Alternative Pharmacokinetic Metrics in Single-Dose Studies to Ensure Bioequivalence of Prolonged-Release Products at Steady State-A Case Study.

(1) Background: this article investigates which PK metrics in a single-dose study (concentration at the end of posology interval, Cτ, partial areas under the curve, pAUCs, or half-value duration, HVD) are more sensitive and less variable for predicting the failure of a prolonged-release product at steady-state that was the bioequivalent for Cmax, AUC0-t and AUC0-inf, in the single-dose study; (2) Methods: a cross-over study was performed in 36 subjects receiving desvenlafaxine 100 mg prolonged-release tablets. Conventional (Cmax, AUC0-t and AUC0-inf) and additional (Cτ, pAUCs and HVD) PK metrics were considered after single-dose conditions. Predicted PK metrics at steady state (AUC0-τ, Cmax,ss, and Cτ,ss) were derived using a population PK model approach; (3) Results: the existing differences in the shape of the concentration-time curves precluded to show equivalence for Cτ,ss in the simulated study at steady state. This failure to show equivalence at steady state was predicted by Cτ, pAUCs and HVD in the single-dose study. Cτ was the most sensitive metric for detecting the different shape, with a lower intra-subject variability than HVD; (4) Conclusions: conventional PK metrics for single-dose studies (Cmax, AUC0-t and AUC0-inf) are not enough to guarantee bioequivalence at steady state for prolonged-release products.

One and Two-Step In Vitro-In Vivo Correlations Based on USP IV Dynamic Dissolution Applied to Four Sodium Montelukast Products.

Montelukast is a weak acid drug characterized by its low solubility in the range of pH 1.2 to 4.5, which may lead to dissolution-limited absorption. The aim of this paper is to develop an in vivo predictive dissolution method for montelukast and to check its performance by establishing a level-A in vitro-in vivo correlation (IVIVC). During the development of a generic film-coated tablet formulation, two clinical trials were done with three different experimental formulations to achieve a similar formulation to the reference one. A dissolution test procedure with a flow-through cell (USP IV) was used to predict the in vivo absorption behavior. The method proposed is based on a flow rate of 5 mL/min and changes of pH mediums from 1.2 to 4.5 and then to 6.8 with standard pharmacopoeia buffers. In order to improve the dissolution of montelukast, sodium dodecyl sulfate was added to the 4.5 and 6.8 pH mediums. Dissolution profiles in from the new method were used to develop a level-A IVIVC. One-step level-A IVIVC was developed from dissolution profiles and fractions absorbed obtained by the Loo-Riegelman method. Time scaling with Levy's plot was necessary to achieve a linear IVIVC. One-step differential equation-based IVIVC was also developed with a time-scaling function. The developed method showed similar results to a previously proposed biopredictive method for montelukast, and the added value showed the ability to discriminate among different release rates in vitro, matching the in vivo clinical bioequivalence results.

Differences in lercanidipine systemic exposure when administered according to labelling: in fasting state and 15 minutes before food intake.

PURPOSE: The aim of this study was to compare the systemic exposure of lercanidipine (Zanidip) after oral administration in the fasted state and 15 min before food intake (meals) to investigate if the recommendations in the Summary of Product Characteristics (SPC) with respect to the intake of meals are adequate. METHODS: The results of three pilot bioequivalence studies performed to develop a lercanidipine generic product, where Zanidip was administered consistently as reference product in the fasted state or 15 min before a standard breakfast, were compared to estimate the drug­food interaction and the similarity of the methods of administration defined in the SPC. RESULTS: The ingestion of a standard (non-high-fat, non-high-calorie) meal 15 min after drug intake increased the area under the concentration­time curve (AUC(0-t)) of S-lercanidipine by 1.78-fold [90% confidence interval (CI) 1.48­2.15, P<0.0001] and the maximum concentration (Cmax) of Slercanidipine by 1.82-fold (90% CI 1.46­2.28, P<0.0001). These values are close to the twofold increase that has been described when Zanidip was taken immediately after a carbohydrate-rich meal. Higher levels would be expected with a high-fat, high-calorie meal. CONCLUSIONS: As intake with a carbohydrate-rich meal is not recommended in the SPC of Zanidip because a twofold difference was considered to be clinically relevant, the intake of lercanidipine only 15 min before food intake does not seem to be consistent with this recommendation. The Marketing Authorisation Holder should clarify the dosing instructions in relation to meals and identify a sufficient time-lapse to ensure an exposure similar to that obtained in phase III clinical efficacy studies.