K-Phos-2 Tablets
It is used to treat or prevent low phosphate levels.It is used to lower the urine's pH.
Drug Class
Urinary acidifier; Phosphate replacement; Nephrolithiasis agent
Pharmacologic Class
Electrolyte; Mineral supplement
Pregnancy Category
Category C
FDA Approved
Jan 1970
DEA Schedule
Not Controlled
Overview
What is this medicine?
K-Phos-2 is a medication that provides your body with phosphate, potassium, and sodium. It's commonly used to help prevent certain types of kidney stones by making your urine more acidic, and also to replace phosphate if your body levels are too low. It's important to take it exactly as prescribed and to monitor your diet as advised by your doctor.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication with meals and at bedtime, or as directed by your doctor. Swallow your medication with a full glass of water.
Storing and Disposing of Your Medication
Keep your medication at room temperature, away from light and moisture. Store it in a dry place, avoiding bathrooms and areas where children and pets can access it. Keep all medications in a safe location. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so by your doctor or pharmacist. Instead, check with your pharmacist for guidance on proper disposal or participate in a local drug take-back program.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's 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 one.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication with meals and at bedtime, or as directed by your doctor. Swallow your medication with a full glass of water.
Storing and Disposing of Your Medication
Keep your medication at room temperature, away from light and moisture. Store it in a dry place, avoiding bathrooms and areas where children and pets can access it. Keep all medications in a safe location. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so by your doctor or pharmacist. Instead, check with your pharmacist for guidance on proper disposal or participate in a local drug take-back program.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's 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 one.
Lifestyle & Tips
- Take with food to minimize stomach upset.
- Drink plenty of fluids throughout the day as directed by your doctor, especially for kidney stone prevention.
- Adhere to any specific dietary recommendations (e.g., low-sodium, low-potassium, or calcium-restricted diets) provided by your healthcare provider.
- Do not take antacids containing aluminum or magnesium within 2 hours of taking this medication, as they can interfere with absorption.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
1 to 2 tablets four times daily with food
Dose Range:
1 - 8 mg
Condition-Specific Dosing:
urinary_acidification_nephrolithiasis_prevention:
1 to 2 tablets four times daily with food, or as directed by physician. Adjust dose to maintain urine pH between 5.5 and 6.0.
hypophosphatemia:
Individualized based on serum phosphate levels and patient's condition. Typically 1 to 2 tablets 3-4 times daily.
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Use with caution; dosage must be individualized based on weight, serum phosphate levels, and renal function. Consult specialist.
Adolescent:
Use with caution; dosage must be individualized based on weight, serum phosphate levels, and renal function. Consult specialist.
Dose Adjustments
Renal Impairment:
Mild:
Use with caution; monitor serum electrolytes (potassium, sodium, phosphate, calcium) and renal function closely. Dose reduction may be necessary.
Moderate:
Contraindicated or use with extreme caution and significant dose reduction; monitor serum electrolytes and renal function frequently. Risk of hyperkalemia, hypernatremia, hyperphosphatemia.
Severe:
Contraindicated due to risk of hyperkalemia, hypernatremia, hyperphosphatemia, and hypocalcemia.
Dialysis:
Contraindicated. Phosphate and potassium are removed by dialysis, but administration can lead to rapid electrolyte shifts and complications.
Hepatic Impairment:
Mild:
No specific adjustment required, but monitor electrolytes if fluid retention or other complications are present.
Moderate:
No specific adjustment required, but monitor electrolytes if fluid retention or other complications are present.
Severe:
No specific adjustment required, but monitor electrolytes if fluid retention or other complications are present.
Pharmacology
Mechanism of Action
K-Phos-2 provides phosphate, potassium, and sodium ions. Phosphate acts as a urinary acidifier, helping to lower urinary pH and increase the solubility of calcium, thereby inhibiting the formation of calcium-containing kidney stones. It also provides a source of phosphate for patients with hypophosphatemia.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 60-70% for oral phosphate salts
Tmax:
Variable, typically 1-6 hours
FoodEffect:
Food may decrease absorption rate but can reduce gastrointestinal upset.
