Figure 1.

Antinociceptive effects (number of writhing responses) during the acetic acid-induced writhing test in mice. The number of writhing responses were recorded in mice following treatment with different doses of A alone (60 and 120 mg/kg, i.v.), N alone (3.5 and 7 mg/kg, i.v.) or N in combination with A (1.75 N + 30 A, 3.5 N + 60 A and 7 N + 120 A mg/kg, i.v.). Data are expressed as the mean ± standard error of the mean, n=8–10 per group. *P<0.05 and **P<0.01 vs. N.S. control; ^##P<0.01 as indicated. A, acetaminophen; N, nefopam; N.S., normal saline; i.v., intravenous.