A 55-year-old patient with severe posthepatitis cirrhosis is started on a diuretic for another condition. Two days later he is found in a coma. The drug most likely to cause coma in a patient with cirrhosis is

Correct Answer: A

Rationale: In this scenario, the correct answer is A) Acetazolamide. Acetazolamide is a carbonic anhydrase inhibitor that can lead to hyperammonemia in patients with severe liver disease like cirrhosis. Hyperammonemia can result in encephalopathy, leading to symptoms such as confusion, coma, and even death. Option B) Amiloride is a potassium-sparing diuretic and is not typically associated with causing coma in cirrhotic patients. Option C) Furosemide and Option D) Hydrochlorothiazide are loop and thiazide diuretics, respectively, which do not directly affect ammonia metabolism and are less likely to cause coma in this patient population. Educationally, this question highlights the importance of understanding the pharmacological effects of medications in patients with liver disease. It emphasizes the need for healthcare providers to consider the potential adverse effects of drugs in individuals with compromised liver function to prevent serious complications like hepatic encephalopathy.

Correct Answer: D

Rationale: The correct answer is D) None of the above. In this scenario, the physician is recommending a drug that blocks 5α reductase in the prostate to address the urinary hesitancy associated with benign prostatic hyperplasia. This drug is likely referring to finasteride or dutasteride, which are 5α reductase inhibitors commonly used in the treatment of BPH. Option A) Atropine is a muscarinic antagonist used for conditions like bradycardia or to reduce salivary and bronchial secretions, not for BPH. Option B) Clonidine is an alpha-2 adrenergic agonist primarily used for hypertension or ADHD, not for BPH. Option C) Hydralazine is a direct-acting vasodilator used for hypertension, not for BPH. Understanding the mechanism of action of drugs used in the treatment of BPH is crucial for healthcare professionals to make appropriate prescribing decisions. This question assesses the knowledge of students on the pharmacological management of BPH and the specific drug classes used to address urinary symptoms in this condition. It highlights the importance of tailoring treatment to the underlying pathophysiology of the patient's condition for optimal outcomes.

Correct Answer: B

Rationale: Yohimbine is an antagonist of α2 receptors. The correct answer is B) α2. Yohimbine is a specific antagonist of α2 adrenergic receptors, blocking their activity. In the context of the peripheral nervous system, α2 receptors play a role in regulating sympathetic nervous system activity. By blocking α2 receptors, yohimbine can lead to increased sympathetic activity. Option A) α1 is incorrect because yohimbine does not target α1 receptors. α1 receptors are involved in vasoconstriction and smooth muscle contraction. Option C) both (a) and (b) is incorrect because yohimbine specifically targets α2 receptors, not α1 or both. Option D) None of the above is incorrect as we have established that yohimbine acts as an antagonist of α2 receptors. Understanding the specific receptor targets of drugs is crucial in pharmacology to predict their effects and potential side effects. By knowing that yohimbine targets α2 receptors, healthcare professionals can anticipate its impact on the sympathetic nervous system and make informed decisions when prescribing or administering this drug.

Correct Answer: C

Rationale: The correct answer to the question is C) Gq. This is because α1-receptors are primarily coupled with the Gq protein. When an agonist binds to the α1-receptor, it activates the Gq protein, which then initiates a signaling cascade leading to various physiological responses such as vasoconstriction, smooth muscle contraction, and glycogenolysis. Option A) Gs is incorrect because Gs proteins are typically associated with stimulating adenylate cyclase to increase cAMP levels, which is not the primary signaling pathway for α1-receptors. Option B) Gi is incorrect because Gi proteins inhibit adenylate cyclase and reduce cAMP levels, which is also not the main pathway for α1-receptors. Option D) Go is incorrect because Go proteins are mainly involved in modulating potassium channels and are not typically associated with α1-receptors. In an educational context, understanding the coupling of receptors with specific G proteins is crucial in pharmacology and therapeutics. Knowing which G protein is associated with a particular receptor helps in predicting the downstream effects of drugs targeting those receptors. This knowledge is essential for healthcare professionals in selecting the most appropriate medications for patients based on their physiological responses.

Correct Answer: A

Rationale: In the case of a patient with a corneal ulcer, the most suitable mydriatic would be Atropine sulfate (Option A). Atropine sulfate is a potent anticholinergic agent that causes pupillary dilation (mydriasis) by blocking the parasympathetic stimulation of the iris sphincter muscle. This dilation helps in alleviating pain associated with corneal ulcers by reducing ciliary muscle spasm and preventing synechiae formation. Homatropine (Option B), Cyclopentolate (Option C), and Tropicamide (Option D) are also mydriatics, but they are less suitable for a corneal ulcer patient. Homatropine and Cyclopentolate have shorter durations of action compared to Atropine sulfate, which is needed for prolonged mydriasis in corneal ulcer cases. Tropicamide has the shortest duration of action and is more commonly used for routine ophthalmic examinations due to its rapid onset and short-lived mydriatic effect. In an educational context, understanding the appropriate use of mydriatics in ophthalmology is crucial for healthcare professionals, especially those working in eye care settings. Knowing the specific indications for each mydriatic helps in providing optimal treatment for patients with different ocular conditions, such as corneal ulcers. By grasping the pharmacological properties and clinical applications of these drugs, healthcare providers can make informed decisions to ensure the best outcomes for their patients.