Neuroleptic malignant syndrome: evaluation of drug safety data from the AMSP program during 1993-2015

Neuroleptic malignant syndrome (NMS) is a rare, but severe adverse drug reaction of drugs with anti-dopaminergic properties. The main symptoms are fever and rigor. In addition, other symptoms such as creatine kinase elevation, alteration of consciousness and various neurological symptoms may occur. A total of 52 NMS cases have been documented in the drug safety program 'Arzneimittelsicherheit in der Psychiatrie' from 1993 to 2015. We calculated incidences and analyzed imputed substances and additional risk factors to study the impact of changing therapy regimes. The overall incidence was 0.16‰. High-potency first-generation antipsychotics (FGAs) had the highest incidences, e.g. flupentixol with 0.61‰. Second-generation antipsychotics (SGAs) had lower incidences. Low-potency FGAs had very low incidences, comparable to SGAs, but in contrast to SGAs, had not been imputed alone in any case of NMS. Preexisting organic pathologies of the central nervous system, lithium treatment, infection/exsiccosis and the withdrawal of medication with anticholinergic properties or alcohol were found to be additional risk factors. With the increasing use of SGAs, one should always be aware of the risk of NMS. Better suited diagnostic criteria for 'atypical NMS' would lead to a better understanding and, therefore, to improved treatment possibilities.