Antidepressants and the serotonin syndrome in general practice.
BACKGROUND
As a consequence of the greater use of agents affecting the serotonergic system, a syndrome of serotonin hyperstimulation has been recognized more frequently. The serotonin syndrome is characterized by a constellation of symptoms that include mental status changes, agitation, myoclonus, hyperreflexia, sweating, shivering, tremor, diarrhoea, lack of coordination, and fever. Deaths have been reported.


OBJECTIVE
To identify cases of the serotonin syndrome among patients prescribed a new antidepressant in general practice, and to determine doctors' awareness of the syndrome.


METHODS
Patients who were dispensed nefazodone in England between 1996 and 1997 were identified using dispensed prescription data. Prescribing doctors were sent questionnaires as part of a post-marketing surveillance study. Patients reported to have experienced two or more features of the serotonin syndrome were identified, and specific questionnaires were sent to their general practitioners.


RESULTS
There was a 96.2% return rate of serotonin syndrome questionnaires. Nineteen cases met criteria for the syndrome (incidence = 0.4 cases per 1000 patient-months of treatment with nefazodone). Eight patients developed symptoms while taking nefazodone alone. Serotonergic symptoms were reported to a similar degree with five other antidepressants studied by the same method. In total, 85.4% of responding general practitioners were unaware of the serotonin syndrome.


CONCLUSIONS
Improved awareness of the syndrome is needed within general practice. There is a need to distinguish the relatively minor serotonergic symptoms from those of a severe, life-threatening serotonin syndrome.
Mackay
F J
FJ
Dunn
N R
NR
Mann
R D
RD
D000293:Adolescent; D000328:Adult; D000368:Aged; D018687:Antidepressive Agents, Second-Generation / Q000009:adverse effects*; D003866:Depressive Disorder / Q000188:drug therapy; D005194:Family Practice / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D010879:Piperazines; D020230:Serotonin Syndrome / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D014230:Triazoles / Q000009:adverse effects*
D018687:Antidepressive Agents, Second-Generation; D010879:Piperazines; D014230:Triazoles; C051752:nefazodone