Improving of the accuracy of in vitro-in vivo linear correlation using kinetic models for ultra sustained release theophylline tablets

Acceleration of in vitro dissolution studies of sustained release dosage form of theophylline and in vitro-in vivo evaluations in terms of correlations

The aim of the study was to accelerate the dissolution of the sustained release dosage forms using both elevated temperature and high rpm rates. Teokap(®) SR 200 mg pellets were tested by in vitro sustained and accelerated dissolution studies using USP XXIII rotating paddle method. Sustained dissolution studies were carried out for 12 h in phosphate buffer at 37 ± 0.5°C and 50 rpm. Accelerated dissolution studies were performed for 48 min in distilled water at 90 ± 1°C and 250 rpm. The results obtained from accelerated and sustained dissolution studies were correlated using both linear and linear kinetic correlation methods by a computer program. While r (2) and maximum error between calculated and observed drug release rates were found to be 0.9129 and 15.9%, respectively, in linear correlation method, these values were observed as 0.9938 and 3.6%, respectively, in linear kinetic correlation method. In vivo plasma concentration data were obtained from six New Zealand rabbits after administration of a single dose of Teokap(®) SR 200 mg pellet. Then, the results of in vivo study were evaluated with in vitro accelerated and sustained dissolution results by applying them to in vitro-in vivo linear correlations. As a result of these correlations, it was shown that the in vitro correlation plots were very similar to the plot which was obtained by the in vivo study (f (2) = 73.81-77.11). This study suggested a way to prevent the loss of time for routine dissolution studies of sustained release preparations for quality control procedures using in vitro accelerated dissolution tests. The storage and quarantine periods of the product in process and process controls in the manufactories could be shortened by this method. Calculation of the in vivo performance of sustained release dosage forms using the results of the accelerated dissolution studies may be counted as another advantage of the method.

Application of the correlation of in vitro dissolution behavior and in vivo plasma concentration profile (IVIVC) for soft-gel capsules--a pointless pursuit?

Plasma concentration profiles of arundic acid ((R)-(-)-2-propyloctanoic acid), an oil-like medicine, administered as soft-gel capsules in human clinical tests were predicted from the dissolution test data of the soft-gel capsules with different storage terms (short- and long-term stored drugs) by applying the in vitro-in vivo correlation (IVIVC). We established two linear-regression IVIVCs, which were characterized by either the in vitro dissolution behaviors against the pH 8.0 dissolution medium or the pH 6.8 dissolution medium containing 2% sodium dodecyl sulfate (SDS), in this study. Also, the prediction accuracies for the in vivo plasma profiles in humans for these two IVIVCs were compared. Regarding dissolution from the long-term stored capsule in pH 8.0 dissolution medium without surfactant, the prediction accuracies of the in vivo plasma profiles in humans were not satisfactory for the obtained IVIVC. The use of pH 6.8 dissolution medium containing 2% SDS, according to the Japanese guideline, improved the dissolution of the long-term stored capsule. Furthermore, the prediction accuracies for the in vivo plasma profiles in humans for these two IVIVCs were compared. The IVIVC established by the in vitro dissolution data obtained with the dissolution medium containing surfactant more effectively predicted the plasma drug concentration profiles following oral administrations of the soft-gel capsules under both storage conditions.

Theophylline granule formulation prepared by the wet granulation method: comparison of in vitro dissolution profiles and estimation of in vivo plasma concentrations

The primary and secondary objectives of this study were to develop and evaluate the predictability of in vitro-in vivo correlation models for theophylline sustained release (SR) granules. Theophylline SR granules meeting the USP Drug Release Test criteria were prepared using ethyl cellulose (EC) and/or stearyl alcohol (SA) and the wet granulation method. In vitro dissolution studies of granule formulation were performed, and a commercial dosage form was prepared using USP XXIII apparatus II at pH 4.5. Differences and similarities between in vitro dissolution curves were compared using both model-dependent (t-test) and -independent (f1, f2 test) statistical techniques, and it was shown that the three dissolution profiles i.e model-dependent, model-independent, and methods based on ANOVA were very similar. The in vivo performance of the commercial dosage form was tested by oral route using male rabbits and in vitro-in vivo correlations were established. This study indicates that the dosage forms with similar in vitro dissolution profiles may have a similar in vivo performance, and that this performance could be estimated using appropriate correlation equations.