The 2009 Compensation Data Insurance survey by Compdata Surveys found high-deductible health plans had the highest prescription medicine copay, $49, compared to non-formulary copays on PPO plans of $47.

Formularies are lists of medications that are covered by an insurer’s health care plan.

Over the last 3 years, the prescription copay cost on PPO plans has increased by 10.4%, reports Compdata, Kansas City, Kan., a unit of Dolan Technologies Corp., Olathe, Kan.

In 2009, the average cost of formulary drugs on PPO plans was $25.44, up 6.1% over the last three years. Indemnity plans had the highest formulary cost, $29, and HMO had the lowest, $26.

In comparison, copays for generic drugs stayed under $15 on all plans in 2009. Generic copays were $10 on PPO and HMO plans. On average, an individual could save over $35 per prescription when choosing a generic over a non-formulary drug, Compdata said.