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Pharmacologic class: Thiazide-like diuretic
Therapeutic class: Diuretic, antihypertensive
Pregnancy risk category B
Unclear. Enhances excretion of sodium, chloride, and water by interfering with transport of sodium ions across renal tubular epithelium. Also may dilate arterioles.
Tablets: 15 mg, 25 mg, 50 mg, 100 mg
Indications and dosages
➣ Edema associated with heart failure, renal dysfunction, cirrhosis, corticosteroid therapy, and estrogen therapy
Adults: 50 to 100 mg/day (30 to 60 mg Thalitone) P.O. or 100 mg every other day (60 mg Thalitone) P.O., up to 200 mg/day (120 mg Thalitone) P.O.
➣ Management of mild to moderate hypertension
Adults: 25 mg/day (15 mg Thalitone) P.O. Based on patient response, may increase to 50 mg/day (30 to 50 mg Thalitone) P.O., then up to 100 mg/day (except Thalitone) P.O.
• Hypersensitivity to drug, other thiazides, sulfonamides, or tartrazine
• Renal decompensation
Use cautiously in:
• renal or severe hepatic disease, abnormal glucose tolerance, gout, systemic lupus erythematosus, hyperparathyroidism, bipolar disorder
• elderly patients
• pregnant or breastfeeding patients.
• Know that dosages above 25 mg/day are likely to increase potassium excretion without further increasing sodium excretion or reducing blood pressure.
CNS: dizziness, vertigo, drowsiness, lethargy, confusion, headache, insomnia, nervousness, paresthesia, asterixis, nystagmus, encephalopathy
CV: hypotension, ECG changes, chest pain, arrhythmias, thrombophlebitis
GI: nausea, vomiting, cramping, anorexia, pancreatitis
GU: polyuria, nocturia, erectile dysfunction, loss of libido
Hematologic: blood dyscrasias
Metabolic: gout attack, dehydration, hyperglycemia, hypokalemia, hypocalcemia, hypomagnesemia, hyponatremia, hypophosphatemia, hyperuricemia, hyperlipidemia,
Musculoskeletal: muscle cramps, muscle spasms
Skin: flushing, photosensitivity, hives, rash, exfoliative dermatitis, toxic epidermal necrolysis
Other: fever, weight loss, hypersensitivity reactions
Drug-drug. Allopurinol: increased risk of hypersensitivity reaction
Amphotericin B, corticosteroids, mezlocillin, piperacillin, ticarcillin: additive hypokalemia
Antihypertensives, barbiturates, nitrates, opiates: increased hypotension
Cholestyramine, colestipol: decreased chlorthalidone blood level
Digoxin: increased risk of hypokalemia
Lithium: increased risk of lithium toxicity
Nonsteroidal anti-inflammatory drugs: decreased diuretic effect
Drug-diagnostic tests. Bilirubin, calcium, creatinine, uric acid: increased levels
Glucose (in diabetic patients): increased blood and urine levels
Magnesium, potassium, protein-bound iodine, sodium, urine calcium: decreased levels
Drug-herbs. Ginkgo: decreased antihypertensive effects
Licorice, stimulant laxative herbs (aloe, cascara sagrada, senna): increased risk of potassium depletion
Drug-behaviors. Acute alcohol ingestion: additive hypotension
Sun exposure: increased risk of photosensitivity
• Closely monitor patient with renal insufficiency.
• Assess for signs and symptoms of hematologic disorders.
• Monitor CBC with white cell differential and serum uric acid and electrolyte levels.
• Assess for signs and symptoms of hypersensitivity reactions, especially dermatitis.
• Watch for fluid and electrolyte imbalances.
• Instruct patient to consume a low-sodium diet containing plenty of potassium-rich foods and beverages (such as bananas, green leafy vegetables, and citrus juice).
• Caution patient to avoid driving and other hazardous activities until he knows whether drug makes him dizzy or affects concentration and alertness.
• Tell patient with diabetes to check urine or blood glucose level frequently.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.
Pharmacologic: thiazide diuretics
- Renal dysfunction,
- Glucocorticoid therapy,
- Estrogen therapy.
Time/action profile (diuretic effect)
|PO||2 hr||2 hr||48–72 hr|
Adverse Reactions/Side Effects
Central nervous system
Fluid and Electrolyte
- hypokalemia (most frequent)
- hypochloremic alkalosis
- blood dyscrasias
- muscle cramps
Drug-Drug interactionAdditive hypotension with other antihypertensive agents, acute ingestion of alcohol ornitrates.Additive hypokalemia with corticosteroids, amphotericin B, piperacillin, or ticarcillin.↓ the excretion of lithium.Cholestyramine or colestipol ↓ absorption.Hypokalemia ↑ risk of digoxin toxicity.NSAIDs may ↓ effectiveness.
Route/DosageWhen used as a diuretic in adults, generally given daily, but may be given every other day or 2–3 days/week
Availability (generic available)
- Monitor BP, intake, output, and daily weight and assess feet, legs, and sacral area for edema daily.
- Assess patient, especially if taking digitalis glycosides, for anorexia, nausea, vomiting, muscle cramps, paresthesia, and confusion. Notify physician or other health care professional if these signs of electrolyte imbalance occur. Patients taking digitalis glycosides are at risk of digitalis toxicity as a result of the potassium-depleting effect of the diuretic.
- Assess patient for allergy to sulfonamides.
- Hypertension: Monitor BP before and periodically throughout therapy.
- Monitor frequency of prescription refills to determine compliance.
- Lab Test Considerations: Monitor electrolytes (especially potassium), blood glucose, BUN, serum creatinine, and uric acid levels before and periodically throughout therapy.
- May cause ↑ in serum and urine glucose in diabetic patients.
- May cause ↑ in serum bilirubin, calcium, creatinine, and uric acid, and ↓ in serum magnesium, potassium, sodium, and urinary calcium concentrations.
- May cause ↑ serum cholesterol, low-density lipoprotein, and triglyceride concentrations.
Potential Nursing DiagnosesExcess fluid volume (Indications)
Risk for deficient fluid volume (Side Effects)
- Administer in the morning to prevent disruption of sleep cycle for urination.
- Intermittent dose schedule may be used for continued control of edema.
- Oral: May give with food or milk to minimize GI irritation. Tablets may be crushed and mixed with fluid to facilitate swallowing.
- Instruct patient to take this medication at the same time each day. If a dose is missed, take as soon as remembered but not just before next dose is due. Do not double doses.
- Instruct patient to monitor weight biweekly and notify health care professional of significant changes.
- Caution patient to change positions slowly to minimize orthostatic hypotension. This may be potentiated by alcohol.
- Advise patient to use sunscreen and protective clothing to prevent photosensitivity reactions.
- Instruct patient to discuss dietary potassium requirements with health care professional (see ).
- Instruct patient to notify health care professional of medication regimen before treatment or surgery.
- Advise patient to report muscle weakness, cramps, nausea, vomiting, diarrhea, or dizziness to health care professional.
- Emphasize the importance of routine follow-up exams.
- Hypertension: Advise patients to continue taking the medication even if feeling better. Medication controls but does not cure hypertension.
- Encourage patient to comply with additional interventions for hypertension (weight reduction, low-sodium diet, regular exercise, smoking cessation, moderation of alcohol consumption, and stress management).
- Instruct patient and family in correct technique for monitoring weekly BP.
- Advise patient to consult health care professional before taking OTC medication, especially cough or cold preparations, concurrently with this therapy.
- Decrease in BP.
- Decrease in edema.