The effect of chitosan on the bioaccessibility and intestinal permeability of acyclovir.

Chitosan is object of pharmaceutical research as a candidate permeability enhancer. However, chitosan was recently shown to reduce the oral bioavailability of acyclovir in humans. The effect of chitosan on two processes determining the oral bioavailability of acyclovir, bioaccessibility and intestinal absorption, was now investigated.

The Influence of Chitosan on the Oral Bioavailability of Acyclovir--a Comparative Bioavailability Study in Humans.

Purpose: The effects of chitosan hydrochloride on the oral absorption of acyclovir in humans were studied to confirm the absorption enhancing effects reported for in vitro and rat studies, respectively.

Methods: A controlled, open-label, randomized, 3-phase study was conducted in 12 healthy human volunteers. Zovirax 200 mg dispersible tablets co-administered with doses of 400 and 1000 mg chitosan HCl were compared with Zovirax only.

Novel insights into excipient effects on the biopharmaceutics of APIs from different BCS classes: Lactose in solid oral dosage forms.

Excipients encompass a wide range of properties that are of importance for the resulting drug product. Regulatory guidelines on biowaivers for immediate release formulations require an in depth understanding of the biopharmaceutic effects of excipients in order to establish bioequivalence between two different products carrying the same API based on dissolution tests alone. This paper describes a new approach in evaluating biopharmaceutic excipient effects.

In vivo methods for drug absorption - comparative physiologies, model selection, correlations with in vitro methods (IVIVC), and applications for formulation/API/excipient characterization including food effects.

This review summarizes the current knowledge on anatomy and physiology of the human gastrointestinal tract in comparison with that of common laboratory animals (dog, pig, rat and mouse) with emphasis on in vivo methods for testing and prediction of oral dosage form performance. A wide range of factors and methods are considered in addition, such as imaging methods, perfusion models, models for predicting segmental/regional absorption, in vitro in vivo correlations as well as models to investigate the effects of excipients and the role of food on drug absorption. One goal of the authors was to clearly identify the gaps in today's knowledge in order to stimulate further work on refining the existing in vivo models and demonstrate their usefulness in drug formulation and product performance testing.

The impact of the EMA change in definition of "dose" on the BCS dose-solubility ratio: a review of the biowaiver monographs.

The Biopharmaceutics Classification System (BCS) defines the solubility characteristics of an active pharmaceutical substance based on its dose-solubility ratio: for highly soluble drugs this ratio is less than 250 mL over a defined pH range. Prior to the revision of the European Medicines Agency (EMA, formerly EMEA) guideline in 2010, the "dose" in this ratio was consistently defined by the US FDA, the EMA, and the WHO biowaiver guidelines as the highest dosage strength. However, in the revised EMA guideline, the dose is defined as the highest single dose administered according to the Summary of Product Characteristics.

Risk analysis in bioequivalence and biowaiver decisions.

This article evaluates the current biowaiver guidance documents published by the FDA, EU and WHO from a risk based perspective. The authors introduce the use of a Failure Mode and Effect Analysis (FMEA) risk calculation tool to show that current regulatory documents implicitly limit the risk for bioinequivalence after granting a biowaiver by reduction of the incidence, improving the detection and limiting the severity of any unforeseen bioinequivalent product. In addition, the authors use the risk calculation to expose yet unexplored options for future extension of comparative in vitro tools for biowaivers.

A phytochemical study of lignans in whole plants and cell suspension cultures of Anthriscus sylvestris.

In the roots of Anthriscus sylvestris 12 different lignans were detected. Arctigenin, dimethylmatairesinol, dimethylthujaplicatin, podophyllotoxin, 7-hydroxyyatein and 7-hydroxyanhydropodorhizol have not been previously reported to be present in A. sylvestris.