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Pronunciation |
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(benz
THYE a
zide) |
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U.S. Brand
Names |
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Exna® |
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Generic
Available |
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Yes |
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Pharmacological Index |
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Diuretic, Thiazide |
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Use |
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Management of mild to moderate hypertension; treatment of edema in congestive
heart failure and nephrotic syndrome |
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Pregnancy Risk
Factor |
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B (per manufacturer); D (based on expert analysis) |
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Contraindications |
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Hypersensitivity to benzthiazide or any component, other thiazides, or
sulfonamide-derived drugs; anuria; renal decompensation;
pregnancy |
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Warnings/Precautions |
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Use with caution in severe renal disease. 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. Use with caution in patients with moderate or high
cholesterol concentrations. Photosensitization may occur. Correct hypokalemia
before initiating therapy. |
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Adverse
Reactions |
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1% to 10%:
Cardiovascular: Orthostatic hypotension
Endocrine & metabolic: Hypokalemia
Dermatologic: Photosensitivity
Gastrointestinal: Anorexia, epigastric distress
<1% (Limited to important or life-threatening symptoms): Purpura, rash,
urticaria, necrotizing angiitis, vasculitis, cutaneous vasculitis, hyperuricemia
or gout, hyponatremia, sexual ability (decreased), hyperglycemia, glycosuria,
nausea, vomiting, cholecystitis, pancreatitis, diarrhea or constipation,
aplastic anemia, hemolytic anemia, leukopenia, agranulocytosis,
thrombocytopenia, hepatic function impairment, uremia |
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Overdosage/Toxicology |
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Symptoms of overdose include hypermotility, diuresis, lethargy, confusion,
muscle weakness
Following GI decontamination, therapy is supportive with I.V. fluids,
electrolytes, and I.V. pressors if needed |
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Drug
Interactions |
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Angiotensin-converting enzyme inhibitors: Increased hypotension if
aggressively diuresed with a thiazide diuretic.
Beta-blockers increase hyperglycemic effects in Type 2 diabetes mellitus.
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. |
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Mechanism of
Action |
|
Like other thiazide diuretics, it inhibits sodium, chloride, and water
reabsorption in the renal distal tubules, thereby producing diuresis with a
resultant reduction in plasma volume; hypothetically may reduce peripheral
resistance through increased prostacyclin synthesis |
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Pharmacodynamics/Kinetics |
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Onset of action: Within 2 hours
Duration: 12 hours |
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Usual Dosage |
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Adults: Oral:
Hypertension: 50-100 mg/day; maintenance: individualize dose (maximum
effective dose: 200 mg/day) |
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Monitoring
Parameters |
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Assess weight, I & O reports daily to determine fluid loss; blood
pressure, serum electrolytes, BUN, creatinine |
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Cardiovascular
Considerations |
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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. |
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Mental Health: Effects
on Mental Status |
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May cause drowsiness |
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Mental Health:
Effects on Psychiatric
Treatment |
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May produce orthostatic hypotension; use caution with concurrent psychotropic
use; rare reports of agranulocytosis; 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 |
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Dental Health: Local
Anesthetic/Vasoconstrictor
Precautions |
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No information available to require special precautions |
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Dental Health:
Effects on Dental Treatment |
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No effects or complications reported |
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Patient
Information |
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Take early in the day and take last dose in early evening to avoid frequent
night urination. Take with food to reduce GI upset. Weigh yourself on a regular
basis (same time, same clothes). Report unresolved weight gain (more than 3-5
pounds in 3 days). You may experience dizziness or drowsiness; change positions
slowly and use caution when driving or engaging in tasks that require alertness
until response to drug is known. May cause photosensitivity; use sunscreen wear
protective clothing and eyewear, and avoid direct sunlight. You may experience
decreased sexual function; this will resolve when medication is discontinued.
Report increased swelling of ankles, fingers, dizziness or trembling, cramps, or
muscle pain. Pregnancy/breast-feeding precautions: Do not get pregnant
while taking this medication; use appropriate barrier contraceptive measures.
Consult prescriber if breast-feeding. |
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Nursing
Implications |
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Take blood pressure with patient lying down and standing |
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Dosage Forms |
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Tablet: 50 mg |
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