| [ Summary ] |
Of the three types of strong opioids available in Japan for cancer pain : oxycodone, fentanyl, and morphine, the latter is still the most important and useful. There are numerous kinds of morphine formulas; tablets, aqueous solutions, powders, capsules, sticks, fine grains, suppositories, and liquids for intravenous or subcutaneous infusion. Immediate release morphine and controlled release morphine are available for oral administration. Immediate release morphine, administered five times a day, is used when a strong opioid needs to be introduced early on in the course, or as a rescue treatment during an intense pain attack. Controlled release morphine is used for continuous administration. Some types are administered twice or three times daily and others are given once or twice a day. It is important to remain alert to the risk of adverse effects, including constipation, nausea / vomiting, and sedation. Since no tolerance is established for constipation, it is managed with the use of motility stimulants and stool softeners. Nausea and vomiting are triggered by several different mechanisms that can be countered by phenothiazines, metoclopramide and haloperidol. Tolerance to sedation usually develops within a few days. Since two metabolites of morphine have adverse effects, it should be used carefully in patients with reduced renal functions. |