Triamterene 50mg Capsules
WARNING: Sometimes, this drug may raise potassium levels in the blood. This can be deadly if it is not treated. The risk is highest in people with diabetes, kidney disease, severe illness, and in older adults. Your doctor will follow you closely to change the dose if needed. @ COMMON USES: It is used to get rid of extra fluid. It may be given to you for other reasons. Talk with the doctor.
Drug Class
Diuretic, Potassium-Sparing
Pharmacologic Class
Epithelial Sodium Channel (ENaC) Inhibitor
Pregnancy Category
Category C
FDA Approved
Aug 1964
DEA Schedule
Not Controlled
Overview
What is this medicine?
Triamterene is a 'water pill' (diuretic) that helps your body get rid of extra salt and water, which can lower blood pressure and reduce swelling. Unlike some other water pills, it helps your body keep potassium, which is important for heart and muscle function.
How to Use This Medicine
Taking Your Medication
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. Unless your doctor advises otherwise, take your medication after meals to help minimize potential side effects. Continue taking your medication as directed by your doctor or healthcare provider, even if you start to feel well.
If you are taking your medication once a day, it is best to take it in the morning. Be aware that this medication may increase the frequency of urination. To avoid sleep disturbances, try to avoid taking your medication too close to bedtime.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature, protected from light and moisture. Avoid storing your medication in a bathroom or any area that is prone to high humidity. Keep all medications in a secure location, out of the reach of children and pets.
When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless specifically instructed to do so by your pharmacist or healthcare provider. Instead, check with your pharmacist for guidance on the best disposal method. Many communities have drug take-back programs that provide a safe and environmentally friendly way to dispose of unwanted medications.
Missing a Dose
If you miss a dose of your medication, take it as soon as you remember. However, if it is close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for a missed dose.
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. Unless your doctor advises otherwise, take your medication after meals to help minimize potential side effects. Continue taking your medication as directed by your doctor or healthcare provider, even if you start to feel well.
If you are taking your medication once a day, it is best to take it in the morning. Be aware that this medication may increase the frequency of urination. To avoid sleep disturbances, try to avoid taking your medication too close to bedtime.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature, protected from light and moisture. Avoid storing your medication in a bathroom or any area that is prone to high humidity. Keep all medications in a secure location, out of the reach of children and pets.
When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless specifically instructed to do so by your pharmacist or healthcare provider. Instead, check with your pharmacist for guidance on the best disposal method. Many communities have drug take-back programs that provide a safe and environmentally friendly way to dispose of unwanted medications.
Missing a Dose
If you miss a dose of your medication, take it as soon as you remember. However, if it is close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for a missed dose.
Lifestyle & Tips
- Avoid potassium supplements and foods very high in potassium (e.g., bananas, oranges, potatoes, leafy greens, salt substitutes) unless directed by your doctor.
- Stay hydrated, especially in hot weather or during exercise, but avoid excessive fluid intake unless advised.
- Report any signs of high potassium (muscle weakness, fatigue, slow or irregular heartbeat) immediately.
- Avoid sudden changes in position (e.g., standing up quickly) to prevent dizziness.
- Limit alcohol intake as it can increase dizziness and lower blood pressure.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
50 mg once daily or 100 mg every other day
Dose Range:
50 - 100 mg
Condition-Specific Dosing:
edema:
Initial: 100 mg once daily after meals. Maintenance: 50-100 mg daily or every other day. Max: 300 mg/day (rarely used).
hypertension:
Typically used in combination with other antihypertensives. 50-100 mg daily or every other day.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established (limited data, generally not recommended due to hyperkalemia risk)
Adolescent:
Not established (limited data, generally not recommended due to hyperkalemia risk)
Dose Adjustments
Renal Impairment:
Mild:
Use with caution; monitor potassium and renal function closely.
Moderate:
Contraindicated if creatinine clearance < 30 mL/min. Use with extreme caution if CrCl 30-50 mL/min; consider lower doses and frequent monitoring.
Severe:
Contraindicated (risk of hyperkalemia and azotemia).
Dialysis:
Contraindicated (risk of hyperkalemia).
Hepatic Impairment:
Mild:
Use with caution; monitor for hyperkalemia and worsening hepatic function.
Moderate:
Use with caution; increased risk of hyperkalemia and hepatic encephalopathy. Consider lower doses and frequent monitoring.
Severe:
Use with caution; increased risk of hyperkalemia and hepatic encephalopathy. May precipitate hepatic coma in severe liver disease.
