CRX.L Regulatory News (CRX)

19th October, 2010

Cyprotex Extends Time Dependent Inhibition Service to Include the

Cytochrome P450 Isoform, CYP2B6

Cyprotex PLC (LSE:CRX), the preclinical ADME Tox services company, today announces that it has extended its time-dependent inhibition service to include the cytochrome P450 (CYP450) isoform, CYP2B6.

Inhibition of the various CYP450 isoforms, including CYP2B6, is one of the main causes of drug-drug interactions. Drug-drug interactions can cause otherwise safe medicines to accumulate in the body resulting in toxicity.

A US FDA update paper by Huang et al., 2008 (J Clin Pharmacol 48; 662-670) has highlighted the importance of CYP2B6 in clinical interactions and recommends that CYP2B6 should be investigated in vitro when assessing whether enzyme inhibition or induction has the potential to produce a drug interaction.

CYP450 inhibition can produce either reversible or irreversible drug-drug interactions. Time-dependent inhibition assays identify compounds which have the potential to form an irreversible drug-drug interaction. These types of drug-drug interactions, although less common, are more serious because the inhibited enzyme must be re-synthesised by the liver before metabolism is restored.

The range of validated CYP450 isoforms in Cyprotex's time-dependent inhibition service now include CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4. These isoforms are also available in Cyprotex's CYP450 reversible inhibition service. Used in combination, these assays act as valuable tools in identifying potential drug-drug interactions, and distinguishing between reversible and irreversible inhibition.

Dr. Katya Tsaioun, Cyprotex's Chief Scientific Officer, comments on the launch of this new service: "Time-dependent CYP inhibition is a growing concern to the pharmaceutical industry because of the increasing proportion of patients on multiple medications. Due to the serious toxicity implications of irreversible CYP interactions, understanding potential drug-drug interaction liabilities at an early stage in drug discovery is critical. Cyprotex is pleased to provide drug-discovery companies with the most advanced assays for identifying potentials for drug-drug interactions early in the process."

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Cyprotex PLC

Cyprotex is the world's largest contract research organisation (CRO) specialising in ADME Tox, which is the analysis of the Absorption, Distribution, Metabolism, Excretion and Toxicity properties of potential drugs, cosmetics, and agrochemicals. It is the only company in the world with in-house capabilities for both in vitro (test tube) and in silico (computer modelling) ADME Tox. Cyprotex was founded in 1999 and listed on the AIM in 2002. It has laboratories in Macclesfield, Cheshire, UK (near Manchester), and Watertown, Massachusetts, USA (near Boston), making it one of only three ADME Tox CROs with international operations.

www.cyprotex.com