Physiological modeling and assessments of regional drug bioavailability of danoprevir to determine whether a controlled release formulation is feasible

Physiologically Based Biopharmaceutics Modeling of regional and colon absorption in humans

Colon absorption is a key determinant for successful development of extended release and colon targeted drug products. This is the first systematic evaluation of the ability to predict in vivo regional differences in absorption and the extent of colon absorption in humans using mechanistic physiologically based biopharmaceutics modeling (PBBM). A new dataset, consisting of 19 drugs with a wide range of biopharmaceutics properties and extent of colon absorption in humans, was established. Mechanistic predictions of the extent of absorption and plasma exposure after oral, or jejunal and direct colon administration were performed in GastroPlus and GI-Sim using an a priori approach. Two new colon models developed in GI-Sim, were also evaluated to assess if the prediction performance could be improved. Both GastroPlus and GI-Sim met the pre-defined criteria for accurate predictions of regional and colon absorption for high permeability drugs irrespective of formulation type, while the prediction performance was poor for low permeability drugs. For solutions, the two new GI-Sim colon models improved the colon absorption prediction performance for the low permeability drugs while maintaining the accurate prediction performance for the high permeability drugs. In contrast, the prediction performance decreased for non-solutions using the two new colon models. In conclusion, PBBM can be used with sufficient accuracy to predict regional and colon absorption in humans for high permeability drugs in candidate selection as well as early design and development of extended release or colon targeted drug products. The prediction performance of the current models needs to be improved to allow high accuracy predictions for commercial drug product applications including highly accurate predictions of the entire plasma concentration-time profiles as well as for low permeability drugs.

Formulation and In Vitro, In Vivo Correlation Between Two Candesartan Cilexetil Tablets

In this study, the in vitro and in vivo interchangeability between generic candesartan 16 mg and the branded formulation was assessed. The in vitro release of these products was conducted in 3 pH media (1.2, 5.0, and 6.8), and similarity factors (f₂ ) were calculated. This bioequivalence study was a randomized, 2-period crossover study that included 42 healthy adult male subjects under fasting conditions with a 9-day washout. The pharmacokinetic (PK) parameters AUC_0-last , AUC_0-∞ , and C_max , t_max , and the elimination half-life time were assessed based on the plasma concentrations of candesartan, using a newly developed and validated liquid chromatography-tandem mass spectrometry bioanalytical method with acceptable degrees of linearity, sensitivity, precision, and accuracy. The geometric mean (ng·h/mL) of the AUC_0-∞ for the test and brand was 1595.49 and 1620.54, respectively, and the C_max (ng/mL) was 160.91 and 160.88, respectively. The 90%CIs of geometric mean ratios (test-to-reference ratios) were 98.26%, 98.45%, and 99.86% for AUC_0-last , AUC_0-∞ , and C_max respectively. These PK parameters lie within the US Food and Drug Administration- and European Medicines Agency-specified bioequivalence limit (80%-125%). Both products were well tolerated by all the subjects. The tested drug product was bioequivalent to the reference drug and had the same safety profile.

Biopharmaceutical Evaluation and CMC Aspects of Oral Modified Release Formulations

This article discusses the range of outcomes from biopharmaceutical studies of specific modified release (MR) product examples in preclinical models and humans. It touches upon five major biopharmaceutical areas for MR drug products: (1) evidence for regional permeability throughout the GI tract, (2) susceptibility to food-effect, (3) susceptibility to pH-effect, (4) impact of chronopharmacology in designing MR products, and (5) implications to narrow therapeutic index products. Robust bioperformance requires that product quality is met through a thorough understanding of the appropriate critical quality attributes that ensure reliable and robust manufacture of a MR dosage form. The quality-by-design (QbD) aspects of MR dosage form design and development are discussed with the emphasis on the regulatory view of the data required to support dosage form development.

Physiologically Based Absorption Modeling to Design Extended-Release Clinical Products for an Ester Prodrug

Absorption modeling has demonstrated its great value in modern drug product development due to its utility in understanding and predicting in vivo performance. In this case, we integrated physiologically based modeling in the development processes to effectively design extended-release (ER) clinical products for an ester prodrug LY545694. By simulating the trial results of immediate-release products, we delineated complex pharmacokinetics due to prodrug conversion and established an absorption model to describe the clinical observations. This model suggested the prodrug has optimal biopharmaceutical properties to warrant developing an ER product. Subsequently, we incorporated release profiles of prototype ER tablets into the absorption model to simulate the in vivo performance of these products observed in an exploratory trial. The models suggested that the absorption of these ER tablets was lower than the IR products because the extended release from the formulations prevented the drug from taking advantage of the optimal absorption window. Using these models, we formed a strategy to optimize the ER product to minimize the impact of the absorption window limitation. Accurate prediction of the performance of these optimized products by modeling was confirmed in a third clinical trial.

