diuretics (thiazide)

Absorption: All are rapidly absorbed after oral administration.

Distribution: Well distributed to tissues.

Metabolism/Excretion: All are excreted mainly unchanged by the kidneys.

Half-Life: Chlorothiazide: 1–2 hr; chlorthalidone: 35–50 hr; hydrochlorothiazide: 6–15 hr.

Time/Action Profile ⬆ ⬇

( diuretic effect)

ROUTE	ONSET	PEAK	DURATION
Chlorothiazide	15 min	30 min	2 hr
Chlorthalidone	2 hr	2 hr	48–72 hr
Hydrochlorothiazide‡	2 hr	3–6 hr	6–12 hr

‡Onset of antihypertensive effect is 3–4 days and does not become maximal for 7–14 days of dosing.

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 impairment;
Hepatic impairment;
OB: Pregnancy (jaundice or thrombocytopenia may be seen in the newborn).

Adv. Reactions/Side Effects ⬆ ⬇

CV: hypotension

Derm: photosensitivity, rash, SKIN CANCER (NONMELANOMA), STEVENS-JOHNSON SYNDROME (SJS)

EENT: acute angle-closure glaucoma (hydrochlorothiazide), acute myopia (hydrochlorothiazide)

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: dizziness, drowsiness, lethargy, weakness

Interactions ⬆ ⬇

Drug-drug:

Additive hypotension with other antihypertensives, acute ingestion of alcohol, or nitrates.
Additive hypokalemia with corticosteroids, amphotericin B, or piperacillin/tazobactam.
May ↑ levels and risk of toxicity of lithium.
Cholestyramine or colestipol may ↓ 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.

Chlorothiazide

IV (Adults ): 500 mg–1 g/day in 1–2 divided doses.
IV (Children >6 mo): 4 mg/kg/day in 1–2 divided doses (maximum dose = 20 mg/kg/day) (unlabeled use).
IV (Neonates ≤6 mo): 1–4 mg/kg every 12 hr (maximum dose = 20 mg/kg/day) (unlabeled use).

Chlorthalidone

PO (Adults ): 12.5–100 mg once daily (daily doses above 25 mg are associated with greater likelihood of electrolyte abnormalities).

Hydrochlorothiazide

PO (Adults ): 12.5–100 mg/day in 1–2 divided doses (up to 200 mg/day); not to exceed 50 mg/day for hypertension; daily doses above 25 mg are associated with greater likelihood of electrolyte abnormalities.
PO (Children >6 mo): 1–3 mg/kg/day in 2 divided doses (not to exceed 37.5 mg/day).
PO (Children <6 mo): 1–3 mg/kg/day in 2 divided doses.

Availability ⬆ ⬇

Chlorothiazide

(Generic available)

Powder for injection: 500 mg/vial

Chlorthalidone

(Generic available)

Tablets: 12.5 mg; 15 mg; 25 mg; 50 mg
In combination with:
In combination with: atenolol (generic only); azilsartan (Edarbyclor). See Combination Drugs

Hydrochlorothiazide

(Generic available)

Tablets: 12.5 mg; 25 mg; 50 mg; 100 mg
Capsules: 12.5 mg
Oral suspension caramel-mint flavor: 10 mg/mL
In combination with:
numerous antihypertensive agents. See Combination Drugs.

Assessment ⬆ ⬇

Monitor BP, intake, output, and daily weight and assess feet, legs, and sacral area for edema daily.
- Assess for anorexia, nausea, vomiting, muscle cramps, paresthesia, and confusion, especially if taking digoxin. Notify health care provider if these signs of electrolyte imbalance occur. Patients taking digoxin are at risk of digoxin toxicity because of the potassium-depleting effect of the diuretic.
- If hypokalemia occurs, consideration may be given to potassium supplements or ↓ dose of diuretic.
- Assess for allergy to sulfonamides.
- Assess for skin rash frequently during therapy. Discontinue diuretic at 1st sign of rash; may be life-threatening. SJS may develop. Treat symptomatically; may recur once treatment is stopped.
Hypertension: Monitor BP before and periodically during therapy.

Lab Test Considerations:

Monitor electrolytes (especially potassium), blood glucose, BUN, serum creatinine, and uric acid before and periodically during therapy.
- May ↑ serum and urine glucose in patients with diabetes.
- May ↑ serum bilirubin, calcium, creatinine, and uric acid, and ↓ serum magnesium, potassium, sodium, and urinary calcium.
- May ↑ cholesterol, low-density lipoprotein, and triglyceride.

Implementation ⬆ ⬇

Do not confuse hydrochlorothiazide with hydroxyzine, hydralazine, or hydroxychloroquine.
Administer in the morning to prevent disruption of sleep cycle.
- 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.

IV Administration:

Intermittent Infusion: Reconstitution: Reconstitute chlorothiazide with 18 mL of sterile water for injection. Shake to dissolve. Solution is stable for 24 hr at room temperature. Diluent: May be given undiluted or may be diluted further with D5W or 0.9% NaCl. Concentration: Up to 28 mg/mL. Rate: If administered undiluted, may give by IV push over 3–5 min. If diluted, may infuse over 30 min.
Y-Site Compatibility:
- alprostadil
- aminophylline
- atropine
- calcium chloride
- calcium gluconate
- chloramphenicol
- cyclophosphamide
- dexamethasone
- digoxin
- edetate calcium disodium
- epinephrine
- erythromycin
- furosemide
- gentamicin
- heparin
- hydrocortisone
- isoproterenol
- lidocaine
- methohexital
- norepinephrine
- oxytocin
- penicillin G
- phenobarbital
- phentolamine
- potassium chloride
- procainamide
- propranolol
- succinylcholine
Y-Site Incompatibility:
- chlorpromazine
- hydralazine
- multivitamins
- prochlorperazine
- promethazine

Patient/Family Teaching ⬆ ⬇

Explain purpose and side effects of medication to patient. Advise patient to read Patient Information before starting therapy. Advise patient to take medication at the same time each day. Take missed dose as soon as remembered but not just before next dose is due. Do not double doses.
Advise patient to notify health care provider of all Rx or OTC medications, vitamins, or herbal products being taken and to consult health care provider before taking other medications, especially cold preparations.
Advise patient to monitor weight biweekly and notify health care provider 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. Advise patient of importance of regular skin cancer screenings.
- Instruct patient to discuss dietary potassium requirements with health care provider (see Food Sources for Specific Nutrients).
- Instruct patient to notify health care provider of medication regimen before treatment or surgery.
- Advise patient to report rash, muscle weakness, cramps, nausea, vomiting, diarrhea, or dizziness to health care provider.
Hypertension: Advise patient 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, stress management).
- Instruct patient and family/caregivers in correct technique for monitoring weekly BP.
Rep: Advise women of reproductive potential to notify health care provider if pregnancy is planned or suspected or if breastfeeding.

section name header

Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇

Time/Action Profile ⬆ ⬇

Contraind./Precautions ⬆ ⬇

Adv. Reactions/Side Effects ⬆ ⬇

Interactions ⬆ ⬇

Route/Dosage ⬆ ⬇

Availability ⬆ ⬇

Assessment ⬆ ⬇

Implementation ⬆ ⬇

Patient/Family Teaching ⬆ ⬇

Evaluation/Desired Outcomes ⬆ ⬇

US Brand Names ⬆