Pharmacology
Mechanism of Action
Triamterene is a potassium-sparing diuretic that acts directly on the distal renal tubule. It inhibits the reabsorption of sodium in exchange for potassium and hydrogen ions by blocking epithelial sodium channels (ENaC) on the luminal membrane of the principal cells in the collecting duct. This action leads to increased excretion of sodium and water, while reducing the excretion of potassium and hydrogen ions.
Pharmacokinetics
Absorption:
Bioavailability:
30-70% (variable)
Tmax:
2-6 hours
FoodEffect:
Food can increase absorption and reduce peak plasma concentrations, potentially prolonging the duration of action.
Distribution:
Vd:
Not precisely quantified, but distributes into body tissues.
ProteinBinding:
Approximately 50-60%
CnssPenetration:
Limited
Elimination:
HalfLife:
Parent drug: 1.5-5 hours; Active metabolite (hydroxytriamterene sulfate): 10-12 hours
Clearance:
Primarily renal excretion of parent drug and metabolites.
ExcretionRoute:
Renal (primarily metabolites, some unchanged drug), Biliary (minor)
Unchanged:
Approximately 20% (renal)
Pharmacodynamics
OnsetOfAction:
2-4 hours
PeakEffect:
6-10 hours
DurationOfAction:
12-16 hours
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor immediately or seek medical attention:
Signs of an allergic reaction, such as:
+ Rash or hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Signs of kidney problems, such as:
+ Inability to pass urine
+ Changes in urine output
+ Blood in the urine
+ Sudden weight gain
Signs of fluid and electrolyte problems, including:
+ Mood changes
+ Confusion
+ Muscle pain or weakness
+ Fast or abnormal heartbeat
+ Severe dizziness or fainting
+ Increased thirst
+ Seizures
+ Feeling very tired or weak
+ Decreased appetite
+ Inability to pass urine or changes in urine output
+ Dry mouth
+ Dry eyes
+ Severe upset stomach or vomiting
Signs of too much acid in the blood (acidosis), such as:
+ Confusion
+ Fast breathing
+ Fast heartbeat
+ Abnormal heartbeat
+ Severe stomach pain, upset stomach, or vomiting
+ Feeling very sleepy
+ Shortness of breath
+ Feeling very tired or weak
Back pain, belly pain, or blood in the urine, which may be signs of a kidney stone
Unexplained bruising or bleeding, signs of infection (such as fever, chills, or sore throat), or feeling very tired or weak, which may indicate low blood cell counts
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to contact your doctor if you notice any of the following:
Feeling dizzy, tired, or weak
Headache
Diarrhea
Upset stomach or vomiting
Dry mouth
This is not an exhaustive list of possible side effects. If you have concerns or questions, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor immediately or seek medical attention:
Signs of an allergic reaction, such as:
+ Rash or hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Signs of kidney problems, such as:
+ Inability to pass urine
+ Changes in urine output
+ Blood in the urine
+ Sudden weight gain
Signs of fluid and electrolyte problems, including:
+ Mood changes
+ Confusion
+ Muscle pain or weakness
+ Fast or abnormal heartbeat
+ Severe dizziness or fainting
+ Increased thirst
+ Seizures
+ Feeling very tired or weak
+ Decreased appetite
+ Inability to pass urine or changes in urine output
+ Dry mouth
+ Dry eyes
+ Severe upset stomach or vomiting
Signs of too much acid in the blood (acidosis), such as:
+ Confusion
+ Fast breathing
+ Fast heartbeat
+ Abnormal heartbeat
+ Severe stomach pain, upset stomach, or vomiting
+ Feeling very sleepy
+ Shortness of breath
+ Feeling very tired or weak
Back pain, belly pain, or blood in the urine, which may be signs of a kidney stone
Unexplained bruising or bleeding, signs of infection (such as fever, chills, or sore throat), or feeling very tired or weak, which may indicate low blood cell counts
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to contact your doctor if you notice any of the following:
Feeling dizzy, tired, or weak
Headache
Diarrhea
Upset stomach or vomiting
Dry mouth
This is not an exhaustive list of possible side effects. If you have concerns or questions, consult your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Signs of high potassium: unusual tiredness, muscle weakness, numbness or tingling, slow or irregular heartbeat.
- Signs of dehydration: severe dizziness, fainting, extreme thirst, dry mouth, decreased urination.
- Signs of kidney stones: severe pain in your side or back, blood in urine, painful urination.
- Signs of allergic reaction: rash, itching, swelling (especially of face/tongue/throat), severe dizziness, trouble breathing.
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
Certain health conditions, including:
+ High potassium levels
+ Kidney disease
+ Liver disease
+ Urinary retention (inability to pass urine)
If you are taking any of the following medications:
+ Amiloride
+ Spironolactone
+ Other medications containing triamterene
If you are breast-feeding. Note that you should not breast-feed while taking this medication.
