AMRIX, A New Once-Daily Extended-Release Muscle Relaxant, Superior To Placebo

Main Category: Pain / Anesthetics
Article Date: 15 Feb 2008 - 2:00 PDT

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Cephalon, Inc. (Nasdaq: CEPH) announced the pooled analysis of two pivotal randomized, placebo-controlled clinical trials showing that AMRIX® (cyclobenzaprine hydrochloride extended-release capsules), a new once-daily extended-release skeletal muscle relaxant, was superior to placebo. AMRIX had similar efficacy to cyclobenzaprine immediate-release (CIR) taken three times a day in alleviating acute muscle spasm associated with lower back and neck pain. In addition, less daytime drowsiness was observed with AMRIX compared to CIR, although such a comparison was not pre-specified in the statistical analysis plan. These results were presented today at the 24th Annual Meeting of the American Academy of Pain Medicine in Orlando, FL.

"Typically, muscle relaxants are taken multiple times a day, which can make it difficult for some of my patients with acute muscle spasm associated with lower back and neck pain to adhere to their treatment regimen," said Arnold J. Weil, MD, of Non-Surgical Orthopaedics in Atlanta, GA, and the lead investigator in these studies. "With data supporting AMRIX as an effective once-daily treatment, health care professionals now have an easy-to-administer treatment option to offer their patients who are suffering from acute muscle spasm."

The data, which were the basis for the U.S. Food and Drug Administration approval of AMRIX, were pooled from two identical 14-day randomized, double-blind, placebo-controlled, multicenter studies, evaluating a total of 504 adults across four study arms (AMRIX 15 mg, AMRIX 30 mg, placebo, and CIR 10 mg three times daily). These participants had moderate-to-severe muscle spasm of cervical or lumbar origin associated with local pain, tenderness, limitation of motion, and restrictions of daily living. In these studies, patients and physicians assessed how helpful the medication was in the treatment of acute muscle spasm. Primary endpoints of the clinical trials were Patient's Rating of Medication Helpfulness at day four of treatment and Physician's Clinical Global Assessment at day four.

Study results of the Patient's Rating of Medication Helpfulness, a measure of efficacy, showed that a higher proportion of patients (p<0.025) taking AMRIX 15 mg (56.0 percent; n=116) and AMRIX 30 mg (56.7 percent; n=120) reported "good" to "excellent" responses compared with the placebo group (40.0 percent; n=115) at day four. The distribution of responses for AMRIX and CIR was similar. The trials did not demonstrate significant differences among the study groups on the Physician's Clinical Global Assessment at day four.

In a scale of Patient-Rated Daytime Drowsiness at day four, more patients in the AMRIX groups (15 mg, 50.4 percent, and 30 mg, 42.1 percent) had "no to very little" drowsiness compared with the CIR group (28.8 percent). As expected, more patients in the AMRIX groups had daytime drowsiness compared with placebo.

The majority of all adverse events reported in these trials were mild in intensity. The most common side effects of AMRIX (greater than or equal to three percent) were dry mouth, dizziness, fatigue, nausea, and constipation. Somnolence (a state of drowsiness) was the most common adverse event leading to discontinuation (two patients in the AMRIX 30 mg group and eight in the CIR group).

About AMRIX

AMRIX is indicated for short-term use (up to two or three weeks) for relief of muscle spasm associated with acute, painful musculoskeletal conditions. The first and only once-daily muscle relaxant, AMRIX is available in 15 and 30 mg dosage strengths.

AMRIX is contraindicated with concomitant use of monoamine oxidase (MAO) inhibitors or within 14 days after their discontinuation; in patients during the acute recovery phase of myocardial infarction; in patients with arrhythmias, heart block conduction disturbances, or congestive heart failure; and in patients with hyperthyroidism. AMRIX may enhance the effects of alcohol, barbiturates, and other CNS depressants. AMRIX should not be used in elderly patients or in patients with impaired hepatic function. AMRIX should be used with caution in patients with a history of urinary retention, angle-closure glaucoma, increased intraocular pressure, and in patients taking anticholinergic medication.

http://www.amrix.com

About Cephalon, Inc.

Founded in 1987, Cephalon, Inc. is an international biopharmaceutical company dedicated to the discovery, development and commercialization of innovative products in four core therapeutic areas: central nervous system, pain, oncology and addiction. A member of the Fortune 1000, Cephalon currently employs approximately 3,000 people in the United States and Europe. U.S. sites include the company's headquarters in Frazer, Pennsylvania, and offices, laboratories or manufacturing facilities in West Chester, Pennsylvania, Salt Lake City, Utah, and suburban Minneapolis, Minnesota. The company's European headquarters are located in Maisons-Alfort, France.

The company's proprietary products in the United States include: PROVIGIL® (modafinil) Tablets [C-IV], FENTORA® (fentanyl buccal tablet) [C-II], TRISENOX® (arsenic trioxide) injection, AMRIX, VIVITROL® (naltrexone for extended-release injectable suspension), GABITRIL® (tiagabine hydrochloride), NUVIGIL™ (armodafinil) Tablets [C-IV] and ACTIQ® (oral transmucosal fentanyl citrate) [C-II]. The company also markets numerous products internationally.

Cephalon, Inc.

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