Effect of meal and antisecretory agents on the pharmacokinetics of danoprevir/ritonavir in healthy volunteers

OBJECTIVES

To evaluate the effect of a low- and high-fat meal and co-administration of ranitidine or omeprazole on the pharmacokinetics of ritonavir-boosted danoprevir (DNVr).

METHODS

In this randomised, open-label, cross-over study, healthy subjects received a single dose of DNVr. In group 1, DNVr was administered while fasting or with a low-fat or high-fat meal. In group 2, DNVr was administered alone or with ranitidine 150 mg (single dose) or omeprazole 40 mg (multiple doses).

KEY FINDINGS

Group 1 (n = 16): relative to fasting conditions, food slightly prolonged absorption but did not alter the extent of absorption. DNV area under the plasma concentration-time curve extrapolated to infinity (AUC0-∞), maximum plasma concentration (C(max)), and plasma concentration 12 h after administration (C12h) geometric mean ratios (GMR%) (90% confidence interval (CI)) with a low-fat meal were 92.3 (80.2-106), 61.8 (51.0-74.9) and 95.2 (80.9-112), versus fasting conditions, and with a high-fat meal 99.5 (86.4-115), 58.9 (48.5-71.6) and 101 (86.0-119). Group 2 (n = 13): ranitidine or omeprazole had no clinically significant effect on DNV pharmacokinetics. DNV AUC0-∞, Cmax and C12h GMR% (90% CI) with ranitidine: 81.9 (68.3-98.1), 104 (86.9-123) and 87.5 (69.3-111), and with omeprazole: 83.0 (67.4-102), 92.7 (70.6-122) and 93.3 (65.6-133).

CONCLUSIONS

The absence of clinically relevant effects of food, ranitidine or omeprazole on DNVr pharmacokinetics suggests that DNVr can be administered without regard to meals and in combination with H2 antagonists or proton pump inhibitors.

Simulation of the pharmacokinetics of bisoprolol in healthy adults and patients with impaired renal function using whole-body physiologically based pharmacokinetic modeling

AIM

To develop and evaluate a whole-body physiologically based pharmacokinetic (WB-PBPK) model of bisoprolol and to simulate its exposure and disposition in healthy adults and patients with renal function impairment.

METHODS

Bisoprolol dispositions in 14 tissue compartments were described by perfusion-limited compartments. Based the tissue composition equations and drug-specific properties such as log P, permeability, and plasma protein binding published in literatures, the absorption and whole-body distribution of bisoprolol was predicted using the 'Advanced Compartmental Absorption Transit' (ACAT) model and the whole-body disposition model, respectively. Renal and hepatic clearances were simulated using empirical scaling methods followed by incorporation into the WB-PBPK model. Model refinements were conducted after a comparison of the simulated concentration-time profiles and pharmacokinetic parameters with the observed data in healthy adults following intravenous and oral administration. Finally, the WB-PBPK model coupled with a Monte Carlo simulation was employed to predict the mean and variability of bisoprolol pharmacokinetics in virtual healthy subjects and patients.

RESULTS

The simulated and observed data after both intravenous and oral dosing showed good agreement for all of the dose levels in the reported normal adult population groups. The predicted pharmacokinetic parameters (AUC, C(max), and T(max)) were reasonably consistent (<1.3-fold error) with the observed values after single oral administration of doses ranging from of 5 to 20 mg using the refined WB-PBPK model. The simulated plasma profiles after multiple oral administration of bisoprolol in healthy adults and patient with renal impairment matched well with the observed profiles.

CONCLUSION

The WB-PBPK model successfully predicts the intravenous and oral pharmacokinetics of bisoprolol across multiple dose levels in diverse normal adult human populations and patients with renal insufficiency.

Predicting feasibility and characterizing performance of extended-release formulations using physiologically based pharmacokinetic modeling

This review presents nine case studies where physiologically based pharmacokinetic modeling has been used in the design and development of extended-release formulations. While the approaches for creating the models were similar, in each case a product-development or drug-delivery problem unique to each compound was solved so that the drug-release rate could be optimized to achieve the best clinical performance. Examples presented include understanding the relationship between colonic absorption and efflux, effect of drug release and gastric emptying on maximum achieved drug concentration in plasma and area under the plasma concentration-time curve for a Biopharmaceutics Classification System class 3 compound, feasibility of an extended-release product for a prodrug, feasibility of an extended-release product for a biopharmaceutics classification system class 4 compound and predicting the pharmacokinetics in humans based on a primate model and coupling the physiologically-based pharmacokinetic model with a pharmacodynamic model so that the clinical efficacy of the formulations could be predicted based on the simulated plasma concentrations. The use of physiologically based pharmacokinetic models in the development of extended-release formulations is rapidly becoming an acceptable part of the knowledge management and design space components of a quality by design approach to product development. As the use of these in silico tools increase and examples become available through scientific presentations and literature, the inclusion of this approach will become a necessary part of the development process rather than the exception.