chlorothiazide

chlorothiazide /chlo·ro·thi·a·zide/ (klor?o-thi´ah-zid) a thiazide diuretic used in the form of the base or the sodium salt to treat hypertension and edema.

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chlorothiazide (klor´thī´zīd´),

n brand name: Diuril;
drug class: thiazide diuretic;
action: acts on distal tubule by increasing excretion of water, sodium chloride, potassium;
uses: edema and hypertension, diuresis.

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chlorothiazide

a thiazide diuretic. Called also Diuril.

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chlorothiazide

Diuril

Pharmacologic class: Thiazide

Therapeutic class: Diuretic, antihypertensive

Pregnancy risk category B

Action

Increases sodium and water excretion and inhibits sodium reabsorption in distal tubule, thereby promoting excretion of chloride, potassium, magnesium, and bicarbonate

Availability

Oral suspension: 250 mg/5 ml

Powder for injection: 500 mg

Tablets: 250 mg, 500 mg

⊘Indications and dosages

➣ Edema associated with heart failure, renal dysfunction, cirrhosis, corticosteroid therapy, or estrogen therapy

Adults: 0.5 to 1 g P.O. daily as a single dose or in two divided doses

Children ages 3 to 6 months: 10 to 20 mg/kg P.O. daily as a single dose or in two divided doses

➣ Mild to moderate hypertension

Adults: 0.5 to 1 g P.O. daily as a single dose or in divided doses. Adjust dosage to blood pressure response.

Children: 10 to 20 mg/kg P.O. daily as a single dose or in two divided doses, not to exceed 375 mg/day (2.5 to 7.5 ml or ½ to 1½ tsp of oral suspension) in infants up to age 2, or 1 g/day in children ages 2 to 12. Infants younger than 6 months may require up to 30 mg/kg daily in two divided doses.

Contraindications

• Hypersensitivity to drug, other thiazides, benzodiazepines, sulfonamides, or tartrazine
• Anuria
• Gout
• Systemic lupus erythematosus
• Glucose tolerance abnormalities
• Hyperparathyroidism
• Bipolar disorder
• Breastfeeding

Precautions

Use cautiously in:
• renal or severe hepatic impairment
• pregnant patients.

Administration

• Be aware that drug is given I.V. in emergency use and for patients unable to receive oral form. I.V. dosage is individualized; use smallest dosage needed to achieve response.
• Know that drug is not safe for I.M. or subcutaneous use, and that I.V. use in children is not recommended.
• Be aware that drug may be ineffective in patients with renal insufficiency.
• Rarely, patients may require up to 2 g/day in divided doses.

Route	Onset	Peak	Duration
P.O.	2 hr	4 hr	6-12 hr
I.V.	15 min	30 min	Unknown

Adverse reactions

CNS: dizziness, drowsiness, lethargy, headache, insomnia, nervousness, vertigo, paresthesia, confusion, fatigue, asterixis, encephalopathy

CV: hypotension, ECG changes, chest pain, thrombophlebitis, arrhythmias

EENT: nystagmus

GI: nausea, vomiting, abdominal cramps, pancreatitis, anorexia

GU: polyuria, nocturia, erectile dysfunction, loss of libido

Hematologic: blood dyscrasias

Hepatic: jaundice, hepatitis

Metabolic: dehydration, hypovolemia, hyperglycemia, hypokalemia, hypocalcemia, hypomagnesemia, hyponatremia, hypophosphatemia, hyperuricemia, gout attack, hypochloremic alkalosis

Musculoskeletal: muscle cramps or spasms

Skin: photosensitivity, rash, urticaria, flushing

Other: fever, weight loss, hypersensitivity reactions

Interactions

Drug-drug. Allopurinol: increased risk of hypersensitivity reaction

Amphotericin B, corticosteroids, mezlocillin, piperacillin, ticarcillin: additive hypokalemia

Antihypertensives, barbiturates, nitrates, opiates: increased hypotension

Cholestyramine, colestipol: increased chlorothiazide absorption

Digoxin: increased risk of hypokalemia

Lithium: decreased lithium excretion, lithium toxicity

Nonsteroidal anti-inflammatory drugs: decreased chlorothiazide efficacy

Drug-diagnostic tests. Bilirubin, serum and urine glucose (in diabetic patients), calcium, creatinine, uric acid: increased levels

Cholesterol, low-density lipoproteins (LDLs), triglycerides: decreased levels

Magnesium, potassium, protein-bound iodine, sodium: decreased levels

Urine calcium: decreased level

Drug-herbs. Ginkgo: decreased antihypertensive effect

Licorice, stimulant laxative herbs (aloe, cascara sagrada, senna): increased risk of hypokalemia

Drug-behaviors. Acute alcohol ingestion: additive hypotension

Sun exposure: increased risk of photosensitivity

Patient monitoring

• Monitor blood pressure.
• Assess electrolyte, bilirubin, creatinine, uric acid, magnesium, cholesterol, LDL, and triglyceride levels.
• Monitor urine calcium level.
• Evaluate blood and urine glucose levels in patients with diabetes.

Patient teaching

• Advise patient to take drug in morning to avoid sleep interruptions caused by nighttime voiding.
☞ Instruct patient to immediately report yellowing of eyes or skin, nausea, vomiting, diarrhea, fatigue, or lethargy.
• Advise patient not to stop taking drug abruptly. Advise him to discuss dosage-tapering schedule with prescriber.
• Caution patient to use alcohol cautiously, if at all.
• Inform patient that drug makes him prone to dehydration. Tell him to stay indoors in hot weather and to increase fluid intake if he sweats more than usual.
• 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.