A 54-year-old man is hospitalized after a planned abdominal surgery. One of his physicians administers a new drug whose mechanism of action you do not know. Shortly after administration of the drug the patient develops flushing, diaphoresis and nausea. His blood pressure is 100/70 mmHg and heart rate is 55/min. His pupils are constricted but reactive to light. This medication is most likely given for which of the following conditions?

Question

A 54-year-old man is hospitalized after a planned abdominal surgery.  One of his physicians administers a new drug whose mechanism of action you do not know.  Shortly after administration of the drug the patient develops flushing, diaphoresis and nausea.  His blood pressure is 100/70 mmHg and heart rate is 55/min.  His pupils are constricted but reactive to light.  This medication is most likely given for which of the following conditions?

Quizplus · Accepted Answer

The patient described in this vignette displays symptoms associated with cholinergic agonists. These medications increase GI tract smooth muscle tone to produce nausea, vomiting, abdominal cramps and diarrhea. Cholinergic agonists decrease heart rate, cardiac conduction and contractility, and may result in bradycardia, partial or complete heart block, and hypotension. Cholinergic-associated peripheral vasodilatation decreases blood pressure due to the stimulation of endothelial nitric oxide synthesis. Cholinergic agonists also increase secretion, leading to excessive sweating, salivation and lacrimation. These drugs can cause dyspnea via bronchoconstriction (increased smooth muscle tone in the tracheobronchial tree) and increased bronchial secretion. There are several cholinergic agonists used in medicine. Bethanechol is a cholinergic agonist used to stimulate peristalsis in postoperative ileus. This drug is also used to treat non-obstructive urinary retention (atonic bladder). Carbachol and pilocarpine are used to lower intraocular pressure in glaucoma. Cholinergic-associated miosis causes the iris to move further from the cornea. This widens the anterior chamber angle and allows for better outflow of the aqueous humor. (Choices A and B) Cholinergic agonists are not used to treat urinary tract infections or urinary obstruction. (Choice D) Clinically evident volume overload is treated with loop diuretics. Cholinergic agents will not help this condition. (Choice E) Hypovolemic shock is treated with IV fluids. Administering a cholinergic agent would likely worsen hypovolemic shock. Educational Objective: Cholinomimetics are indicated in non-obstructive urinary retention, paralytic ileus, and glaucoma. Their side effects include nausea, vomiting, abdominal cramps, diarrhea, dyspnea and increased secretions (sweating, lacrimation and salivation).

A 54-Year-Old Man Is Hospitalized After a Planned Abdominal Surgery