Horizon Therapeutics, Inc (PALO ALTO, California), a privately-held, late-stage biopharmaceutical company, has initiated a phase III follow-on safety study (HZ-CA-304) of its lead product candidate HZT-501, an investigational prescription NSAID (nonsteroidal anti-inflammatory drug) designed to be "GI-friendly."

HZT-501 is a proprietary fixed dose combination pill containing the most prescribed traditional NSAID, ibuprofen, with a high dose of the most potent H2 antagonist, famotidine. HZT-501 is specifically designed to provide pain relief while reducing stomach acidity, lowering the risk for gastrointestinal (GI) ulceration. In a randomized pilot clinical study, famotidine was demonstrated to significantly reduce the incidence of GI and duodenal ulcers versus placebo when administered with NSAIDs.

The long-term safety study will support the two ongoing pivotal phase III trials (HZ-CA-301 and HZ-CA-303) involving a total of 1400 patients with mild-to-moderate pain, including patients with osteoarthritis. These trials will evaluate the efficacy and safety of HZT-501 with the primary endpoint being reduction in the risk of ibuprofen-associated upper GI ulcers in patients who require the use of ibuprofen. Trials began in March 2007, and an NDA (New Drug Application) is expected to be filed in the fourth quarter of 2008.

The HZ-CA-304 safety study is a multicenter, double-blind trial that expects to enroll approximately 200 patients who previously participated in the 301 or 303 phase III trials. Study participants will continue to receive either HZT-501 (ibuprofen 800 mg/famotidine 26.6 mg) or ibuprofen 800 mg. They will receive medication for up to 28 weeks.

According to the company, NSAIDs have been linked to serious GI side effects in up to 25% of all chronic arthritis patients and NSAID-induced GI toxicity causes an estimated 16,000 deaths and more than 100,000 hospitalizations annually in the US.