The effects of systemic procaine, lidocaine and dimethocaine on nociception in mice

1. Different local anesthetics were tested for analgesic activity in three antinociceptive models, the acetic acid-induced abdominal constriction, tail-flick and hot plate tests in the mouse. 2. In the abdominal constriction test, subcutaneous, SC, injection of lidocaine (10, 20 or 30 mg/kg) and dimethocaine (5, 10 or 20 mg/kg) induced dose-dependent antinociceptive responses. Procaine (20, 30 or 50 mg/kg) was also able to reduce the response to noxious chemical stimuli. 3. The IP injection of lidocaine and dimethocaine significantly inhibited the tail-flick and paw-licking hot plate responses; procaine was weak or inactive in these tests, in which heat was the noxious stimulus. 4. Taken together, these results suggest that antinociception produced by systemically administered lidocaine and dimethocaine at nontoxic doses in mice is due, at least in part, to their central effects.