Calphron Tablets
It is used to lower high phosphate levels.
Drug Class
Phosphate binder
Pharmacologic Class
Calcium salt
Pregnancy Category
C
FDA Approved
Aug 1989
DEA Schedule
Not Controlled
Overview
What is this medicine?
Calcium acetate is a medication used by people with kidney disease, especially those on dialysis, to help control high levels of phosphate in their blood. It works by binding to the phosphate in the food you eat, preventing your body from absorbing it. This helps keep your bones healthy and prevents other problems caused by too much phosphate.
How to Use This Medicine
Taking Your Medication
To get the most benefit from your medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. Take your medication with meals to help your body absorb it properly. Additionally, be sure to follow the diet plan recommended by your doctor.
Important Administration Instructions
Do not chew your medication. Instead, swallow it whole to ensure you receive the correct dose.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature in a dry place. Avoid storing it in a bathroom, as the moisture and humidity can affect the medication. 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 doctor or pharmacist. Instead, check with your pharmacist for guidance on the best disposal method. You may also want to explore local drug take-back programs in your area.
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 get the most benefit from your medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. Take your medication with meals to help your body absorb it properly. Additionally, be sure to follow the diet plan recommended by your doctor.
Important Administration Instructions
Do not chew your medication. Instead, swallow it whole to ensure you receive the correct dose.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature in a dry place. Avoid storing it in a bathroom, as the moisture and humidity can affect the medication. 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 doctor or pharmacist. Instead, check with your pharmacist for guidance on the best disposal method. You may also want to explore local drug take-back programs in your area.
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 calcium acetate with each meal and snack to ensure it binds to the phosphate in your food.
- Do not crush or chew tablets; swallow them whole.
- Adhere to your prescribed diet, especially regarding phosphate intake, as advised by your doctor or dietitian.
- Avoid taking other medications (especially antibiotics like tetracyclines or fluoroquinolones, and thyroid hormones) at the same time as calcium acetate. Separate doses by at least 1-2 hours.
- Report any symptoms of high calcium (hypercalcemia) to your doctor immediately.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
Initial dose: 1334 mg (2 tablets) with each meal. Adjust dose based on serum phosphate levels.
Dose Range:
667 - 2668 mg
Condition-Specific Dosing:
hyperphosphatemia_ESRD:
Initial dose: 1334 mg (2 tablets) with each meal. Titrate dose every 2-3 weeks to achieve target serum phosphate levels (typically 3.5-5.5 mg/dL). Most patients require 3-4 tablets with each meal. Max dose: 10000 mg/day (15 tablets/day).
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Dosing not well-established; use with caution and individualize based on serum phosphate and calcium levels. Some sources suggest starting at 667 mg (1 tablet) with each meal and titrating.
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment needed, as it's used to treat hyperphosphatemia in renal impairment.
Moderate:
No specific adjustment needed, as it's used to treat hyperphosphatemia in renal impairment.
Severe:
No specific adjustment needed, as it's used to treat hyperphosphatemia in renal impairment (ESRD). Dose is titrated to phosphate levels.
Dialysis:
Primary indication for use in patients on dialysis. Dose is titrated to achieve target serum phosphate levels while monitoring serum calcium.
Hepatic Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed.
Pharmacology
Mechanism of Action
Calcium acetate acts as a phosphate binder. When taken with meals, it combines with dietary phosphate in the gastrointestinal tract to form insoluble calcium phosphate, which is then excreted in the feces. This reduces the absorption of dietary phosphate, thereby lowering serum phosphate concentrations in patients with end-stage renal disease (ESRD).
Pharmacokinetics
Absorption:
Bioavailability:
Variable (approximately 20-30% of calcium is absorbed from the GI tract, but the primary action is local binding)
Tmax:
Not directly applicable for phosphate binding action; calcium absorption Tmax is typically 1-2 hours.
FoodEffect:
Must be taken with meals to bind dietary phosphate effectively.
Distribution:
Vd:
Not available (calcium is widely distributed in the body, primarily in bone)
ProteinBinding:
Approximately 40-45% of serum calcium is protein-bound (primarily to albumin).
CnssPenetration:
Limited (calcium ions do not readily cross the blood-brain barrier in significant amounts).
Elimination:
HalfLife:
Not applicable for calcium as a mineral; serum calcium homeostasis is tightly regulated.
Clearance:
Not applicable; excess calcium is primarily excreted via kidneys and feces.
ExcretionRoute:
Fecal (as insoluble calcium phosphate) and renal (unbound calcium ions).
Unchanged:
Not applicable
Pharmacodynamics
OnsetOfAction:
Within hours of administration (with meals) for phosphate binding.