Distribution:
Vd:
Not readily quantifiable for inorganic ions; widely distributed throughout the body, primarily in bone (85% of total body phosphate).
ProteinBinding:
Minimal for inorganic phosphate
CnssPenetration:
Limited
Elimination:
HalfLife:
Variable, dependent on renal function (normal renal function: 2-6 hours for phosphate)
Clearance:
Primarily renal clearance
ExcretionRoute:
Renal (urine)
Unchanged:
Nearly 100% of absorbed phosphate is excreted unchanged or incorporated into bone/soft tissue.
Pharmacodynamics
OnsetOfAction:
Within hours for urinary acidification; days to weeks for significant changes in stone formation rates.
PeakEffect:
Variable, depends on clinical endpoint (e.g., urine pH, serum phosphate levels).
DurationOfAction:
Dependent on renal function and continuous dosing; urinary acidification effect lasts as long as drug is present.
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 electrolyte problems, including:
+ Mood changes
+ Confusion
+ Muscle pain, cramps, or spasms
+ Weakness
+ Shakiness
+ Change in balance
+ Abnormal heartbeat
+ Seizures
+ Loss of appetite
+ Severe upset stomach or vomiting
A fast heartbeat
Severe headache
Seizures
Dizziness or fainting
Abnormal sensations, such as burning, numbness, or tingling
Shortness of breath, significant weight gain, or swelling in the arms or legs
Feeling extremely tired or weak
Bone or joint pain
Feeling of heaviness in the arms or legs
Decreased urine production
Unusual thirst
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 discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms, contact your doctor for advice:
Diarrhea
Stomach pain
Upset stomach
* Vomiting
This is not an exhaustive list of potential side effects. If you have questions or concerns, 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 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 electrolyte problems, including:
+ Mood changes
+ Confusion
+ Muscle pain, cramps, or spasms
+ Weakness
+ Shakiness
+ Change in balance
+ Abnormal heartbeat
+ Seizures
+ Loss of appetite
+ Severe upset stomach or vomiting
A fast heartbeat
Severe headache
Seizures
Dizziness or fainting
Abnormal sensations, such as burning, numbness, or tingling
Shortness of breath, significant weight gain, or swelling in the arms or legs
Feeling extremely tired or weak
Bone or joint pain
Feeling of heaviness in the arms or legs
Decreased urine production
Unusual thirst
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 discuss any concerns with your doctor. If you experience any of the following side effects or any other unusual symptoms, contact your doctor for advice:
Diarrhea
Stomach pain
Upset stomach
* Vomiting
This is not an exhaustive list of potential side effects. If you have questions or concerns, 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:
- Severe stomach pain, nausea, vomiting, or diarrhea
- Muscle cramps or weakness
- Numbness or tingling in hands or feet
- Fast, slow, or irregular heartbeat
- Swelling of ankles, feet, or hands
- Unusual tiredness or weakness
- Confusion or dizziness
- Increased thirst or urination
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 allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, including:
+ Kidney disease
+ High phosphate levels
+ Infected phosphate stones
This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor.
To ensure your safety, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Natural products and vitamins you are using
* Any health problems you have
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to confirm it is safe for you to do so.
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 allergic reaction you experienced, including any symptoms that occurred.
Certain health conditions, including:
+ Kidney disease
+ High phosphate levels
+ Infected phosphate stones
This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor.
To ensure your safety, provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Natural products and vitamins you are using
* Any health problems you have
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to confirm it is safe for you to do so.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Regular blood work and laboratory tests should be conducted as directed by your doctor to monitor your condition.
If you are currently using a salt substitute containing potassium, a potassium-sparing diuretic, or any potassium product, consult with your doctor to discuss potential interactions. Additionally, if you have a history of kidney stones, you may experience the passage of old stones when initiating this medication; therefore, it is crucial to discuss this with your doctor.
