Is hydrochlorothiazide (HCTZ) suitable for patients with chronic renal failure and asthma as a medication for hypertension?

From the Guidelines

Hydrochlorothiazide (HCTZ) is not the preferred choice for patients with chronic renal failure and asthma who need treatment for hypertension. For patients with chronic renal failure, HCTZ becomes ineffective when creatinine clearance falls below 30 mL/min, and may even worsen kidney function, as noted in the guidelines 1. Loop diuretics like furosemide would be more appropriate for these patients, as they are preferred diuretics in patients with symptomatic heart failure and moderate-to-severe chronic kidney disease (CKD) with a GFR <30 mL/min 1.

Regarding asthma, while HCTZ does not directly affect the airways, thiazide diuretics can cause metabolic abnormalities like hypokalemia that may potentially worsen bronchospasm in some asthmatic patients. Better alternatives for hypertension management in these patients would include ACE inhibitors (if renal function permits), calcium channel blockers like amlodipine, or ARBs such as losartan. These medications effectively control blood pressure without the concerns associated with thiazides in renal failure. However, ACE inhibitors should be used cautiously as they may cause cough which could be confused with asthma symptoms, as mentioned in the guidelines 1.

Blood pressure, renal function, and electrolytes should be regularly monitored regardless of which antihypertensive is selected, to ensure the best possible outcomes for patients with chronic renal failure and asthma. The most recent guidelines from 2018 1 provide the best evidence for managing hypertension in these patients, emphasizing the importance of careful selection and monitoring of antihypertensive therapy to minimize risks and maximize benefits.

Some key points to consider in the management of hypertension in patients with chronic renal failure and asthma include:

• The use of loop diuretics for volume control in patients with moderate or severe heart failure or significant renal impairment 1.
• The potential for thiazide diuretics to cause hypokalemia and worsen bronchospasm in asthmatic patients 1.
• The importance of monitoring renal function and electrolytes in patients with CKD, especially when using diuretics or ACE inhibitors/ARBs 1.
• The need for careful consideration of the potential benefits and risks of different antihypertensive agents in patients with complex comorbidities like chronic renal failure and asthma.

From the FDA Drug Label

In patients with renal disease, plasma concentrations of hydrochlorothiazide are increased and the elimination half-life is prolonged Hydrochlorothiazide is eliminated primarily by renal pathways. Hydrochlorothiazide may reduce glomerular filtration rate

HCTZ is not ideal for patients with chronic renal failure and asthma as a medication for hypertension, due to its potential to reduce glomerular filtration rate and accumulate in the body in patients with renal disease, which may worsen renal function. Additionally, caution is advised when using HCTZ in patients with asthma, as it may exacerbate asthma symptoms. 2

From the Research

Suitability of HCTZ for Patients with Chronic Renal Failure and Asthma

• HCTZ can be used to treat hypertension in patients with chronic renal failure, as it has been shown to increase the fractional excretion of sodium and chloride, and decrease mean arterial blood pressure 3.
• However, the use of HCTZ in patients with advanced renal failure is debated, and loop diuretics are often considered the drugs of choice for treating hypertension in these patients 3, 4.
• In patients with asthma, HCTZ can be used with caution, as it may cause respiratory side effects such as wheezing and shortness of breath, although this is not a common occurrence 4.
• The combination of HCTZ with other medications, such as beta-blockers, angiotensin-converting enzyme inhibitors, and calcium channel blockers, can be effective in treating hypertension, but may also increase the risk of adverse effects 4, 5.
• Close monitoring of electrolyte levels, particularly potassium and magnesium, is necessary when using HCTZ, especially in patients with chronic renal failure or those taking other medications that can affect electrolyte levels 6, 7.

Efficacy of HCTZ in Chronic Renal Failure

• Small randomized controlled trials have shown that HCTZ can significantly improve mean arterial pressure in patients with chronic kidney disease (CKD) 6.
• However, the use of HCTZ in advanced CKD requires careful consideration, as it may cause electrolyte abnormalities and other adverse effects 6.
• Further studies are needed to determine the efficacy and safety of HCTZ in patients with advanced CKD 6.

Safety Considerations

• HCTZ can cause hypokalemia, hypomagnesemia, and other electrolyte abnormalities, particularly in patients with chronic renal failure or those taking other medications that can affect electrolyte levels 4, 7.
• Close monitoring of electrolyte levels and renal function is necessary when using HCTZ, especially in patients with chronic renal failure or those taking other medications that can affect electrolyte levels 4, 6, 7.