PeakEffect:
Achieved with consistent dosing over days to weeks as serum phosphate levels stabilize.
DurationOfAction:
Dependent on continued administration with meals.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Attention Immediately
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience 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 high calcium levels, including:
+ Weakness
+ Confusion
+ Feeling tired
+ Headache
+ Upset stomach and vomiting
+ Constipation
+ Bone pain
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 symptoms that bother you or do not go away, contact your doctor or seek medical help:
* Upset stomach
Note: This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, consult your doctor. For medical advice about side effects, you can also contact your doctor. Additionally, you can report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience 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 high calcium levels, including:
+ Weakness
+ Confusion
+ Feeling tired
+ Headache
+ Upset stomach and vomiting
+ Constipation
+ Bone pain
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 symptoms that bother you or do not go away, contact your doctor or seek medical help:
* Upset stomach
Note: This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, consult your doctor. For medical advice about side effects, you can also contact your doctor. Additionally, you can 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:
- Nausea
- Vomiting
- Constipation
- Loss of appetite
- Unusual tiredness or weakness
- Muscle pain or weakness
- Increased thirst or urination
- Confusion
- Irregular heartbeat
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 as a result of the allergy.
If you have elevated calcium levels in your blood.
This medication may interact with other health conditions or medications. To ensure your safety, it is crucial to provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Your existing health problems
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to confirm that it is safe to do so. This will help prevent potential interactions and ensure the safe use of this medication.
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 as a result of the allergy.
If you have elevated calcium levels in your blood.
This medication may interact with other health conditions or medications. To ensure your safety, it is crucial to provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Your existing health problems
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to confirm that it is safe to do so. This will help prevent potential interactions and ensure the safe use of this medication.
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 tests will be necessary, as directed by your doctor, to monitor your condition. Be sure to discuss any concerns or questions with your doctor.
To avoid interactions, do not take calcium supplements or products containing calcium, such as antacids, while taking this medication. Additionally, this drug may interfere with the absorption of other oral medications. If you are taking other medications by mouth, your doctor may recommend taking them at a different time than this medication to ensure their effectiveness.
If you are pregnant, planning to become pregnant, or breastfeeding, it is crucial to consult with your doctor. You and your doctor will need to discuss the potential benefits and risks of this medication to both you and your baby to make an informed decision.
To avoid interactions, do not take calcium supplements or products containing calcium, such as antacids, while taking this medication. Additionally, this drug may interfere with the absorption of other oral medications. If you are taking other medications by mouth, your doctor may recommend taking them at a different time than this medication to ensure their effectiveness.
If you are pregnant, planning to become pregnant, or breastfeeding, it is crucial to consult with your doctor. You and your doctor will need to discuss the potential benefits and risks of this medication to both you and your baby to make an informed decision.
Overdose Information
Overdose Symptoms:
- Severe hypercalcemia (e.g., calcium levels >12 mg/dL)
- Severe constipation
- Abdominal pain
- Nausea, vomiting
- Muscle weakness
- Lethargy, stupor, coma
- Cardiac arrhythmias
- Kidney stones (with chronic overdose)
What to Do:
Discontinue calcium acetate. Hydration with intravenous fluids (saline) to promote calcium excretion. Loop diuretics (e.g., furosemide) may be used after adequate hydration. In severe cases, calcitonin, bisphosphonates, or dialysis may be required. Call 1-800-222-1222 (Poison Control).
Drug Interactions
Major Interactions
- Digitalis glycosides (e.g., digoxin): Hypercalcemia can potentiate digitalis toxicity.
- Tetracyclines (e.g., doxycycline, minocycline): Calcium can chelate tetracyclines, reducing their absorption.
- Fluoroquinolones (e.g., ciprofloxacin, levofloxacin): Calcium can chelate fluoroquinolones, reducing their absorption.
- Bisphosphonates (e.g., alendronate, risedronate): Calcium can interfere with bisphosphonate absorption.
Moderate Interactions
- Thyroid hormones (e.g., levothyroxine): Calcium can interfere with absorption.
- Iron supplements: Calcium can interfere with iron absorption.
- Phosphate supplements: Counteracts the effect of calcium acetate.
- Vitamin D analogs (e.g., calcitriol, paricalcitol, doxercalciferol): Increase calcium absorption, increasing risk of hypercalcemia.
- Thiazide diuretics (e.g., hydrochlorothiazide): Reduce urinary calcium excretion, increasing risk of hypercalcemia.
Minor Interactions
- Other oral medications: Separate administration by at least 1-2 hours if possible to avoid potential binding.
Monitoring
Baseline Monitoring
Serum Phosphate
Rationale: To establish baseline hyperphosphatemia and guide initial dosing.
Timing: Prior to initiation of therapy.
