• To estimate the proportion of women who have a 50% or greater reduction in frequency of hot flashes following 4 weeks of paroxetine or conjugated equine estrogen. [ Time Frame: Following 4 weeks of study medication ] [ Designated as safety issue: No ]
  
• To evaluate baseline and change in binding of the serotonin transporter in postmenopausal women who suffer hot flashes before and after 4 weeks of paroxetine or conjugated equine estrogen using PET. [ Time Frame: Following 4 weeks of study medication ] [ Designated as safety issue: No ]
  
• To correlate baseline and change in binding of the serotonin transporter using PET with reduction of hot flashes after 4 weeks of conjugated equine estrogen or paroxetine. [ Time Frame: Following 4 weeks of study medication ] [ Designated as safety issue: No ]
  

Drug: Paroxetine controlled-release
2-12.5 mg tablets, orally, every day for 4 weeks
Drug: Conjugated equine estrogen
0.625 mg tablet, orally, every day for 4 weeks

Hot flashes represent the most common complaint among peri- and postmenopausal women. Over 60% of postmenopausal women experience hot flashes, and 10-20% of all postmenopausal women find them nearly intolerable. Despite the prevalence of hot flashes, their pathophysiology is not well understood. Treatment options include non-pharmacological approaches, hormonal interventions, and non-hormonal pharmacological agents. The most effective treatment for hot flashes is estrogen. The most promising non-hormonal treatments for hot flashes are selective serotonin or noradrenergic reuptake inhibitors (SSRI/SNRI). Although estrogen withdrawal is implicated in the initiation of hot flashes, and serotonin's role is well established in thermoregulation, the relationship between estrogen and serotonin is not known. Preclinical studies suggest that both estrogen and SSRI down regulate the serotonin transporter. Clinical studies that further delineate the relationship between effective treatments for hot flashes and the serotonin transporter may shed a new light into the pathophysiology of these symptoms and more importantly, into design of new-targeted treatments.