Triamterene/Hydrochlorothiazide

Description

Triamterene and hydrochlorothiazide tablets, USP, are a combination of triamterene, a potassium-conserving diuretic, and hydrochlorothiazide, a natriuretic agent. These tablets are available in two strengths: 75 mg/50 mg and 37.5 mg/25 mg. Each 75 mg/50 mg tablet contains 75 mg of triamterene, USP, and 50 mg of hydrochlorothiazide, USP, while each 37.5 mg/25 mg tablet contains 37.5 mg of triamterene, USP, and 25 mg of hydrochlorothiazide, USP.

For oral administration, both strengths of the tablets include the following inactive ingredients: anhydrous lactose, microcrystalline cellulose, polacrilin potassium, polyethylene glycol 8000, povidone, and magnesium stearate. The 37.5 mg/25 mg strength also contains FD&C Blue #2.

Triamterene is chemically defined as 2, 4, 7-triamino-6-phenylpteridine, with a molecular weight of 253.27. It is practically insoluble in water, benzene, chloroform, ether, and dilute alkali hydroxides, but is soluble in formic acid and sparingly soluble in methoxyethanol. It is very slightly soluble in acetic acid, alcohol, and dilute mineral acids.

Hydrochlorothiazide is identified as 6-chloro-3, 4-dihydro-2H-1, 2, 4-benzothiadiazine-7-sulfonamide 1, 1-dioxide, with a molecular weight of 297.73. Hydrochlorothiazide is slightly soluble in water and freely soluble in sodium hydroxide solution, n-butylamine, and dimethylformamide. It is sparingly soluble in methanol and insoluble in ether, chloroform, and dilute mineral acids.

Uses and Indications

This fixed combination drug is indicated for the treatment of hypertension or edema in patients who develop hypokalemia while on hydrochlorothiazide alone. It is not indicated for the initial therapy of edema or hypertension except in individuals where the risk of developing hypokalemia cannot be tolerated.

Triamterene and hydrochlorothiazide is also indicated for patients who require a thiazide diuretic and are at risk for hypokalemia, such as those on concomitant digitalis preparations or with a history of cardiac arrhythmias. This medication may be used alone or in combination with other antihypertensive agents, including beta-blockers; however, dosage adjustments may be necessary due to potential enhancement of the actions of these drugs.

Limitations of Use: The routine use of diuretics in otherwise healthy pregnant women is inappropriate and poses unnecessary risks to both mother and fetus. Diuretics do not prevent the development of toxemia in pregnancy, nor is there satisfactory evidence supporting their efficacy in treating established toxemia.

In cases of edema during pregnancy, thiazides may be indicated when the edema is due to pathological causes. However, dependent edema resulting from the mechanical effects of pregnancy should be managed through non-pharmacological means, such as elevation of the lower extremities and the use of support hose. The hypervolemia associated with normal pregnancy is generally not harmful to the mother or fetus, and if discomfort arises, increased recumbency is often sufficient for relief. In rare instances where edema causes extreme discomfort unrelieved by rest, a short course of diuretics may be appropriate.

Dosage and Administration

The usual dosage of triamterene and hydrochlorothiazide is 37.5 mg/25 mg or 75 mg/50 mg administered as a single daily dose. There is no clinical experience supporting the use of dosages exceeding 75 mg/50 mg daily.

Administration of 37.5 mg/25 mg twice daily in divided doses has been associated with an increased risk of electrolyte imbalance and renal dysfunction; therefore, this dosing regimen is not recommended. For patients receiving 50 mg of hydrochlorothiazide who develop hypokalemia, a direct transfer to the 75 mg/50 mg formulation is appropriate. Similarly, patients on 25 mg of hydrochlorothiazide who become hypokalemic may be transitioned directly to the 37.5 mg/25 mg formulation.

In cases where patients require hydrochlorothiazide therapy but cannot tolerate the risk of hypokalemia, treatment may be initiated with 37.5 mg/25 mg of triamterene and hydrochlorothiazide. If optimal blood pressure control is not achieved with this initial dosage, the dose may be increased to 75 mg/50 mg daily as a single dose. Should blood pressure remain uncontrolled, the addition of another antihypertensive agent should be considered.

When transitioning patients from less bioavailable formulations to triamterene and hydrochlorothiazide tablets, it is essential to monitor them clinically and assess serum potassium levels following the transfer.

