Insomnia is the most common type of sleep disorder and is considered to be a symptom rather than an actual disease or syndrome.
Affecting 20-50% of the population, insomnia is characterised by one or more of the following symptoms: patients have difficulty in falling asleep and in sleeping without interruption. They wake up frequently, or very early, and feel that they have slept lightly and do not feel rested after sleeping.
Considering the number of patients suffering from insomnia, the market for therapeutic drugs for sleep disorders is small compared with other CNS disorders. The main explanation for this is that a large number of these patients do not receive any treatment or use unregistered medicine/health products or other non-pharmacological therapies.
The most frequently used drugs on the market today are Stilnox®/Ambien® (zolpidem) from Sanofi-Synthelabo, Imovane® (zopiclone) from Aventis, and Sonata® (zaleplon) from Wyeth-Lederle. Today, these three drugs, of which Stilnox®/Ambien® holds the largest market share by far, greatly contribute to growth in the global market for anti-insomnia drugs. Global sales of zolpidem, zopiclone and zaleplon were USD 1.4 billion in 2001, an increase of 27% over 2000. Stilnox®/Ambien® accounted for 82% of 2001 revenue, with revenue in North America accounting for 76% of global sales.
