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Zorluk: OrtaPharmacologic Interventions

A 4242-year-old man comes to the clinic for a follow-up evaluation of elevated blood pressure. During his last visit three months ago, his blood pressure was 152/94 mmHg152/94 \text{ mmHg}, and he was advised to initiate a low-sodium diet and start an exercise program. Today, his blood pressure is 156/96 mmHg156/96 \text{ mmHg}. His heart rate is 72 /min72\text{ /min}. The physical examination is unremarkable. The patient has a 55-year history of bipolar I disorder that has been well controlled with lithium monotherapy. He takes no other medications. Laboratory studies show a serum creatinine of 0.9 mg/dL0.9 \text{ mg/dL}, serum sodium of 140 mEq/L140 \text{ mEq/L}, and a serum lithium level of 0.8 mEq/L0.8 \text{ mEq/L} (therapeutic range: 0.6−1.2 mEq/L0.6-1.2 \text{ mEq/L}). The physician decides to start pharmacotherapy for primary hypertension. Which of the following is the most appropriate medication for this patient?

  1. AmlodipineCevap
  2. B
    Hydrochlorothiazide
  3. C
    Lisinopril
  4. D
    Losartan
  5. E
    Metoprolol

Cevap

Amlodipine
The correct answer is amlodipine. This patient requires pharmacologic treatment for primary hypertension. Standard first-line agents include thiazide diuretics, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), and calcium channel blockers (CCBs). However, this patient is taking lithium, which has a narrow therapeutic index and is almost entirely excreted by the kidneys. Lithium reabsorption is closely linked to sodium handling in the proximal convoluted tubule. Thiazide diuretics, ACE inhibitors, ARBs, and nonsteroidal anti-inflammatory drugs (NSAIDs) all significantly decrease renal lithium clearance, potentially precipitating severe neurotoxicity. Dihydropyridine CCBs, such as amlodipine, do not significantly affect renal lithium handling and represent the safest first-line choice for this patient.

Adım Adım Çözüm

1
Identify the patient's new diagnosis and therapeutic requirement.
The patient has stage 2 primary hypertension requiring initiation of first-line antihypertensive pharmacotherapy.
Blood pressure remains elevated (>140/90 mmHg>140/90 \text{ mmHg}) despite a 3-month trial of lifestyle modifications.
2
Review the patient's comorbidities and current medication list for potential interactions.
The patient has bipolar I disorder and is stable on lithium monotherapy.
Lithium has a narrow therapeutic index and its serum levels are heavily dependent on renal clearance.
3
Evaluate standard first-line antihypertensives (thiazides, ACE inhibitors, ARBs, CCBs) for safety in the context of lithium therapy.
Thiazides, ACE inhibitors, and ARBs profoundly decrease renal lithium clearance. CCBs do not.
Avoiding iatrogenic lithium toxicity dictates the choice of the antihypertensive agent.
4
Select the most appropriate pharmacologic intervention.
Amlodipine is chosen.
It is a first-line agent for primary hypertension that does not interfere with renal lithium handling.

Anahtar Kavram

In patients taking lithium, first-line antihypertensives such as thiazide diuretics, ACE inhibitors, and ARBs must be avoided due to their ability to decrease renal lithium clearance and cause severe toxicity. Calcium channel blockers are the safest first-line alternative.
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Pharmacologic Interventions

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