Contraindications

Triamterene and hydrochlorothiazide are contraindicated in the following situations:

Use is contraindicated in patients with elevated serum potassium levels (≥ 5.5 mEq/liter) due to the risk of hyperkalemia. If hyperkalemia develops, the medication should be discontinued, and a thiazide alone should be substituted.

The combination should not be administered to patients receiving other potassium-conserving agents, such as spironolactone or amiloride hydrochloride, or to those using other formulations containing triamterene. Additionally, concomitant potassium supplementation, including medications, potassium-containing salt substitutes, or potassium-enriched diets, is contraindicated.

This medication is also contraindicated in patients with anuria, acute or chronic renal insufficiency, or significant renal impairment, as these conditions may exacerbate renal function.

Lastly, triamterene and hydrochlorothiazide should not be used in individuals who are hypersensitive to triamterene, hydrochlorothiazide, or other sulfonamide-derived drugs.

Warnings and Precautions

Patients receiving triamterene and hydrochlorothiazide must be closely monitored for the potential development of hyperkalemia, characterized by serum potassium levels of 5.5 mEq/liter or greater. This condition is particularly prevalent in individuals with renal impairment, diabetes (regardless of renal function), the elderly, or those who are severely ill. Due to the risk of fatal outcomes associated with uncorrected hyperkalemia, it is imperative that serum potassium levels are assessed frequently, especially during the initiation of therapy, following dosage adjustments, or in the presence of any illness that may affect renal function.

In cases where hyperkalemia is suspected—indicated by symptoms such as paresthesias, muscular weakness, fatigue, flaccid paralysis of the extremities, bradycardia, or shock—an electrocardiogram (ECG) should be performed. It is crucial to note that mild hyperkalemia may not present with ECG changes, thus ongoing monitoring of serum potassium levels is essential. Should hyperkalemia be confirmed, triamterene and hydrochlorothiazide must be discontinued immediately, and a thiazide diuretic should be substituted. If serum potassium levels exceed 6.5 mEq/liter, more aggressive treatment is warranted, which may include intravenous calcium chloride, sodium bicarbonate, and/or glucose with rapid-acting insulin. Cationic exchange resins, such as sodium polystyrene sulfonate, may also be administered orally or rectally, and persistent hyperkalemia may necessitate dialysis.

The risk of hyperkalemia is heightened in patients with renal impairment. Therefore, individuals with mild renal functional impairment should not be prescribed this combination without rigorous and continuous monitoring of serum electrolytes, as cumulative drug effects may occur. Additionally, diabetic patients are at increased risk for hyperkalemia even in the absence of renal impairment; thus, the use of triamterene and hydrochlorothiazide in this population should be approached with caution, ensuring frequent monitoring of serum electrolytes. Caution is also advised when co-administering these agents with angiotensin-converting enzyme (ACE) inhibitors due to their potassium-sparing effects.

General precautions include vigilant monitoring for fluid and electrolyte imbalances, such as hyponatremia, hypochloremic alkalosis, hypokalemia, and hypomagnesemia. Serum electrolyte levels should be determined at appropriate intervals, particularly in patients experiencing vomiting or receiving parenteral fluids. Symptoms indicative of fluid and electrolyte imbalance include dryness of the mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle cramps, hypotension, oliguria, tachycardia, and gastrointestinal disturbances.

Triamterene and hydrochlorothiazide may elevate blood urea nitrogen (BUN) and creatinine levels; therefore, periodic assessments of these parameters are recommended, especially in elderly patients or those with suspected hepatic or renal insufficiencies. If azotemia worsens, discontinuation of the medication is advised. Caution is warranted in patients with impaired hepatic function or progressive liver disease, as even minor fluid and electrolyte imbalances could precipitate hepatic coma.

The use of triamterene and hydrochlorothiazide should also be approached with caution in patients with a history of renal lithiasis, as triamterene has been associated with the formation of renal stones. Additionally, due to its weak folic acid antagonistic properties, periodic blood evaluations are recommended in patients with diminished folic acid stores to monitor for potential megaloblastosis. Hyperuricemia and acute gout may also be precipitated in certain patients receiving thiazide therapy. Sensitivity reactions to thiazides can occur in patients with or without a prior history of allergy or bronchial asthma.

In summary, careful monitoring of serum potassium levels, BUN, creatinine, and electrolytes is essential for patients on triamterene and hydrochlorothiazide, particularly in those with risk factors for hyperkalemia or renal impairment.

Side Effects

Adverse reactions associated with the use of triamterene and hydrochlorothiazide have been observed across various organ systems, with some reactions categorized by seriousness and frequency.

