chlorothiazide

Absorption: Poor (10–20%) after oral administration.

Distribution: Distributed into extracellular space; crosses the placenta and enters breast milk.

Metabolism/Excretion: Excreted mainly unchanged by the kidneys.

Half-Life: 1–2 hr.

Time/Action Profile ⬆ ⬇

(diuretic effect)

ROUTE	ONSET	PEAK	DURATION
PO, IV	2 hr	4 hr	6–12 hr
IV	2 hr	4 hr	2 hr

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity (cross-sensitivity with other thiazides or sulfonamides may exist);
Some products contain tartrazine and should be avoided in patients with known intolerance;
Anuria;
Lactation: Lactation.

Use Cautiously in:

Renal or hepatic impairment;
OB: Use during pregnancy only if clearly needed;
Pedi: May cause jaundice or thrombocytopenia in newborn;
Geri: Appears on Beers list. May worsen or cause hyponatremia in older adults. Use with caution in older adults and monitor sodium concentrations closely when initiating therapy or the dose..

Adv. Reactions/Side Effects ⬆ ⬇

CV: hypotension

Derm: photosensitivity, rash

EENT: blurred vision

Endo: hyperglycemia

F and E: hypokalemia, dehydration, hypercalcemia, hypochloremic alkalosis, hypomagnesemia, hyponatremia, hypophosphatemia, hypovolemia

GI: anorexia, cramping, hepatitis, nausea, PANCREATITIS, vomiting

Hemat: thrombocytopenia

Metab: hypercholesterolemia, hyperuricemia

MS: muscle cramps

Neuro: drowsiness, dizziness, weakness

Interactions ⬆ ⬇

Drug-drug:

Additive hypotension with other antihypertensives, acute ingestion of alcohol or nitrates.
Additive hypokalemia with corticosteroids, amphotericin B, loop diuretics, or piperacillin.
↓excretion of lithium.
Cholestyramine orcolestipol↓ absorption.
Hypokalemia ↑ risk of digoxin toxicity.
NSAIDs may ↓ effectiveness.

Route/Dosage ⬆ ⬇

When used as a diuretic in adults, generally given daily, but may be given every other day or 2–3 days/wk
PO (Adults ): 125 mg–2 g/day as a single dose or in 2 divided doses.
PO (Children >6 mo): 20 mg/kg/day as a single dose or in 2 divided doses. Maximum dose: 1 g/day.
PO (Neonates up to 6 mo): 20–40 mg/kg/day in 2 divided doses. Maximum dose: 375 mg/day.
IV (Adults ): Diuretic: 100–500 mg/day as a single dose or 2 divided doses.
IV (Children >6 mo): 4 mg/kg/day in 1–2 divided doses. Maximum dose: 20 mg/kg/day.
IV (Neonates up to 6 mo): 2–8 mg/kg/day in 2 divided doses. Maximum dose: 20 mg/kg/day.

Availability ⬆ ⬇

(Generic available)

Oral suspension: 250 mg/5 mL
Powder for injection: 500 mg/vial

Assessment ⬆ ⬇

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 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 for allergy to sulfonamides.
Hypertension: Monitor BP before and periodically during 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 during therapy.
- May cause ↑ serum and urine glucose in diabetic patients.
- May cause ↑ serum bilirubin, calcium, creatinine, and uric acid, and ↓ serum magnesium, potassium, sodium, and urinary calcium concentrations.
- May cause ↑ serum cholesterol, low-density lipoprotein, and triglyceride concentrations.

Implementation ⬆ ⬇

Administer in the morning to prevent disruption of sleep cycle for urination.
- Intermittent dose schedule may be used for continued control of edema.
PO: May give with food or milk to minimize GI irritation. Tablets may be crushed and mixed with fluid to facilitate swallowing.
- Shake oral suspension before using.

IV Administration:

Intermittent Infusion: Reconstitution: Reconstitute 500 mg vial of chlorothiazide with at least 18 mL of sterile water for injection; do not use 18 mL for reconstitution. Shake to dissolve. Stable for 24 hr at room temperature. Diluent: May be diluted further with D5W or 0.9% NaCl. Concentration: Not to exceed 28 mg/mL.
Rate: Administer over 30 min. Administer slowly and monitor IV site; may be an irritant.

Patient/Family Teaching ⬆ ⬇

Instruct patient to take this medication at the same time each day. Take missed doses 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 Food Sources for Specific Nutrients).
- 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.
- May cause fetal harm. Advise females of reproductive potential to avoid use of chlorothiazide during pregnancy and breastfeeding and to notify health care professional if pregnancy is planned or suspected.
- 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 other Rx, OTC, or herbal products, especially cough or cold preparations, concurrently with this therapy.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