Aug 29 (Reuters) - Arena Pharmaceuticals Inc said a patient being treated with the company's experimental lung drug experienced a heart rhythm disorder, raising concerns over the drug's safety.
Arena said its trial investigator considered the heart rhythm disorder to be possibly related to the treatment.
The company said in a statement Wednesday that there were no serious adverse events observed in the trial but revised it on Thursday to include the transient atrial fibrillation event that occurred in one patient.
The drug, APD811, was being tested as a treatment for pulmonary arterial hypertension (PAH) - in which arteries of the lungs constrict, forcing the heart to work harder.
In the early-stage trial, 40 healthy volunteers received the drug and 15 received placebo, with the most frequent treatment related adverse events being headache, nausea and jaw pain.
Arena said it planned to start mid-stage trial for the drug in the first quarter of 2014, and the results of the early-stage program led to its decision to proceed with further development of the drug.
The mid-stage development of APD811 will include further exploration of dosing regimens in PAH patients, Arena said.
The company, which made the first obesity drug to be approved in the United States in 13 years, has two other drugs in clinical trials - for treating autoimmune diseases and blood-clot related disorders.
Arena shares closed at $6.69 on Wednesday on the Nasdaq.