Levamisole may inhibit MAO and catechol-O-methyltransferase activity, prolonging the presence of catecholamine neurotransmitters in the synapse, adding to the reuptake-inhibition effect of cocaine, and augmenting its effects (some cases of mood elevation have been reported in humans as a side effect of adjuvant therapy with levamisole for colon carcinoma) [6]. This evidence concerns the gene COMT and colon carcinoma.