracted by carbachol. The effects of TQ were significantly potentiated by pretreatment of the tracheal preparations with quinacrine, a phospholipase A2 inhibitor, nordihydroguiaretic acid, a lipoxygenase inhibitor and by pretreatment with methylene blue, an inhibitor of soluble guanylyl cyclase. On the other hand, the effects of TQ were not influenced by pretreatment of the tracheal preparations with indomethacin, a cyclooxygenase inhibitor, propranolol, a non-selective beta-adrenoceptor blocker or by the pretreatment with theophylline, an adenosine receptors antagonist TQ totally abolished the pressor effects of histamine and serotonin on the guinea-pig isolated tracheal and ileum smooth muscles. The results of the present study suggest that TQ induced relaxation of precontracted tracheal preparation is probably mediated, at least in part, by inhibition of lipoxygenase products of arachidonic acid metabolism and possibly by non-selective blocking of the histamine and serotonin receptors. This relaxant effect of TQ, further support the traditional use of black seeds either alone or in combination with honey to treat bronchial asthma.