K-Phos 500mg Tablets
It is used to lower the urine's pH.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Electrolyte replacement; Urinary acidifier
Pharmacologic Class
Phosphate salt; Potassium salt
Pregnancy Category
Category C
FDA Approved
Jan 1970
DEA Schedule
Not Controlled
Overview
What is this medicine?
K-Phos 500mg Tablets are a medication that provides your body with two important minerals: potassium and phosphate. These minerals are essential for many body functions, including strong bones, energy production, and proper nerve and muscle function. It is often used to replace low levels of phosphate in the blood or to make your urine more acidic to help prevent certain kidney stones.
How to Use This Medicine
Taking Your Medication Correctly
To ensure you get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your medication and follow the instructions closely.
To prepare your medication, dissolve it in 6 to 8 ounces (180 to 240 mL) of water. Let it soak for 2 to 5 minutes or longer if needed, then stir well. If any pieces remain, crush them and stir again to ensure they are fully dissolved before taking your medication.
Take your medication with meals and at bedtime, or as directed by your doctor.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep the lid tightly closed and store all medications in a safe location, out of the reach of children and pets.
What to Do If You Miss 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 dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses.
To ensure you get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your medication and follow the instructions closely.
To prepare your medication, dissolve it in 6 to 8 ounces (180 to 240 mL) of water. Let it soak for 2 to 5 minutes or longer if needed, then stir well. If any pieces remain, crush them and stir again to ensure they are fully dissolved before taking your medication.
Take your medication with meals and at bedtime, or as directed by your doctor.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding the bathroom. Keep the lid tightly closed and store all medications in a safe location, out of the reach of children and pets.
What to Do If You Miss 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 dose, skip the missed dose and resume your regular schedule. Do not take two doses at the same time or take extra doses.
Lifestyle & Tips
- Take K-Phos with or immediately after meals to reduce stomach upset.
- Swallow tablets whole with a full glass of water. Do not crush or chew unless specifically instructed by your doctor or pharmacist.
- Maintain adequate fluid intake as directed by your healthcare provider.
- Avoid antacids containing aluminum, magnesium, or calcium within 2 hours of taking K-Phos, as they can interfere with its absorption.
- Follow any dietary recommendations provided by your doctor, especially regarding potassium and phosphate intake.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
Dosage is highly individualized based on patient's phosphate and potassium levels, renal function, and clinical condition. Each K-Phos 500mg tablet contains 114 mg (3.7 mmol) of phosphorus and 144 mg (3.7 mEq) of potassium.
Dose Range:
1 - 2 mg
Condition-Specific Dosing:
Hypophosphatemia (mild to moderate):
1 to 2 tablets orally, 3 to 4 times daily, with or after meals.
Urinary Acidification (to prevent calcium stones):
1 to 2 tablets orally, 4 times daily, with or after meals.
Pediatric Dosing
Neonatal:
Not established for this specific product formulation. Dosing for phosphate and potassium in neonates is typically based on elemental content and clinical need, often administered intravenously.
Infant:
Not established for this specific product formulation. Dosing for phosphate and potassium in infants is typically based on elemental content (e.g., 0.5-1 mmol/kg/day of phosphorus) and clinical need.
Child:
Not established for this specific product formulation. Dosing for phosphate and potassium in children is typically based on elemental content (e.g., 0.5-1 mmol/kg/day of phosphorus) and clinical need. Oral doses may be similar to adults but adjusted for weight.
Adolescent:
Dosing may be similar to adult dosing, individualized based on phosphate and potassium levels, renal function, and clinical condition.
Dose Adjustments
Renal Impairment:
Mild:
Use with caution. Monitor serum phosphate, potassium, and calcium levels closely.
Moderate:
Reduced dosage or increased dosing interval may be necessary. Contraindicated if severe renal impairment (CrCl < 30 mL/min) or anuria due to risk of hyperphosphatemia and hyperkalemia.
Severe:
Contraindicated due to high risk of hyperphosphatemia, hyperkalemia, and hypocalcemia.
Dialysis:
Contraindicated in patients with anuria or severe renal impairment. In patients on dialysis, phosphate and potassium supplementation should be carefully managed by a nephrologist, often requiring specific formulations or dietary management rather than general supplementation.
Hepatic Impairment:
Mild:
No specific dosage adjustment required.
Moderate:
No specific dosage adjustment required.
Severe:
No specific dosage adjustment required. However, monitor electrolytes if there are associated renal complications.
