Which of the following was most likely the reason for the adverse effects reported by the patient?

Correct Answer: B

Rationale: The most likely reason for the adverse effects reported by the patient is the decreased renal elimination of lithium caused by the antihypertensive treatment with hydrochlorothiazide. Thiazide diuretics like hydrochlorothiazide can decrease renal elimination of lithium, leading to an increase in lithium levels in the blood and potential toxicity. This interaction can result in symptoms such as lithium toxicity, which may present as mood swings and other adverse effects in a patient with bipolar disorder receiving lithium therapy. Therefore, choice B is the correct answer.

Correct Answer: C

Rationale: Amiloride is a potassium-sparing diuretic that can help reduce excessive urination and fluid intake in patients with symptoms of diabetes insipidus. It works by affecting the reabsorption of sodium and water in the kidneys, helping to balance fluid levels and decrease urinary output. Furosemide, hydrochlorothiazide, spironolactone, and conivaptan are not typically used to treat the specific symptoms described in the case.

Correct Answer: B

Rationale: Norepinephrine is a neurotransmitter that plays a role in regulating blood pressure. Drugs that increase norepinephrine levels can lead to elevated blood pressure, as seen in this patient. Atomoxetine, phenylephrine, guanfacine, and clonidine do not directly affect norepinephrine levels in a way that would cause high blood pressure.

Correct Answer: D

Rationale: The lateral hypothalamus is known to be involved in the regulation of hunger and satiety. Amphetamines, which act by increasing catecholamine release in the central nervous system, can suppress appetite by affecting the lateral hypothalamus. This region plays a key role in regulating feeding behavior and energy balance, making it a likely site of anorectic action for drugs like amphetamines.

Correct Answer: B

Rationale: Dextroamphetamine is a commonly prescribed medication for ADHD, especially in children who exhibit symptoms such as hyperactivity, impulsivity, and inattention. It acts by increasing the levels of dopamine and norepinephrine in the brain, helping to improve focus and reduce hyperactive behavior in individuals with ADHD.