Gastrointestinal adverse reactions include intrahepatic cholestatic jaundice, pancreatitis, nausea, appetite disturbance, taste alteration, vomiting, diarrhea, constipation, anorexia, gastric irritation, and cramping. Central nervous system effects reported by patients encompass drowsiness, fatigue, insomnia, headache, dizziness, dry mouth, depression, anxiety, vertigo, restlessness, and paresthesias. Cardiovascular reactions may manifest as tachycardia, shortness of breath, chest pain, and orthostatic hypotension, which can be exacerbated by alcohol, barbiturates, or narcotics.

Renal adverse reactions include acute renal failure, acute interstitial nephritis, renal stones composed of triamterene in association with other calculus materials, and urine discoloration. Hematologic reactions reported include leukopenia, agranulocytosis, thrombocytopenia, aplastic anemia, hemolytic anemia, and megaloblastosis. Ophthalmic effects such as xanthopsia and transient blurred vision have also been noted.

Hypersensitivity reactions can be serious and include anaphylaxis, photosensitivity, rash, urticaria, purpura, necrotizing angiitis (vasculitis, cutaneous vasculitis), fever, and respiratory distress, including pneumonitis. Other adverse reactions reported by patients include muscle cramps, weakness, and decreased sexual performance, as well as sialadenitis.

Monitoring for hyperkalemia is critical, as abnormal elevation of serum potassium levels (≥5.5 mEq/liter) can occur with triamterene and hydrochlorothiazide. This condition is more likely in patients with renal impairment, diabetes, or those who are elderly or severely ill. Uncorrected hyperkalemia may be fatal, necessitating frequent serum potassium level monitoring, particularly when initiating treatment or adjusting dosages.

Altered laboratory findings have been observed, including hyperkalemia, hypokalemia, hyponatremia, hypomagnesemia, and hypochloremia. Reversible elevations in blood urea nitrogen (BUN) and serum creatinine have been documented in hypertensive patients treated with this combination. Additionally, hyperglycemia, glycosuria, and diabetes mellitus have been reported, along with elevated liver enzymes in patients receiving triamterene and hydrochlorothiazide.

Drug Interactions

Thiazide diuretics may enhance the effects of other antihypertensive agents, potentially leading to additive hypotensive effects. Clinicians should monitor blood pressure closely when initiating or adjusting therapy with thiazides in patients already receiving antihypertensive medications.

Thiazides can diminish arterial responsiveness to norepinephrine; however, this effect does not compromise the therapeutic efficacy of norepinephrine as a pressor agent. Additionally, thiazides have been shown to increase responsiveness to neuromuscular blocking agents such as tubocurarine, which may necessitate adjustments in dosing or monitoring of neuromuscular function.

Concomitant use of lithium with diuretics, including thiazides, is generally contraindicated due to the potential for reduced renal clearance of lithium, significantly increasing the risk of lithium toxicity. It is advisable to consult the package insert for lithium prior to considering this combination.

Caution is warranted when administering non-steroidal anti-inflammatory drugs (NSAIDs) such as indomethacin in patients receiving triamterene and hydrochlorothiazide, as acute renal failure has been reported in some cases. Monitoring of renal function is recommended in these patients.

The combination of potassium-sparing agents with angiotensin-converting enzyme (ACE) inhibitors should be approached with caution due to a markedly increased risk of hyperkalemia. Frequent monitoring of serum potassium levels is advised to mitigate this risk.

Lastly, triamterene and quinidine share similar fluorescence spectra, which may interfere with the accurate measurement of quinidine levels when used concurrently with triamterene and hydrochlorothiazide. Clinicians should consider this potential interaction when interpreting quinidine levels in patients receiving these medications.

Packaging & NDC

The table below lists all NDC Code configurations of Triamterene and Hydrochlorothiazide, the U.S. brand-name prescription product. Columns show Packaging, Formulation Type, and Active Ingredient Strength.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established. Therefore, the use of this medication in children, infants, and adolescents should be approached with caution until further data is available.

Geriatric Use

Elderly patients are at an increased risk for hyperkalemia, necessitating careful monitoring of serum potassium levels at frequent intervals. This risk is particularly pronounced in this population, and healthcare providers should remain vigilant.

Additionally, studies have demonstrated that renal clearances of hydrochlorothiazide and the pharmacologically active metabolite of triamterene are reduced in elderly patients, leading to increased plasma levels of these medications. Therefore, it is essential to consider dose adjustments based on renal function.

