Arena Pharmaceuticals, Inc.’s ARNA shares inched up 2.7% after the company announced favorable results from a phase Ib study on its pain candidate, APD371.The randomized, double-blind, placebo-controlled study evaluated the safety, tolerability and pharmacokinetics of multiple ascending doses of the candidate in healthy adults (n~36). Subjects in the study received doses of 50 mg, 100 mg or 200 mg of APD371 or placebo three times per day for 10 days. Data from the study revealed that drug levels at all doses were well above those believed to be necessary to stimulate the cannabinoid 2 receptor.Most common adverse events included headache and nausea, both classified as mild. Subjects also revealed a reduction in their blood pressure and heart rate level, although none were symptomatic. Moreover, there was one discontinuation in the high-dose group due to mild thirst and somnolence.Drugs currently approved to treat pain include – Opana ER, Zohydro ER, and Belbuca among others.We note that Arena Pharma has two other candidates in its pipeline – ralinepag and APD334. Currently, the company is evaluating ralinepag in a phase II study for the treatment of pulmonary arterial hypertension. Another candidate at the company’s pipeline, APD334, is being evaluated in a phase II study for the treatment of patients with ulcerative colitis.Arena Pharma currently has a Zacks Rank #5 (Strong Sell). Some better-ranked stocks in the health care sector are AMAG Pharmaceuticals, Inc. AMAG, Anika Therapeutics Inc. ANIK and Emergent BioSolutions, Inc. EBS, each sporting a Zacks Rank #1 (Strong Buy).Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report AMAG PHARMA INC (AMAG): Free Stock Analysis Report ARENA PHARMA (ARNA): Free Stock Analysis Report ANIKA THERAPEUT (ANIK): Free Stock Analysis Report EMERGENT BIOSOL (EBS): Free Stock Analysis Report To read this article on Zacks.com click here. Zacks Investment Research