Pupil Studies in Depressed Patients: An Investigation of the Mechanism of Action of Desipramine

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Abstract
Summary: Six depressed patients were treated routinely with desipramine, a relatively selective noradrenergic uptake blocking drug. After 0, 1 and 3 weeks' treatment pupillary responses to tyramine, phenylephrine and pilocarpine were measured using a photographic technique. Both 1 and 3 weeks' treatment significantly inhibited tyramine and phenylephrine-induced mydriasis, but did not inhibit pilocarpine-induced miosis; in fact the longer treatment enhanced miosis due to pilocarpine. Resting pupil size was significantly increased after 1 and 3 weeks' treatment.The findings can be explained by the known ability of desipramine to block noradrenaline uptake and α adrenoceptors: they provide no evidence of muscarinic receptor blockade or of a slowly developing adaptation at a adrenoceptors.