CNS Drug Discoveries: Depression Chapter

Depression

Antidepressants accounted for around 21% of the total CNS drug sales in 2007, with sales of US$19.4 billion. However, we anticipate that within our forecast period to 2014, the market will show negative growth as the emergence of new products is offset by the impact of generics on leading brands.

Current market leaders will launch a number of combination therapies to optimise the life-cycle management of their drugs including Eli Lilly's Symbyax. Other companies have opted to develop second-generation products to bolster their franchises such as Pristiq, a metabolite of Wyeth's Effexor. But they are only likely to offer marginal improvements over existing therapies. Meanwhile some companies will try to gain a foothold in the market by gaining approval for established products from other therapeutic areas such as AstraZeneca's schizophrenia treatment, Seroquel.

Pharmaceutical companies have also been evaluating other ways to modulate monoaminergic pathways through the agonism and antagonism of a variety of serotonin receptors such as, 5-HT1A partial agonists (MN 305 from MediciNova),
5-HT2 antagonists (valdoxan from Servier/Novartis) and even beta-3 receptor antagonists (amibegron from sanofi-aventis), as well as developing dual acting compounds which block serotonin receptors and the uptake of serotonin itself, such as Clinical Data's vilazodone.

Research into alternative targets such as CRF and NK receptors may pay off as products enter late-stage development such as sanofi-aventis' saredutant. However, there have been many casualties and it is still uncertain whether these drugs will offer any significant benefit over current therapies.

Key depression questions answered include:

• What series of events are undermining Pfizer's position?
• Five new products are expected to launch by 2010 - what are they and who are their developers?
• Sales of Wyeth's Pristiq could reach US$1.2 billion by 2014, but what are the prospects for its generically challenged sister product Effexor in the same year?

Key products analysed and forecast

• Cipralex/LexaproLundbeck/Forest Laboratories
• CymbaltaEli Lilly
• EffexorWyeth
• NS2358/GSK372475NeuroSearch/GlaxoSmithKline
• ProzacEli Lilly
• Paxil/SeroxatGlaxoSmithKline
• PristiqWyeth
• Saredutantsanofi-aventis
• ValdoxanNovartis/Servier
• WellbutrinGlaxoSmithKline
• ZoloftPfizer