More than half of older patients taking a class of anti-inflammatory drugs called COX-2 inhibitors are also on aspirin therapy, possibly negating the reason for using expensive COX-2s in the first place, a study sponsored by Express Scripts Inc. found.

The popular prescription pain and arthritis medicines known as COX-2 inhibitors, such as Celebrex and Vioxx, are often prescribed because they don’t cause the stomach problems associated with much less expensive painkillers like aspirin and ibuprofen.

But the 95,000-patient survey funded by Express Scripts, the pharmacy benefit manager - always looking to control costs - found a high rate of aspirin use among those taking COX-2s, and suggested a less expensive combination might be just as effective. The study was published on Monday in the Archives of Internal Medicine.

“I’m speaking to that Medicare beneficiary who is paying out of pocket the full price of these medications,” said Emily Cox, the lead author of the Express Scripts study. “It’s important to just encourage patients to talk to their physician about what combination of therapies is appropriate to them that will help save them money,” she said.

This class of drugs takes its name from the COX-2 enzyme, commonly found at the site of inflammation, such as arthritic knees. COX is an acronym for cyclooxygenase enzyme.

Drugs inhibiting the COX-2 enzyme help curb inflammation, but have fewer side effects than non-selective drugs, because they do not affect the body’s functions that are regulated by the COX-1 enzyme, such as maintaining the stomach lining.

Ibuprofen and aspirin are non-steroidal anti-inflammatory drugs (NSAIDs), which are effective against pain but can cause ulcers and dangerous stomach bleeding.

The study also found that half of those patients using aspirin to help prevent heart disease and stroke were taking higher doses than necessary, putting themselves at greater risk for stomach problems.

Cox said patients over the age of 60 or 65 who are at risk for gastric irritation should consider switching from COX-2 inhibitors to a lower-cost NSAID in combination with a type of gastric medicine called proton pump inhibitors, or PPIs, such as Prilosec, which is now available in cheaper generic versions.

She acknowledged that a combination of aspirin therapy, a prescription COX-2 inhibitor and a prescription PPI, such as AstraZeneca’s Nexium or Prilosec, would cover all three bases of cardiac, gastric and pain problems - in patients for whom cost is not an issue.

But clearly insurance companies and pharmacy benefit managers, such as Express Scripts, would like to see a move to far less expensive therapies. “If we were in situation with totally unlimited resources, nobody would even be questioning this,” Cox said.