What medication adjustments are recommended for a patient with morbid obesity, hypotension, and a history of borderline hyponatremia, currently taking Losartan (Angiotensin II Receptor Antagonist) 100 mg and Hydrochlorothiazide (HCTZ) (Thiazide Diuretic) 25 mg?

Medication Management for Morbidly Obese Patient with Hypotension and Borderline Hyponatremia

The HCTZ should be discontinued due to the patient's borderline hyponatremia and hypotension, while maintaining the Losartan 100 mg but monitoring closely for blood pressure response.

Current Medication Assessment

The patient is currently taking:

• Losartan 100 mg (Angiotensin II Receptor Blocker)
• HCTZ 25 mg (Thiazide Diuretic)

Key clinical concerns:

• Morbid obesity
• Hypotension (contradicting the need for antihypertensive therapy)
• Borderline hyponatremia (likely due to HCTZ)
• Improving SBP but DBP remains elevated (mid 80s to mid 90s mmHg)

Recommended Medication Adjustments

Primary Recommendation

1. Discontinue HCTZ 25 mg immediately

   • HCTZ is associated with hyponatremia, which is already present in this patient 1
   • Thiazide diuretics can cause dose-dependent electrolyte abnormalities including hyponatremia 2
   • The patient's hypotension suggests overtreatment with the current regimen

2. Maintain Losartan 100 mg

   • Losartan is effective as monotherapy for hypertension 3
   • Losartan has a better metabolic profile than HCTZ, particularly important in obese patients 4
   • The maximum recommended dose is 100 mg daily, which the patient is already taking 3

3. Monitor blood pressure closely

   • If DBP remains elevated (>90 mmHg) after 2-4 weeks without HCTZ, consider alternative agents
   • If hypotension persists, consider reducing Losartan dose to 50 mg daily 3

Rationale for Recommendations

Why Discontinue HCTZ?

• Hyponatremia risk: HCTZ is associated with hyponatremia, which the patient is already experiencing 1
• Hypotension: The patient's hypotension indicates possible overtreatment with the current regimen
• Metabolic concerns: In obese patients, thiazides may have unwanted metabolic effects 4

Why Maintain Losartan?

• Efficacy in obesity: ARBs like Losartan are appropriate first-line agents in obese hypertensive patients 4
• Better metabolic profile: Losartan does not negatively impact insulin sensitivity unlike thiazides 4
• DBP control: The elevated DBP suggests some antihypertensive therapy is still needed

Monitoring Recommendations

1. Blood pressure monitoring:

   • Check BP within 1-2 weeks after medication change
   • Target BP should be individualized based on the patient's overall cardiovascular risk

2. Electrolyte monitoring:

   • Recheck sodium levels 1-2 weeks after discontinuing HCTZ
   • Monitor potassium levels, as Losartan can cause hyperkalemia 1

3. Kidney function:

   • Monitor renal function, especially if the patient has any underlying kidney disease

Alternative Approaches if Initial Plan Fails

If DBP remains elevated after discontinuing HCTZ:

1. Consider a calcium channel blocker (e.g., amlodipine 5-10 mg daily) as an alternative to HCTZ 5

   • Metabolically neutral option for obese patients 4
   • Effective for DBP control

2. Consider a low-dose chlorthalidone (6.25 mg) if diuretic therapy is absolutely necessary 6

   • More effective than HCTZ 12.5 mg for 24-hour BP control
   • Use with caution and monitor sodium levels closely

Important Caveats and Pitfalls

• Avoid reinitiating HCTZ if hyponatremia resolves, as recurrence is likely
• Avoid rapid discontinuation of antihypertensive medications, which can lead to rebound hypertension
• Be cautious with fluid restriction in a patient with hypotension
• Consider sleep apnea evaluation in morbidly obese patients, as it can contribute to resistant hypertension
• Do not combine ARBs with ACE inhibitors as this increases adverse effects without significant BP benefit 5

By discontinuing HCTZ while maintaining Losartan, you address the immediate concerns of hyponatremia and hypotension while still providing treatment for the elevated DBP. Close monitoring will allow for further adjustments as needed.