Periodic assessments of blood urea nitrogen (BUN) and creatinine levels are recommended, especially for elderly patients, to ensure safe medication management. Furthermore, cumulative drug effects may be observed in geriatric patients with impaired renal function, highlighting the importance of individualized treatment plans and close monitoring in this demographic.

Pregnancy

The use of triamterene and hydrochlorothiazide tablets during pregnancy is categorized as Category C. Animal reproduction studies have not been conducted to assess the potential for fetal harm; however, a One Generation Study in rats, utilizing a 1:1 ratio of triamterene to hydrochlorothiazide (30:30 mg/kg/day), demonstrated no evidence of teratogenicity at doses that were 15 and 30 times the Maximum Recommended Human Dose (MRHD) based on body weight, and 3.1 and 6.2 times the MRHD based on body-surface area.

The safety of triamterene and hydrochlorothiazide tablets in pregnant patients has not been established due to the absence of adequate and well-controlled studies in this population. Therefore, these tablets should only be used during pregnancy if the potential benefits justify the risks to the fetus.

Reproduction studies with triamterene in rats at doses up to 20 times the MRHD based on body weight and 6 times the MRHD based on body-surface area revealed no evidence of fetal harm. Similarly, hydrochlorothiazide has been administered to pregnant mice and rats during critical periods of organogenesis at doses up to 3000 mg/kg/day for mice and 1000 mg/kg/day for rats, with no observed fetal harm at these levels. However, the predictive value of animal studies for human response is limited, necessitating caution.

Both thiazides and triamterene are known to cross the placental barrier and can be detected in cord blood. The use of these medications in pregnant women requires careful consideration of the anticipated benefits against potential risks, which may include fetal or neonatal jaundice, pancreatitis, thrombocytopenia, and other adverse reactions observed in adults.

Lactation

Thiazides and triamterene in combination have not been studied in nursing mothers. However, triamterene has been shown to appear in animal milk, suggesting that it may also be excreted in human breast milk. Additionally, thiazides are known to be excreted in human breast milk.

If the use of the combination drug product is deemed essential, it is recommended that the lactating mother discontinue breastfeeding.

Renal Impairment

Patients with renal impairment are at an increased risk for hyperkalemia, particularly those with diabetes (even in the absence of renal impairment), elderly patients, or those who are severely ill. Serum potassium levels should be monitored at frequent intervals, especially when initiating treatment with triamterene and hydrochlorothiazide, during dosage adjustments, or in the presence of any illness that may affect renal function.

The risk of hyperkalemia associated with potassium-sparing diuretics is heightened in patients with reduced kidney function. For patients with mild renal functional impairment, the use of this medication is not recommended without close and ongoing monitoring of serum electrolytes.

Cumulative drug effects may occur in individuals with impaired renal function, as evidenced by reduced renal clearances of hydrochlorothiazide and the active metabolite of triamterene, leading to increased plasma levels in elderly patients and those with renal impairment. In cases where hyperkalemia is detected, it is imperative to discontinue triamterene and hydrochlorothiazide immediately and consider substituting with a thiazide alone.

Additionally, frequent evaluations of acid/base balance and serum electrolytes are essential for severely ill patients, particularly those at risk for respiratory or metabolic acidosis.

Hepatic Impairment

Patients with hepatic impairment have not been specifically studied in relation to the use of this medication. Consequently, there are no established dosage adjustments, special monitoring requirements, or precautions outlined for individuals with compromised liver function. It is recommended that healthcare providers exercise caution when prescribing this medication to patients with hepatic impairment, given the lack of data on its safety and efficacy in this population. Regular monitoring of liver function may be prudent in these cases, although specific parameters are not defined in the available information.

Overdosage

In cases of overdosage with triamterene and hydrochlorothiazide, it is important to note that specific data regarding human overdosage are lacking, and no specific antidote is available. The primary concern in such situations is the potential for fluid and electrolyte imbalances.

Excessive doses of the triamterene component may lead to hyperkalemia, dehydration, nausea, vomiting, and weakness, with a risk of hypotension. Conversely, overdosing on hydrochlorothiazide has been associated with hypokalemia, hypochloremia, hyponatremia, dehydration, and lethargy, which may progress to coma, as well as gastrointestinal irritation.

Management of overdosage is primarily symptomatic and supportive. It is recommended that therapy with triamterene and hydrochlorothiazide be discontinued immediately. Healthcare professionals should consider inducing emesis or performing gastric lavage to mitigate the effects of the overdose.

