The drug, marketed under the brand name Diprivan, is used to keep patients unconscious during a colonoscopy, a procedure used to diagnose cancer that involves inserting a tube up into the lower intestine, ABC News reported Sunday.

Unlike weaker sedatives typically used, however, propofol requires an anesthesiologist be present, which can cost up to $400 -- often more than the gastroenterologist performing the colonoscopy is paid.

Last week, Aetna notified doctors it plans to stop covering the drug in all but a few exceptional cases April 1. Two of its large competitors, WellPoint and Humana, have already eliminated coverage of the drug, ABC News said.

Some doctors applauded the move, saying it will be an effective way to cut costs, since the drug is unnecessary for the vast majority of patients.

Others, however, said the heavier sedation drastically improves patients' experience during the uncomfortable procedure, and insurance companies should not interfere with a decision that should be made between a patient and a doctor.