Development of capillary gas chromatographic-mass spectrometric methodology for the simultaneous determination of ibuprofen and [ar-2H4]ibuprofen in serum: demonstration of kinetic equivalence in the beagle

Use of stable isotopes for evaluation of drug delivery systems: comparison of ibuprofen release in vivo and in vitro from two biphasic release formulations utilizing different rate-controlling polymers

Certain delivery systems are intended to release the active ingredient in different phases to obtain the desired therapeutic effect. For these formulations, such as a bilayer tablet, it is desirable to distinguish and measure the release of drug from the different phases simultaneously. Mass spectrometric methods were developed to measure three ibuprofen isotopomers in serum and two in dissolution fluid. The analytical methods were linear (r > or = 0.992) over the concentration range of interest and recovery was greater than 99.2% for all isotopomers. Coadministration of [2H0]ibuprofen, [2H4]ibuprofen, and [2H7]ibuprofen to male beagles demonstrated that the isotopomers were bioequivalent and verified the absence of any kinetic isotope effect due to deuterium incorporation (p = 0.286). These methods were then used to evaluate a bilayer tablet formulation composed of an immediate release layer of 100 mg [2H4]ibuprofen and a sustained release layer with a drug load of 300 mg [2H0]ibuprofen. Two different rate-controlling polymer matrices that provided similar in vitro dissolution profiles were compared in the sustained release phase, while the immediate release formulation remained the same. In male beagles, the HPMC matrix delivered a significantly greater amount of ibuprofen (p < 0.05). The AUC was threefold greater for HPMC (1067 +/- 437 nmole*h/ml) versus EUDRAGIT (320 +/- 51), and Cmax was nearly four times greater (145 +/- 62.1 nmole/ml for HPMC versus 37.9 +/- 14.4 for EUDRAGIT).(ABSTRACT TRUNCATED AT 250 WORDS)

Analytical techniques in dissolution testing and bioavailability studies

The rate and extent of absorption of a drug into the bloodstream is an important quality characteristic of a dosage form. In vivo bioavailability and in vitro dissolution studies are important in the development and ultimately in the quality control of a dosage form. The integrity of these tests is dependent on the analytical methods used. The advent of very potent drugs used in low dosage and the development of novel drug delivery systems require that the most sophisticated methods are used. This paper surveys recent trends in analytical advances that are useful in dissolution and bioavailability testing and suggests some future directions.