Continuous monitoring of serum electrolyte levels and fluid balance is essential. Supportive measures should be instituted as necessary to maintain hydration, electrolyte balance, and the proper functioning of respiratory, cardiovascular, and renal systems.

Nonclinical Toxicology

No teratogenic effects were observed in studies involving hydrochlorothiazide. In terms of non-teratogenic effects, hydrochlorothiazide did not adversely affect the fertility of mice and rats of either sex when these species were exposed to doses of up to 100 mg/kg/day and 4 mg/kg/day, respectively, prior to mating and throughout gestation. These doses correspond to multiples of the Maximum Recommended Human Dose (MRHD) of 100 times for mice and 4 times for rats based on body weight, and 9.4 times for mice and 0.8 times for rats based on body surface area.

Long-term studies evaluating the triamterene/hydrochlorothiazide combination have not been conducted. In studies conducted under the auspices of the National Toxicology Program, groups of rats were administered diets containing 0, 150, 300, or 600 ppm triamterene, while groups of mice received diets containing 0, 100, 200, or 400 ppm triamterene. Male and female rats at the highest concentration received approximately 25 mg/kg/day and 30 mg/kg/day, respectively, while male and female mice received approximately 45 mg/kg/day and 60 mg/kg/day, respectively. An increased incidence of hepatocellular neoplasia, primarily adenomas, was noted in male and female mice at the highest dosage level, which represents 7.5 times and 10 times the MRHD of 300 mg/kg (or 6 mg/kg/day based on a 50 kg patient) for male and female mice, respectively, when calculated based on body weight, and 0.7 times and 0.9 times the MRHD when based on body surface area. In contrast, hepatocellular neoplasia in the rat study was limited to triamterene-exposed males, with no dose-dependent relationship and no statistically significant difference from control incidence at any dose level.

Two-year feeding studies in mice and rats, also conducted under the auspices of the National Toxicology Program, involved doses of hydrochlorothiazide up to 600 mg/kg/day in mice and 100 mg/kg/day in rats. These doses correspond to 600 times the MRHD for hydrochlorothiazide in mice and 100 times in rats, based on body weight, and 56 times in mice and 21 times in rats based on body surface area. These studies revealed no evidence of carcinogenic potential for hydrochlorothiazide in rats or female mice, although equivocal evidence of hepatocarcinogenicity was observed in male mice.

Studies assessing the mutagenic potential of the triamterene and hydrochlorothiazide combination have not been performed. Triamterene was found to be non-mutagenic in various strains of bacteria (S. typhimurium strains TA 98, TA 100, TA 1535, or TA 1537) with or without metabolic activation. It did not induce chromosomal aberrations in Chinese hamster ovary (CHO) cells in vitro, but it did induce sister chromatid exchanges in CHO cells under both conditions. Hydrochlorothiazide was not genotoxic in in vitro assays using multiple strains of Salmonella typhimurium, in the CHO test for chromosomal aberrations, or in in vivo assays involving mouse germinal cell chromosomes, Chinese hamster bone marrow chromosomes, and the Drosophila sex-linked recessive lethal trait gene. However, positive results were obtained in the in vitro CHO sister chromatid exchange test and in mouse lymphoma cell assays at concentrations ranging from 43 to 1300 mcg/mL. Additionally, positive results were noted in the Aspergillus nidulans nondisjunction assay using an unspecified concentration of hydrochlorothiazide. Studies investigating the effects of the triamterene/hydrochlorothiazide combination or triamterene alone on animal reproductive function have not been conducted.

Postmarketing Experience

Postmarketing experience has identified a range of adverse events reported voluntarily or through surveillance programs.

Gastrointestinal events include intrahepatic cholestatic jaundice, pancreatitis, nausea, appetite disturbance, taste alteration, vomiting, diarrhea, constipation, anorexia, gastric irritation, and cramping. Central nervous system effects encompass drowsiness, fatigue, insomnia, headache, dizziness, dry mouth, depression, anxiety, vertigo, restlessness, and paresthesias. Cardiovascular events reported include tachycardia, shortness of breath, chest pain, and orthostatic hypotension, which may be exacerbated by alcohol, barbiturates, or narcotics.

Renal adverse events consist of acute renal failure, acute interstitial nephritis, renal stones composed of triamterene in association with other calculus materials, and urine discoloration. Hematologic events include leukopenia, agranulocytosis, thrombocytopenia, aplastic anemia, hemolytic anemia, and megaloblastosis. Ophthalmic effects reported are xanthopsia and transient blurred vision. Hypersensitivity reactions include anaphylaxis, photosensitivity, rash, urticaria, purpura, necrotizing angiitis (vasculitis, cutaneous vasculitis), fever, and respiratory distress, including pneumonitis.

