Nokea
We have a 48-year-old female patient with a history of myasthenia gravis. She has been treated with an oral acetylcholinesterase inhibitor for several years and has done well till now. She presents with muscle weakness and other signs and symptoms that could reflect either a cholinergic crisis (excess dosages of her maintenance drug) or a myasthenic crisis (insufficient treatment). We will use a rapidly acting parenteral acetylcholinesterase inhibitor (AChE) to help make the differential diagnosis. Which of the following drugs would be most appropriate for this use?
Correct Answer: A
Rationale: The correct answer is A: Edrophonium. Edrophonium is a short-acting acetylcholinesterase inhibitor that can help differentiate between a cholinergic crisis and a myasthenic crisis. In this scenario, administering edrophonium will temporarily increase acetylcholine levels at the neuromuscular junction. If the patient's symptoms improve following edrophonium administration, it suggests a myasthenic crisis due to insufficient treatment. On the other hand, if the symptoms worsen, it indicates a cholinergic crisis due to excess dosages of the maintenance drug.
Choice B: Malathion is an organophosphate insecticide and is not used for diagnosing myasthenia gravis.
Choice C: Physostigmine is a longer-acting acetylcholinesterase inhibitor and is not appropriate for rapidly assessing the patient's condition in this scenario.
Choice D: Pralidoxime is used as an antidote for organophosphate