New Drug for Insomnia After Sleep-Time Shift
Tasimelteon, an Agonist of Melatonin, Shows High Effectiveness
Dec 29, 2008
Frequent travelers and night worker shift often suffer from transient insomnia and sleep disturbance due to a transient disorder of their biological clock, also called the circadian rhythm. This sleep disorder is characterized by a recurrent sleepiness during the day and insomnia symptoms when trying to sleep at night.
Circadian Rhythm and Melatonin
The circadian rhythm is under the control of melatonin, a hormone normally secreted during the night by the pineal gland located in the center of the brain. The secretion of melatonin by the pineal gland is itself under the control of the hypothalamus, which receives information from the retina about light and darkness.
Melatonin taken orally as a pill, in the afternoons and the evenings, is used to treat circadian rhythm disorders. However, the efficiency of melatonin pills is questionable for treating transient sleep disorder caused by jet lag effects and work shifts. Indeed, the effects of melatonin pills are not well reproduced among independent studies.
Tasimelteon is an Agonist of Melatonin
Tasimelteon, also known as VEC-162, is a novel synthetic agonist of melatonin. An agonist is a drug that mimics the action of the natural molecule and produces a pharmacological response. Tasimelteon has a high affinity for the melatonin receptor where it could replace melatonin in a more efficient manner.
Santha Rajaratnam and Elizabeth Klerman, from Vanda Pharmaceuticals Inc. and Harvard Medical School, reported on the efficacy of Tasimelteon to treat circadian disorders when simulating changes in during the night. The study was published in December 2nd, 2008 as ¨Melatonin agonist Tasimelteon (VEC-162) for transient insomnia after sleep-time: two randomized controlled multicentre trials¨ (The Lancet, vol 8, pp 61812-61817, 2008).
Tasimelteon, VEC-162, May Treat Insomnia Caused by Jet Lag
The scientists analyzed different parameters to evaluate the efficiency of the sleep of volunteers during the night. They provoked a 5 hours advance in sleep-wake schedule to mimic a jet lag effect.
The scientists found that during the middle third of the night volunteers treated with Tasimelteon had a higher sleep efficiency and a total increase sleep time compared to volunteer taking a placebo.
Hope for Millions of People Suffering From Circadian Rhythm Disorders
Every year, several million people travel internationally and are subjected to jet lag effects. Canadian researchers from Laval University estimated than insomnia costs more than 6 billion dollars annually to the Quebec economy, as reported on the CBC website. ("Insomnia costs Quebec billions annually, study says", CBC News, January 1, 2009). Vanda Pharmaceutical Inc researchers said that Tasimelteon has a tremendous therapeutic potential even if the efficiency of Tasimelteon was not compared to the efficiency of melatonin. The researchers also suggest that Tasimelteon might help the some 20 millions of American who start work before sunrise and are subjected to chronic sleep restriction.
 |
