Which of the following is true of sildenafil

Correct Answer: C

Rationale: In this quiz question about sildenafil, the correct answer is C) It is indicated only for treatment of erectile dysfunction in men. Sildenafil, commonly known as Viagra, is a medication specifically indicated for the treatment of erectile dysfunction in men. It works by increasing blood flow to the penis, which helps to achieve and maintain an erection during sexual stimulation. Option A is incorrect because while sildenafil may enhance sexual performance by aiding in achieving an erection, it is not intended to enhance sexual enjoyment in normal men. Option B is also incorrect as sildenafil is not used to delay ejaculation; it is focused on erectile dysfunction. Option D is incorrect because sildenafil does not block cavernosal α2 adrenoceptors; it acts by inhibiting phosphodiesterase type 5 enzyme. In an educational context, it is important for learners to understand the specific indications and mechanisms of action of medications like sildenafil to ensure safe and effective use in clinical practice. Understanding the correct applications of drugs is crucial in providing quality patient care and avoiding potential medication errors.

Correct Answer: A

Rationale: In this question, the correct answer is A) Pancuronium. Pancuronium is a neuromuscular blocker that has a prominent antivagal action. This means that it helps prevent the activation of the vagus nerve, which can lead to bradycardia (slow heart rate) and other cardiac issues during surgery or other procedures. Option B) Vecuronium and Option C) Atracurium are neuromuscular blockers that do not have prominent antivagal actions like Pancuronium. They primarily act on skeletal muscle to induce paralysis for procedures requiring muscle relaxation. Option D) Gallamine triethiodide is also a neuromuscular blocker, but it is not specifically known for its antivagal action. It is more commonly used in research settings rather than clinical practice. Understanding the mechanisms of action of different peripheral nervous system drugs is crucial for healthcare professionals, especially anesthesiologists and surgical teams. Knowing which medications have specific effects, such as antivagal actions, can help in selecting the most appropriate drug for a given situation to ensure patient safety and optimal outcomes.

Correct Answer: A

Rationale: The correct answer is A) 4-aminopyridine. 4-aminopyridine is a potassium channel blocker that enhances the evoked release of acetylcholine by prolonging the action potential duration at nerve terminals. This leads to increased calcium influx and subsequent release of acetylcholine, ultimately enhancing neurotransmission. Option B) Vesamicol is incorrect because it is actually an acetylcholine storage inhibitor. It inhibits the vesicular acetylcholine transporter, leading to decreased release of acetylcholine. Option C) Magnesium ion is incorrect because it acts as a calcium channel blocker, which would inhibit the release of acetylcholine by reducing calcium influx into the nerve terminals. Providing this educational context helps students understand the mechanism of action of these drugs in the context of the peripheral nervous system. Understanding how different drugs affect neurotransmitter release is crucial in pharmacology and neurology, as it impacts the treatment of various neurological conditions such as myasthenia gravis or Lambert-Eaton syndrome.

Correct Answer: A

Rationale: The correct answer is A) High oral bioavailability. The 'amine' ergot alkaloid differs from 'amino acid' ergot alkaloids in that it has high oral bioavailability, which means it can be effectively absorbed and utilized when taken orally. This characteristic is crucial for drugs as it determines the amount of the drug that reaches systemic circulation and can exert its therapeutic effects. Option B) Better CNS penetrability is incorrect because the difference between 'amine' and 'amino acid' ergot alkaloids lies in their bioavailability, not their ability to penetrate the central nervous system. Option C) Weaker oxytocic action is incorrect because the question is focusing on the pharmacokinetic properties of the ergot alkaloids, not their specific pharmacological actions. Option D) Strong anti-5-HT action is incorrect as this property is not a defining characteristic that distinguishes 'amine' ergot alkaloids from 'amino acid' ergot alkaloids. In an educational context, understanding the differences in pharmacokinetic properties such as bioavailability is essential for healthcare professionals to make informed decisions about drug selection, dosing, and administration routes to ensure optimal patient outcomes. This knowledge is particularly relevant when prescribing medications that belong to the ergot alkaloid class, as their efficacy can be influenced by their bioavailability.

Correct Answer: A

Rationale: The correct answer is A) Atropine. In the plant Datura stramonium, also known as thorn apple, the main muscarinic antagonist present is atropine. Atropine is a naturally occurring tropane alkaloid that acts as a competitive antagonist at muscarinic acetylcholine receptors in the peripheral nervous system. It blocks the action of acetylcholine, leading to effects such as pupil dilation, decreased secretions, and increased heart rate. Option B) Hyoscine, also known as scopolamine, is another muscarinic antagonist, but it is not the main component found in Datura stramonium. Option C) Homatropine is a synthetic muscarinic antagonist used in ophthalmology to induce mydriasis. It is not the primary antagonist in Datura stramonium. Option D) Dicyclomine is an anticholinergic drug used to treat irritable bowel syndrome and is not typically found in plants like Datura stramonium. Understanding the pharmacological properties of plants like Datura stramonium and the specific muscarinic antagonists they contain is crucial for healthcare professionals, especially pharmacists, to provide appropriate care and treatment. Knowledge of these drugs helps in managing conditions where muscarinic receptors need to be targeted or blocked. Learning about these drugs in the context of the peripheral nervous system provides a deeper understanding of their mechanisms of action and therapeutic uses.