Autonomic Drugs in Urological Disorders — MCQs
Enuresis persists, and the patient is placed on desmopressin acetate (DDAVP). This medication works by which of the following mechanisms?
What is mirabegron?
All of the following drugs are used for the treatment of urinary incontinence except:
Which of the following diuretics can lead to erectile dysfunction?
Sensory afferent fibers from the fallopian tubes ascend to:
Alpha-1a adrenergic blocker giving symptomatic relief in benign prostatic hyperplasia (BPH) is:
Which antimuscarinic drug is used in overactive bladder?
A 68-year-old with depression and chronic pain is on amitriptyline. What side effect may arise if given oxybutynin for overactive bladder?
Ocular effects that include mydriasis are characteristic of which of the following drugs?
Which of the following anesthetics is known to increase intraocular pressure?
Autonomic Drugs in Urological Disorders Indian Medical PG Practice Questions and MCQs
Question 1: Enuresis persists, and the patient is placed on desmopressin acetate (DDAVP). This medication works by which of the following mechanisms?
- A. Decrease detrusor muscle tone
- B. Increase water permeability and reabsorption in collecting tubules (Correct Answer)
- C. Increase external sphincter contraction
- D. Improves alertness of the patient during the sleep cycle
Explanation: ***Increase water permeability and reabsorption in collecting tubules*** - **Desmopressin acetate (DDAVP)** is a synthetic analog of **antidiuretic hormone (ADH)**, which acts on the V2 receptors in the **collecting tubules** of the kidneys [2], [3]. - This action increases the **permeability** of the collecting tubule cells to water, leading to increased **water reabsorption** and a reduction in urine production, thus controlling enuresis [1], [2]. *Decrease detrusor muscle tone* - This mechanism is associated with medications like **anticholinergics** (e.g., oxybutynin), which relax the **detrusor muscle** to reduce bladder contractions and urgency. - DDAVP does not directly affect the tone of the detrusor muscle; its primary action is on renal water handling [2]. *Increase external sphincter contraction* - Medications that strengthen the **external urethral sphincter** (e.g., alpha-adrenergic agonists) are used to improve continence in cases of stress incontinence. - DDAVP's mechanism is not related to sphincter contraction but rather to reducing the volume of urine produced [2]. *Improves alertness of the patient during the sleep cycle* - This mechanism would involve stimulating the central nervous system to awaken the patient when their bladder is full. - DDAVP does not act as a central nervous system stimulant and does not affect the patient's sleep cycle or alertness [2].
Question 2: What is mirabegron?
- A. Beta 3 agonist (Correct Answer)
- B. Alpha 2 antagonist
- C. Beta 1 blocker
- D. Beta 2 blocker
Explanation: ***Beta 3 agonist*** - Mirabegron is a **beta-3 adrenergic agonist** that selectively activates beta-3 receptors in the bladder smooth muscle [1]. - This activation leads to **relaxation of the detrusor muscle** during the storage phase of the bladder fill-void cycle, increasing bladder capacity. *Alpha 2 antagonist* - **Alpha-2 adrenergic antagonists** primarily block alpha-2 receptors found in the central nervous system and some peripheral tissues [2]. - They are generally used for conditions like **hypertension** or **depression**, not bladder overactivity. *Beta 1 blocker* - **Beta-1 adrenergic blockers** (e.g., metoprolol) primarily target beta-1 receptors in the **heart**, causing decreased heart rate and contractility. - They are used for cardiovascular conditions like hypertension, angina, and heart failure, and do not affect bladder function in this manner [3]. *Beta 2 blocker* - **Beta-2 adrenergic blockers** are not typically used therapeutically as they would cause significant **bronchoconstriction** and other adverse effects due to their presence in the lungs and smooth muscles [3]. - While beta-2 receptors are present in some tissues, their selective blockade is not the mechanism of action for mirabegron.
Question 3: All of the following drugs are used for the treatment of urinary incontinence except:
- A. Ipratropium (Correct Answer)
- B. Oxybutynin
- C. Tolterodine
- D. Darifenacin
Explanation: ***Ipratropium*** - **Ipratropium** is a short-acting muscarinic antagonist primarily used as a **bronchodilator** in obstructive lung diseases. - While it has anticholinergic properties, it is not typically used for **urinary incontinence** due to its limited systemic absorption and short duration of action, making it less effective for bladder control compared to other agents. *Oxybutynin* - **Oxybutynin** is a commonly prescribed **muscarinic antagonist** that acts by relaxing the bladder detrusor muscle, increasing bladder capacity and reducing involuntary contractions. - It is effective in treating **overactive bladder** and urge incontinence. *Tolterodine* - **Tolterodine** is a **muscarinic receptor antagonist** that specifically targets M2 and M3 receptors in the bladder, reducing bladder hyperreactivity. - It is used for the symptomatic treatment of **urge incontinence** and overactive bladder. *Darifenacin* - **Darifenacin** is a highly M3-selective muscarinic receptor antagonist, which means it primarily blocks the M3 receptors responsible for **detrusor muscle contraction**. - Its selectivity helps minimize side effects common to less selective anticholinergics and is used for the treatment of **overactive bladder** with symptoms of urgency, frequency, and urge incontinence.
