Possible analgesic and anti-inflammatory interactions of aspartame with opioids and NSAIDs.

The purpose of the present study was to investigate analgesic and anti-inflammatory properties of aspartame, an artificial sweetner and its combination with various opioids and NSAIDs for a possible synergistic response. The oral administration of aspartame (2-16mg/kg, po) significantly increased the pain threshold against acetic acid-induced writhes in mice. Co-administration of aspartame (2mg/kg, po) with nimesulide (2 mg/kg, po) and naproxen (5 mg/kg, po) significantly reduced acetic acid-induced writhes as compared to effects per se of individual drugs. Similarly when morphine (1 mg/kg, po) or pentazocine (1 mg/kg, po) was co-administered with aspartame it reduced the number of writhes as compared to their effects per se. Aspartame (4,8,16 mg/kg, po) significantly decreased carrageenan-induced increase in paw volume and also reversed the hyperalgesic effects in rats in combination with nimesulide (2 mg/kg, po). The study indicated that aspartame exerted analgesic and anti-inflammatory effects on its own and have a synergistic analgesic response with conventional analgesics of opioid and non-opioid type, respectively.