Triamterene 100mg 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
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 because other diuretics can cause potassium levels to drop too low.
How to Use This Medicine
Taking Your Medication Correctly
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 better.
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 your urine production, so try to avoid taking it too close to bedtime to prevent sleep disturbances.
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 it in a bathroom or any area that may be exposed to excessive heat or 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. Instead, consult with your pharmacist for guidance on the proper disposal method. Many communities have drug take-back programs that can help you dispose of your medication safely.
What to Do If You Miss a Dose
If you miss a dose, 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 the missed one.
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 better.
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 your urine production, so try to avoid taking it too close to bedtime to prevent sleep disturbances.
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 it in a bathroom or any area that may be exposed to excessive heat or 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. Instead, consult with your pharmacist for guidance on the proper disposal method. Many communities have drug take-back programs that can help you dispose of your medication safely.
What to Do If You Miss a Dose
If you miss a dose, 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 the missed one.
Lifestyle & Tips
- Avoid potassium supplements or salt substitutes that contain potassium, unless specifically instructed by your doctor.
- Limit foods very high in potassium (e.g., bananas, oranges, potatoes, leafy greens, dried fruits) while taking this medication, especially if you have kidney problems or are taking other medications that increase potassium.
- Stay hydrated, especially in hot weather or during exercise, but avoid excessive fluid intake unless advised by your doctor.
- Report any signs of dizziness, lightheadedness, muscle weakness, or irregular heartbeat to your doctor immediately.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
100 mg once daily or 50 mg twice daily
Dose Range:
50 - 300 mg
Condition-Specific Dosing:
edema:
Initial: 100 mg once daily or 50 mg twice daily. Max 300 mg/day. Maintenance: 100-200 mg/day.
hypertension:
Typically used in combination with other antihypertensives. Initial: 50-100 mg/day.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established (use generally not recommended due to limited data and risk of hyperkalemia)
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
Use with caution; monitor electrolytes and renal function closely.
Moderate:
Reduce dose; monitor electrolytes and renal function frequently. Avoid if GFR < 30 mL/min.
Severe:
Contraindicated (GFR < 10 mL/min or anuria) due to high risk of hyperkalemia.
Dialysis:
Contraindicated; not effectively removed by dialysis.
Hepatic Impairment:
Mild:
Use with caution; monitor electrolytes and renal function.
Moderate:
Reduce dose; monitor closely due to increased risk of hyperkalemia and hepatic encephalopathy.
Severe:
Contraindicated due to increased risk of hyperkalemia and hepatic encephalopathy.
Pharmacology
Mechanism of Action
Triamterene is a potassium-sparing diuretic that acts directly on the distal renal tubule. It inhibits the reabsorption of sodium ions 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%
Tmax:
2-6 hours
FoodEffect:
Food may increase the extent of absorption.
Distribution:
Vd:
3.7 L/kg
ProteinBinding:
50-67%
CnssPenetration:
Limited
Elimination:
HalfLife:
1.5-5 hours (parent drug); 10-12 hours (active metabolite)
Clearance:
Not available
ExcretionRoute:
Renal (primarily as metabolites), fecal
Unchanged:
Approximately 20% (renal)
Pharmacodynamics
OnsetOfAction:
2-4 hours
PeakEffect:
6-8 hours
DurationOfAction:
12-16 hours
Safety & Warnings
Side Effects
Serious Side Effects: Seek Medical Attention Immediately
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 or seek medical help right away:
Signs of an allergic reaction, such as:
+ Rash
+ 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. However, many people experience no side effects or only mild ones. If you notice any of the following side effects or any other unusual symptoms, contact your doctor or seek medical help if they bother you or do not go away:
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 questions or concerns about side effects, contact 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 or seek medical help right away:
Signs of an allergic reaction, such as:
+ Rash
+ 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. However, many people experience no side effects or only mild ones. If you notice any of the following side effects or any other unusual symptoms, contact your doctor or seek medical help if they bother you or do not go away:
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 questions or concerns about side effects, contact 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 (hyperkalemia): unusual tiredness, muscle weakness, numbness or tingling, slow or irregular heartbeat.
