metolazone (Zaroxolyn, Diulo, Mykrox)
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Introduction
Tradenames: Zaroxolyn, Diulo, Mykrox.
Indications
- treatment of hypertension & edema
- may be more effective than thiazides for edema in patients with renal impairment
- adjunctive therapy used with loop diuretic
- given 30 minutes before Lasix, may result in diuresis in refractory cases.
Dosage
Tabs: 2.5, 5, 10 mg
Pharmacokinetics
- incompletely & poorly absorbed after oral administration
- 50-70% of drug is bound to erythrocytes
- 33% of drug is bound to plasma proteins
- onset of action is 30-60 minutes
- 70-95% of the drug is excreted in the urine unchanged
- elimination 1/2life is 14 hours
elimination via kidney
elimination via liver
1/2life = 14 hours
elimination by hemodialysis = -
Adverse effects
- laboratory abnormalities
- hyperuricemia
- hypokalemia & K+ depletion
- hypochloremic alkalosis
- dilutional hyponatremia
- hyperglycemia
- increased low-density lipoprotein (LDL)
- pre-renal azotemia
- increased PTH with chronic use
- pancreatitis
- vasculitis (esp. exacerbation of SLE)
- cross-sensitivity in patients with sulfa allergies
- orthostatic hypotension
- photosensitivity
- uncommon (< 1%)
- drug adverse effects of renin-angiotensin-aldosterone system inhibitors (RAAS inhibitors)
- drug adverse effects of thiazide diuretics
- drug adverse effects of sulfonamides
- drug adverse effects of diuretics
- drug adverse effects of antihypertensive agents
Drug interactions
- drugs that lower serum K+
- decreases Li+ clearance, resulting in increased Li+ plasma levels
- increased requirements of hypoglycemic agents
- probenecid
- NSAIDs in combination increases risk of NSAID-induced renal toxicity
- drug interaction(s) anticonvulsants with anti-bacterial agents
- drug interaction(s) SGLT2 inhibitors (flozins) with diuretics
- drug interaction(s) of diuretics in combination with Zn+2
- drug interaction(s) of antiarrhythmic agents in combination with diuretics
- drug interaction(s) of beta-2 adrenergic receptor agonists with thiazide diuretics
- drug interaction(s) of calcium channel blockers with diuretics
- drug interaction(s) of renin-angiotensin-aldosterone inhibitors with trimethoprim-sulfamethoxazole
- drug interaction(s) of antibiotics with warfarin
- drug interaction(s) of benzodiazepines with thiazide diuretics
- drug interaction(s) of lithium carbonate with thiazide diuretics
- drug interaction(s) of diuretics with angiotensin II receptor antagonists
- drug interaction(s) of diuretics with ACE inhibitors
- drug interaction(s) of NSAIDs, diuretics & angiotensin II receptor antagonists
- drug interaction(s) of NSAIDs, diuretics & ACE inhibitors
- drug interaction(s) of NSAIDs & antihypertensives
Mechanism of action
- thiazide-like diuretic
- site of action: proximal & distal tubules
- enhances secretion of Na+, Cl- & H2O by interfering with Na+ & Cl- transport across the renal tubular epithelium mediated by SLC12A3
- effects excretion of other electrolytes including K+ & HCO3-
More general terms
References
- ↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996.
- ↑ Manual of Medical Therapeutics, 28th ed, Ewald & McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 123
- ↑ Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
- ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998