Learning Outcomes
By the end of this section, you should be able to:
- 34.5.1 Identify the characteristics of thiazide and thiazide-like diuretic drugs used for fluid volume excess and renal system disorders.
- 34.5.2 Explain the indications, actions, adverse reactions, and interactions of thiazide and thiazide-like diuretic drugs used for fluid volume excess and renal system disorders.
- 34.5.3 Describe nursing implications of thiazide and thiazide-like diuretic drugs used for fluid volume excess and renal system disorders.
- 34.5.4 Explain the client education related to thiazide and thiazide-like diuretic drugs used for fluid volume excess and renal system disorders.
Introduction and Use
The thiazide and thiazide-like diuretics treat hypertension and edema. They are considered first-line therapies for hypertension, although their antihypertensive effects are not well understood. They treat edema related to congestive heart failure, cirrhosis, and acute and chronic renal diseases, including nephrotic syndrome, acute glomerulonephritis, and chronic renal failure. Thiazide and thiazide-like diuretics are frequently used in combination with other antihypertensives and diuretic types.
Thiazide and thiazide-like diuretics have three major properties: inhibition of sodium reabsorption, increased reabsorption of calcium, and creation of mild extracellular fluid losses:
- Thiazide and thiazide-like diuretics inhibit the reabsorption of sodium in the distal convoluted tubule by competing with chloride on the Na-Cl transporter, resulting in the loss of chloride and the passive loss of sodium; however, the therapy decreases reabsorption of only 3%–5% of the sodium in the filtrate. This transporter is similar to the NKCC in the loop of Henle. The drugs also exert some inhibitory effect on sodium reabsorption in the proximal tubules and the collecting ducts; however, this diuretic action is countered by the additional reabsorption of sodium in the same area of the nephron.
- Thiazide and thiazide-like diuretics increase the rate of calcium reabsorption in two ways. First, the drugs directly increase the reabsorption rate of calcium that normally occurs in the distal tubule. Second, the drugs decrease extracellular fluid volume by limiting reabsorption of sodium, and this volume change indirectly triggers increased calcium reabsorption into the proximal tubule.
- Thiazide and thiazide-like diuretics block sodium reabsorption from the distal convoluted tubule; this can result in hyponatremia, which increases water loss. The drugs also create mild extracellular fluid loss, which can decrease the tubular volume in the loop of Henle, resulting in decreased free water loss.
Hydrochlorothiazide is one of the most commonly used diuretics. Metolazone is a thiazide-like diuretic that, unlike the thiazide drugs, is also effective in chronic renal disease because it does not affect the GFR. In addition, metolazone does not trigger the RAAS, which means that the use of metolazone combined with a loop diuretic can minimize diuretic resistance and increase renal response with fewer adverse effects (Bond et al., 2022). Chlorthalidone is a thiazide-like diuretic with prolonged action (48–72 hours).
Table 34.7 lists common thiazide and thiazide-like diuretics and typical routes and dosing for adult clients.
| Drug | Routes and Dosage Ranges |
|---|---|
| Hydrochlorothiazide (Hydrodiuril, Microzide) | Hypertension: Initial dose: 25 mg orally once daily; may increase dose to 50 mg/day in 1–2 divided doses. Edema: 25–100 mg orally daily as a single or divided dose; administration on alternate days or 3–5 days per week may also be effective. |
| Chlorothiazide (Diuril) |
Edema: 500–1000 mg IV once or twice daily. |
| Metolazone (Zaroxolyn) |
Edema: 5–20 mg orally once daily. Hypertension: 2.5–5 mg orally once daily. |
| Chlorthalidone (Thalitone) |
Hypertension: 25 mg orally daily; start with lowest dose and titrate to response. Edema: 25 mg orally daily; start with lowest dose and titrate to response. |
Adverse Effects and Contraindications
The adverse effects of thiazide diuretics are related to the sodium losses and the ionic imbalance created by those losses (Akbari & Khorasani-Zedah, 2022). Adverse effects include metabolic alkalosis, hypercalcemia, hyperglycemia, hyperuricemia, hyperlipidemia, photosensitivity reactions, hyponatremia due to decreased reabsorption, and hypokalemia due to action of the sodium–potassium pump in the distal convoluted tubule. Their photosensitizing effects also appear to increase the risk of skin cancer (Shin et al., 2019).
Thiazide and thiazide-like diuretics are contraindicated in individuals with sulfonamide allergy. Sensitivity reactions occur most commonly in clients who experience frequent allergic reactions and less commonly than previously believed in sulfa-sensitive clients. Reactions can include rash, hives, angioedema, wheezing, and anaphylaxis (Akbari & Khorasani-Zedah, 2022). Thiazide and thiazide-like diuretics can increase the risk of digoxin toxicity, and the drugs also should not be administered with lithium. Thiazide and thiazide-like diuretics should be used with caution in clients with renal disease and are contraindicated for clients who are anuric.
