Exacerbation of myasthenia gravis with voriconazole.

INTRODUCTION

We describe a patient with stable generalized myasthenia gravis who presented with new onset severe ophthalmoplegia and ptosis after initiation of voriconazole for aspergillosis.

METHODS

Ligand-protein docking software was used to simulate the interaction of voriconazole with the acetylcholine receptor (AChR). We tested voriconazole binding to AChR in comparison to high affinity and neutral compounds.

RESULTS

There was no clinical improvement after intravenous immunoglobulin infusion and plasmapheresis. However, the patient improved slowly after withdrawal of voriconazole. Based on our results, voriconazole binds favorably to AChR and may putatively block muscle nicotinic AChRs. Other theoretical explanations include blocking potassium channels and reducing their intracellular trafficking.

CONCLUSIONS

The mechanisms involved in ocular exacerbation may be multi-factorial, reflecting the intricate dynamics of the neuromuscular junction. It is important to consider medications that harbor pyridine or pyrimidine moieties as potential causes of exacerbation in myasthenic patients, especially those who present with ocular symptoms.