This list is not exhaustive, and it is crucial to discuss all your medications (prescription, over-the-counter, natural products, and vitamins) and health problems with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other medications and health conditions. Never start, stop, or change the dose of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
Certain health conditions, including:
+ High potassium levels
+ Kidney disease
+ Liver disease
+ Urinary retention (inability to pass urine)
If you are taking any of the following medications:
+ Amiloride
+ Spironolactone
+ Other medications containing triamterene
If you are breast-feeding. Note that you should not breast-feed while taking this medication.
This list is not exhaustive, and it is crucial to discuss all your medications (prescription, over-the-counter, natural products, and vitamins) and health problems with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other medications and health conditions. Never start, stop, or change the dose of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
Before operating a vehicle or engaging in activities that require alertness, wait until you understand how this medication affects you.
If you have diabetes (high blood sugar), consult with your doctor, as this medication may impact blood sugar control. Your diabetes treatment regimen may need to be adjusted.
Monitor your blood sugar levels as directed by your doctor.
Also, check your blood pressure as instructed by your doctor.
Regularly have blood tests done as recommended by your doctor and discuss the results with them.
Be aware that this medication may interfere with certain laboratory tests. Inform all your healthcare providers and laboratory personnel that you are taking this medication.
If you are following a low-salt or salt-free diet, consult with your doctor.
Additionally, if you are using a salt substitute containing potassium, a potassium-sparing diuretic, or a potassium product, discuss this with your doctor.
Be vigilant for signs of gout attacks.
This medication may increase your susceptibility to sunburn. Exercise caution when exposed to the sun, and notify your doctor if you experience increased sensitivity to the sun.
If you are 65 years or older, use this medication with caution, as you may be more prone to side effects.
If you are pregnant or planning to become pregnant, consult with your doctor to discuss the potential benefits and risks of using this medication during pregnancy.
Before operating a vehicle or engaging in activities that require alertness, wait until you understand how this medication affects you.
If you have diabetes (high blood sugar), consult with your doctor, as this medication may impact blood sugar control. Your diabetes treatment regimen may need to be adjusted.
Monitor your blood sugar levels as directed by your doctor.
Also, check your blood pressure as instructed by your doctor.
Regularly have blood tests done as recommended by your doctor and discuss the results with them.
Be aware that this medication may interfere with certain laboratory tests. Inform all your healthcare providers and laboratory personnel that you are taking this medication.
If you are following a low-salt or salt-free diet, consult with your doctor.
Additionally, if you are using a salt substitute containing potassium, a potassium-sparing diuretic, or a potassium product, discuss this with your doctor.
Be vigilant for signs of gout attacks.
This medication may increase your susceptibility to sunburn. Exercise caution when exposed to the sun, and notify your doctor if you experience increased sensitivity to the sun.
If you are 65 years or older, use this medication with caution, as you may be more prone to side effects.
If you are pregnant or planning to become pregnant, consult with your doctor to discuss the potential benefits and risks of using this medication during pregnancy.
Overdose Information
Overdose Symptoms:
- Severe hyperkalemia (muscle weakness, fatigue, paresthesias, bradycardia, cardiac arrhythmias, cardiac arrest)
- Hypotension
- Dehydration
- Electrolyte imbalances (hyponatremia, metabolic acidosis)
- Acute renal failure
What to Do:
Seek immediate medical attention or call Poison Control at 1-800-222-1222. Treatment is supportive and symptomatic, focusing on correcting hyperkalemia (e.g., IV calcium, insulin/glucose, sodium bicarbonate, potassium-binding resins, dialysis if severe) and maintaining fluid/electrolyte balance.
Drug Interactions
Contraindicated Interactions
- Potassium supplements
- Other potassium-sparing diuretics (e.g., spironolactone, amiloride)
- Severe renal impairment (CrCl < 30 mL/min)
Major Interactions
- ACE inhibitors (e.g., enalapril, lisinopril)
- Angiotensin Receptor Blockers (ARBs) (e.g., valsartan, losartan)
- NSAIDs (e.g., ibuprofen, naproxen, celecoxib) - especially in elderly or renally impaired patients
- Cyclosporine
- Tacrolimus
- Trimethoprim (alone or in co-trimoxazole)
- Lithium (increased lithium toxicity)
Moderate Interactions
Minor Interactions
- Corticosteroids (may reduce diuretic effect)
- Pressor amines (e.g., norepinephrine, may reduce arterial responsiveness)
Monitoring
Baseline Monitoring
Serum Potassium (K+)
Rationale: To establish baseline and identify pre-existing hyperkalemia risk.
