The danger is greatest with people who already have sleep apnea or who are overweight, the experts say. Doctors familiar with the problem caution patients and their families to pay attention to possible warnings, such as snoring and obstructive breathing. Someone with no history of snoring who suddenly begins after taking a new prescription may be in prescription-induced trouble.

That's something Grey hears a lot as he talks to families whose loved one died. Several days after starting a methadone prescription, a widow might say, "he was snoring so loudly I couldn't sleep in the same room. The next morning, he was dead."

Respiratory suppression can happen with other drugs, too — drugs that patients often assume are safe because a doctor prescribed them, says Nancy Mismash, an attorney with Robert DeBry & Associates. Mismash is representing the family of Debbie Barlow, who died in March 2005 after using Duragesic, a transdermal patch containing a gel form of the synthetic opioid fentanyl. The drug is up to 100 times as strong as morphine.

A lawsuit filed in 3rd District Court contends that the Duragesic patch was defective, allowing fentanyl to leak so that Barlow received an excess dose. Barlow, 38 and the mother of two children, suffered from chronic pain and migraine headaches. She died within hours of applying the patch.

Barbara Crouch, director of the Poison Control Center at the University of Utah, cites several worries about prescription drugs: interactions between the drug and the disease, drug-drug interactions, how different bodies process a drug, and patients failing to take the drugs as intended.

Taking a painkiller along with a non-prescription sleep remedy, for example, can double the sedative effect. In some cases the combination can create an exponential effect that "places someone in grave danger," Crouch says.

While many patients are cautious about prescription interactions, they pay less attention to other things they ingest — foods, alcohol, herbal supplements and non-prescription drugs, although those too can alter the effects. Sleep aids and antihistamines, combined with pain prescriptions, may multiply the sedative effect, impairing breathing. Some dietary supplements, such as kava and valerian, also have sedative effects. Many pain drugs interact with anti-anxiety or depression medications.

Some drugs, prescription or not, can also affect how a pain medication is metabolized, slowing the body's ability to eliminate it.

Each doctor who treats you should know everything you're taking, says Crouch. She also recommends using a single pharmacist, who may spot the potential for dangerous interactions.<

Methadone's quirks