<p>Additive depressant effects with other CNS depressants (e.g. sedatives, hypnotics, general anaesth, phenothiazines, other tranquilisers). May enhance the neuromuscular blocking action of skeletal muscle relaxants. Reduced analgesic effect with mixed agonist/antagonist opioid analgesics (e.g. pentazocine, nalbuphine, buprenorphine). Increased plasma concentrations with cimetidine. May reduce the efficacy of diuretics by inducing the release of antidiuretic hormone. May delay the absorption of mexiletine. May antagonise the GI effect of cisapride, domperidone and metoclopramide. May produce hyperpyrexia and CNS toxicity with dopaminergics.</p>