Examkin

Question

Difficulty: Very hardBipolar and Related Disorders

A 46-year-old woman is evaluated in the psychiatric clinic for an acute bipolar depressive episode. She has a history of bipolar I disorder with multiple past hospitalizations for severe mania. Her medical history includes hypertension, chronic lower back pain, and Hashimoto thyroiditis. Her current medications are lisinopril, naproxen (taken daily), and levothyroxine. Laboratory studies show a normal serum creatinine with an estimated glomerular filtration rate (eGFR) of 95 mL/min/1.73m² and a normal thyroid-stimulating hormone (TSH) level. The psychiatrist plans to initiate lithium carbonate for her current depressive episode and for long-term maintenance.

Which of the following are appropriate steps in the management of this patient prior to or during the initiation of lithium therapy? (Select all that apply)

  1. Discontinue lisinopril and transition to amlodipine for blood pressure controlAnswer
  2. Instruct the patient to discontinue naproxen and use acetaminophen for analgesiaAnswer
  3. Obtain a baseline electrocardiogram (ECG) to evaluate for conduction abnormalitiesAnswer
  4. D
    Delay lithium therapy and initiate paroxetine monotherapy for the acute depressive episode
  5. E
    Initiate concurrent hydrochlorothiazide to prevent lithium-induced polyuria and nephrogenic diabetes insipidus

Answer

The correct steps are discontinuing lisinopril in favor of amlodipine, replacing naproxen with acetaminophen, and obtaining a baseline ECG.
Safe initiation of lithium requires managing dangerous drug interactions and performing age-appropriate medical screening. Lisinopril (ACE inhibitor) and naproxen (NSAID) both significantly decrease renal lithium clearance and must be replaced with safe alternatives like amlodipine and acetaminophen. Furthermore, patients over age 40 require a baseline ECG prior to lithium initiation due to the risk of conduction abnormalities.

Step-by-Step Solution

1
Analyze the patient's current medication list for pharmacokinetic interactions with lithium.
Identify lisinopril (an ACE inhibitor) and naproxen (an NSAID) as high-risk interacting drugs.
Lithium has a narrow therapeutic index, and its renal clearance is significantly decreased by ACE inhibitors and NSAIDs, which can precipitate life-threatening lithium toxicity.
2
Determine appropriate substitutions for the interacting medications.
Select amlodipine (a calcium channel blocker) instead of lisinopril, and acetaminophen instead of naproxen.
Calcium channel blockers and acetaminophen do not significantly alter renal lithium clearance and are safe alternatives for blood pressure and pain management in this context.
3
Evaluate the patient's age and cardiovascular risk for necessary pre-treatment screening.
Identify the need for a baseline electrocardiogram (ECG).
The patient is 46 years old, which meets the guideline threshold (age > 40) for a baseline ECG prior to lithium initiation to rule out underlying cardiac conduction disease.
4
Evaluate the proposed alternative or adjunctive psychiatric interventions for safety and efficacy.
Reject paroxetine monotherapy and prophylactic hydrochlorothiazide.
SSRI monotherapy risks a manic switch in bipolar I disorder, and starting a thiazide would drastically increase lithium levels and toxicity risk.

Key Concept

Pre-treatment workup and pharmacokinetic drug interactions of lithium therapy in bipolar disorder.
Rate this question

Topics

Bipolar and Related Disorders

More questions from this topic