Caffeine as an analgesic adjuvant in the treatment of headache

Objective: To summarize the data on caffeine as an analgesic adjuvant, when combined with acetaminophen and aspirin in headache pain. Study Selection: The caffeine adjuvant effect has been demonstrated in a number of clinical trials. Most notable are a series of four clinical studies comparing the analgesic efficacy of two tablets of the combination acetaminophen (500mg), aspirin (500mg), and caffeine (130mg) (APAP/ASA/CAF), two tablets of acetaminophen (1000mg), and placebo in the treatment of tension-type headaches. Patients receiving the APAP/ASA/CAF formulation experienced significantly greater analgesia compared with either acetaminophen alone or placebo. A meta-analysis of 30 clinical studies involving over 10,000 patients estimated that caffeine-containing analgesics have a relative potency of 1.41. Conclusion: There is substantial evidence that establishes caffeine as an adjuvant when combined with analgesics. The addition of caffeine in a dose of 130mg augments the anti-nociceptive effects of the combination of acetaminophen and aspirin. This effect is independent of the consumption of caffeine through dietary sources. Controlled clinical trials specific to tension-type headache have reported a greater relative potency of caffeine adjuvancy (1.65 to 1.85). From a clinical perspective, this appears to be borne out by the significant effect APAP/ASA/CAF has on the relief of migraine headache pain, which has been documented in three independent double-blind, parallel-group, placebo-controlled trials.