Serum Calcium (total and ionized)
Rationale: To establish baseline calcium levels and assess risk of hypercalcemia.
Timing: Prior to initiation of therapy.
Serum Parathyroid Hormone (PTH)
Rationale: To assess bone and mineral metabolism status in ESRD.
Timing: Prior to initiation of therapy.
Routine Monitoring
Serum Phosphate
Frequency: Every 2-3 weeks during dose titration, then monthly once stable.
Target: Typically 3.5-5.5 mg/dL (KDOQI guidelines).
Action Threshold: If above target, increase dose; if below target or trending low, decrease dose or consider alternative binder.
Serum Calcium (total and ionized)
Frequency: Every 2-3 weeks during dose titration, then monthly once stable.
Target: Total calcium: 8.4-9.5 mg/dL (corrected for albumin); Ionized calcium: 1.12-1.32 mmol/L.
Action Threshold: If hypercalcemia (e.g., corrected total calcium >10.2 mg/dL or ionized calcium >1.32 mmol/L) occurs, reduce or temporarily discontinue calcium acetate, and consider alternative phosphate binder.
Calcium x Phosphate Product
Frequency: Monthly once stable.
Target: <55 mg²/dL².
Action Threshold: If persistently elevated, indicates increased risk of vascular calcification; adjust therapy.
Symptom Monitoring
- Symptoms of hypercalcemia (e.g., nausea, vomiting, constipation, anorexia, muscle weakness, fatigue, polyuria, polydipsia, confusion, cardiac arrhythmias).
- Symptoms of hypophosphatemia (rare with this drug, but possible with excessive binding: muscle weakness, bone pain, confusion).
Special Patient Groups
Pregnancy
Calcium acetate is Pregnancy Category C. It should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Hyperphosphatemia in pregnant women with ESRD needs to be managed, and calcium acetate may be considered, but careful monitoring of maternal calcium levels is crucial to avoid hypercalcemia.
Trimester-Specific Risks:
First Trimester:
Risk of hypercalcemia in the mother, which could potentially affect fetal development. Data are limited.
Second Trimester:
Risk of hypercalcemia in the mother. Fetal calcium homeostasis is tightly regulated by the placenta.
Third Trimester:
Risk of hypercalcemia in the mother. Fetal calcium homeostasis is tightly regulated by the placenta. Excessive maternal calcium could theoretically affect fetal parathyroid function.
Lactation
Calcium is a normal component of breast milk. While calcium acetate is generally considered compatible with breastfeeding when used at therapeutic doses, caution is advised. Monitor the infant for signs of hypercalcemia (e.g., constipation, poor feeding, lethargy) and the mother for hypercalcemia.
Infant Risk:
L3 (Moderate risk) - While calcium is naturally present, excessive maternal calcium intake could theoretically increase infant exposure. Monitor infant for hypercalcemia symptoms.
Pediatric Use
Safety and efficacy in pediatric patients have not been established. Use in children should be approached with caution, with careful individualization of dose based on serum phosphate and calcium levels, and close monitoring for hypercalcemia. Other phosphate binders may be preferred in younger children.
Geriatric Use
No specific dose adjustments are typically required based solely on age. However, elderly patients may be more susceptible to constipation and hypercalcemia. Close monitoring of serum calcium and phosphate levels is essential.
Clinical Information
Clinical Pearls
- Calcium acetate is a first-line phosphate binder due to its efficacy and cost-effectiveness, especially in patients with low or normal serum calcium levels.
- Always administer calcium acetate with meals or snacks to maximize its phosphate-binding capacity.
- Hypercalcemia is the most common and significant side effect. Regular monitoring of serum calcium is critical.
- If hypercalcemia occurs, the dose should be reduced or temporarily discontinued. Consider non-calcium-based phosphate binders if hypercalcemia is persistent or severe.
- Patients should be educated on the importance of dietary phosphate restriction in conjunction with phosphate binder therapy.
- Separate administration of calcium acetate from other medications that can be chelated (e.g., tetracyclines, fluoroquinolones, thyroid hormones) by at least 1-2 hours before or 4-6 hours after.
Alternative Therapies
- Sevelamer (Renvela, Renagel) - non-calcium, non-aluminum phosphate binder
- Lanthanum carbonate (Fosrenol) - non-calcium, non-aluminum phosphate binder
- Ferric citrate (Auryxia) - iron-based phosphate binder, also treats iron deficiency anemia
- Sucroferric oxyhydroxide (Velphoro) - iron-based phosphate binder
- Aluminum hydroxide (rarely used due to aluminum toxicity risk, but effective)
Cost & Coverage
Average Cost:
$20 - $100 per 200 tablets (667 mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (generic), Tier 3 (brand)
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.