Pharmacology
Mechanism of Action
K-Phos 500mg Tablets provide a source of phosphate and potassium. Phosphate is an essential intracellular anion involved in numerous physiological processes, including energy metabolism (ATP), bone mineralization, and buffering systems. Potassium is the major intracellular cation, crucial for nerve impulse transmission, muscle contraction, and maintaining intracellular tonicity. As a urinary acidifier, phosphate ions increase the acidity of urine, which helps to prevent the formation of calcium-containing kidney stones.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 60-70% for oral phosphate; Potassium is well absorbed.
Tmax:
Serum phosphate levels typically peak within 2-6 hours after oral administration.
FoodEffect:
Absorption may be slightly reduced by food, but taking with food is recommended to minimize gastrointestinal upset.
Distribution:
Vd:
Phosphate is widely distributed throughout the body, with approximately 85% found in bone. Potassium is primarily distributed intracellularly.
ProteinBinding:
Phosphate is not significantly protein bound. Potassium is not protein bound.
CnssPenetration:
Limited
Elimination:
HalfLife:
Variable; influenced by renal function and homeostatic mechanisms. Not a standard pharmacokinetic parameter for these ions.
Clearance:
Primarily renal clearance, regulated by parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23) for phosphate, and aldosterone for potassium.
ExcretionRoute:
Renal (urine)
Unchanged:
100% (as ions)
Pharmacodynamics
OnsetOfAction:
Within hours for electrolyte repletion.
PeakEffect:
Within 2-6 hours for serum phosphate levels.
DurationOfAction:
Dependent on renal function and ongoing physiological needs; typically requires multiple daily dosing to maintain levels.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
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 high potassium levels, including:
+ Abnormal heartbeat
+ Confusion
+ Weakness, lightheadedness, or dizziness
+ Feeling like passing out
+ Numbness or tingling
+ Shortness of breath
Signs of low calcium levels, such as:
+ Muscle cramps or spasms
+ Numbness and tingling
+ Seizures
Signs of low magnesium levels, including:
+ Mood changes
+ Muscle pain or weakness
+ Muscle cramps or spasms
+ Seizures
+ Shakiness
+ Decreased appetite
+ Severe stomach upset or vomiting
+ Abnormal heartbeat
Inability to move
Feeling of heaviness in the arms or legs
Chest pain or pressure
Difficulty urinating or changes in urine output
Bone or joint pain
Other Possible Side Effects
As with any medication, you may experience side effects. While many people have no 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 if they bother you or persist, contact your doctor:
Diarrhea
Stomach pain
Upset stomach
* Vomiting
This is not an exhaustive list of possible 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.
While rare, some people may experience severe and potentially life-threatening side effects when taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
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 high potassium levels, including:
+ Abnormal heartbeat
+ Confusion
+ Weakness, lightheadedness, or dizziness
+ Feeling like passing out
+ Numbness or tingling
+ Shortness of breath
Signs of low calcium levels, such as:
+ Muscle cramps or spasms
+ Numbness and tingling
+ Seizures
Signs of low magnesium levels, including:
+ Mood changes
+ Muscle pain or weakness
+ Muscle cramps or spasms
+ Seizures
+ Shakiness
+ Decreased appetite
+ Severe stomach upset or vomiting
+ Abnormal heartbeat
Inability to move
Feeling of heaviness in the arms or legs
Chest pain or pressure
Difficulty urinating or changes in urine output
Bone or joint pain
Other Possible Side Effects
As with any medication, you may experience side effects. While many people have no 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 if they bother you or persist, contact your doctor:
Diarrhea
Stomach pain
Upset stomach
* Vomiting
This is not an exhaustive list of possible 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 weakness, numbness, or tingling in hands or feet
- Irregular heartbeat or palpitations
- Shortness of breath
- Confusion or unusual tiredness
- Seizures
- Signs of low calcium (e.g., muscle cramps, spasms, twitching, numbness around the mouth)
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:
+ Abnormal levels of phosphate, potassium, or calcium in your blood.
+ Infected kidney stones or kidney disease.
This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor.
To ensure your safety, tell your doctor and pharmacist about:
All prescription and over-the-counter medications you are taking.
Any natural products or vitamins you are using.
* All your health problems.
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 symptoms you experienced.
Certain health conditions, including:
+ Abnormal levels of phosphate, potassium, or calcium in your blood.
+ Infected kidney stones or kidney disease.
This list is not exhaustive, and it is crucial to discuss all your health problems and medications with your doctor.
To ensure your safety, tell your doctor and pharmacist about:
All prescription and over-the-counter medications you are taking.
Any natural products or vitamins you are using.
* All your health problems.
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
Important Warnings and Cautions
When taking this medication, it is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are using this drug. Regular blood tests will be necessary, as directed by your doctor, to monitor your condition. Be sure to discuss any concerns or questions with your doctor.
