Aluminum and Magnesium Hydroxide Antacid Dosing
For adults, the standard dose of combined aluminum and magnesium hydroxide antacid is 1.425-2.85 g of aluminum hydroxide daily (typically divided into multiple doses), often combined with magnesium hydroxide in ratios ranging from 1:0.6 to 1:3.5 to balance the constipating effects of aluminum with the laxative effects of magnesium. 1, 2
Adult Dosing
Standard therapeutic dosing:
- Aluminum hydroxide: 1.425-2.85 g per day in divided doses for phosphate binding in chronic kidney disease 1
- Combined formulations: The ratio of aluminum oxide to magnesium hydroxide typically ranges from 1:0.6 to 1:3.5, allowing selection based on desired gastrointestinal effects 2
- For heartburn/reflux: Two chewable tablets of high-potency aluminum/magnesium hydroxide formulations provide effective esophageal pH control with onset of action within minutes and duration of approximately 60-82 minutes 3
Important considerations for adults:
- Aluminum hydroxide has extensive clinical experience in CKD and ESRD, though aluminum accumulates in bone and neural tissue with long-term use 1
- The bioavailability of mycophenolic acid may be reduced by aluminum/magnesium hydroxide-containing antacids, requiring dose separation 1
- Contraindication: Aluminum hydroxide is not recommended when GFR < 35 mL/min/1.73 m² due to accumulation risk 1
Pediatric Dosing
For gastroesophageal reflux in children:
- 700 mmol/1.73 m²/day of combined aluminum and magnesium hydroxide administered for 8 weeks showed significant efficacy in reducing reflux episodes 4
- This translates to approximately 15-20 mL of standard suspension (containing ~200-400 mg aluminum hydroxide and 200-400 mg magnesium hydroxide per 5 mL) given 3-4 times daily for a typical child 4
Critical pediatric safety considerations:
- Aluminum-based phosphate binders should be limited to 1-2 days in children to avoid cumulative aluminum toxicity 1
- Aluminum hydroxide dose: 50-150 mg/kg/day divided every 6 hours for hyperphosphatemia, but use should be restricted to 1-2 days maximum 1
- Alternative phosphate binders (calcium carbonate, sevelamer, lanthanum) should be considered for longer-term use in children 1
Administration Guidelines
Optimal timing and preparation:
- Antacids should be taken 1 hour after meals for heartburn/reflux to maximize esophageal contact time 3
- Shake suspensions well before use to ensure uniform distribution of active ingredients 2
- Separate administration from other medications by at least 2 hours to avoid drug interactions, particularly with antibiotics, bisphosphonates, and immunosuppressants 1
Formulation considerations:
- Aluminum/magnesium hydroxide combinations demonstrate superior esophageal pH control compared to calcium carbonate, with faster onset and longer duration of action 3
- High-potency formulations provide more consistent acid-neutralizing capacity with smaller volumes 2, 3
Critical Safety Warnings
Absolute contraindications:
- Severe renal impairment (GFR < 35 mL/min/1.73 m²) due to aluminum accumulation risk 1
- Concurrent use with azathioprine and allopurinol requires extreme caution or avoidance 1
Monitoring requirements:
- Assess renal function before initiating aluminum-containing antacids 1
- Monitor for signs of aluminum toxicity with prolonged use: encephalopathy, bone disease, anemia 1
- Watch for gastrointestinal effects: constipation (aluminum) versus diarrhea (magnesium) 2
Drug interactions requiring dose adjustment:
- Mycophenolate mofetil bioavailability reduced; separate dosing by 2+ hours 1
- Bisphosphonates: avoid concurrent administration 1
- Fluoroquinolones and tetracyclines: significantly reduced absorption 1
Duration of Therapy
Short-term use (preferred):
- For acute symptoms: use as needed, typically not exceeding 2 weeks without medical evaluation 3
- For hyperphosphatemia in children: limit to 1-2 days maximum to prevent aluminum toxicity 1
Long-term considerations: