Calcium acetate + Magnesium carbonate

Approved Indications:

• Hyperphosphatemia in End-Stage Renal Disease (ESRD):
  Indicated for the control of serum phosphorus levels in adult patients with chronic kidney disease (CKD) on hemodialysis or peritoneal dialysis.
• Adjunct to Dialysis:
  Used as a phosphate binder in conjunction with dietary phosphate restriction to prevent hyperphosphatemia-related complications such as secondary hyperparathyroidism and vascular calcification.

Off-label/Clinically Accepted Uses:

• Mild to moderate hyperphosphatemia in pre-dialysis CKD patients (with caution, under supervision).
• Hyperphosphatemia in pediatric dialysis patients, though limited safety and efficacy data are available.

General Dosage (Adults with ESRD):

• Initial dose: 1 tablet (e.g., Calcium Acetate 435 mg + Magnesium Carbonate 235 mg) three times daily with meals.
• Titration: Adjust dose every 2–3 weeks based on serum phosphorus level, aiming to maintain phosphorus within target range (3.5–5.5 mg/dL).
• Maximum dose: Typically does not exceed 12 tablets/day.

Pediatric Use:

• Not well established. Use only if clearly needed under nephrology supervision.

Elderly:

• Use with caution due to the risk of hypercalcemia or hypermagnesemia.

Renal or Hepatic Impairment:

• Already used in renal failure patients; monitor serum calcium, magnesium, and phosphate regularly.
• Hepatic impairment: No specific dose adjustment needed, but caution advised.

Administration Notes:

• Take with meals to maximize phosphate binding.
• Tablets must be swallowed whole, not crushed or chewed.

Calcium acetate and magnesium carbonate act as phosphate binders in the gastrointestinal tract. They bind dietary phosphate to form insoluble calcium and magnesium phosphate complexes, which are excreted in feces, thereby reducing intestinal phosphate absorption. This results in a lowering of serum phosphate levels, helping to mitigate the risks associated with hyperphosphatemia in patients with chronic kidney disease undergoing dialysis.

• Absorption:
  Minimal systemic absorption of calcium and magnesium occurs from the gastrointestinal tract when used as phosphate binders.
• Distribution:
  Calcium and magnesium are primarily distributed in bone, extracellular fluid, and soft tissues.
• Metabolism:
  Not metabolized; act locally in the GI tract.
• Elimination:
  Excess unbound calcium and magnesium are excreted in feces. Absorbed calcium is excreted via kidneys, while magnesium elimination also occurs through the kidneys.
• Onset of Action:
  Within 1–2 hours after administration with meals.
• Half-life:
  Not applicable due to local (GI tract) action.

• Pregnancy:
  No FDA pregnancy category assigned. Use only if clearly needed. High doses may lead to maternal hypercalcemia or hypermagnesemia, affecting fetal development.
• Lactation:
  Calcium and magnesium are excreted in breast milk. Caution is advised; monitor infant serum calcium/magnesium if large maternal doses are used.
• General Recommendation:
  Use during pregnancy or lactation only when benefits outweigh risks.

• Primary Class: Phosphate Binder
• Sub-class: Calcium-based and magnesium-based non-aluminum phosphate binder

• Known hypersensitivity to calcium acetate, magnesium carbonate, or any excipients
• Hypercalcemia
• Hypermagnesemia
• Severe soft tissue calcification
• Hypophosphatemia
• Active gastrointestinal bleeding or obstruction

• Risk of Hypercalcemia and Hypermagnesemia:
  Especially in patients taking other calcium/magnesium supplements or vitamin D.
• Frequent Serum Monitoring:
  Regular monitoring of serum calcium, magnesium, and phosphate is necessary.
• Gastrointestinal Symptoms:
  May cause nausea, diarrhea, or constipation. Discontinue if severe symptoms occur.
• Use with Caution in Cardiac Patients:
  Elevated magnesium can lead to bradycardia, hypotension, or arrhythmias.
• Aluminum Accumulation Avoidance:
  Preferred over aluminum-based binders due to lower risk of neurotoxicity and bone disease.

Common Side Effects:

• Gastrointestinal:
  Nausea, constipation, diarrhea, flatulence, abdominal discomfort
• Metabolic:
  Hypercalcemia, hypermagnesemia, hypophosphatemia (with overtreatment)

Serious/Rare Side Effects:

• Cardiac arrhythmias (due to high serum calcium or magnesium)
• Soft tissue calcification
• CNS depression, confusion (from hypermagnesemia)
• Muscle weakness or hypotonia

• Calcium/Magnesium Chelation:
  May reduce absorption of tetracyclines, quinolones (e.g., ciprofloxacin), levothyroxine, and iron supplements.
• Vitamin D Analogues:
  May increase risk of hypercalcemia.
• Antacids or Laxatives containing magnesium or calcium:
  Additive effect increasing risk of electrolyte imbalance.
• Bisphosphonates & Sodium Fluoride:
  Decreased absorption due to complex formation.

Mechanism of Interaction:

• Chelation in GI tract, altered pH, or competition at intestinal transporters.

• KDIGO 2024 Guidelines:
  Recommend using calcium-containing phosphate binders cautiously to avoid hypercalcemia, especially in high-risk patients.
• EMA Safety Review:
  Emphasized close monitoring of magnesium levels in elderly patients or those on multiple magnesium sources.

• Store below 30°C.
• Protect from moisture and direct light.
• Keep in original container, tightly closed.
• Do not freeze.
• Keep out of reach of children.