Possible Interaction: Phenelzine and Tryptophan

“When L-tryptophan or 5-hydroxytryptophan is administered with phenelzine (a monoamine oxidase inhibitor) and carbidopa (a selective peripheral L-amino acid decarboxylase inhibitor) to raise brain serotonin, a significant increase in myocardial electrical stability is observed.”

“The turning induced by 5-methoxy-N,N-dimethyltryptamine and in the same direction after treatment with phenelzine plus L-tryptophan.”

“The authors report acute behavioral and neurologic toxicity immediately after tryptophan administration in a patient taking phenelzine.”

“Cortical 5-HT2 receptors were significantly reduced within 3 h of tryptophan (150 or 500 mg/kg) given to phenelzine-treated rats.”

“Pretreatment of mice with 100 mg kg−1 phenelzine was followed by a significant rise in both brain tryptophan and 5‐hydroxytryptamine (5‐HT) concentrations which lasted for 24 h. Therefore, the changes in pethidine effects could have been due to raised brain tryptophan and 5‐HT concentrations.”

“ Brain tryptophan concentration was also markedly increased by phenmetrazine, phenelzine , dl -fenfluramine, bulbocapnine, γ-hydroxybutyrate and probenecid.”