What is characteristic of the oral route?

Correct Answer: B

Rationale: The correct answer is B because absorption of drugs taken orally depends on the secretion and motor function of the gastrointestinal (GI) tract. This is because the drug needs to be properly broken down and absorbed through the GI tract before entering the bloodstream. Other choices are incorrect because: A: Fast onset of effect is more characteristic of routes like intravenous or inhalation. C: A drug reaching the blood passing the liver is more characteristic of the hepatic first-pass effect, not specific to the oral route. D: Sterilization of medicinal forms is not obligatory for the oral route, as proper storage and handling can ensure safety.

Correct Answer: D

Rationale: The correct answer is D because a vasoconstrictor actually enhances the effects of a local anesthetic by reducing its uptake by the surrounding nerves. This helps to prolong the duration of action of the anesthetic. Choices A and B are incorrect because a vasoconstrictor can retard drug removal from the injection site, which can increase the chance of toxicity. Choice C is incorrect because a vasoconstrictor actually decreases blood levels by constricting blood vessels at the site of administration, which can lead to localized effects.

Correct Answer: D

Rationale: The correct answer is D because ganglion-blockers (A) and neuromuscular junction blockers (C) both belong to the group of nicotinic receptor-blocking drugs. Ganglion-blockers act on nicotinic receptors in autonomic ganglia, while neuromuscular junction blockers act on nicotinic receptors at the neuromuscular junction. Atropine-similar drugs (B) do not directly block nicotinic receptors, so they are not part of this particular group of drugs. Therefore, choices A and C cover all the drugs that block nicotinic receptors, making D the correct answer.

Correct Answer: D

Rationale: The correct answer is D: Diaphragm. The diaphragm is more resistant to block and recovers rapidly due to its involuntary nature and vital role in breathing. The diaphragm contracts and relaxes continuously, making it more resilient compared to voluntary muscles like the hand, leg, and neck. The other choices are incorrect because voluntary muscles are more susceptible to fatigue and blockage due to their reliance on conscious control and are not essential for immediate survival like the diaphragm.

Correct Answer: C

Rationale: Rationale: Isoproterenol is a non-selective beta-adrenergic agonist that primarily acts on beta-1 and beta-2 receptors. It increases heart rate and contractility, leading to an increase in cardiac output (A) and tachycardia (D). Isoproterenol causes vasodilation, resulting in a fall in diastolic and mean arterial pressure (B). However, it does not cause bronchoconstriction (C) as it stimulates beta-2 receptors leading to bronchodilation. Therefore, the correct answer is C.