Which of the following drugs most likely caused the patient's symptoms?

Correct Answer: C

Rationale: The correct answer is C: Amitriptyline. The patient's symptoms suggest anticholinergic toxicity, which aligns with amitriptyline's side effects due to its strong anticholinergic properties. Amitriptyline can cause dry mouth, blurred vision, urinary retention, and confusion. Bupropion (A) is unlikely to cause these specific symptoms. Mirtazapine (B) is more sedating than anticholinergic. Paroxetine (D) is an SSRI and does not typically cause anticholinergic toxicity.

Correct Answer: B

Rationale: The correct answer is B: Clonidine. Clonidine is an alpha-2 adrenergic agonist, which means it acts by stimulating presynaptic alpha-2 receptors, leading to a decrease in norepinephrine release. This matches the drug described in the question that blocks presynaptic alphareceptors. Amitriptyline (A) is a tricyclic antidepressant that primarily acts by blocking the reuptake of serotonin and norepinephrine. Bupropion (C) is an atypical antidepressant that inhibits the reuptake of dopamine and norepinephrine. Mirtazapine (D) is a noradrenergic and specific serotonergic antidepressant that enhances serotonin and norepinephrine activity through different mechanisms. Therefore, Clonidine is the most likely drug given due to its action on presynaptic alphareceptors, while the other choices have different mechanisms

Correct Answer: B

Rationale: The correct answer is B: Decreased renal elimination of lithium. Thiazides reduce lithium excretion leading to lithium accumulation and toxicity. Thiazide-induced dilutional hypernatremia (A) is unlikely as thiazides generally cause hyponatremia. Decreased hepatic metabolism of lithium (C) is not a major factor in lithium toxicity. Thiazide-induced hypokalemia (D) is a possible side effect but not the primary reason for lithium toxicity in this scenario.

Correct Answer: C

Rationale: The correct answer is C: Lamotrigine. This drug is commonly prescribed for patients with past episodes of depression and mania as it is a mood stabilizer effective in treating bipolar disorder. It helps in regulating mood swings and preventing both manic and depressive episodes. Valproic acid (A) is also a mood stabilizer, but Lamotrigine is more commonly used in this context. Aripiprazole (B) is an atypical antipsychotic often used for bipolar disorder but is not as specific for treating past episodes of depression and mania. Imipramine (D) is a tricyclic antidepressant used for major depressive disorder and not typically prescribed for bipolar disorder.

Correct Answer: B

Rationale: The correct answer is B: Mesolimbic pathway. In ADHD, dysfunction in the mesolimbic pathway, involved in reward and motivation, is often implicated. Stimulant medications like those used to treat ADHD act on this pathway to improve focus and impulse control. The other pathways listed do not play as significant of a role in ADHD symptomatology. A: Tuberoinfundibular is involved in hormonal regulation, not ADHD. C: Corticostriatal is more associated with movement control. D: Mesocortical is related to cognitive functions, but not the main site of therapeutic action for ADHD.