Answers

Correct answer A: The man has consumed oral albuterol, a selective β2-adrenergic agonist, for the last 3 days. The physical examination is most likely to reveal tachycardia, which is a common and important adverse effect of albuterol.

β2-adrenergic receptor agonists are used as reliever medications in the management of asthma. β2-adrenergic receptor agonists act as bronchodilators and provide quick relief from bronchospasm. The inhaled formulations are preferred because inhaled formulations exert greater local effects and the systemic side effects are minimal; however, if inhaled formulations are unavailable, oral formulations may be used.

The important adverse effects of β2-agonists include tachycardia, skeletal muscle tremors, hyperglycemia, and hypokalemia. These adverse effects are significantly more common with oral formulations than with inhaled formulations

Option B: Upbeat nystagmus is not a known side effect of albuterol. Upbeat nystagmus is commonly seen in association with lesions in the anterior vermis of the cerebellum and lesions in the medulla. Phenytoin and ethanol are also known to produce nystagmus.

Option C: Albuterol is not known to produce myoclonus. Drugs that are known to produce myoclonus include levodopa, benzodiazepines, tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), lithium, bismuth subsalicylate, clozapine, phenytoin, phenobarbital, gabapentin, pregabalin, lamotrigine, and propofol.

Option D: Albuterol is known to produce hypokalemia, but albuterol does not produce hyperkalemia. Examples of drugs that cause hyperkalemia include spironolactone, triamterene, amiloride, NSAIDs, ACE inhibitors, angiotensin receptor blockers, cyclosporine, tacrolimus, trimethoprim-sulfamethoxazole, heparin, and pentamidine.

Option E: Albuterol does not produce hypermagnesemia. Examples of drugs that cause hypermagnesemia include lithium, magnesium-containing antacids or laxatives, and theophylline.

Option F: Albuterol is known to produce hyperglycemia, but albuterol does not produce hypoglycemia. Examples of drugs that cause hypoglycemia include ethanol, salicylates, quinine, haloperidol, pentamidine, oral hypoglycemics, insulin, disopyramide, clofibrate, and lithium.

Learning objective: The important adverse effects of β2-agonists include tachycardia, skeletal muscle tremors, hyperglycemia, and hypokalemia. These adverse effects are significantly more common with oral formulations than with inhaled formulations.

First Aid for the USMLE Step 1 (2020, 30th ed): 242, 687

First Aid for the USMLE Step 1 (2019, 29th ed): 242, 672

First Aid for the USMLE Step 1 (2018, 28th ed): 668

First Aid for the USMLE Step 1 (2017, 27th ed): 649