If you are following a low-potassium diet, or if you are taking a salt substitute that contains potassium, a potassium-sparing diuretic, or a potassium product, consult with your doctor to ensure safe use of this medication.
To avoid potential interactions, do not take antacids that contain aluminum, magnesium, or calcium while using this drug.
If you are pregnant, planning to become pregnant, or are breastfeeding, inform your doctor. It is crucial to discuss the benefits and risks of this medication to both you and your baby.
Special Considerations for Lowering Urine pH
If you have a history of kidney stones, be aware that you may pass old stones when starting this medication. Consult with your doctor to discuss any concerns or questions you may have regarding this potential effect.
When taking this medication, it is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are using this drug. Regular blood tests will be necessary, as directed by your doctor, to monitor your condition. Be sure to discuss any concerns or questions with your doctor.
If you are following a low-potassium diet, or if you are taking a salt substitute that contains potassium, a potassium-sparing diuretic, or a potassium product, consult with your doctor to ensure safe use of this medication.
To avoid potential interactions, do not take antacids that contain aluminum, magnesium, or calcium while using this drug.
If you are pregnant, planning to become pregnant, or are breastfeeding, inform your doctor. It is crucial to discuss the benefits and risks of this medication to both you and your baby.
Special Considerations for Lowering Urine pH
If you have a history of kidney stones, be aware that you may pass old stones when starting this medication. Consult with your doctor to discuss any concerns or questions you may have regarding this potential effect.
Overdose Information
Overdose Symptoms:
- Hyperphosphatemia (high phosphate levels): Nausea, vomiting, diarrhea, lethargy, seizures, tetany, ectopic calcification (calcium deposits in soft tissues).
- Hyperkalemia (high potassium levels): Muscle weakness, paresthesias (tingling/numbness), fatigue, bradycardia (slow heart rate), hypotension, characteristic ECG changes (peaked T waves, widened QRS, absent P waves), cardiac arrest.
- Hypocalcemia (low calcium levels): Muscle cramps, spasms, numbness/tingling, tetany, seizures (due to phosphate binding calcium).
What to Do:
Seek immediate medical attention. Call 911 or your local poison control center (e.g., 1-800-222-1222 in the US). Treatment involves discontinuing the medication, intravenous calcium (for hypocalcemia), glucose and insulin, sodium bicarbonate, or potassium-binding resins for hyperkalemia, and potentially dialysis in severe cases.
Drug Interactions
Contraindicated Interactions
- Drugs that increase potassium levels (e.g., potassium-sparing diuretics, ACE inhibitors, ARBs, NSAIDs, cyclosporine, tacrolimus, trimethoprim) in patients with renal impairment or predisposition to hyperkalemia.
- Antacids containing aluminum, magnesium, or calcium (e.g., aluminum hydroxide, magnesium hydroxide, calcium carbonate) due to binding of phosphate and reduced absorption.
Major Interactions
- Vitamin D analogs (e.g., calcitriol, doxercalciferol, paricalcitol): May increase serum phosphate and calcium levels, increasing risk of hyperphosphatemia and hypercalcemia.
- Thiazide diuretics: May decrease urinary calcium excretion, potentially leading to hypercalcemia, which can be exacerbated by phosphate administration if calcium levels are not monitored.
Moderate Interactions
- Corticosteroids: May alter phosphate and calcium metabolism.
- Bisphosphonates: Concurrent use may affect calcium and phosphate balance.
Minor Interactions
- Laxatives (phosphate-containing): Increased risk of hyperphosphatemia.
Monitoring
Baseline Monitoring
Serum Phosphate
Rationale: To establish baseline levels and guide initial dosing for hypophosphatemia.
Timing: Prior to initiation of therapy.
Serum Potassium
Rationale: To establish baseline levels and assess risk of hyperkalemia.
Timing: Prior to initiation of therapy.
Serum Calcium
Rationale: To establish baseline levels and assess risk of hypocalcemia (due to phosphate binding) or hypercalcemia.
Timing: Prior to initiation of therapy.
Renal Function (BUN, Creatinine, eGFR)
Rationale: To assess kidney function, which is critical for phosphate and potassium excretion.
Timing: Prior to initiation of therapy.
Routine Monitoring
Serum Phosphate
Frequency: Daily initially, then 2-3 times per week, or as clinically indicated.
Target: 2.5-4.5 mg/dL (0.81-1.45 mmol/L)
Action Threshold: Below 2.5 mg/dL (consider dose increase); Above 4.5 mg/dL (consider dose reduction/hold).
Serum Potassium
Frequency: Daily initially, then 2-3 times per week, or as clinically indicated.
