Anticonvulsants and substance P antagonists are two of the new classes of compounds being assessed for use in treating depression, according to the Association of the British Pharmaceutical Industry (APBI). In a new booklet, Target Depression, the association indicates that there is a need for new antidepressants and explains that several companies are devoting a significant proportion of research to developing such compounds.
Glaxo Wellcome's lamotrigine has reached Phase 3 trials in serious bipolar disorder, says the report. It has been suggested that lamotrigine prevents the onset of mania in bipolar disorder by acting on the depressive stage of the condition, it says. Parke-Davis is assessing gabapentin for the same condition.
The report also notes that scientists at Pfizer have used the discovery of CP-96,345, the first substance P antagonist, as a starting point for developing a series of compounds with improved selectivity and potency, and which block the activation of nerves in the locus ceruleus, an area involved in mood regulation. The programme is still at the pre-clinical stage. Merck Sharp & Dohme's MK-869, another substance P antagonist, has been assessed in a preliminary clinical trial and showed a similar level of activity to the SSRIs.
Another approach mentioned is Lundbeck's work with a selective S-isomer of citalporam.
Target Depression, is available free of charge from the ABPI, 12 Whitehall, London SW1A 2DY.