PALM SPRINGS, CALIF. — Just 45% of prescriptions for the opiate OxyContin (oxycodone HCl controlled release) are taken as directed by patients being treated for nonmalignant pain, according to a study of urine samples from approximately 5% of the nation's outpatient pain clinics.
Fully 40% of the drug was recycled among other patients being treated for pain in 264 clinics whose combined caseloads exceeded 33,000 patients, Michael Kell, M.D., of the Labyrinth Institute of Smyrna, Ga., reported at the annual meeting of the American Academy of Pain Medicine.
Another 15% of OxyContin prescriptions were diverted to the black market, said Dr. Kell, who was chosen to present his poster in an oral format at the meeting.
Dr. Kell, a toxicologist, collected his data using software technology that interprets highly specific urinalysis results that control for urine concentration and acidity and patient BMI.
The urine from 55% of approximately 11,000 patients prescribed OxyContin either contained more of the drug, or less, than what would be expected based on the amount prescribed. To allow for time of day and other variations, Dr. Kell considered a patient compliant if the level of OxyContin in his or her urine was within three standard deviations of the mean.
Interestingly, about 15% of patients prescribed OxyContin had none of the drug in their urine. At the same time, many patients being treated with other pain drugs in the clinics had OxyContin in their urine, suggesting that “most of the diversion was patient to patient,” Dr. Kell said.
Funding for Dr. Kell's study was provided by UD Testing Inc., a Marco Island, Fla., company that uses Dr. Kell's software to monitor patient compliance with prescription medicine.
Another study presented at the meeting described very preliminary results from a novel oxycodone drug formulation called Remoxy. The formulation delivers a long-acting dose of the opiate in a gel cap designed to be impervious to efforts to extract the full dose to achieve a “spike” effect by crushing, freezing, heating, or dissolving it in various substances. Current formulations of the drug can be manipulated in this way, adding to abuse and diversion.
Plasma concentrations were markedly lower in 20 subjects who took Remoxy after it had been tampered with, compared with concentrations among people who had taken crushed controlled-release formulations of oxycodone.
The industry-designed study was funded by Pain Therapeutics Inc. of San Francisco.