Classifications: thiazide-like diuretic; antihypertensive; Therapeutic: antihypertensive; thiazide-like diuretic
Pregnancy Category: D
2.5 mg, 5 mg, 10 mg tablets
Diuretic structurally and pharmacologically similar to hydrochlorothiazide. Diuretic action is associated with interference
with transport of sodium ions across renal tubular epithelium. This enhances excretion of sodium, chloride, potassium, bicarbonate,
Produces a decrease in the systolic and diastolic BPs, and reduces edema in CHF and kidney failure patients.
Management of hypertension as sole agent or to enhance effectiveness of other antihypertensives in severe form of hypertension;
also edema associated with CHF and kidney disease.
Anuria, hypokalemia; hepatic coma or precoma; hypersensitivity to metolazone and sulfonamides; SLE; pregnancy (category
History of gout; elderly; allergies; concomitant use of digitalis glycosides; kidney and liver dysfunction.
Route & Dosage
Adult: PO 520 mg/d
Child: PO 0.20.4 mg/kg/d divided q1224h
Adult: PO 2.55 mg/d
- Do not interchange slow availability tablets and rapid availability tablets. They are not equivalent.
- Schedule doses to avoid nocturia and interrupted sleep. Give early in a.m. after eating to prevent gastric irritation (if
given in 2 doses, schedule second dose no later than 3 p.m.).
- Store at 15°30° C (59°86° F) in tightly closed container.
Adverse Effects (≥1%)GI:
. Body as a Whole:
Vertigo, orthostatic hypotension. Hematologic:
Venous thrombosis, leukopenia
Dehydration, hypokalemia, hyperuricemia, hyperglycemia.
InteractionsDrug: Amphotericin B
increase hypokalemic effects; may antagonize hypoglycemic effects of sulfonylureas
, insulin; cholestyramine, colestipol
decrease thiazide absorption; intensifies hypoglycemic and hypotensive effects of diazoxide;
because of increased potassium and magnesium loss, may cause digoxin toxicity
; decreases lithium
excretion, increasing its toxicity
s may attenuate diuresisincreased risk of nsaid
-induced kidney failure.
Incomplete; Mykrox has greater absorption. Onset:
1 h. Peak:
28 h. Duration:
1224 h. Distribution:
Distributed throughout extracellular tissue
; concentrates in kidney; crosses placenta; distributed in breast milk. Metabolism:
Does not appear to be metabolized. Elimination:
In urine. Half-Life:
Assessment & Drug Effects
- Anticipate overdosage and adverse reactions in geriatric patients; may be more sensitive to effects of usual adult dose.
- Terminate therapy when adverse reactions are moderate to severe.
- Expect possible antihypertensive effects in 3 or 4 d, but 34 wk are required for maximum effect.
- Lab tests: Determine serum potassium at regular intervals. Prolonged treatment and inadequate potassium intake increase potential
for hypokalemia (see Appendix F). Periodic plasma glucose and urinalysis determinations.
Patient & Family Education
- Do not drink alcohol; it potentiates orthostatic hypotension.
- Antihypertensive therapy may require as adjunct a high-potassium, low-sodium, and low-calorie diet.
- Include potassium-rich foods in the diet.
- Be aware that if hypokalemia develops, dietary potassium supplement of 10002000 mg (2550 mEq) is usually adequate