The nurse is teaching a group of patients about the mood-stabilizing medication, lithium carbonate. Which of the following medications should instruct the patients to avoid because of the increased risk of lithium toxicity?

1. A

   Hypoglycemic agents

2. B

   Antibiotics

3. C

   Diuretics

4. D

   Antacids

Appeared in: JODHPUR AIIMS SNO-2018

Explanation

• Diuretics, particularly thiazide diuretics, cause the body to excrete sodium through the kidneys.
• The kidneys process lithium and sodium similarly. When sodium levels are low, the kidneys try to conserve it.
• In the process of conserving sodium, the kidneys also increase the reabsorption of lithium back into the bloodstream.
• This reduced renal clearance causes serum lithium levels to rise, significantly increasing the risk of reaching toxic levels.

Why Other Options Were Wrong

• Option A: Hypoglycemic agents are used to manage blood glucose and do not have a primary, clinically significant interaction that increases lithium levels.
• Option B: This is not a class-wide interaction. While a few specific antibiotics like metronidazole can increase lithium levels, most do not pose a risk.
• Option D: Antacids, particularly those containing sodium bicarbonate, can increase the renal excretion of lithium, which would lower its concentration and risk subtherapeutic levels, not toxicity.

Related Visual

Clinical Relevance

• Nursing practice connection: Knowing Drug interactions with lithium carbonate leading to toxicity helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
• Lithium has a very narrow therapeutic window (0.6-1.2 mEq/L), making patient education on drug interactions a critical safety measure.
• Nurses must teach patients to maintain a consistent intake of salt and fluids, as dehydration or low-sodium diets can precipitate toxicity.
• Patients should be warned against taking over-the-counter NSAIDs (except aspirin) and should inform all healthcare providers they are taking lithium.

How to Approach the Question

• First, identify the key concept in the question: a drug interaction that increases the risk of lithium toxicity.
• Recall the basic pharmacology of lithium, specifically that its excretion by the kidneys is closely linked to sodium levels.
• Analyze each option based on its known effect on kidney function and sodium balance.
• Diuretics are designed to alter fluid and electrolyte balance, primarily by increasing sodium excretion.
• Connect this action to lithium: increased sodium excretion leads to compensatory lithium reabsorption by the kidneys.
• Conclude that diuretics are the class of medication among the choices that poses a well-documented and significant risk for increasing lithium levels and causing toxicity.

Concept Tested & Keywords

• Concept Tested: Drug interactions with lithium carbonate leading to toxicity.
• Stem keywords: lithium carbonate, mood-stabilizing, medications to avoid, lithium toxicity
• Lead-in keywords: Which of the following
• Negative lead-in flag: false

Question ID

QkKYOg2rxjf0IdhFjdbcPk

Copy ID

Reference Book

E6 Pharmacology Nursing Lilley 11e Part 1 p. 272-274

E6 Kaplan Sadock's Synopsis of Psychiatry-2022 (pp 1-3768 of 3768) p. 2063-2065