Romanian Society of Pharmaceutical Sciences
 

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EXPERIMENTAL RESEARCH SHOWING THE BENEFICIAL EFFECT OF ORAL ZINC ADMINISTRATION IN OPIOID TOLERANCE

DIANA CIUBOTARIU1, CRISTINA MIHAELA GHICIUC1, RAOUL VASILE LUPUȘORU2*, NELA BIBIRE3, LUMINIŢA AGOROAEI4, CĂTĂLINA ELENA LUPUȘORU1

“Grigore T. Popa” University of Medicine and Pharmacy, 16 Universităţii Street, code 700115, Iaşi, Romania
1.Faculty of Medicine, Department of Pharmacology
2.Faculty of Medicine, Department of Pathophysiology
3.Faculty of Pharmacy, Department of Analytical Chemistry
4.Faculty of Pharmacy, Department of Toxicology

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There are studies showing that zinc attenuates opioid-dependence. The aim of the present study was to assess the effect of oral zinc sulphate on opioid analgesia in tolerant rats. Analgesia was assessed in 3 rat groups: non-dependent (group A) and dependent (groups B and C), each with 3 subgroups. Dependence was induced with morphine in increasing doses (B: 5-day schedule, C: 10-day schedule; from 5 mg/kg bw - day 1 to 40 mg/kg bw - day 5, respectively 90 mg/kg bw - day 10). Subgroups 1 received saline, subgroups 2 and 3 received ZnSO4, 14 days, 2 mg, respectively 4 mg/kg bw/day, orally, before inducing dependence in groups B and C. Basal and exposure latencies were assessed by the tail-flick test, before and 30 min after morphine administration: 5 mg/kg bw (group A, at the end of zinc treatment); 10 mg and 15 mg/kg bw (groups B and C, at the end of dependence schedule). Morphine induced strong analgesia in naïve and tolerant rats. In subgroup 1, the exposure latency increased vs. basal with 41% in group A (from 10.2 ± 0.4 s to 14.5 ± 0.4 s; p < 0.001) and with 19%, respectively 15% in groups B and C, where analgesia was reduced vs. non-dependent rats. Zinc did not influence pain perception. Zinc supplementation in patients on opioids for pain is worth being evaluated.