Indicate the barbituric acid derivative which has 4-5 days elimination half-life:

Correct Answer: C

Rationale: The correct answer is C: Phenobarbital. Phenobarbital has a longer elimination half-life of 4-5 days due to its extensive hepatic metabolism and slow excretion. Secobarbital (A) has a shorter half-life around 15 hours. Thiopental (B) has a very short half-life of 5-10 hours. Amobarbital (D) has a half-life of around 10-25 hours, making it shorter than phenobarbital. Therefore, based on the pharmacokinetics of these drugs, phenobarbital is the most likely choice with a 4-5 days elimination half-life.

Correct Answer: D

Rationale: Rationale for correct answer D: Levodopa therapy for Parkinson's disease has well-documented characteristics. A: Tolerance can develop to both beneficial effects (reduced over time) and adverse effects (increased over time). B: Levodopa is most effective in the initial years of treatment due to progressive loss of response. C: After 5 years, patients may experience dose-related dyskinesias, inadequate response, or toxicity due to disease progression and medication adjustments. Therefore, all statements are accurate and reflect the complexities of long-term levodopa therapy in Parkinson's disease.

Correct Answer: B

Rationale: The correct answer is B: Naltrexone. Naltrexone is a pure opioid antagonist with a half-life of 10 hours, making it the most appropriate choice. Naloxone (A) is a short-acting opioid antagonist used for emergency overdose situations. Tramadol (C) is a weak opioid agonist with additional effects on serotonin and norepinephrine reuptake. Pentazocine (D) is a mixed opioid agonist-antagonist. Therefore, only Naltrexone fits the criteria of a pure opioid antagonist with a 10-hour half-life.

Correct Answer: D

Rationale: Rationale: - A: D1 receptors are indeed found in the striatum - B: D2 receptors are present in the striatum and limbic areas - C: D4 receptors are located in the frontal cortex and mesolimbic system Therefore, the correct answer is D as all statements are true, covering the distribution of D1, D2, and D4 receptors in the specified brain regions. Other choices are incorrect as they do not include all the correct statements.

Correct Answer: C

Rationale: Rationale: C: Both MAO inhibitors and tricyclic antidepressants increase levels of biogenic amines like serotonin, norepinephrine, and dopamine by inhibiting their reuptake or breakdown. A: Both act presynaptically by inhibiting the reuptake of neurotransmitters, not postsynaptically. B: Only MAO inhibitors interact with certain foods to cause hypertensive crisis, not tricyclic antidepressants. D: Tricyclic antidepressants are used for bipolar depression, not the manic phase.