This month a novel drug has been launched in Britain, named mirtazapine (trade name Remeron in the US and Zispin in Britain). It’s the first of a new class of mood enhancers which has been named noradrenergic and specific serotonergic antidepressants, unsurprisingly abbreviated to NaSSA. In contrast to the previous generation of anti-depressants — of which Prozac is the best known example — which act only on serotonin (hence their generic name of selective serotonin re-uptake inhibitors or SSRIs), these new drugs act on two neurotransmitters, noradrenaline and serotonin, but in the case of serotonin do so selectively. It is claimed that not only does mirtazapine work more quickly and more effectively, but that it lacks some of the side effects of earlier anti-depressants, which include nausea, restlessness, and disturbances of libido and sleeping patterns; it also seems to be less dangerous when taken in excess. As always, though, there is a down-side: it acts as a mild sedative and causes some patients to gain weight.