Oral morphine remains the drug of choice for most patients with severe cancer pain, and the sustained-release form (MS-Contin, Roxanol SR), has certain advantages, Ronald Blum, MD, said at a conference sponsored by Cancer Care, Inc.
Oral morphine remains the drug of choice for most patients withsevere cancer pain, and the sustained-release form (MS-Contin,Roxanol SR), has certain advantages, Ronald Blum, MD, said ata conference sponsored by Cancer Care, Inc.
Sustained-release morphine has a half-life of from 8 to 12 hours."You can give it at hour zero and maintain a blood levelfor 12 hours," said Dr. Blum, deputy director, Kaplan ComprehensiveCancer Center, New York University Medical Center. Morphine sulfatesolution has to be given every 4 hours.
Patients can be started directly on sustained-release morphineor can be converted from other opioid narcotic analgesics, hesaid. "What we tend to do, and what I recommend, is to startout with immediate-release morphine and gradually, over time,as the patient stabilizes, convert to MS Contin."
Since it takes time to reach steady- state concentrations withthe sustained-release form, patients should continue to take animmediate-release morphine preparation for several days afterstarting the sustained-release drug, he said.
Dr. Blum stressed that the enteral route should be used if possible,ie, any access routes to the GI tract (oral, buccal, rectal, tube).Approximately 30 mg of oral morphine is equivalent to 10 mg ofinjected morphine, he said. Roughly 4 mg of oral hydromorphoneis equivalent to 15 mg of oral morphine.
Methadone probably should not be used for patients with chronicsevere pain, because of the long half-life of the toxic metabolites,Dr. Blum warned. Similarly, meperidine (Demerol), although highlyeffective when given parenterally at 75 mg for acute pain, isnot recommended for the management of chronic pain. The equaloral analgesic dose is 300 mg, which, over time, is associatedwith a high degree of side effects (primarily sedation).
Fentanyl Patch an Alternative
Dr. Blum singled out fentanyl as a well-tolerated alternativeto oral analgesics. Fentanyl is used in the operating room foranesthesia and has been available for a number of years as a transdermalpatch (Duragesic). "The problem with fentanyl is that it'svery short acting," he said, "but the patch allows continuousrelease through the skin."
Fentanyl is particularly useful for people who do not have anenteral tract available, or have nausea and vomiting and cannottake oral medication. At about 50 mcg per hour, it is approximatelyequivalent to 30 mg of morphine by mouth or 10 mg given parenterally,Dr. Blum said.
Because of its slow onset of action, patients should take a short-actingnarcotic analgesic while building up their fentanyl dose, he said."But it does arrive at a steady state and does last from48 to 72 hours; the patch can be replaced approximately every3 days ".