- Signs of dehydration: severe dizziness, fainting, excessive thirst, very dry mouth, decreased urination.
- Signs of kidney problems: swelling in your feet or ankles, decreased urine output, unusual tiredness.
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. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, such as:
+ High potassium levels
+ Kidney disease
+ Liver disease
+ Inability to urinate
If you are taking any of the following medications:
+ Amiloride
+ Spironolactone
+ Other medications containing triamterene
If you are breast-feeding, as 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. Be sure to describe the allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, such as:
+ High potassium levels
+ Kidney disease
+ Liver disease
+ Inability to urinate
If you are taking any of the following medications:
+ Amiloride
+ Spironolactone
+ Other medications containing triamterene
If you are breast-feeding, as 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 engaging in activities that require alertness, such as driving, wait until you understand how this drug affects you.
If you have diabetes (high blood sugar), consult with your doctor, as this medication may impact blood sugar control. You may need to adjust your diabetes medications. Monitor your blood sugar levels as instructed by your doctor.
Regularly check your blood pressure as advised by your doctor. Additionally, 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 drug.
If you are following a low-salt or salt-free diet, discuss this with your doctor. Also, if you are taking a salt substitute containing potassium, a potassium-sparing diuretic, or a potassium product, consult with your doctor.
Be vigilant for signs of gout attacks while taking this medication. Furthermore, this drug may increase your susceptibility to sunburn. Exercise caution when exposed to the sun, and notify your doctor if you experience easy sunburning while taking this medication.
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, discuss the benefits and risks of using this medication with your doctor.
If you have diabetes (high blood sugar), consult with your doctor, as this medication may impact blood sugar control. You may need to adjust your diabetes medications. Monitor your blood sugar levels as instructed by your doctor.
Regularly check your blood pressure as advised by your doctor. Additionally, 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 drug.
If you are following a low-salt or salt-free diet, discuss this with your doctor. Also, if you are taking a salt substitute containing potassium, a potassium-sparing diuretic, or a potassium product, consult with your doctor.
Be vigilant for signs of gout attacks while taking this medication. Furthermore, this drug may increase your susceptibility to sunburn. Exercise caution when exposed to the sun, and notify your doctor if you experience easy sunburning while taking this medication.
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, discuss the benefits and risks of using this medication with your doctor.
Overdose Information
Overdose Symptoms:
- Electrolyte imbalance (especially hyperkalemia)
- Dehydration
- Hypotension (low blood pressure)
- Cardiac arrhythmias (due to hyperkalemia)
- Metabolic acidosis
- Nausea, vomiting, diarrhea
What to Do:
Seek immediate medical attention. Call 911 or your local poison control center (1-800-222-1222 in the US). Treatment is supportive and may include IV fluids, measures to lower potassium (e.g., insulin/glucose, sodium bicarbonate, calcium gluconate, potassium-binding resins), and monitoring of vital signs and electrolytes.
Drug Interactions
Contraindicated Interactions
- Potassium supplements
- Other potassium-sparing diuretics (e.g., spironolactone, amiloride, eplerenone)
- Salt substitutes containing potassium
Major Interactions
- ACE inhibitors (e.g., enalapril, lisinopril): Increased risk of severe hyperkalemia.
- Angiotensin Receptor Blockers (ARBs) (e.g., valsartan, losartan): Increased risk of severe hyperkalemia.
- NSAIDs (e.g., ibuprofen, naproxen): May reduce diuretic and antihypertensive effects, and increase risk of renal dysfunction and hyperkalemia.
- Lithium: Triamterene may reduce renal clearance of lithium, leading to increased lithium toxicity.
- Cyclosporine: Increased risk of renal dysfunction and hyperkalemia.
- Tacrolimus: Increased risk of renal dysfunction and hyperkalemia.
Moderate Interactions
- Digoxin: Triamterene may increase serum digoxin levels by reducing renal clearance; also, hyperkalemia can reduce digoxin's effects.
- Amantadine: Increased risk of amantadine toxicity.
- Metformin: Increased risk of lactic acidosis in patients with renal impairment.
- Trimethoprim (often in co-trimoxazole): Increased risk of hyperkalemia.
