The bioavailability of three lots of a generic 200-mg carbamazepine tablet, which had been withdrawn from the market, was compared to the bioavailability of one lot of the innovator product in 24 healthy volunteers. Fifty-three lots of the generic product had been recalled by the manufacturer because of concerns over reports of clinical failures for several of the lots. The three generic lots tested in this study exhibited a wide range of bioavailability, as well as large differences in the in vitro dissolution rates. The mean maximum carbamazepine plasma concentrations for two of the generic lots were only 61-74% that of the innovator product, while the third lot was 142% of the innovator. The mean areas under the plasma concentration-time curve for the three generic lots ranged from 60 to 113% that of the innovator product. The results clearly indicate a significant difference in the rate and extent of absorption of the generic products compared to the innovator, as well as among the generic lots. A good relationship was found between the in vivo parameters and the in vitro dissolution results for the four dosage forms.

Doxycycline, potassium iodide, and ciprofloxacin, which are stockpiled in solid tablet form, can conveniently be prepared into more palatable formulations, using common household foods and drinks. The electronic tongue can be used to perform an initial screening for palatability.

The purpose of the study was to examine the bioequivalence of five commercially available oral prednisone products. The in vivo study utilized 18 healthy males, each of whom was administered 20 mg of prednisone as a reference solution or as a tablet in a 6-week, six-way crossover design. Blood was collected and serum was assayed, using an HPLC procedure specific for prednisone and prednisolone. Mean pharmacokinetic parameters (t 1/2, ke, Cmax, tmax, and AUC) were determined. ANOVA was performed on the prednisone and prednisolone data (F-test, p less than 0.05) as well as Duncan's multiple range analysis. Dissolution tests were also performed on each of the five products in order to test the relationship between dissolution and bioequivalence among prednisone products. The in vitro study consisted of a standard USP dissolution test which included tablets from the same lots as the tablets used in the in vivo study. The data showed no statistical difference in any of the pharmacokinetic parameters among tableted products, subjects, or dosing periods in the study. There was also no statistical difference in the dissolution study among the five commercial tablet forms.

The pharmacokinetic-pharmacodynamic predictor of antimicrobial activity for tetracyclines is reported to be the area under the concentration-time curve at steady state (AUC(ss)) divided by the minimal inhibitory concentration of the targeted pathogen. Here, we estimate AUC(ss) values for oxytetracycline (OTC) in serum of rainbow trout Oncorhynchus mykiss by using a destructive sampling study design. Seventy-two rainbow trout were fed OTC-medicated feed at 74.7 +/- 1.5 mg/kg (mean +/- SD) body weight (BW) by oral gavage for 10 consecutive days. Serum was collected from nine fish at 1, 3, 6, 8, 10, 12, 15, and 22 d after dosing began. Serum OTC concentrations were measured by high-performance liquid chromatography with a 0.01-microg/mL limit of detection. The average OTC AUC(ss) was 29.2 microg x h/mL and was estimated using nonlinear mixed-effects modeling and bootstrap resampling techniques. The elimination half-life was estimated as 85.0 h, and the fraction of steady state achieved was estimated as 0.85. The calculated AUC(ss) (24.8 microg x h/mL) following 10 d of oral dosing with 75 mg OTC/kg BW was less than the estimated AUC(ss). Results suggest that the pharmacokinetics of OTC exposure, including the AUC(ss), is better evaluated by using multiday dosimetry than by using a standard single-dose protocol.