Names and pronunciation
(me-tole′a-zone) Zaroxolyn
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Drug reference
(me-tole′a-zone) Zaroxolyn
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Func. class.: Diuretic, antihypertensive
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Chem. class.: Thiazide-like quinazoline derivative
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Do not confuse: metolazone/methotrexate/methadone/ metoclopramide
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ACTION: Acts on distal tubule by increasing excretion of water, sodium, chloride, potassium, magnesium, bicar- bonate; decreases GFR
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USES: Edema, hypertension, heart fail- ure, nephrotic syndrome
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CONTRAINDICATIONS: Hyper- sensitivity to thiazides, sulfonamides; anuria, hepatic coma, hepatic encephalopathy Precautions: Pregnancy, breastfeeding, geriatric patients, hypokalemia, renal/ hepatic disease, gout, COPD, lupus erythe- matosus, diabetes mellitus, hypotension, his- tory of pancreatitis; electrolyte imbalance
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SIDE EFFECTS CNS: Drowsiness, lethargy CV: Orthostatic hypotension, palpita- tions, hypotension, chest pain, volume depletion ELECT: Hypokalemia, hypercalcemia, hyponatremia, hyperuricemia, hypomag- nesemia, hypophosphatemia, hypovolemia GI: Nausea, vomiting, anorexia, consti- pation, diarrhea, cramps, pancreatitis, GI irritation, dry mouth, jaundice, hepatitis GU: Urinary frequency, polyuria, ure- mia, glucosuria, nocturia, impotence, hyperuricemia HEMA: Aplastic anemia, hemolytic anemia, leukopenia, agranulocytosis, neutropenia EENT: Blurred vision INTEG: Rash, urticaria, purpura, photo- sensitivity, fever, dry skin, toxic epidermal necrolysis, Stevens-Johnson syndrome ENDO: Hyperglycemia, increased creati- nine, BUN MS: Muscle cramps, joint pain, swelling
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INTERACTIONS Increase: hyperglycemia—antidiabetics Increase: hypokalemia—mezlocillin, piperacillin, amphotericin B, glucocorti- M coids, digoxin, stimulant laxatives Increase: hypotension—alcohol (large amounts), nitrates, antihypertensives, barbiturates, opioids Increase: toxicity—lithium Increase: metOLazone effects—loop diuretics Decrease: action of metOLazone, increase renal failure risk—NSAIDs, salicylates Drug/Food Increase: severe hypokalemia—licorice Drug/Herb Decrease: antihypertensive effect— ephedra (ma huang) Increase: antihypertensive effect— hawthorn Drug/Lab Test Increase: calcium, cholesterol, glucose, triglycerides Decrease: potassium, sodium, chloride, magnesium, WBC, Hb Interference: parathyroid function tests
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TREATMENT OF OVERDOSE: Lavage if taken orally; monitor electrolytes; administer dextrose in saline; monitor hydration, CV, renal status HIGH ALERT
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DOSAGE AND ROUTES Edema in heart failure/renal disease • Adult: PO 5-20 mg/day; max 20 mg/ day Hypertension • Adult: PO 2.5-5 mg/day • Child: PO 0.2-0.4 mg/kg/day in di- vided doses q12-24hr
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Available forms: Tabs 2.5, 5, 10 mg
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Administer: • In AM to avoid interference with sleep if using product as diuretic • Potassium replacement if potassium <3 mg/dL • With food if nausea occurs; absorption may be decreased slightly
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Assess: • Weight, I&O daily to determine fluid loss; effect of product may be decreased if used daily • HF: improvement in edema of feet, legs, sacral area daily if product being used • Hypertension: B/P lying, standing; pos- tural hypotension may occur • Electrolytes: potassium, magnesium, sodium, chloride; include BUN, blood glucose, CBC, serum creatinine, blood pH, ABGs, uric acid, calcium • Hypokalemia: postural hypotension, malaise, fatigue, tachycardia, leg cramps, weakness • Rashes, temperature daily • Confusion, especially among geriatric patients; take safety precautions if needed • Hepatic encephalopathy: do not use in hepatic coma or precoma; fluctuations in electrolytes can occur rapidly and pre- cipitate hepatic coma; use caution in pa- tients with impaired hepatic function • Pregnancy/breastfeeding: use in pregnancy only if needed, no well-con- trolled studies; do not breastfeed, ap- pears in breast milk • Beers: use with older adults may exac- erbate or cause SIADH; monitor sodium level frequently
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Evaluate: • Therapeutic response: decreased edema, B/P
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CLINICAL CONSIDERATIONS
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Patient and caregiver information: • To rise slowly from lying or sitting position • To notify prescriber of muscle weak- ness, cramps, nausea, dizziness • That product may be taken with food or milk • To use sunscreen, protective clothing for photosensitivity • That blood glucose may be increased in diabetics • To take early in day to avoid nocturia, to take at same time of day, not to skip or double doses, that skipped dose should be taken when remembered if not close to next dose • To avoid alcohol • To avoid sodium foods; to increase potassium foods in diet • Not to stop product abruptly
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PHARMACOKINETICS Protein binding 33%, peak 8 hr, duration 12-24 hr, excreted unchanged by kid- neys, crosses placenta, enters breast milk, half-life 14 hr
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• Adult: PO 5-20 mg/day; max 20 mg/ day Hypertension
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• Adult: PO 2.5-5 mg/day
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• Child: PO 0.2-0.4 mg/kg/day in di- vided doses q12-24hr
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