You review a 62-year-old man three days after he had been admitted with an acute coronary syndrome. His past medical history includes myasthenia gravis for which he takes long-term prednisolone. Since admission his symptoms of myasthenia have become markedly worse. In particular you notice bilateral ptosis and slurring of speech. Which of the following recently started medications is most likely to be responsible?
Clopidogrel
Atorvastatin
Ramipril
Aspirin
Bisoprolol
Bisoprolol\
Beta-blockers such as bisoprolol are common precipitants of myasthenic crises.