TRIAMTERENE AND HYDROCHLOROTHIAZIDE

Each triamterene and hydrochlorothiazide capsule, USP for oral use contains triamterene, USP 37.5 mg and hydrochlorothiazide, USP 25 mg. Hydrochlorothiazide, USP is a diuretic/antihypertensive agent and triamterene, USP is an antikaliuretic agent. Hydrochlorothiazide, USP is slightly soluble in water. It is soluble in dilute ammonia, dilute aqueous sodium hydroxide, and dimethylformamide. It is sparingly soluble in methanol. Hydrochlorothiazide, USP is 6-chloro-3,4-dihydro-2 H -1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide, and its structural formula is: Molecular Formula: C 7 H 8 CIN 3 O 4 S 2 M.W. 297.74 At 50°C, triamterene, USP is practically insoluble in water (less than 0.1%). It is soluble in formic acid, sparingly soluble in methoxyethanol, and very slightly soluble in alcohol. Triamterene, USP is 2,4,7-triamino-6-phenylpteridine and its structural formula is: Molecular Formula: C 12 H 11 N 7 M.W. 253.26 Inactive ingredients consist of lactose monohydrate, pregelatinized starch, sodium starch glycolate, polysorbate 80, citric acid anhydrous, povidone, and magnesium stearate. The capsule shell consists of titanium dioxide and gelatin. The capsule imprinting ink consists of shellac glaze in ethanol, iron oxide black, n-butyl alcohol, propylene glycol, ethanol, methanol, FD&C Blue # 2 Aluminum Lake, FD&C Red # 40 Aluminum Lake, FD&C Blue # 1 Aluminum Lake, and D&C Yellow # 10 Aluminum Lake. Triamterene and hydrochlorothiazide capsules, USP meet USP Dissolution Test 3 as published in the current USP monograph for Triamterene and Hydrochlorothiazide Capsules. image description image description

This fixed combination drug is not indicated for the initial therapy of edema or hypertension except in individuals in whom the development of hypokalemia cannot be risked. Triamterene and hydrochlorothiazide capsules are indicated for the treatment of hypertension or edema in patients who develop hypokalemia on hydrochlorothiazide alone. Triamterene and hydrochlorothiazide capsules are also indicated for those patients who require a thiazide diuretic and in whom the development of hypokalemia cannot be risked. Triamterene and hydrochlorothiazide capsules may be used alone or as an adjunct to other antihypertensive drugs, such as beta-blockers. Since triamterene and hydrochlorothiazide capsules may enhance the action of these agents, dosage adjustments may be necessary. Usage in Pregnancy: The routine use of diuretics in an otherwise healthy woman is inappropriate and exposes mother and fetus to unnecessary hazard. Diuretics do not prevent development of toxemia of pregnancy, and there is no satisfactory evidence that they are useful in the treatment of developed toxemia. Edema during pregnancy may arise from pathological causes or from the physiologic and mechanical consequences of pregnancy. Diuretics are indicated in pregnancy when edema is due to pathologic causes, just as they are in the absence of pregnancy. Dependent edema in pregnancy resulting from restriction of venous return by the expanded uterus is properly treated through elevation of the lower extremities and use of support hose; use of diuretics to lower intravascular volume in this case is illogical and unnecessary. There is hypervolemia during normal pregnancy which is harmful to neither the fetus nor the mother (in the absence of cardiovascular disease), but which is associated with edema, including generalized edema in the majority of pregnant women. If this edema produces discomfort, increased recumbency will often provide relief. In rare instances this edema may cause extreme discomfort which is not relieved by rest. In these cases, a short course of diuretics may provide relief and may be appropriate.

The usual dose of triamterene and hydrochlorothiazide capsules is 1 or 2 capsules given once daily, with appropriate monitoring of serum potassium and of the clinical effect (see WARNINGS , Hyperkalemia) .

Antikaliuretic Therapy and Potassium Supplementation: Triamterene and hydrochlorothiazide capsules should not be given to patients receiving other potassium-sparing agents such as spironolactone, amiloride, or other formulations containing triamterene. Concomitant potassium-containing salt substitutes should also not be used. Potassium supplementation should not be used with triamterene and hydrochlorothiazide capsules except in severe cases of hypokalemia. Such concomitant therapy can be associated with rapid increases in serum potassium levels. If potassium supplementation is used, careful monitoring of the serum potassium level is necessary. Impaired Renal Function: Triamterene and hydrochlorothiazide capsules are contraindicated in patients with anuria, acute and chronic renal insufficiency, or significant renal impairment. Hypersensitivity: Hypersensitivity to either drug in the preparation or to other sulfonamide-derived drugs is a contraindication. Hyperkalemia: Triamterene and hydrochlorothiazide capsules should not be used in patients with pre-existing elevated serum potassium.

Adverse effects are listed in decreasing order of severity. Hypersensitivity: Anaphylaxis, rash, urticaria, subacute cutaneous lupus erythematosus-like reactions, photosensitivity. Cardiovascular: Arrhythmia, postural hypotension. Metabolic: Diabetes mellitus, hyperkalemia, hypokalemia, hyponatremia, acidosis, hypercalcemia, hyperglycemia, glycosuria, hyperuricemia, hypochloremia. Gastrointestinal: Jaundice and/or liver enzyme abnormalities, pancreatitis, nausea and vomiting, diarrhea, constipation, abdominal pain. Renal: Acute renal failure (one case of irreversible renal failure has been reported), interstitial nephritis, renal stones composed primarily of triamterene, elevated BUN and serum creatinine, abnormal urinary sediment. Hematologic: Leukopenia, thrombocytopenia and purpura, megaloblastic anemia. Musculoskeletal: Muscle cramps. Central Nervous System: Weakness, fatigue, dizziness, headache, dry mouth. Miscellaneous: Impotence, sialadenitis. Thiazides alone have been shown to cause the following additional adverse reactions: Central Nervous System: Paresthesias, vertigo. Ophthalmic: Xanthopsia, transient blurred vision. Respiratory: Allergic pneumonitis, pulmonary edema, respiratory distress. Other: Necrotizing vasculitis, exacerbation of lupus. Hematologic: Aplastic anemia, agranulocytosis, hemolytic anemia. Neonate and infancy: Thrombocytopenia and pancreatitis–rarely, in newborns whose mothers have received thiazides during pregnancy. Skin: Erythema multiforme, including Stevens-Johnson syndrome; exfoliative dermatitis, including toxic epidermal necrolysis. 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.