Noradrenergic and serotonergic modulation to treat vasomotor symptoms.

Hot flushes are a major clinical problem for many menopausal women. Their aetiology is unknown. Centrally acting neurotransmitters are involved, but this involvement is yet to be fully characterized. In clinical trials with optimal patient selection and compliance, estrogen can reduce the frequency of hot flushes by 70-80%, and placebo by 20-40%. For some women, however, there are contraindications to the use of estrogen, and others are unwilling to use it. Furthermore, hot flushes may persist in spite of adequate estrogen replacement, and to improve symptoms physicians then have either to add another drug to the regimen or find an alternative to estrogen. The most commonly used non-hormonal alternatives for climacteric symptoms are neurotransmitter modulators such as the selective serotonin reuptake inhibitors. These reduce the frequency of hot flushes by 60%. The mechanism of this effect appears to differ from that underlying their effect on mood. They are generally well tolerated and rates of adverse events are far lower than those reported in studies of the use of these agents for depression. The limited efficacy of clonidine suggests that adrenergic mechanisms may be involved and data are awaited for more specific selective noradrenaline reuptake inhibitors. Thus, non-hormonal treatments are not as effective as estrogens in relieving hot flushes but may have a place as an alternative.