Other reported events include muscle cramps, weakness, decreased sexual performance, and sialadenitis. Altered laboratory findings have also been noted, including hyperkalemia, hypokalemia, hyponatremia, hypomagnesemia, and hypochloremia. Reversible elevations in blood urea nitrogen (BUN) and serum creatinine have been observed in hypertensive patients treated with triamterene and hydrochlorothiazide tablets. Additionally, hyperglycemia, glycosuria, and diabetes mellitus have been reported, along with elevated liver enzymes in patients receiving triamterene and hydrochlorothiazide tablets.

Patient Counseling

Patients should be monitored for fluid or electrolyte imbalances, including conditions such as hyponatremia, hypochloremic alkalosis, hypokalemia, and hypomagnesemia. Healthcare providers should emphasize the importance of frequent serum and urine electrolyte determinations, particularly when the patient is experiencing vomiting or receiving parenteral fluids.

Patients should be informed about warning signs or symptoms of fluid and electrolyte imbalance, which may include dryness of the mouth, increased thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, and gastrointestinal disturbances such as nausea and vomiting. It is crucial for patients receiving triamterene and hydrochlorothiazide to report any signs of hyperkalemia, including paresthesias, muscular weakness, fatigue, flaccid paralysis of the extremities, bradycardia, and shock. In cases where hyperkalemia is suspected, an electrocardiogram (ECG) should be obtained promptly.

Patients should be advised that if hyperkalemia is confirmed, triamterene and hydrochlorothiazide should be discontinued immediately, and a thiazide alone should be substituted. Additionally, patients should be cautioned about the potential for acute myopia and secondary angle-closure glaucoma associated with hydrochlorothiazide. Symptoms of these conditions include an acute onset of decreased visual acuity or ocular pain, and patients should be instructed to discontinue hydrochlorothiazide as rapidly as possible if they experience such symptoms.

It is important to inform patients that triamterene and hydrochlorothiazide may lead to elevated blood urea nitrogen (BUN) levels, creatinine levels, or both. Periodic determinations of BUN and creatinine should be conducted, especially in elderly patients or those with suspected or confirmed hepatic disease or renal insufficiencies. Patients should also be advised to avoid potassium supplements or potassium-containing salt substitutes while taking triamterene and hydrochlorothiazide.

Healthcare providers should communicate that the use of diuretics in otherwise healthy women during pregnancy is inappropriate and poses unnecessary risks to both the mother and fetus. If the use of triamterene and hydrochlorothiazide is deemed essential during pregnancy, patients should be informed that the anticipated benefits must be carefully weighed against potential hazards to the fetus. Furthermore, nursing mothers should be advised that triamterene appears in animal milk, and this may also occur in humans; if the use of the combination drug product is considered essential, the patient should discontinue nursing.

Storage and Handling

The product is supplied in a tight, light-resistant container that complies with USP standards and features a child-resistant closure. It should be stored at a temperature range of 20° to 25°C (68° to 77°F), in accordance with USP Controlled Room Temperature guidelines. Additionally, it is essential to protect the product from light to maintain its integrity.

Additional Clinical Information

Clinicians should perform regular laboratory tests to monitor serum electrolytes in patients receiving triamterene and hydrochlorothiazide, particularly to detect potential electrolyte imbalances. Serum and urine electrolyte determinations are crucial, especially in patients experiencing vomiting or those receiving parenteral fluids. Additionally, periodic assessments of blood urea nitrogen (BUN) and creatinine levels are recommended, particularly for elderly patients or those with suspected hepatic or renal impairments.

The standard dosage for triamterene and hydrochlorothiazide is 37.5 mg/25 mg or 75 mg/50 mg daily, administered as a single dose, with careful monitoring of serum potassium levels. Patients should be counseled on the importance of monitoring for signs of fluid or electrolyte imbalances, which may include symptoms such as dryness of mouth, thirst, weakness, and gastrointestinal disturbances. Warning signs of hyperkalemia, such as paresthesias and muscular weakness, necessitate an electrocardiogram (ECG) for further evaluation.

FDA Insert (PDF)

This document is the official FDA-approved prescribing information for Triamterene and Hydrochlorothiazide as submitted by Aidarex Pharmaceuticals LLC. It includes detailed information about indications, dosage, contraindications, warnings, and clinical pharmacology.

View full prescribing information (PDF)