Melatonin Receptor Agonists Evaluated for Prevention of Delirium

Study authors were not able to recommend routine use of melatonin receptor agonists for the prevention of delirium, according to results of a literature review published in Annals of Pharmacotherapy. 

Cheri K. Walker, PharmD, and Mark A. Gales, PharmD, from Southwestern Oklahoma State University College of Pharmacy, OK, reviewed existing prospective controlled trials for the use of melatonin receptor agonists for delirium prevention. Drs. Walker and Gales searched MEDLINE and included trials with delirium prevention as an outcome. 

Five randomized and 1 non-randomized prospective controlled clinical trial was evaluated. Study authors found conflicting results across clinical trials regarding the use of melatonin receptor agonists for delirium prevention. Changes in the incidence of delirium ranged from none to significant reductions of approximately 12-30%. Melatonin was the investigated agent in 4 trials, L-tryptophan in 1 trial, and ramelteon in 1 trial. The study setting also varied where 4 trials were conducted in surgical patients and 2 were conducted among medical patients. 

Study results were inconsistent with melatonin; 3 trials demonstrated a decreased delirium incidence, and the largest randomized controlled trial showed no benefit. L-tryptophan offered no benefit in delirium prevention, while ramelteon showed reduced incidence of delirium in a single, small study. Half of the studies found adverse effects comparable to placebo and the other half did not evaluate adverse effects. 

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