Current Drug Metabolism - Volume 8, Issue 7, 2007

The ability to successfully predict pharmacokinetic properties plays a crucial role in the selection of candidate drugs and significantly reduces the number of potential failures in drug development. Current drug candidates typically show a very high affinity for the target receptors; however, the drawback is that many new lead compounds represent large, lipophilic molecules with low solubility, dissolution and/or permeability and Read More

The majority (84%) of the 50 most-sold pharmaceutical products in the US and European markets are given orally. The dominating role of this route in drug therapy is a consequence of it being safe, efficient and easily accessible with minimal discomfort to the patient in comparison with other routes of drug administration. A successful drug discovery and development of oral pharmaceutical products require an in-depth unders Read More

Although the liver has long been thought to play the major role in drug metabolism, also the metabolic capacity of the intestine is more and more recognized. In vivo studies eventually pointed out not only the significance of first-pass metabolism by the intestinal wall for the bioavailability of several compounds, but also the relevance of transporters in this process. Only a few methods are available to study drug metabolism i Read More

Despite a lower content of many drug metabolising enzymes in the intestinal epithelium compared to the liver (e.g. intestinal CYP3A abundance in the intestine is 1% that of the liver), intestinal metabolic extraction may be similar to or exceed hepatic extraction. Modelling of events on first-pass through the intestine requires attention to the complex interplay between passive permeability, active transport, binding, relevant blood Read More

For certain CYP3A4 substrates intestinal first-pass metabolism makes a substantial contribution to low oral bioavailability and extent of drug-drug interactions (DDI). In order to include the contribution of enzyme inhibition in the gut wall in the assessment of DDI potential, the ratio of the intestinal wall availability in the presence and absence of an inhibitor (FG’ and FG, respectively) has been incorporated into a prediction Read More

Over the past decade, our knowledge concerning the importance of intestinal metabolism in the disposition of xenobiotics has significantly improved. Compounds such as midazolam can be extensively extracted in the intestine upon first-pass metabolism after oral dosing. Conversely, the intestine plays a less important, albeit less characterized role in systemic metabolism. This manuscript is meant to review the publis Read More

RNA interference (RNAi) is a powerful technique that utilizes RNA molecules to specifically knock down the expression of targeted gene at posttranscriptional level. These small interfering RNAs (siRNAs) not only have broad application to basic biomedical research but may be developed as therapeutic agents. Drug-metabolizing enzymes (DMEs) and drug transporters (DTs) are molecular determinants of pharmacokinetic Read More

Over the last few decades, understanding of the mechanisms involved in the process of neuronal cell death has grown. Recent findings have established that DNA damage, and specifically ataxia telangiectasia mutated protein (ATM), is key to the cascade of regulation of neuronal apoptosis. Another characteristic common to all neurodegenerative diseases is oxidative stress. Likewise, a common feature in the brain Read More

It has long been suggested that some of the neuropharmacological, neurochemical and behavioural effects of ethanol are mediated by its first metabolite, acetaldehyde. In spite of the well documented psychoactivity of acetaldehyde, the precise role of this compound in alcohol abuse remains a matter of intense debate among scientists devoted to the study of alcoholism. Very frequently, the main drawback has been r Read More

Cytochromes P450 (CYPs) comprise a number of enzyme subfamilies responsible for the oxidative metabolism of a wide range of therapeutic agents, environmental toxicants, mutagens, and carcinogens. In particular, cytochrome P450 2E1 (CYP2E1) is implicated in the oxidative bioactivation of a variety of small hydrophobic chemicals including a number of epoxide-forming drugs and environmentally important t Read More