Study of the analgesic, anti-inflammatory, and gastric effects of gabapentin.

Gabapentin, a drug used to treat neuropathic pain, was evaluated in models of acute nociceptive pain, in instances of haloperidol-induced catalepsy, carrageenan-induced paw edema, gastric lesions caused by indomethacin or ethanol, and gastric acid secretion in rats. Reaction time in a hot plate assay was delayed by gabapentin. The antinociceptive effect of the drug was produced with a dose of 12.5 mg/kg and a maximal increase in hot plate latency of 68% 1 h after drug administration was produced at 100 mg/kg. Gabapentin (25, 50 or 100 mg/kg) caused a significant rise in current threshold in a tail electrical stimulation test in mice, resulting in values of 20, 30, and 60.5% vs. control values, 1 h post-dosing. With the agent, the duration of paw licking following intraplantar capsaicin injection decreased in a dose-dependent manner. In contrast, gabapentin failed to have antinociceptive action in a mouse acetic-acidinduced writhing assay. The drug (12.5-50 mg/kg) increased the duration of catalepsy induced by haloperidol by 33.5, 47.4, and 53.2%, respectively. It had an anti-inflammatory effect at doses of 25 or 50 mg/kg. Gabapentin (12.5-50 mg/kg) reduced the number and severity of gastric mucosal lesions induced by subcutaneous indomethacin (20 mg/kg) or intragastric 96% ethanol, but at doses of 50 and 100 mg/kg it increased gastric acid secretion. In conclusion, gabapentin decreased thermal, electrical, and chemogenic pain but not visceral pain and had a gastric protective effect.