Target: 3.5-5.0 mEq/L
Action Threshold: Below 3.5 mEq/L (consider dose increase or additional potassium); Above 5.0 mEq/L (consider dose reduction/hold).
Serum Calcium
Frequency: Daily initially, then 2-3 times per week, or as clinically indicated.
Target: 8.5-10.5 mg/dL (2.1-2.6 mmol/L)
Action Threshold: Below 8.5 mg/dL (consider calcium supplementation); Above 10.5 mg/dL (investigate cause).
Renal Function (BUN, Creatinine)
Frequency: Weekly or as clinically indicated, especially in patients with impaired renal function.
Target: Within normal limits for patient's age and baseline.
Action Threshold: Significant increase in BUN/Creatinine (re-evaluate dosing, consider discontinuation).
Urinary pH (for urinary acidification)
Frequency: Periodically, as needed to confirm acidification.
Target: 5.5-6.0
Action Threshold: Above 6.0 (consider dose adjustment).
Symptom Monitoring
- Symptoms of hyperphosphatemia (e.g., nausea, vomiting, diarrhea, lethargy, seizures, tetany, ectopic calcification)
- Symptoms of hyperkalemia (e.g., muscle weakness, paresthesias, fatigue, bradycardia, ECG changes)
- Symptoms of hypocalcemia (e.g., muscle cramps, spasms, numbness/tingling, tetany, seizures)
- Symptoms of gastrointestinal upset (e.g., nausea, vomiting, diarrhea, abdominal pain)
Special Patient Groups
Pregnancy
Use with caution during pregnancy. While phosphate and potassium are essential nutrients, excessive levels or electrolyte imbalances can be harmful. Administer only if clearly needed and the potential benefits outweigh the risks. Close monitoring of maternal electrolyte levels is recommended.
Trimester-Specific Risks:
First Trimester:
Risk of electrolyte imbalance, though generally low with appropriate dosing.
Second Trimester:
Risk of electrolyte imbalance, though generally low with appropriate dosing.
Third Trimester:
Risk of electrolyte imbalance, particularly hyperkalemia or hyperphosphatemia, which could affect fetal development or maternal health. Close monitoring is crucial.
Lactation
Potassium and phosphate are naturally present in breast milk. While generally considered compatible with breastfeeding, caution is advised. Monitor the infant for any signs of electrolyte imbalance (e.g., lethargy, poor feeding, muscle weakness) and monitor maternal electrolyte levels.
Infant Risk:
Low risk with appropriate maternal dosing and monitoring. High maternal doses could potentially lead to electrolyte disturbances in the infant.
Pediatric Use
Use with extreme caution. Dosing must be precisely calculated based on elemental phosphorus and potassium content, body weight, and clinical need. Children, especially infants and neonates, are more susceptible to electrolyte imbalances. Close monitoring of serum phosphate, potassium, and calcium is essential.
Geriatric Use
Geriatric patients may have age-related decline in renal function, increasing their risk of hyperphosphatemia and hyperkalemia. Initiate therapy with lower doses and monitor serum phosphate, potassium, calcium, and renal function more frequently. Avoid use in severe renal impairment.
Clinical Information
Clinical Pearls
- K-Phos 500mg tablets contain 114 mg (3.7 mmol) of phosphorus and 144 mg (3.7 mEq) of potassium. Always clarify the elemental content when prescribing or administering.
- Administer with or immediately after meals to minimize gastrointestinal irritation (e.g., diarrhea, nausea).
- Contraindicated in patients with hyperphosphatemia, hyperkalemia, hypocalcemia, severe renal impairment (CrCl < 30 mL/min), or active urinary tract infection (if used for acidification).
- Monitor serum phosphate, potassium, calcium, and renal function (BUN, creatinine) closely, especially during initiation of therapy and in patients with compromised renal function.
- For urinary acidification, the goal is typically a urinary pH of 5.5-6.0. Monitor urinary pH periodically.
- Educate patients on symptoms of electrolyte imbalance and when to seek medical attention.
Alternative Therapies
- Oral phosphate supplements (e.g., sodium phosphate tablets/solutions)
- Intravenous phosphate (for severe hypophosphatemia)
- Potassium chloride supplements (if only potassium repletion is needed)
- Dietary modifications (e.g., phosphate-rich foods for hypophosphatemia, potassium-rich foods for hypokalemia)
- Other urinary acidifiers (e.g., methionine, ammonium chloride - less common for stone prevention)
Cost & Coverage
Average Cost:
Varies widely, typically $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 this 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 emergency medical attention. When seeking help, be prepared to provide details about the medication, including the amount taken and the time it happened, to facilitate prompt and effective treatment.