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More on the aspirin - ibuprofen debate I ran these two drugs through a drug interaction program and strangely enough it seems that the use of these two drugs in combination may actually decrease the effects of aspirin on platlets. Anyway the information I came up with is below so you can take it for what it is worth. Safe Diving Mike Seeley mseeley@po*.ne* ASPIRIN -- IBUPROFEN Adverse Effect: Concurrent use of ASPIRIN and IBUPROFEN may result in reduced ibuprofen serum levels or reduced duration of aspirin-induced antiplatelet effects. Clinical Management Monitor for signs and symptoms of excessive gastrointestinal irritation; consider monotherapy in absence of clinical evidence of enhanced therapeutic response with concomitant use. Onset: delayed Severity: minor Documentation: poor Probable Mechanism: displacement of ibuprofen from protein binding sites and enhanced elimination (Aarons et al, 1983); binding of ibuprofen to cyclooxygenase blocks acetylation of this enzyme by aspirin. Summary: Studies indicate that concurrent salicylate administration to both healthy volunteers and arthritic patients may lower ibuprofen blood levels and antiinflammatory action without affecting the NSAID elimination half-life (Prod Info Motrin(R), 1999; Miller, 1981). Single dose bioavailability studies and reports of unpublished clinical observations, however, have failed to demonstrate a significant effect of aspirin on ibuprofen blood levels (Prod Info Motrin(R), 1999; Davis, 1975). The duration of aspirin-induced antiplatelet effects is shortened by concurrent use of ibuprofen (Rao et al, 1983). Literature In a crossover trial, Grennam et al (1979) administered placebo, 2.4 grams/day aspirin, 800 milligrams/day ibuprofen or both drugs together to 16 patients for 2 weeks. A further 14 patients entered a similar study using 3.6 grams/day aspirin and 1600 milligrams/day ibuprofen. Lower doses of aspirin and ibuprofen scored better than placebo in subjective and observer scores but not on objective scores. The combined therapy offered no benefit over single drug therapy. High doses of aspirin and ibuprofen did better than placebo on subjective and objective scores. Combined therapy scored better than single drug therapy. A double-blind crossover study investigating the efficacy of ibuprofen combined with aspirin was conducted in 2 parts, each lasting 14 days. The first trial consisted of low doses of each medication and the second of high doses. The authors subjectively concluded the patient's fitness was superior with the combination, however, objective parameters indicated no significant difference between the 2 treatment trials (Miller, 1981). Nonsteroidal antiinflammatory drugs such as ibuprofen apparently bind to the same cyclooxygenase inhibitory site as aspirin. This binding blocks the the acetylation of cyclooyxgenase by aspirin, which is responsible for the long duration of antiplatelet action. Ibuprofen administration prior to aspirin dosing resulted in a return to normal platelet activity within 24 hours after aspirin (Rao et al, 1983). Citation: Product Information: Motrin(R), ibuprofen. Pharmacia & Upjohn Company, Kalamazoo, MI, 1999. Rao GHR, Johnson GG, Reddy KR et al: Ibuprofen protects platelet cyclooxygenase from irreversible inhibition by aspirin. Arteriosclerosis 1983; 3:383-388. Miller DR: Combination use of nonsteroidal antiinflammatory drugs. Drug Intell Clin Pharm 1981; 15:3-7. Davis LJ: Ibuprofen. Drug Intell Clin Pharm 1975; 9:501-502. Grennan DM, Ferry DG, Ashworth ME et al: The aspirin-ibuprofen interaction in rheumatoid arthritis. Br J Clin Pharmacol 1979; 8:497- 503. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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