Timing: Before initiation of therapy.
Serum Sodium (Na+)
Rationale: To establish baseline and identify pre-existing hyponatremia.
Timing: Before initiation of therapy.
Renal Function (BUN, Serum Creatinine, eGFR)
Rationale: To assess baseline renal function, as impaired renal function increases hyperkalemia risk.
Timing: Before initiation of therapy.
Blood Pressure
Rationale: To establish baseline and guide therapy for hypertension.
Timing: Before initiation of therapy.
Routine Monitoring
Serum Potassium (K+)
Frequency: Within 1 week of initiation or dose change, then monthly for first few months, then every 3-6 months or as clinically indicated.
Target: 3.5-5.0 mEq/L
Action Threshold: >5.5 mEq/L (consider dose reduction or discontinuation); >6.0 mEq/L (urgent intervention required).
Serum Sodium (Na+)
Frequency: Periodically, especially if symptoms of hyponatremia develop.
Target: 135-145 mEq/L
Action Threshold: <130 mEq/L (investigate cause, consider dose adjustment/discontinuation).
Renal Function (BUN, Serum Creatinine, eGFR)
Frequency: Within 1 week of initiation or dose change, then every 3-6 months or as clinically indicated.
Target: Stable within patient's baseline
Action Threshold: Significant increase in BUN/Creatinine or decrease in eGFR (investigate, consider dose adjustment/discontinuation).
Blood Pressure
Frequency: Regularly, as per hypertension management guidelines.
Target: Individualized, e.g., <130/80 mmHg
Action Threshold: Not at goal (consider dose adjustment or add-on therapy); symptomatic hypotension (reduce dose).
Symptom Monitoring
- Symptoms of hyperkalemia (e.g., muscle weakness, fatigue, paresthesias, bradycardia, irregular heartbeat)
- Symptoms of dehydration/hypovolemia (e.g., dizziness, lightheadedness, dry mouth, excessive thirst)
- Symptoms of hyponatremia (e.g., headache, nausea, confusion, lethargy, seizures)
- Symptoms of gout (joint pain, swelling)
- Symptoms of kidney stones (flank pain, hematuria)
Special Patient Groups
Pregnancy
Category C. Animal studies have shown adverse effects, and there are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus. Diuretics are generally not recommended for routine use in healthy pregnant women with mild edema.
Trimester-Specific Risks:
First Trimester:
Potential for fetal harm, though human data are limited.
Second Trimester:
Potential for fetal harm, though human data are limited.
Third Trimester:
May cause electrolyte disturbances in the mother and fetus. Risk of neonatal jaundice, thrombocytopenia, and other adverse reactions that have occurred in adults.
Lactation
L3 (Moderately safe). Limited human data suggest that triamterene is excreted into breast milk in small amounts. Risk of infant harm appears low, but caution is advised, especially in preterm infants or those with underlying conditions. Monitor infant for electrolyte imbalances.
Infant Risk:
Low risk of infant harm, but monitor for electrolyte disturbances.
Pediatric Use
Safety and efficacy have not been established in pediatric patients. Use is generally not recommended due to the risk of hyperkalemia and lack of sufficient data.
Geriatric Use
Use with caution in elderly patients due to increased risk of hyperkalemia, dehydration, and renal impairment. Start with lower doses and monitor potassium and renal function more frequently. Elderly patients are more susceptible to adverse effects.
Clinical Information
Clinical Pearls
- Always monitor serum potassium levels closely, especially at initiation, with dose changes, or when adding interacting medications (e.g., ACE inhibitors, ARBs, NSAIDs).
- Advise patients to avoid potassium-rich foods and potassium supplements unless specifically instructed by their physician.
- Triamterene can cause blue fluorescence in urine, which is harmless.
- It can cause kidney stones (nephrolithiasis) due to its low solubility and potential to precipitate in the urine, especially at higher doses or in patients with pre-existing stone disease.
- Often used in combination with thiazide diuretics (e.g., hydrochlorothiazide) to mitigate potassium loss associated with thiazides.
- Administer after meals to reduce gastrointestinal upset and potentially improve absorption.
Alternative Therapies
- Other potassium-sparing diuretics (e.g., Spironolactone, Amiloride, Eplerenone)
- Thiazide diuretics (e.g., Hydrochlorothiazide, Chlorthalidone)
- Loop diuretics (e.g., Furosemide, Bumetanide, Torsemide)
- ACE inhibitors
- Angiotensin Receptor Blockers (ARBs)
- Beta-blockers
- Calcium channel blockers
Cost & Coverage
Average Cost:
$10 - $50 per 30 capsules (generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it occurred.