Question 4: Which of the following diuretics can lead to erectile dysfunction?
- A. Thiazide diuretics (Correct Answer)
- B. Carbonic anhydrase inhibitor
- C. Loop diuretics
- D. Mannitol
Explanation: ***Thiazide diuretics*** - **Thiazide diuretics** can cause **erectile dysfunction**, possibly due to effects on vascular function and **reduced blood flow** to the penis. - This adverse effect is a known concern and can impact patient adherence to **antihypertensive therapy**. *Carbonic anhydrase inhibitor* - **Carbonic anhydrase inhibitors** like acetazolamide are primarily used for glaucoma, altitude sickness, and metabolic alkalosis, and do not typically cause **erectile dysfunction**. - Their primary side effects relate to **metabolic acidosis** and electrolyte imbalances, not sexual function. *Loop diuretics* - **Loop diuretics** like furosemide are potent diuretics used in conditions like heart failure and edema; **erectile dysfunction** is not a common or significant side effect. - Their main adverse effects include **hypokalemia**, ototoxicity, and hypovolemia. *Mannitol* - **Mannitol** is an osmotic diuretic used to reduce intracranial and intraocular pressure. - It is administered intravenously and its side effects primarily involve **fluid and electrolyte disturbances**, not **erectile dysfunction**.
Question 5: Sensory afferent fibers from the fallopian tubes ascend to:
- A. T 8
- B. T 10 (Correct Answer)
- C. L 2
- D. L 4
Explanation: ***T 10*** - The **fallopian tubes** and **ovaries** share sensory innervation primarily through the **T10** and **T11** spinal segments. [2] - This is consistent with the **visceral pain** referral pattern often experienced in the periumbilical region during pain originating from these organs. [2] *T 8* - Sensory innervation to **T8** primarily covers the epigastric region, which is typically associated with organs higher in the abdomen, such as the stomach and gallbladder. [1] - Pain from the fallopian tubes is generally referred lower than the epigastrium. *L 2* - The **L2** spinal segment mainly innervates structures in the lower abdomen and upper thigh, like parts of the colon and the hip joint. [1] - This dermatomal level is too low to be the primary sensory afferent pathway for the fallopian tubes. *L 4* - **L4** sensory innervation is largely associated with the knee and medial calf regions. - It does not correspond to the visceral sensory pathways from pelvic organs like the fallopian tubes.
Question 6: Alpha-1a adrenergic blocker giving symptomatic relief in benign prostatic hyperplasia (BPH) is:
- A. Tamsulosin (Correct Answer)
- B. Tolazoline
- C. Doxazosin
- D. Prazosin
Explanation: ***Tamsulosin*** - **Tamsulosin** is a **uroselective alpha-1a adrenergic blocker** primarily targeting alpha-1a receptors in the prostate and bladder neck, causing relaxation of smooth muscle and improving urine flow with minimal impact on blood pressure. - This selectivity makes it highly effective for **symptomatic relief of BPH** with a lower risk of orthostatic hypotension compared to non-selective alpha-blockers. *Doxazosin* - **Doxazosin** is a **non-selective alpha-1 adrenergic blocker** that acts on alpha-1 receptors in both the prostate and peripheral vasculature. - While effective for BPH, its non-selectivity leads to a higher incidence of **orthostatic hypotension** and dizziness compared to tamsulosin, as it also lowers blood pressure significantly. *Tolazoline* - **Tolazoline** is a **non-selective alpha-adrenergic antagonist**, primarily used as a vasodilator to treat pulmonary hypertension and peripheral vascular disease. - It is not indicated for the treatment of BPH and has a different pharmacological profile and significant side effects unrelated to prostatic smooth muscle relaxation. *Prazosin* - **Prazosin** is a **non-selective alpha-1 adrenergic blocker** used to treat hypertension and, off-label, for BPH, but it has a short half-life requiring multiple daily doses. - Similar to doxazosin, its non-selective action on vascular smooth muscle can cause significant **first-dose syncope** and orthostatic hypotension, making it less favorable for BPH treatment compared to uroselective agents.
Question 7: Which antimuscarinic drug is used in overactive bladder?
- A. Trospium (Correct Answer)
- B. Atropine
- C. Tropicamide
- D. Pirenzepine
Explanation: ***Trospium*** - **Trospium** is a quaternary ammonium compound that acts as an **antimuscarinic agent** primarily used to treat **overactive bladder (OAB)**. - Its **polar nature** limits its ability to cross the blood-brain barrier, reducing central nervous system side effects common with other antimuscarinics. *Tropicamide* - **Tropicamide** is an **antimuscarinic** agent primarily used as a **mydriatic** (to dilate pupils) and **cycloplegic** (to paralyze the ciliary muscle) for ophthalmic examinations. - It has a short duration of action, making it unsuitable for chronic conditions like overactive bladder. *Atropine* - **Atropine** is a non-selective **muscarinic antagonist** with a wide range of uses, including bradycardia, organophosphate poisoning, and ophthalmic procedures. - While it has antimuscarinic effects on the bladder, its systemic side effects (e.g., dry mouth, blurred vision, tachycardia) limit its use for overactive bladder. *Pirenzepine* - **Pirenzepine** is a selective **M1 muscarinic antagonist** primarily used to treat **peptic ulcers** by reducing gastric acid secretion. - Its selectivity for M1 receptors means it has limited efficacy for relieving bladder symptoms, which are primarily mediated by M2 and M3 receptors.
