Hydroflumethiazide

Pronunciation

(hye droe floo meth EYE a zide)

U.S. Brand Names

Diucardin® [DSC]; Saluron® [DSC]

Generic Available

Yes

Canadian Brand Names

Diucardin®; Saluron®

Use

Management of mild to moderate hypertension; treatment of edema in congestive heart failure and nephrotic syndrome

Restrictions

Not available in U.S.

Pregnancy Risk Factor

Contraindications

Hypersensitivity to hydroflumethiazide, any component of the formulation, thiazides, or sulfonamide-derived drugs; anuria; renal decompensation; pregnancy

Warnings/Precautions

Avoid in severe renal disease (ineffective). Electrolyte disturbances (hypokalemia, hypochloremic alkalosis, hyponatremia) can occur. Use with caution in severe hepatic dysfunction; hepatic encephalopathy can be caused by electrolyte disturbances. Gout can be precipitate in certain patients with a history of gout, a familial predisposition to gout, or chronic renal failure. Cautious use in diabetics; may see a change in glucose control. Hypersensitivity reactions can occur. Can cause SLE exacerbation or activation. Use with caution in patients with moderate or high cholesterol concentrations. Photosensitization may occur. Correct hypokalemia before initiating therapy.

Chemical similarities are present among sulfonamides, sulfonylureas, carbonic anhydrase inhibitors, thiazides, and loop diuretics (except ethacrynic acid). Use in patients with thiazide or sulfonamide allergy is specifically contraindicated in product labeling, however, a risk of cross-reaction exists in patients with allergy to any of these compounds; avoid use when previous reaction has been severe.

Adverse Reactions

1% to 10%: Endocrine & metabolic: Hypokalemia

<1% (Limited to important or life-threatening): Agranulocytosis, anorexia, aplastic anemia, drowsiness, fluid and electrolyte imbalances (hypercalcemia, hypocalcemia, hypomagnesemia, hyponatremia), hemolytic anemia, hepatitis, hyperglycemia, hypotension, leukopenia, pancreatitis, paresthesia, photosensitivity, polyuria, prerenal azotemia, rarely blood dyscrasias, rash, thrombocytopenia, uremia

Overdosage/Toxicology

Symptoms of overdose include hypermotility, diuresis, lethargy

Following GI decontamination, therapy is supportive with I.V. fluids, electrolytes, and I.V. pressors if needed

Drug Interactions

ACE inhibitors: Increased hypotension if aggressively diuresed with a thiazide diuretic.

Beta-blockers increase hyperglycemic effects in type 2 diabetes mellitus (noninsulin dependent, NIDDM)

Cyclosporine and thiazides can increase the risk of gout or renal toxicity; avoid concurrent use.

Digoxin toxicity can be exacerbated if a thiazide induces hypokalemia or hypomagnesemia.

Lithium toxicity can occur by reducing renal excretion of lithium; monitor lithium concentration and adjust as needed.

Neuromuscular blocking agents can prolong blockade; monitor serum potassium and neuromuscular status.

NSAIDs can decrease the efficacy of thiazides reducing the diuretic and antihypertensive effects.

Mechanism of Action

The diuretic mechanism of action is primarily inhibition of sodium, chloride, and water reabsorption in the renal distal tubules, thereby producing diuresis with a resultant reduction in plasma volume

Pharmacodynamics/Kinetics

Onset of action: Diuresis: ~2 hours

Peak effect: ~4 hours

Duration: 12-24 hours

Dosage

Oral:

Children (not approved): 1 mg/kg/24 hours

Adults:

Edema:

Initial: 50 mg 1-2 times/day

Maintenance: 25-200 mg/day (use divided doses when >100 mg/day)

Hypertension:

Initial: 50 mg twice daily

Maintenance: 50-100 mg/day; maximum: 200 mg/day

Monitoring Parameters

Assess weight, I & O reports daily to determine fluid loss; blood pressure, serum electrolytes, BUN, creatinine

Test Interactions

Increased ammonia (B), increased amylase (S), increased calcium (S), increased chloride (S), increased glucose, increased uric acid (S); decreased chloride (S), decreased magnesium, decreased potassium (S), decreased sodium (S)

Patient Education

May be taken with food or milk; take early in day to avoid nocturia. A few people who take this medication become more sensitive to sunlight and may experience skin rash, redness, itching or severe sunburn, especially if sunblock SPF

15 is not used on exposed skin areas.

Nursing Implications

Take blood pressure with patient lying down and standing

Additional Information

Not available in U.S.

Cardiovascular Considerations

Thiazide diuretics are effective first-line therapeutic agents in the management of hypertension and have proven to be of benefit in terms of cardiovascular outcome. They may act synergistically to lower blood pressure when combined with an ACE inhibitor or beta-blocker. The initial concern about thiazide diuretic-induced hypokalemia, glucose intolerance, and lipid profiles does not appear to be of substantial clinical consequence in the treatment of hypertension. The benefits of this class of agents in the treatment of hypertension is established and compares well with other first-line therapeutic agents.

Diuretics are standard therapy for the management of edema in patients with heart failure.

Dental Health: Effects on Dental Treatment

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Mental Health: Effects on Mental Status

May cause drowsiness

Mental Health: Effects on Psychiatric Treatment

May rarely cause agranulocytosis; use caution with clozapine and carbamazepine; may decrease lithium clearance resulting in an increase in serum lithium levels and potential lithium toxicity; monitor serum lithium levels

Dosage Forms

Tablet: 50 mg

References

Chobanian AV, Bakris GL, Black HR, et al, "The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: The JNC 7 Report," JAMA , 2003, 289(19):2560-71.

International Brand Names

Diucardin® (CA); Saluron® (CA)

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