Treatment Options
Melatonin Receptor Agonists
The strategy underlying the development of melatonin receptor agonists is to produce an agent with the therapeutic and safety benefits of melatonin, but with a longer half-life than the endogenous substance. In addition to Circadin®, data is currently available on two synthetic melatonin agonists – ramelteon (Rozerem® in the USA) and agomelatine (Valdoxan®). The chemical structure of these agents is shown in Figure 1, and the characteristics of these two melatonin agonists are shown in Table 1. Ramelteon is indicated for the treatment of sleep-onset insomnia in the US, (www.nlm.nih.gov/medlineplus). Filing in EU resulted in a non-approval from the EU's CHMP, based on lack of efficacy, in June 2008. However this verdict has been appealed.
Agomelatine, which has primarily been studied in patients with mood disorders, is to be filed in the EU during 2008 for the treatment of depression.(www.servier.com) However, studies have been carried out which specifically evaluate sleep disorders in depression with the belief that addressing the comorbid sleep issues will ease the depression.1
| Generic name | Brand name | Half-life (hr) | Tmax (hr) | Dose (mg) |
|---|---|---|---|---|
| Ramelteon | Rozerem® | 1.0–2.6 | 0.75 | 8.0 |
| Agomelatine | Valdoxan® | ~1.0 | 1.0 | 25–50 |
References:
1. Lam RW. Sleep disturbances and depression: a challenge for antidepressants. Int Clin Psychopharmacol 2006; 21 (Suppl 1): S25–S29.