The new analgesic combination tramadol/acetaminophen.

Background: Combinations of analgesic drugs provide the opportunity for better efficacy with less overall morbidity than provided by single analgesic agents. This article discusses the rationale, efficacy and safety for a novel analgesic combination: tramadol and acetaminophen (paracetamol).

Methods: Data supporting the rationale of combining tramadol and acetaminophen to provide pain relief will be reviewed in addition to clinical data demonstrating the efficacy and safety of this combination in acute and chronic pain states.

Results: Tramadol and acetaminophen are a rational combination product in that their mechanisms of action do not overlap and that in preclinical studies this combination acts synergistically. Also, this combination would be expected to provide more rapid pain relief than tramadol alone, and more persistent pain relief than acetaminophen alone. Moreover, each compound is broken down along separate metabolic pathways. Acute dental pain studies showed that pain relief and improvements in pain intensity associated with tramadol 75 mg plus acetaminophen 650 mg are superior to placebo, or tramadol or acetaminophen alone. This combination provided a rapid onset of action, identical to that achieved with acetaminophen alone, but the pain relief was also sustained, as for tramadol alone. Tramadol/acetaminophen also had the same adverse event profile as tramadol monotherapy. A chronic low back/osteoarthritic pain study showed that the drug combination can also be used similarly to codeine/acetaminophen combinations in treating benign chronic pain. The safety profile of the tramadol/ acetaminophen combination is at least as favourable as that of codeine/acetaminophen, and is well tolerated with long-term use.

Conclusions: Tramadol/acetaminophen combination is a new preparation that is effective in acute or chronic moderate-to-moderately severe pain. It benefits from the complementary actions of the constituent analgesics, having the rapid onset of acetaminophen and the sustained effect of tramadol. The analgesic efficacy of this combination is comparable to that of positive controls, and its adverse event profile is in line with that of its single components.