Hypotension tricyclic antidepressant-induced

Many inhibitors of the amine transporters for norepinephrine, dopamine, and serotonin are used clinically. Although specificity is not absolute, some are highly selective for one of the transporters. Many antidepressants, particularly the older tricyclic antidepressants can inhibit norepinephrine and serotonin reuptake to different degrees. This may lead to orthostatic tachycardia as a side effect. Some antidepressants of this class, particularly imipramine, can induce orthostatic hypotension presumably by their clonidine-like effect or by blocking 04 receptors, but the mechanism remains unclear. 

Acute poisoning with a tricyclic antidepressant often is clinically complex brief excitement and restlessness, sometimes with myoclonus, tonic-clonic seizures, or dystonia, followed by rapid development of coma, often with depressed respiration, hypoxia, depressed reflexes, hypothermia, and hypotension. Antidepressants with strong antimuscarinic potency commonly induce an atropine-like syndrome of mydriasis, flushed dry skin and dry mucosae, absent bowel sounds. 

Tricyclic antidepressants may increase the risk of arrhythmias and hypotension during anaesthesia. Tachyarrhythmias have been seen in patients taking imipramine who were given halothane and pancuronium. Some very limited evidence su ests that amitriptyline may increase the likelihood of enflurane-induced seizure activity. A man taking maprotiline and lithium developed a tonic-clonic seizure when given propofol. Tricyclics may cause an increase in the duration of barbiturate anaesthesia and lower doses of barbiturates may be required. 

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