Minor Interactions
- Alcohol: May enhance orthostatic hypotension.
- Barbiturates/Narcotics: May enhance orthostatic hypotension.
Monitoring
Baseline Monitoring
Serum Potassium (K+)
Rationale: To establish baseline and assess risk of hyperkalemia.
Timing: Before initiation of therapy.
Serum Sodium (Na+)
Rationale: To establish baseline and assess risk of hyponatremia.
Timing: Before initiation of therapy.
Blood Urea Nitrogen (BUN) and Serum Creatinine
Rationale: To assess baseline renal function, as impairment increases hyperkalemia risk.
Timing: Before initiation of therapy.
Blood Pressure (BP)
Rationale: To establish baseline and monitor therapeutic effect.
Timing: Before initiation of therapy.
Routine Monitoring
Serum Potassium (K+)
Frequency: Weekly for the first month, then monthly or as clinically indicated, especially after dose changes or initiation of interacting drugs.
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: Monthly or as clinically indicated.
Target: 135-145 mEq/L
Action Threshold: <130 mEq/L (investigate cause, consider dose adjustment).
Blood Urea Nitrogen (BUN) and Serum Creatinine
Frequency: Monthly or as clinically indicated, especially in elderly or those with pre-existing renal impairment.
Target: Normal range for age/sex
Action Threshold: Significant increase from baseline (e.g., >25% increase in creatinine) warrants investigation and dose adjustment.
Blood Pressure (BP)
Frequency: Regularly, as clinically indicated.
Target: Individualized based on treatment goals.
Action Threshold: Failure to achieve target BP or symptomatic hypotension.
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, confusion, nausea, muscle cramps)
- Signs of renal dysfunction (e.g., decreased urine output, edema)
Special Patient Groups
Pregnancy
Category C. Triamterene should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. There are no adequate and well-controlled studies in pregnant women. Animal studies have shown adverse effects at doses higher than human therapeutic doses.
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 imbalances in the mother and fetus. Diuretics are generally not recommended for routine use in healthy pregnant women with mild edema because of the risk of decreased placental perfusion.
Lactation
Triamterene is excreted into breast milk. Due to the potential for serious adverse reactions in the nursing infant (e.g., electrolyte disturbances, reduced milk supply), a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Infant Risk:
Risk L3 (Moderate Concern) - Potential for electrolyte disturbances in infant; potential for decreased milk production in mother.
Pediatric Use
Safety and effectiveness in pediatric patients have not been established. Use is generally not recommended due to limited data and the risk of hyperkalemia, especially in infants and young children who may have immature renal function.
Geriatric Use
Elderly patients are at increased risk of developing hyperkalemia, hyponatremia, and renal impairment due to age-related decline in renal function. Close monitoring of electrolytes and renal function is essential. Start with lower doses and titrate carefully.
Clinical Information
Clinical Pearls
- Triamterene is often used in combination with thiazide diuretics (e.g., hydrochlorothiazide) to counteract the potassium-wasting effect of the thiazide, thereby reducing the risk of hypokalemia.
- The primary risk associated with triamterene is hyperkalemia, especially in patients with renal impairment, diabetes, or those also taking ACE inhibitors, ARBs, NSAIDs, or potassium supplements.
- Patients should be advised to avoid potassium-rich foods and salt substitutes unless specifically instructed by their physician.
- Triamterene may cause blue fluorescence in urine, which is a harmless effect of the drug.
- Cases of kidney stones (nephrolithiasis) composed of triamterene have been reported, particularly with high doses or prolonged use.
Alternative Therapies
- Amiloride (another ENaC inhibitor)
- Spironolactone (aldosterone antagonist, potassium-sparing diuretic)
- Eplerenone (selective aldosterone antagonist, potassium-sparing diuretic)
- Loop diuretics (e.g., furosemide, bumetanide - for more potent diuresis, but potassium-wasting)
- Thiazide diuretics (e.g., hydrochlorothiazide - for hypertension and mild edema, but potassium-wasting)
Cost & Coverage
Average Cost:
$10 - $30 per 30 capsules (generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 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 happened.