Speedel has started a Phase IIa clinical trial of its renin inhibitor SPP635 for the treatment of hypertension, a follow-up to lead product Tekturna/Rasilez (aliskiren), which is partnered with Novartis and awaiting marketing approval in the USA and Europe.

SPP635 is one of several new proprietary renin inhibitors originated by the company's late-stage research unit Speedel Experimenta. Like aliskiren the drug is expected to offer long-acting blood pressure control, at least over 24 hours, with placebo-like tolerability.

The start of the Phase IIa trial follows the successful completion of a Phase I safety and tolerability study, where plasma concentrations reached levels that were predicted by earlier human microdosing studies reported in February 2005.

The microdosing studies supported earlier suggestions that SPP635 has a bioavailability of about 25%-30% in man, with a half-life of approximately 24 hours, making it ideal for once per day dosing.

The four-week Phase IIa trial in hypertension will be carried out in Europe with results due around third-quarter 2007. It will study the safety and efficacy of SPP635 in about 35 patients with mild-to-moderate hypertension by measuring office and ambulatory blood pressure.