Muscarinic antagonists — MCQs

An 18-year-old boy presents to the clinic with shortness of breath and fever for the last 2 days. He also has a cough for the same duration. He is asthmatic and uses inhaled albuterol for symptom relief when required. He used albuterol today 3 times at 10-minute intervals but has not had relief of his symptoms. On physical examination, his temperature is 38.3°C (101.0°F), pulse is 130/min, blood pressure is 116/80 mm Hg, and respirations are 28/min. Auscultation of the chest reveals bilateral crackles. Considering that he has already taken inhaled albuterol and has tachycardia, the physician nebulizes him with inhaled ipratropium bromide, which significantly improves his symptoms. Which of the following is the mechanism of action of this drug?

A forty-five-year-old farmer with past medical history of diabetes, hypertension, and possible narrow angles comes into your emergency room confused, diaphoretic, salivating, vomiting and shedding tears. He has pinpoint pupils. You conclude that he is showing effects of acute organophosphate poisoning. While administering the antidote, you should carefully monitor for which of the following side effects?

A 43-year-old man is brought to the emergency department by his wife because of a 1-hour history of confusion and strange behavior. She reports that he started behaving in an agitated manner shortly after eating some wild berries that they had picked during their camping trip. His temperature is 38.7°C (101.7°F). Physical examination shows warm, dry skin and dry mucous membranes. His pupils are dilated and minimally reactive to light. His bowel sounds are decreased. The patient is admitted and pharmacotherapy is initiated with a drug that eventually results in complete resolution of all of his symptoms. This patient was most likely administered which of the following drugs?

A 78-year-old man suffers a fall in a nursing home and is brought to the emergency room. A right hip fracture is diagnosed, and he is treated with a closed reduction with internal fixation under spinal anesthesia. On the second postoperative day, the patient complains of pain in the lower abdomen and states that he has not urinated since the surgery. An ultrasound shows increased bladder size and volume. Which of the following is the mechanism of action of the drug which is most commonly used to treat this patient’s condition?

An 83-year-old man with advanced-stage prostate cancer comes to the physician because of a 1-week history of worsening lower back and hip pain. The patient's analgesic regimen includes oxycodone, ibuprofen, and alendronic acid. Physical examination shows localized tenderness over the lumbar spine and right hip. His current pain management requires opioid dose escalation. Which of the following opioid side effects is most likely to remain unaffected by the mechanism underlying this patient's need for a higher drug dose?

A 67-year-old man presents to the emergency department acutely confused. The patient's wife found him mumbling incoherently in the kitchen this morning as they were preparing for a hike. The patient was previously healthy and only had a history of mild forgetfulness, depression, asthma, and seasonal allergies. His temperature is 98.5°F (36.9°C), blood pressure is 122/62 mmHg, pulse is 119/min, and oxygen saturation is 98% on room air. The patient is answering questions inappropriately and seems confused. Physical exam is notable for warm, flushed, and dry skin. The patient's pupils are dilated. Which of the following is also likely to be found in this patient?

A 33-year-old man comes to the emergency department because of a dry mouth and blurred vision for the past 30 minutes. Prior to this, he was on a road trip and started to feel nauseous, dizzy, and fatigued, so his friend gave him a drug that had helped in the past. Physical examination shows dry mucous membranes and dilated pupils. The remainder of the examination shows no abnormalities. Administration of which of the following drugs is most likely to cause a similar adverse reaction in this patient?

Choose the correctly matched pairs regarding the drugs used in schizophrenia: 1. D2 antagonism: Reduces positive symptoms 2. 5HT2A antagonism: Reduces negative symptoms 3. 5HT1A agonism: Weight loss 4. Muscarinic antagonism: Reduces extrapyramidal symptoms

A 26-year-old man is brought to the hospital by his wife who complains that her husband has been behaving oddly for the past few hours. The patient’s wife says that she has known him for only 4 months. The wife is unable to give any past medical history. The patient’s speech is difficult to follow, and he seems very distracted. After 15 minutes, he becomes agitated and starts to bang his head on a nearby pillar. He is admitted to the psychiatric ward and is given an emergency medication, after which he calms down. In the next 2 days, he continues to become agitated at times and required 2 more doses of the same drug. On the 4th day of admission, he appears very weak, confused, and does not respond to questions appropriately. His vital signs include: temperature 40.0°C (104.0°F), blood pressure 160/95 mm Hg, and pulse 114/min. On physical examination, he is profusely diaphoretic. He is unable to stand upright or even get up from his bed. Which of the following is the mechanism of action of the drug which most likely caused this patient’s current condition?

A 28-year-old man is brought to the emergency department after his girlfriend found him twitching and jerking in the yard while gardening. Shortly after he became obtunded, emergency medical services reported 1 episode of emesis during transport. His blood pressure is 85/50 mmHg, pulse is 55/min, and respirations are irregular. Physical examination demonstrates marks on his left forearm, pinpoint pupils, diaphoresis, and fasciculations of his left calf. Following initial stabilization and respiratory support, what is the best next step?