To avoid potential interactions, do not take antacids that contain aluminum, magnesium, or calcium while taking this drug. It is also important to notify your doctor if you are pregnant, planning to become pregnant, or are breastfeeding, as you will need to discuss the benefits and risks of this medication to both you and your baby.
If you are currently using a salt substitute containing potassium, a potassium-sparing diuretic, or any potassium product, consult with your doctor to discuss potential interactions. Additionally, if you have a history of kidney stones, you may experience the passage of old stones when initiating this medication; therefore, it is crucial to discuss this with your doctor.
To avoid potential interactions, do not take antacids that contain aluminum, magnesium, or calcium while taking this drug. It is also important to notify your doctor if you are pregnant, planning to become pregnant, or are breastfeeding, as you will need to discuss the benefits and risks of this medication to both you and your baby.
Overdose Information
Overdose Symptoms:
- Hyperkalemia (muscle weakness, fatigue, irregular heartbeat, confusion, tingling of extremities)
- Hypernatremia (excessive thirst, confusion, lethargy, seizures, coma)
- Hyperphosphatemia (nausea, vomiting, diarrhea, muscle cramps, tetany, calcification of soft tissues, renal failure)
- Hypocalcemia (muscle spasms, cramps, numbness/tingling around mouth or in fingers/toes, seizures)
- Metabolic acidosis (rapid breathing, confusion, lethargy)
What to Do:
Immediately contact emergency services or a poison control center (Call 1-800-222-1222). Treatment involves discontinuing the drug, administering intravenous calcium for hypocalcemia, glucose and insulin for hyperkalemia, sodium polystyrene sulfonate for hyperkalemia, and potentially dialysis in severe cases of electrolyte imbalance or renal failure.
Drug Interactions
Contraindicated Interactions
- Aluminum-containing antacids (e.g., aluminum hydroxide) - bind phosphate, reducing absorption.
- Magnesium-containing antacids (e.g., magnesium hydroxide) - bind phosphate, reducing absorption.
- Potassium-sparing diuretics (e.g., spironolactone, amiloride, triamterene) - increased risk of hyperkalemia.
- ACE inhibitors (e.g., lisinopril, enalapril) - increased risk of hyperkalemia.
- Angiotensin Receptor Blockers (ARBs) (e.g., valsartan, losartan) - increased risk of hyperkalemia.
Major Interactions
- Other potassium supplements - increased risk of hyperkalemia.
- Other sodium supplements - increased risk of hypernatremia.
- Calcium supplements - may reduce phosphate absorption and vice versa; monitor calcium and phosphate levels.
- Vitamin D analogs (e.g., calcitriol) - may increase phosphate and calcium absorption, leading to hyperphosphatemia/hypercalcemia.
Moderate Interactions
- Corticosteroids (e.g., prednisone) - may alter calcium and phosphate metabolism.
- Sucralfate - may bind phosphate, reducing absorption.
- Laxatives containing sodium phosphate - increased risk of hyperphosphatemia and hypernatremia.
Minor Interactions
- None specifically noted for minor interactions beyond general electrolyte monitoring.
Monitoring
Baseline Monitoring
Serum Electrolytes (Potassium, Sodium, Calcium, Phosphate)
Rationale: To establish baseline levels and identify pre-existing imbalances or contraindications.
Timing: Prior to initiation of therapy.
Renal Function (BUN, Creatinine, eGFR)
Rationale: To assess kidney function, as the drug is renally eliminated and renal impairment is a major contraindication/risk factor.
Timing: Prior to initiation of therapy.
Urine pH
Rationale: To establish baseline and guide initial dosing for urinary acidification.
Timing: Prior to initiation of therapy.
Routine Monitoring
Serum Electrolytes (Potassium, Sodium, Calcium, Phosphate)
Frequency: Weekly initially, then monthly or as clinically indicated, especially with dose changes or renal impairment.
