Failure of mianserin to affect autonomic function in the pupils of depressed patients

The autonomic effects of mianserin were tested in seven depressed patients by comparing pupillary responses to adrenergic and cholinergic agonists before and after treatment. Mianserin failed to affect pilocarpine-evoked miosis and tyramine- or phenylephrine-evoked mydriasis, despite adequate plasma levels of the drug. There was, however, a significant reduction in resting pupillary size after 1 and 3 weeks of treatment: this could result either from a central action, or from interactions at receptors other than cholinergic or adrenergic ones in the pupil of the eye. It is concluded that in clinical dosage mianserin is devoid of effects upon muscarinic receptors, alpha 1 adrenoceptors and noradrenaline uptake in the pupil.