Pharmacokinetic simulations to explore dissolution criteria of BCS I and III biowaivers with and without MDR-1 efflux transporter.

In this study, a pharmacokinetic simulation model was used to explore the dissolution acceptance criteria for BCS I and III biowaivers and to examine the risk of MDR-1 efflux transporter on bioequivalence of substrates. The compartmental absorption and transit (CAT) model with one- or two systemic compartments was used. The parameter values used in the simulations were based on the pharmacokinetics of existing 70 BCS I and III drugs. Based on the simulations BCS I drug products with Tmax of >0.9 h, both dissolution criteria "very rapid" and "rapid and similar" were acceptable. For rapidly absorbed and distributed BCS I drug products with Tmax of 0.6-0.9 h, the dissolution criterion "very rapid" is preferred. If Tmax is less than 0.6 h there is a risk of bioinequivalence for the BCS I drug products regardless of the dissolution criteria. Based on the simulations, all BCS III drug products were good biowaiver candidates with both dissolution criteria. Almost all the BCS III drug products (>89%) and many BCS I products (9-57%) showed risks of bioinequivalence, if an excipient in either product inhibits MDR1-efflux transport of the drug. To eliminate these risks excipients with prior use in bioequivalent products should be used for MDR-1 efflux substrates.

Evaluation of the use of partition coefficients and molecular surface properties as predictors of drug absorption: a provisional biopharmaceutical classification of the list of national essential medicines of Pakistan.

BACKGROUND AND THE PURPOSE OF THE STUDY: Partition coefficients (log D and log P) and molecular surface area (PSA) are potential predictors of the intestinal permeability of drugs. The aim of this investigation was to evaluate and compare these intestinal permeability indicators. METHODS: Aqueous solubility data were obtained from literature or calculated using ACD/Labs and ALOGPS. Permeability data were predicted based on log P, log D at pH 6.0 (log D(6.0)), and PSA. RESULTS: Metoprolol's log P, log D(6.0,) and a PSA of <65 Å correctly predicted 55.9%, 50.8% and 54.2% of permeability classes, respectively. Labetalol's log P, log D(6.0) and PSA correctly predicted 54.2%, 64.4% and 61% of permeability classes, respectively. Log D(6.0) correlated well (81%) with Caco-2 permeability (P(app)). Of the list of national essential medicines, 135 orally administered drugs were classified into biopharmaceutical classification system (BCS). Of these, 57 (42.2%), 28 (20.7%), 44 (32.6%), and 6 (4.4%) were class I, II, III and IV respectively. CONCLUSION: Log D(6.0) showed better prediction capability than log P. Metoprolol as permeability internal standard was more conservative than labetalol.

Very rapid dissolution is not needed to guarantee bioequivalence for biopharmaceutics classification system (BCS) I drugs.

Currently, the EMEA, FDA, and WHO as regulatory authorities accept rapidly dissolving (>85% dissolved in 30 min) biopharmaceutics classification system (BCS) I drug products for biowaiver candidates. In the draft EMEA guideline the requirement has been set tighter, that is, the drug product should be very rapidly dissolving (>85% dissolved in 15 min) to be eligible for a biowaiver. Pharmacokinetic modeling of 32 BCS I drugs was performed to demonstrate that very rapid dissolution is not necessary to guarantee bioequivalence for them. Rapid dissolution and similar dissolution profiles are sufficient criteria for all BCS I drugs.