Target: Within normal physiological limits (e.g., K: 3.5-5.0 mEq/L, Na: 135-145 mEq/L, Ca: 8.5-10.5 mg/dL, P: 2.5-4.5 mg/dL)
Action Threshold: Any value outside normal range, especially hyperkalemia (>5.5 mEq/L), hypernatremia (>145 mEq/L), hyperphosphatemia (>4.5 mg/dL), or hypocalcemia (<8.5 mg/dL); requires immediate evaluation and dose adjustment/cessation.
Renal Function (BUN, Creatinine)
Frequency: Monthly or as clinically indicated, especially in patients with pre-existing renal impairment or those on concomitant nephrotoxic drugs.
Target: Stable or within acceptable limits for the patient.
Action Threshold: Significant increase in BUN/Creatinine or decrease in eGFR; requires dose adjustment or discontinuation.
Urine pH
Frequency: Daily or several times a week initially, then weekly or as needed to maintain target pH.
Target: 5.5 - 6.0 (for urinary acidification/stone prevention)
Action Threshold: pH consistently outside target range; requires dose adjustment.
Symptom Monitoring
- Nausea
- Vomiting
- Diarrhea
- Abdominal discomfort
- Muscle weakness
- Fatigue
- Confusion
- Irregular heartbeat (palpitations)
- Swelling of ankles/feet (edema)
- Increased thirst
- Increased urination
Special Patient Groups
Pregnancy
Use only if clearly needed and the potential benefits outweigh the potential risks. Monitor maternal electrolyte levels closely.
Trimester-Specific Risks:
First Trimester:
No specific data indicating increased risk of congenital anomalies. Monitor electrolyte balance.
Second Trimester:
Monitor maternal electrolyte balance, especially potassium, sodium, and phosphate.
Third Trimester:
Monitor maternal electrolyte balance, particularly for hyperkalemia or hypernatremia, which could affect fetal heart rate or fluid balance.
Lactation
Potassium, sodium, and phosphate are natural components of breast milk. While generally considered compatible with breastfeeding when used at therapeutic doses, caution is advised. Monitor the infant for signs of electrolyte imbalance (e.g., irritability, poor feeding, changes in bowel habits).
Infant Risk:
Low risk, but theoretical risk of electrolyte imbalance in the infant if maternal doses are high or infant has renal impairment.
Pediatric Use
Use with extreme caution. Dosage must be individualized based on body weight, serum electrolyte levels, and renal function. Pediatric patients, especially infants, are more susceptible to severe electrolyte imbalances. Close monitoring by a specialist is essential.
Geriatric Use
Geriatric patients are at increased risk of renal impairment and concomitant conditions that may predispose them to electrolyte imbalances (hyperkalemia, hypernatremia, hyperphosphatemia, hypocalcemia). Initiate therapy at lower doses and monitor serum electrolytes and renal function frequently.
Clinical Information
Clinical Pearls
- Always take K-Phos-2 with food to minimize gastrointestinal irritation and improve tolerability.
- Strict adherence to monitoring of serum electrolytes (K, Na, Ca, P) and renal function is crucial due to the narrow therapeutic index and potential for severe electrolyte imbalances.
- Urine pH monitoring is essential for patients using K-Phos-2 for urinary acidification to ensure efficacy and prevent over-acidification.
- Patients should be advised to avoid over-the-counter antacids containing aluminum or magnesium, as these can bind phosphate and reduce the effectiveness of K-Phos-2.
- Educate patients on the symptoms of electrolyte imbalances (e.g., muscle weakness, irregular heartbeat, confusion) and when to seek immediate medical attention.
Alternative Therapies
- Potassium Citrate (for urinary alkalinization and prevention of calcium oxalate/uric acid stones)
- Thiazide diuretics (for hypercalciuria and calcium stone prevention)
- Allopurinol (for uric acid stones)
- Oral phosphate supplements (e.g., Fleet Phospho-Soda, but typically not for chronic use due to high sodium/phosphate load)
Cost & Coverage
Average Cost:
$20 - $60 per 100 tablets
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 happened.