Slumping US sales of GlaxoSmithKline’s Avandia have begun to level off in the wake of last month’s New England Journal of Medicine (NEJM) report suggesting the diabetes pill increases the risk of heart attack in patients.

Citigroup analysts, citing IMS Health data for the third week since the May 21 publication of the analysis, said Avandia accounted for 7.4% of new prescriptions versus 7.6% a week earlier. Avandia’s share was 8.8% during the previous week. The week before that it was 12.1%. Avandia’s total prescription share was 9.1% in the week to June 8, versus 9.3%, 10.1% and 12.3 % in the preceding weeks.

Deutsche Bank told Reuters that more up to date prescription data compiled by ImpactRx showed new written prescription share for Avandia was now well off its lows, with its share in the primary care physician setting having fallen from 12.9% to 3.9% but rebounding to 5.9% for the week ending June 17.

Avandia sales plummeted following the NEJM‘s publication of analysis conducted by Dr. Steven Nissen, head of cardiology at the Cleveland Clinic, suggesting that the diabetes treatment raised heart attack risk in patients by 43%. Nissen’s analysis was based on conclusions drawn from pooled data from 42 trials involving nearly 28,000 patients.

GSK disputed Nissen’s findings, arguing that data from other trials shows Avandia is just as safe as other diabetes drugs.

An FDA advisory panel is scheduled to study the issue of Avandia’s safety at a meeting on July 30.