Pharmacology and clinical experience with tramadol in osteoarthritis.

Tramadol is a centrally acting analgesic that has been shown to be effective in a variety of acute and chronic pain states. Unlike other centrally acting analgesics, it exerts a dual action by binding to the opioid receptor site in the central nervous system and by weakly inhibiting the reuptake of biogenic amines. Tramadol is rapidly and almost completely absorbed, with an onset of action occurring within 1 hour of oral administration. The recommended dosage is 50 to 100 mg every 4 to 6 hours; however, regular administration is an alternative, particularly for chronic pain states such as osteoarthritis, where the use of the recently developed sustained release formulation may represent an important advantage. Published studies specifically evaluating the use of tramadol in this disease support its effectiveness. Nausea, drowsiness, constipation, dizziness, and sweating have been reported in association with tramadol use. Nausea occurs early in the course of administration, and may be reduced by slowly titrating the dose of tramadol against response. Tramadol would appear to be particularly useful in the elderly population affected by osteoarthritis because, unlike nonsteroidal anti-inflammatory drugs, it does not aggravate hypertension or congestive heart failure, nor does it have the potential to cause peptic ulcer disease. Compared with narcotics, tramadol does not induce significant respiratory depression, constipation, or have significant abuse potential.