Dissolution testing of modified release products with biorelevant media: An OrBiTo ring study using the USP apparatus III and IV.

During the OrBiTo project, our knowledge on the gastrointestinal environment has improved substantially and biorelevant media composition have been refined. The aim of this study was to propose optimized biorelevant testing conditions for modified release products, to evaluate the reproducibility of the optimized compendial apparatus III (USP apparatus III) and compendial apparatus IV (USP apparatus IV, open-loop mode) dissolution methods and to evaluate the usefulness of these methods to forecast the direction of food effects, if any, based on the results of two «ring» studies and by using two model modified release (MR) products, Ciproxin / Cipro XR and COREG CR. Six OrBiTo partners participated in each of the ring studies.

An in silico approach to determine challenges in the bioavailability of ciprofloxacin, a poorly soluble weak base with borderline solubility and permeability characteristics.

Ciprofloxacin is administered as the hydrochloride salt in immediate release formulations for the treatment of various infectious diseases in different patient populations. Due to its weakly basic properties and poor solubility, the in vivo behaviour of this compound could be influenced by both physicochemical and physiological factors. The first aim of this study was to investigate the behaviour of ciprofloxacin (Ciprobay® 500 mg tablets) in the human gastro-intestinal tract with in vitro dissolution, transfer and two-stage experiments.

Advantage of the Dissolution/Permeation System for Estimating Oral Absorption of Drug Candidates in the Drug Discovery Stage.

In order to increase the success rate in the development of oral drugs, an in vitro method, which can accurately estimate human oral absorption of a large variety of compounds from solid formulations, is required in the drug discovery stage. A dissolution/permeation (D/P) system is an in vitro system that simultaneously evaluates dissolution and permeation processes of drugs administered orally. In this study, we have investigated the advantages of a D/P system for use in the provisional estimation of human oral absorption of a drug (absorbed fraction, Fa) by applying it in its solid state.

Novel comb-shaped PEG modification enhances the osteoclastic inhibitory effect and bone delivery of osteoprotegerin after intravenous administration in ovariectomized rats.

Purpose: Recombinant osteoprotegerin (OPG) has been proven to be useful for treating various bone disorders such as osteoporosis. To improve its in vivo pharmacological effect, OPG was conjugated to novel comb-shaped co-polymers of polyethylene glycol (PEG) allylmethylether and maleamic acid (poly(PEG), 5 kDa). Biodistribution and bioactivity were evaluated.

In vitro evaluation of the potential for drug-induced toxicity based on (35)S-labeled glutathione adduct formation and daily dose.

Background: Drug-induced toxicity such as idiosyncratic drug toxicity is believed to be reduced when either reactive metabolite formation or exposure to a drug is minimized. The objective of the present study was therefore to clarify the relationship between the daily doses, the formation rates of reactive metabolite adduct with (35)S-glutathione (RM-GS) and the safety profiles of compounds.

Results: The RM-GS formation rates for 113 test compounds were determined by incubation with human liver microsomes, and the test compounds were classified into three categories of safe, warning and withdrawn/black box warning.

Distribution of KAI-9803, a novel δ-protein kinase C inhibitor, after intravenous administration to rats.

KAI-9803 is composed of a selective δ-protein kinase C (δPKC) inhibitor peptide derived from the δV1-1 portion of δPKC (termed "cargo peptide"), conjugated reversibly to the cell-penetrating peptide 11-amino acid, arginine-rich sequence of the HIV type 1 transactivator protein (TAT₄₇₋₅₇; termed "carrier peptide") via a disulfide bond. KAI-9803 administration at the end of ischemia has been found to reduce cardiac damage caused by ischemia-reperfusion in a rat model of acute myocardial infarction. In the study presented here, we examined the TAT₄₇₋₅₇-mediated distribution of KAI-9803 in rats after a single intravenous bolus administration (1 mg/kg).

Combination of GSH trapping and time-dependent inhibition assays as a predictive method of drugs generating highly reactive metabolites.

Covalent binding (CB) of reactive metabolites (RMs) is potentially involved in severe adverse drug reactions. Because the CB assay is of low throughput and costly, a qualitative trapping assay using agents such as [(35)S]GSH is often performed in the early stages of drug discovery. However, trapping methods alone cannot replace the CB assay.

Use of an intravenous microdose of 14C-labeled drug and accelerator mass spectrometry to measure absolute oral bioavailability in dogs; cross-comparison of assay methods by accelerator mass spectrometry and liquid chromatography-tandem mass spectrometry.

A technique utilizing simultaneous intravenous microdosing of (14)C-labeled drug with oral dosing of non-labeled drug for measurement of absolute bioavailability was evaluated using R-142086 in male dogs. Plasma concentrations of R-142086 were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and those of (14)C-R-142086 were measured by accelerator mass spectrometry (AMS). The absence of metabolites in the plasma and urine was confirmed by a single radioactive peak of the parent compound in the chromatogram after intravenous microdosing of (14)C-R-142086 (1.

Appearance of double peaks in plasma concentration-time profile after oral administration depends on gastric emptying profile and weight function.

Purpose: Mechanism for double-peak occurrence in plasma concentration profile after oral administration of drugs is controversial, although irregular gastric emptying would be an important factor. The objective of this study was to assess the effect of gastric emptying and a weight function, i.e.