Is there any relationship between antinociception, doses and plasma levels of clomipramine during subchronic treatment in rats?

The antinociceptive effects and the plasma levels (evaluated by high liquid pressure chromatography) of clomipramine during a subchronic (5 days) treatment were studied in rats using the Nilsen's test. Clomipramine (10, 20, 30 and 40 mg/kg administered by mouth) showed a clear dose-dependent analgesic effect. The study of the partial correlation coefficients did not found a relationship between plasma levels and antinociception under our experimental conditions. These results suggest that regular monitoring of plasma levels of clomipramine appears to be useless in the treatment of patients with chronic pain.