Clomipramine and neuroleptic malignant syndrome

Editor—Clomipramine is not a neuroleptic and is classed as an “antidepressant.” However, as mentioned in our article, this drug has an appreciable blocking effect at dopamine receptor sites, the traditional domain of the neuroleptic drug. This is a weak effect, but it is more potent than several other antidepressant agents.¹ This action is recognised in the current edition of the BNF, which says that neuroleptic malignant syndrome may, very rarely, arise in the course of antidepressant treatment.²

We also made reference to 50 worldwide reports received regarding clomipramine and neuroleptic malignant syndrome or suspected neuroleptic malignant syndrome, in addition to four reports received by the Committee on Safety of Medicines and two published case reports.

We agree that we should have made clear that this patient's muscle rigidity was of the lead pipe variety, although some widely accepted diagnostic criteria require only severe muscle rigidity.³ The diagnostic criteria that we tabulated were based on Levinson and Sternabach and referenced in our article.⁴,⁵

We described in this patient an earlier diagnosed episode of serotonin syndrome, and no clinical evidence of rigidity was found on that occasion.

In view of the action at dopamine sites of clomipramine, and the statement in the BNF from the BMA and the Royal Pharmaceutical Society of Great Britain, we would continue to support our diagnosis of neuroleptic malignant syndrome in this informative case.