Question 8: A 68-year-old with depression and chronic pain is on amitriptyline. What side effect may arise if given oxybutynin for overactive bladder?
- A. Severe dry mouth (Correct Answer)
- B. Bradycardia
- C. Increased sweating
- D. Urinary incontinence
Explanation: ***Severe dry mouth*** - Both **amitriptyline** (a tricyclic antidepressant) and **oxybutynin** (an anticholinergic for overactive bladder) have significant anticholinergic effects. - The combination of these two drugs can lead to an additive effect, causing pronounced anticholinergic side effects such as **severe dry mouth**, blurred vision, constipation, and cognitive impairment. *Bradycardia* - **Anticholinergic drugs** typically cause **tachycardia** (increased heart rate) by blocking the parasympathetic nervous system's muscarinic receptors on the heart, rather than bradycardia. - While amitriptyline can affect cardiac conduction, severe bradycardia is not a typical **additive anticholinergic side effect** in this context. *Increased sweating* - **Anticholinergic drugs** like amitriptyline and oxybutynin inhibit the activity of sweat glands, which are primarily innervated by cholinergic nerves. - Therefore, the combination of these drugs would likely lead to **decreased sweating** (anhidrosis) rather than increased sweating. *Urinary incontinence* - **Oxybutynin** is prescribed specifically to treat **overactive bladder** and reduce urinary incontinence by relaxing the detrusor muscle. - Therefore, it would improve rather than worsen urinary incontinence; however, it can cause **urinary retention** due to its anticholinergic effect, especially in older male patients.
Question 9: Ocular effects that include mydriasis are characteristic of which of the following drugs?
- A. phenylephrine (alpha agonist) (Correct Answer)
- B. neostigmine (cholinesterase inhibitor)
- C. phentolamine (alpha blocker)
- D. mecamylamine (ganglionic blocker)
Explanation: ***phenylephrine (alpha agonist)*** - **Phenylephrine** is a direct-acting **alpha-1 adrenergic agonist** that causes contraction of the **pupillary dilator muscle**, leading to **mydriasis** (pupil dilation). [1] - It is frequently used clinically to dilate pupils for **ophthalmologic examinations** due to its selective action on alpha-1 receptors in the eye. [2] *neostigmine (cholinesterase inhibitor)* - **Neostigmine** inhibits acetylcholinesterase, increasing acetylcholine at the neuromuscular junction and muscarinic receptors. This leads to **miosis** (pupil constriction), not mydriasis. - Its ophthalmic use is primarily for treating **glaucoma** by improving aqueous humor outflow through cholinergic effects on the ciliary muscle. *phentolamine (alpha blocker)* - **Phentolamine** is a **non-selective alpha-adrenergic antagonist** that blocks both alpha-1 and alpha-2 receptors. - Alpha-1 receptor blockade in the eye would relax the pupillary dilator muscle, leading to **miosis** or prevention of mydriasis, not its induction. *mecamylamine (ganglionic blocker)* - **Mecamylamine** is a **ganglionic blocker** that antagonizes nicotinic receptors in both sympathetic and parasympathetic ganglia. - Blocking parasympathetic ganglia can cause some mydriasis, but ganglionic blockers have widespread, non-selective autonomic effects and are not primarily used for isolated mydriasis.
Question 10: Which of the following anesthetics is known to increase intraocular pressure?
- A. Thiopental
- B. Alfentanil
- C. Ketamine (Correct Answer)
- D. Propofol
Explanation: ***Ketamine*** - **Ketamine** is known to increase **intraocular pressure (IOP)**, making it generally avoided in patients with **glaucoma** or those undergoing ocular surgery. - This effect is due to its influence on sympathetic nervous system activity and extraocular muscle tone. *Thiopental* - **Thiopental**, a barbiturate, typically causes a **reduction in intraocular pressure**, which can be beneficial in certain ocular procedures. - Its mechanism involves decreasing cerebral blood flow and metabolic rate, indirectly leading to a decrease in IOP. *Alfentanil* - **Alfentanil**, an opioid, generally has **minimal to no significant effect on intraocular pressure**. - Its primary actions are analgesia and sedation, without direct impact on oculomotor tone or fluid dynamics. *Propofol* - **Propofol** is known to **decrease intraocular pressure**, making it a favorable agent for ophthalmic surgery. - This effect is attributed to a reduction in cerebral blood flow and an inhibition of aqueous humor production.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free