Drug interactions do not support reduction in serotonin turnover as the mechanism of action of benzodiazepines.

Interactions between 5-methoxy, N,N-dimethyltryptamine (5-MeODMT), chlordiazepoxide and para-chlorophenylalanine (pCPA) on conflict behaviour were studied. 5-Methoxy, N,N-dimethyltryptamine (1.0 and 3.0 mg/kg), induced observable effects and reduced unpunished response rates but did not affect punished behaviour either alone, on in the presence of 5 or 10 mg/kg chlordiazepoxide. However, 5-MeODMT (1 mg/kg) reversed the anti-conflict effects of chronic administration of pCPA (100 mg/kg). Chronic administration of pCPA did not prevent the increase in punished response rates induced by chlordiazepoxide (5 mg/kg). These findings are discussed in the context of the serotonin hypothesis of benzodiazepine action, with the conclusion that benzodiazepines act at a site distal to that of serotonergic drugs on conflict behaviour.