ADVERSE DRUG-REACTIONS AND DEBRISOQUINE SPARTEINE (P450IID6) POLYMORPHISM IN PATIENTS WITH FIBROMYALGIA/

Objective: To assess the frequency of adverse drug reaction in patient s with fibromyalgia in relation to medications prescribed for this con dition, To evaluate the potential role of the P450IID6 phenotype in th e pathogenesis of these adverse drug reactions. Methods: Thirty-five p atients with fibromyalgia were assessed using a structured questionnai re with demographic and clinical data and perceived adverse drug react ions, A sample of 60 patients with rheumatoid arthritis and 62 patient s with localized back pain served as controls, The P450IID6 phenotype was determined for each of the fibromyalgia patients. Results: Overall , 141 patients had used NSAID and 79 (56%) of them reported adverse ef fects, Antidepressant drugs were used by 68 patients and 35 (51%) pati ents had adverse effects, Muscle relaxant drugs were used by 48 patien ts and 15 (31%) of them reported side effects, Analgesics were used by 122 patients and 22 (18%) had experienced adverse effects, Statistica l differences in the frequency of adverse effects were found with anti depressant drugs in the fibromyalgia group, compared with rheumatoid a rthritis (p=0.01) and back pain (p=0.02), Four of the 35 patients (11. 4%) had a metabolic ratio (M.R.) greater than 0.30 (log M.R.=-0.52) in dicative of the poor metabolizers (PM) phenotype, M.R. varied from 0.0 05 (log M.R.=-2.30) to 4.99 (log M.R.=0.70). Conclusions: The problem of adverse drug reactions in fibromyalgia patients does not appear to correlate with the PM phenotype of the P450IID6 oxidative enzyme, It a lso is unlikely that altered xenobiotic detoxification attributable to this PM phenotype would have a significant role in the development of fibromyalgia.