Which route of drug administration is most likely to lead to the first-pass effect?

Correct Answer: B

Rationale: The correct answer is B: Oral. When a drug is administered orally, it passes through the gastrointestinal tract and then the liver before reaching systemic circulation, leading to the first-pass effect. This effect occurs because the liver metabolizes a portion of the drug before it reaches the bloodstream. Sublingual administration (choice A) bypasses the liver initially, reducing the first-pass effect. Intravenous (choice C) and intramuscular (choice D) routes also bypass the liver initially, thus reducing the first-pass effect compared to oral administration.

Correct Answer: C

Rationale: Step-by-step rationale: 1. The anesthetic effect of short and intermediate duration agents is primarily influenced by their metabolism and distribution in the body. 2. Dopamine is not commonly used to prolong anesthesia as it primarily acts as a neurotransmitter and vasopressor. 3. Epinephrine, norepinephrine, and phenylephrine are commonly used to prolong anesthesia due to their vasoconstrictive properties. 4. Therefore, the correct answer is C (Dopamine) as it does not have the same vasoconstrictive effects as the other choices.

Correct Answer: C

Rationale: Correct Answer: C (Pralidoxime) Rationale: 1. Pralidoxime reactivates inhibited cholinesterase enzymes. 2. This helps counteract the toxic effects of organophosphate cholinesterase inhibitors. 3. Atropine is used to treat the symptoms but does not directly counteract the toxic effects. 4. Pilocarpine and edrophonium are not used for acute toxic effects of organophosphate poisoning.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Succinylcholine causes transient muscle fasciculations due to its depolarizing mechanism of action. 2. It binds to nicotinic acetylcholine receptors, causing initial muscle twitching. 3. This fasciculation phase is a distinct feature of succinylcholine. 4. Mivacurium, Pancuronium, and Tubocurarine are non-depolarizing blockers, so they do not cause initial muscle fasciculations. Summary: A, B, and D are incorrect because they are non-depolarizing blockers and do not induce muscle fasciculations like succinylcholine.

Correct Answer: D

Rationale: Isoproterenol is a nonselective beta receptor agonist. It activates both beta1 and beta2 adrenergic receptors. This is because it has a higher affinity for beta receptors compared to alpha receptors, making it nonselective. Therefore, option D is correct. Option A is incorrect because isoproterenol does not significantly activate alpha receptors. Option B is incorrect as it is not beta1-selective. Option C is incorrect as isoproterenol activates both beta1 and beta2 receptors.