Zimelidine attenuates the development of tolerance to morphine-induced antinociception

OBJECTIVES

The aim of this study was to investigate effect of zimelidine (a serotonin reuptake inhibitor) on morphine-induced tolerance in rats.

MATERIALS AND METHODS

Male Wistar albino rats weighing 160-180 g were used in these experiments (n=72). A 3-day cumulative dosing regimen was used for the induction of morphine tolerance. To constitute of morphine tolerance, animals received morphine twice daily for 3 days. After the last dose morphine was injected on the fourth day, morphine tolerance was evaluated. The analgesic effects of zimelidine (15 mg/kg; i.p.) and morphine (5 mg/kg) were considered at 30-min time intervals (0, 30, 60, 90 and 120 min) by tail-flick and hot-plate analgesiometer (n=6 in each experimental group).

RESULTS

The results showed that zimelidine significantly attenuated the development and expression of morphine tolerance. The maximal antinociceptive effect of zimelidine was obtained at the 60 minutes measurements in the zimelidine group and at the 30 minutes measurements in the morphine tolerant group by the tail-flick and hot-plate tests. Administration of zimelidine with morphine showed additive analgesic effect.

CONCLUSION

In conclusion, our results show that zimelidine reduces the development of tolerance to morphine-induced antinociception in rats.

Effects of antidepressants on skilled performance

Effects of amitriptyline 50 mg, desipramine 100 mg, and zimelidine 200 mg alone and in combination with ethanol 0.8 g/kg were investigated in healthy, male volunteers. Amitriptyline increased body sway and impaired tracking as well as information processing. It had an additive deleterious pharmacodynamic interaction with ethanol. Desipramine and zimelidine were free of adverse effects on performance and did not have significant interactions with ethanol. The dose of ethanol used in the present study did not inhibit biotransformation of the antidepressants.