Romanian Society of Pharmaceutical Sciences
 

« Back to Farmacia Journal 6/2015

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

Download Full Article PDF

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.