Enhancement of Antinociceptive Effect by Co-administration of Amitriptyline and Crocus Sativus in a Rat Model of Neuropathic Pain

The aim of this study was to evaluate the anti-nociceptive effects of a low, sub-effective dose of amitriptyline, in combination with the different doses of ethanolic and aqueous extracts of Crocus sativus following sciatic nerve chronic constriction injury (CCI) in rats. Amitriptyline (3, 10 and 30 mg/Kg, i.p.) and the extracts (25, 50 and 100 mg/Kg, i.p.), were separately administered at the time of CCI for 7 consecutive days. In combination therapy, the sub-antinociceptive dose of amitriptyline (3 mg/Kg) was given with the three different doses of extracts for seven days. Mechanical allodynia, thermal allodynia and thermal hyperalgesia were evaluated by von Frey, acetone and radiant heat tests, respectively, 1 day before and on days 3, 5 and 7 after surgery. Co-administration of amitriptyline (3 mg/Kg) with aqueous extract (50, 100 mg/Kg,) produced more potent cold anti-allodynic (P < 0.01 and P < 0.001, respectively) as well as thermal anti-hyperalgesic (P < 0.05) effects than that produced by each of them. Amitriptyline (3 mg/Kg) plus ethanolic extract (50, 100 mg/Kg) produced more potent cold anti-allodynic (P < 0.05 and P < 0.001, respectively) as well as thermal anti-hyperalgesic (P < 0.05) effects as compared with the sum effects produced by each of them. Mechanical anti-allodynia effect was only potentiated with the co-administration of amitriptyline with the high dose of aqueous extract (100 mg/Kg, P < 0.001). Our study supports the use of saffron as an adjunctive to amitriptyline to improve the therapeutic outcome in the management of neuropathic pain.