Tricyclic antidepressant drug | definition of tricyclic antidepressant drug by Medical dictionary
tricyclic antidepressant drug
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tricyclic antidepressant drug One of a group of drugs whose structure is based on three six-carbon rings. The tricyclics produce an elevation of mood but this does not occur until the drugs have been taken for two to three weeks (an important point as depressed people may commit suicide during this period). These drugs have an anticholinergic effect and may cause dry mouth, constipation, urinary retention and blurred vision. The tricyclic antidepressants are the most widely used group for depression. They act by blocking the re-uptake of noradrenaline and serotonin at synapses thus allowing these stimulatory neurotransmitters to act for longer. With use, actual changes occur in the synapses that are of benefit. FLUOXETINE (Prozac) is not a tricyclic. It has only two rings and is a selective re-uptake inhibitor of serotonin only. Other tricyclic atidepressant drugs are AMITRIPTYLINE, DOXEPIN, IMIPRAMINE, NORTRIPTYLINE, and TRIMIPRAMINE. Up to 50 per cent of patients have genetic variations that prevent them from responding to these drugs.