General

Pronunciation
me-TOLE-a-zone

Trade Name(s)

• Zaroxolyn

Pregnancy Category
Category B

Ther. class.
antihypertensives
diuretics

Pharm. class.
thiazide like diuretics

Indications

• Mild to moderate hypertension

• Edema associated with CHF or the nephrotic syndrome

Action

• Increases excretion of sodium and water by inhibiting sodium reabsorption in the distal tubule

• Promotes excretion of chloride, potassium, magnesium, and bicarbonate

• May produce arteriolar dilation

Therapeutic Effect(s):

• Lowering of blood pressure in hypertensive patients

• Diuresis with subsequent mobilization of edema. Effect may continue in renal impairment

Pharmacokinetics

Absorption: Absorption is variable

Distribution: Unknown

Metabolism and Excretion: Excreted mainly unchanged by the kidneys

Half-life: 8 hr

TIME/ACTION PROFILE (diuretic effect†)

ROUTE	ONSET	PEAK	DURATION
PO	1 hr	2 hr	12–24 hr

†Full antihypertensive effect may take days–weeks

Contraindication/Precautions

Contraindicated in:

• Hypersensitivity

• Cross-sensitivity with other sulfonamides may exist

• Anuria

• OB: Lactation

Use Cautiously in:

• Severe hepatic impairment

• Geri: Increased sensitivity

• OB: Pregnancy or children (safety not established; children may be more susceptible to diuretic and hypokalemic effects)

Adverse Reactions/Side Effects

CNS: drowsiness, lethargy.

CV: chest pain, hypotension, palpitations.

GI: anorexia, bloating, cramping, drug-induced hepatitis, nausea, vomiting.

Derm: photosensitivity, rashes.

Endo: hyperglycemia.

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

Hemat: blood dyscrasias.

Metabolic: hyperuricemia.

MS: muscle cramps.

Misc: chills, pancreatitis.

*CAPITALS indicates life-threatening.
*italic indicates most frequent.

Interactions

Drug-Drug

• risk of hypotension with nitrates, acute ingestion of alcohol, or other antihypertensives

• risk of hypokalemia with corticosteroids, amphotericin B, piperacillin, or ticarcillin

• May the risk of digoxin toxicity

• the excretion of lithium; may cause toxicity

• May the effectiveness of methenamine

• Stimulant laxatives (including aloe, senna) may risk of potassium depletion

Drug-Food
Food may extent of absorption

Route/Dosage

• PO (Adults):
Hypertension—2.5–5 mg/day;
edema—5–20 mg/day.

Availability

• Tablets: 2.5 mg, 5 mg, 10 mg

» Cost:
Generic: 2.5 mg $99.99/90, 5 mg $110.09/90, 10 mg $121.97/90.

Assessment

• Monitor blood pressure, intake and output, and daily weight, and assess feet, legs, and sacral area for edema daily

» Assess patient, especially if taking digoxin, 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 digoxin are at risk of digoxin toxicity because of the potassium-depleting effect of the diuretic

» Assess patient for allergy to sulfonamides

Hypertension

• Monitor blood pressure before and periodically during therapy

» Monitor frequency of prescription refills to determine compliance

Lab Test Considerations

• Monitor electrolytes (especially potassium), blood glucose, BUN, and serum creatinine and uric acid levels before and periodically during therapy

» May cause in serum and urine glucose in diabetic patients

» May cause an in serum bilirubin, calcium, creatinine, and uric acid, and a in serum magnesium, potassium, and sodium and urinary calcium concentrations

» May cause serum protein-bound iodine (PBI) concentrations

» May cause serum cholesterol, low-density lipoprotein, and triglyceride concentrations

Potential Nursing Diagnoses

• Excess fluid volume (Indications)

• Risk for deficient fluid volume (Side Effects)

Implementation

• 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

Patient/Family Teaching

• Instruct patient to take metolazone 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; may be potentiated by alcohol

» Advise patient to use sunscreen and protective clothing in the sun 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

» Emphasize the importance of routine follow-up exams

• 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, and stress management)

» Instruct patient and family in correct technique for monitoring weekly blood pressure

» Advise patient to consult health care professional before taking OTC medication, especially cough or cold preparations, concurrently with this therapy

Evaluation/Desired Outcomes

• Decrease in blood pressure

• Increase in urine output

• Decrease in edema

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