hydrochlorothiazide (Microzide, HydroDiuril, Hydro, Esidrix, HCTZ, Oretic)

Dosing and uses of Microzide, HydroDiuril (hydrochlorothiazide)

• Adult
• Pediatric
• Geriatric

 

Adult dosage forms and strengths

tablet/capsule

• 12.5mg
• 25mg
• 50mg

 

Hypertension

12.5-50 mg PO once daily

 

Edema

25-100 mg PO once daily or twiced daily; not to exceed 200 mg/day

 

Hypertension in Heart Failure (Off-label)

25 mg PO qDay or twice daily; not to exceed 200 mg/day

 

Mild Fluid Retention in Heart Failure (Off-label)

25 mg PO qDay or twice daily; not to exceed 200 mg/day

 

Dosing Considerations

Overdose management

• Normal saline may be used for volume replacement
• Dopamine or norepinephrine may be used to treat hypotension
• If dysrhythmia due to decreased potassium or magnesium is suspected, replace aggressively
• If no symptoms are noted after 6 hours, discontinue treatment

 

Dosing Modifications

Renal impairment

• CrCl <10 mL/min: Avoid use
• CrCl ≥10 mL/min: Dose adjustment not necessary; not effective with CrCl <30 mL/min unless used in combination with loop diuretic

 

Pediatric dosage forms and strengths

tablet/capsule

• 12.5mg
• 25mg
• 50mg

 

Hypertension

<6 months: 1-3 mg/kg/day PO divided q12hr; not to exceed 37.5 mg/day

6 months-2 years: 1-2 mg/kg/day PO in single daily dose or divided twice daily; not to exceed 37.5 mg/day

2-12 years: 1-3 mg/kg/day; not to exceed 3 mg/kg/day (100 mg/day)

 

Edema

<6 months: 1-3 mg/kg/day PO divided q12hr; not to exceed 37.5 mg/day

6 months-2 years: 1-3 mg/kg/day PO in single daily dose or divided twice daily; not to exceed 37.5 mg/day

2-12 years: 1-3 mg/kg/day; not to exceed 3 mg/kg/day (100 mg/day)

 

Geriatric dosage forms and strengths

Increased hypotension and side effects in elderly

Potential for electrolyte imbalance in elderly; monitor serum electrolytes

 

Diuresis

12.5-25 mg/day PO; titrated in increments of 12.5 mg/day

Increased electrolyte disturbances are seen with dosages >50 mg/day

 

Microzide, HydroDiuril (hydrochlorothiazide) adverse (side) effects

Frequency not defined

Anaphylaxis

Anorexia

Confusion

Disorder of hematopoietic structure

Dizziness

Epigastric distress

Fatigue

Headache

Hepatotoxicity

Hypercalcemia

Hypercholesterolemia

Hyperglycemia

Hyperlipidemia

Hyperuricemia

Hypokalemia

Hypomagnesemia

Hypotension

Interstitial nephritis

Metabolic acidosis

Muscle weakness or cramps

Nausea

Necrotizing angiitis

Pancreatitis

Phototoxicity

Pneumonitis

Pulmonary edema

Purpura

Rash

Respiratory distress

Stevens-Johnson syndrome

Toxic epidermal necrolysis

Vertigo

Vomiting

Xanthopsia

 

Warnings

Contraindications

Documented hypersensitivity to hydrochlorothiazide or sulfonamides

Anuria

 

Cautions

Use with caution in diabetes mellitus, fluid or electrolyte imbalance, hypercholesterolemia, hyperuricemia or gout, hypercalcemia, hypotension, systemic lupus erythematosus, liver or renal disease, hypokalemia, parathyroid disease

May aggravate digitalis toxicity

Sensitivity reactions may occur with or without history of allergy or asthma

Avoid concurrent use with lithium (reduction of lithium dosage by 50% may be necessary)

Risk of male sexual dysfunction

Causes systemic lupus exacerbation or activation

Azotemia may occur with severe renal disease

Acute transient myopia and acute angle-closure glaucoma have been reported, particularly with history of sulfonamide or penicillin allergy (hydrochlorothiazide is sulfonamide)

FDA-approved product labeling for many medications have included a broad contraindication in patients with a prior allregic reaction to sulfonamides; however, recent studies have suggested that crossreactivity between antibiotic sulfonamides and nonantibiotic sulfonamides is unlikely to occur

Photosensitization may occur

Electrolyte disturbances (eg, hypokalemia, hyponatremia, hypochloremic alkalosis) may occur

 

Pregnancy and lactation

Pregnancy category: B

Lactation: Drug excreted in breast milk; use with caution (American Academy of Pediatrics states that it is "compatible with nursing")

 

Pregnancy categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

 

Pharmacology of Microzide, HydroDiuril (hydrochlorothiazide)

Mechanism of action

Thiazide diuretic; inhibits sodium reabsorption in distal renal tubules, resulting in increased excretion of water and of sodium, potassium, and hydrogen ions

 

Absorption

Onset: Diuresis, ~2 hr; hypertension, 3-4 days

Peak plasma time: 1-2.5 hr

Peak effect: Diuresis, 4-6 hr

Bioavailability: 65-75%

 

Distribution

Protein bound: 40-68%

Vd: 3.6-7.8 L/kg

 

Metabolism

Minimally metabolized

 

Elimination

Half-life: 5.6-14.8 hr

Dialyzable: Hemodialysis, no

Excretion: Urine