Table 34.8 is a drug prototype table for thiazide and thiazide-like diuretics featuring hydrochlorothiazide. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.
| Drug Class Thiazide and thiazide-like diuretics Mechanism of Action Exact mechanism unknown, but affects electrolyte reabsorption at the distal renal tubule Increases excretion of sodium and chloride |
Drug Dosage Hypertension: Initial dose: 25 mg orally once daily; may increase dose to 50 mg/day in 1–2 divided doses. Edema: 25–100 mg orally daily as a single or divided dose; administration on alternate days or 3–5 days per week may also be effective. |
| Indications Edema related to congestive heart failure, cirrhosis, and acute and chronic renal diseases, including nephrotic syndrome, acute glomerulonephritis, and chronic renal failure Hypertension Therapeutic Effects Decreased edema Decreased blood pressure |
Drug Interactions Lithium Nonsteroidal anti-inflammatory drugs (NSAIDs) Corticosteroids Antidiabetic drugs Food Interactions Alcohol |
| Adverse Effects Electrolyte imbalances Hypotension (including orthostatic hypotension) Renal dysfunction Photosensitivity reactions Erythema multiforme, including Stevens–Johnson syndrome Aplastic anemia |
Contraindications Sulfa sensitivity Anuria |
Safety Alert
Thiazide Diuretics
Thiazide diuretics increase the risk for photosensitivity reactions. The client should avoid long periods of sun exposure and should always use sunscreen.
(Source: DailyMed, Hydrochlorothiazide, 2018)
Unfolding Case Study
Part B
Read the following clinical scenario to answer the questions that follow. This case study is a follow-up to Case Study Part A.
Gordon Jefferson completes his diagnostic evaluation, and the health care provider diagnoses him with edema. He follows up with his health care provider 1 week later to get the results of his diagnostic studies and review his treatment plan. He is prescribed metolazone 10 mg once daily by mouth for his edema.
Nursing Implications
The nurse should do the following for clients taking thiazide or thiazide-like diuretics:
- Assess the client’s blood pressure before giving the initial dose and then intermittently during drug therapy on an ongoing basis.
- Monitor for evidence of cardiac changes by assessing heart rate and ECG rhythm strips.
- Evaluate the client’s response to therapy as evidenced by decreased edema.
- Monitor the client’s urine output and laboratory tests for electrolyte imbalances.
- Assess and monitor the client for other adverse effects, drug and food interactions, and contraindications.
- Provide client teaching regarding the drug and when to call the health care provider. See below for additional client teaching guidelines.
Clinical Tip
Accurate Assessment of Client’s Fluid Volume Status
Clients with heart failure are often hospitalized to correct fluid volume overload. Nurses are responsible for accurate physical assessment, data collection, and documentation of the client’s fluid volume status, which is critical for effective diuretic therapy. The nurse should monitor the client’s response to treatment by measuring urine output, monitoring their weight daily, auscultating lung sounds for rales or crackles, and assessing the client’s lower extremities and other dependent areas to determine whether the edema is decreasing.
(Source: Malik et al., 2022)
Client Teaching Guidelines
The client taking a thiazide or thiazide-like diuretic should:
- Follow a balanced diet with moderate intake of potassium-rich foods.
- Wear sunscreen and avoid excessive sun exposure because of risk for photosensitivity reactions.
The client taking a thiazide or thiazide-like diuretic should not:
- Take nonsteroidal anti-inflammatory drugs.
Unfolding Case Study
Part C
Read the following clinical scenario to answer the questions that follow. This case study is a follow-up from Case Study Parts A and B.
Gordon Jefferson is following up with the health care provider 3 months after his initial diagnosis of edema. He reports that the swelling in his legs has improved; however, he is now reporting generalized weakness. The health care provider examines the client and reviews the chemistry panel results from laboratory work drawn earlier in the morning. Gordon says he has been taking his prescribed medications:
Current Medications
Losartan 50 mg orally daily
Dapagliflozin 10 mg orally daily
Metolazone 10 mg orally daily
| Vital Signs | Physical Examination | Chemistry Panel | |
|---|---|---|---|
| Temperature: | 98.0°F |
|
Sodium: 140 mEq/L Potassium: 2.9 mEq/L BUN: 24 mg/dL Creatinine: 1.4 mg/dL eGFR: 40 mL/minute/1.73 m2 |
| Blood pressure: | 138/88 mm Hg | ||
| Heart rate: | 76 beats/min | ||
| Respiratory rate: | 16 breaths/min | ||
| Oxygen saturation: | 98% on room air | ||
| Height: | 5'9" | ||
| Weight: | 191 lb | ||
The health care provider diagnoses the client with hypokalemia, prescribes a potassium supplement, and recommends a low-sodium diet with potassium-rich foods.