Triamterene and Hydrochlorothiazide (Page 4 of 5)

Hydrochlorothiazide

Hydrochlorothiazide was orally administered to pregnant mice and rats during respective periods of major organogenesis at doses up to 3000 and 1000 mg/kg/day, respectively. At these doses, which are multiples of the MRHD equal to 3000 for mice and 1000 for rats, based on body-weight, and equal to 282 for mice and 206 for rats, based on body-surface area, there was no evidence of harm to the fetus. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Nonteratogenic Effects

Thiazides and triamterene have been shown to cross the placental barrier and appear in cord blood. The use of thiazides and triamterene in pregnant women requires that the anticipated benefits be weighed against possible hazards to the fetus. These hazards include fetal or neonatal jaundice, pancreatitis, thrombocytopenia, and possibly other adverse reactions that have occurred in the adult.

Nursing Mothers

Thiazides and triamterene in combination have not been studied in nursing mothers. Triamterene appears in animal milk and this may occur in humans. Thiazides are excreted in human breast milk. If use of the combination drug product is deemed essential, the patient should stop nursing.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

Information for Patients

Non-melanoma Skin Cancer
Instruct patients taking hydrochlorothiazide to protect skin from the sun and undergo regular skin cancer screening.

ADVERSE REACTIONS

Side effects observed in association with the use of triamterene and hydrochlorothiazide tablets, other combination products containing triamterene/hydrochlorothiazide, and products containing triamterene or hydrochlorothiazide include the following:

Gastrointestinal: jaundice (intrahepatic cholestatic jaundice), pancreatitis, nausea, appetite disturbance, taste alteration, vomiting, diarrhea, constipation, anorexia, gastric irritation, cramping.

Central Nervous System: drowsiness and fatigue, insomnia, headache, dizziness, dry mouth, depression, anxiety, vertigo, restlessness, paresthesias.

Cardiovascular: tachycardia, shortness of breath and chest pain, orthostatic hypotension (may be aggravated by alcohol, barbiturates or narcotics).

Renal: acute renal failure, acute interstitial nephritis, renal stones composed of triamterene in association with other calculus materials, urine discoloration.

Hematologic: leukopenia, agranulocytosis, thrombocytopenia, aplastic anemia, hemolytic anemia and megaloblastosis.

Ophthalmic: xanthopsia, transient blurred vision.

Hypersensitivity: anaphylaxis, photosensitivity, rash, urticaria, purpura, necrotizing angiitis (vasculitis, cutaneous vasculitis), fever, respiratory distress including pneumonitis.

Other: muscle cramps and weakness, decreased sexual performance and sialadenitis.

Whenever adverse reactions are moderate to severe, therapy should be reduced or withdrawn.

Altered Laboratory Findings

Serum Electrolytes: hyperkalemia, hypokalemia, hyponatremia, hypomagnesemia, hypochloremia (see WARNINGS and PRECAUTIONS).

Creatinine, Blood Urea Nitrogen: Reversible elevations in BUN and serum creatinine have been observed in hypertensive patients treated with triamterene and hydrochlorothiazide.

Glucose: hyperglycemia, glycosuria and diabetes mellitus (see PRECAUTIONS).

Serum Uric Acid, PBI and Calcium: (see PRECAUTIONS).

Other: Elevated liver enzymes have been reported in patients receiving triamterene and hydrochlorothiazide.

Postmarketing Experience

Non-melanoma Skin Cancer
Hydrochlorothiazide is associated with an increased risk of non-melanoma skin cancer. In a study conducted in the Sentinel System, increased risk was predominantly for squamous cell carcinoma (SCC) and in white patients taking large cumulative doses. The increased risk for SCC in the overall population was approximately 1 additional case per 16,000 patients per year, and for white patients taking a cumulative dose of ≥ 50,000 mg the risk increase was approximately 1 additional SCC case for every 6,700 patients per year.

OVERDOSAGE

No specific data are available regarding triamterene and hydrochlorothiazide overdosage in humans and no specific antidote is available.

Fluid and electrolyte imbalances are the most important concern. Excessive doses of the triamterene component may elicit hyperkalemia, dehydration, nausea, vomiting and weakness and possibly hypotension. Overdosing with hydrochlorothiazide has been associated with hypokalemia, hypochloremia, hyponatremia, dehydration, lethargy (may progress to coma) and gastrointestinal irritation. Treatment is symptomatic and supportive. Therapy with triamterene and hydrochlorothiazide should be discontinued. Induce emesis or institute gastric lavage. Monitor serum electrolyte levels and fluid balance.

Institute supportive measures as required to maintain hydration, electrolyte balance, respiratory, cardiovascular and renal function.

DOSAGE AND ADMINISTRATION

Note: 37.5 mg/25 mg = 37.5 mg triamterene and 25 mg hydrochlorothiazide
   75 mg/50 mg = 75 mg triamterene and 50 mg hydrochlorothiazide

The usual dose of Triamterene and Hydrochlorothiazide 37.5 mg/25 mg is one or two tablets daily, given as a single dose, with appropriate monitoring of serum potassium (see WARNINGS). The usual dose of Triamterene and Hydrochlorothiazide 75 mg/50 mg is one tablet daily, with appropriate monitoring of serum potassium (see WARNINGS). There is no experience with the use of more than one 75 mg/50 mg tablet daily or more than two 37.5 mg/25 mg tablets daily. Clinical experience with the administration of two 37.5 mg/25 mg tablets daily in divided doses (rather than as a single dose) suggests an increased risk of electrolyte imbalance and renal dysfunction.

Patients receiving 50 mg of hydrochlorothiazide who become hypokalemic may be transferred to 75 mg/50 mg product directly. Patients receiving 25 mg hydrochlorothiazide who become hypokalemic may be transferred to a 37.5 mg triamterene/25 mg hydrochlorothiazide directly.

In patients requiring hydrochlorothiazide therapy and in whom hypokalemia cannot be risked, therapy may be initiated with 37.5 mg/25 mg of triamterene and hydrochlorothiazide. If an optimal blood pressure response is not obtained with 37.5 mg/25 mg of triamterene and hydrochlorothiazide, the dose should be increased to two 37.5 mg/25 mg tablets daily as a single dose, or one 75 mg/50 mg tablet daily. If blood pressure still is not controlled, another antihypertensive agent may be added (see PRECAUTIONS, Drug Interactions).

Clinical studies have shown that patients taking less bioavailable formulations of triamterene and hydrochlorothiazide in daily doses of 25 mg to 50 mg hydrochlorothiazide and 50 mg to 100 mg triamterene may be safely changed to one 37.5 mg/25 mg of triamterene and hydrochlorothiazide daily. All patients changed from less bioavailable formulations to triamterene and hydrochlorothiazide should be monitored clinically and for serum potassium after the transfer.

HOW SUPPLIED

Triamterene and Hydrochlorothiazide Tablets, USP, 37.5 mg/ 25 mg are available for oral administration as green, oval biconvex tablets, scored and engraved “37.5” bisect “25” on one side, “APO” on the other side. They are supplied as follows:
Unit dose packages of 30 (5 x 6) NDC 68084-750-25

Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature].
Protect from light.

FOR YOUR PROTECTION: Do not use if blister is torn or broken.

APOTEX INC.
TRIAMTERENE HYDROCHLOROTHIAZIDE TABLETS, USP
37.5 mg/25 mg and 75 mg/50 mg

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