What is the recommended dosage of Maalox (aluminum hydroxide/magnesium hydroxide) for adults?

Maalox Dosing for Adults

For symptomatic relief of heartburn and acid indigestion, Maalox is typically dosed at 10-20 mL (or 2-4 tablets) four times daily, taken 1 hour after meals and at bedtime, with higher maintenance doses of up to 3 tablets twice daily used for duodenal ulcer prevention.

Standard Dosing Regimens

Acute Symptom Relief

• The standard dosing pattern involves administration four times daily: 1 hour after the three main meals (morning, midday, and evening) and at bedtime 1
• This q.i.d. dosing schedule (at approximately 1000h, 1400h, 1900h, and 2300h) provides consistent acid neutralization throughout the 24-hour period 1

Duodenal Ulcer Prevention (Maintenance Therapy)

• For preventing duodenal ulcer relapse, Maalox TC at 3 tablets twice daily (morning and bedtime, totaling 162 mmol neutralizing capacity) has proven efficacy comparable to cimetidine 400 mg at bedtime 2
• A lower maintenance dose of 3 tablets at bedtime only (81 mmol) showed intermediate effectiveness but was less effective than the twice-daily regimen 2
• The twice-daily regimen demonstrated a 23% cumulative relapse rate at one year versus 57% with placebo, representing significant clinical benefit 2

Clinical Considerations

Duration of Action

• Maalox provides effective acid neutralization during the first hour post-administration, with significant increases in median intragastric pH compared to placebo 1
• No clinically significant acid rebound occurs during the 2nd and 3rd post-antacid hours or at night, making it safe for regular use 1

Important Drug Interactions

• Maalox must be administered at least 4 hours after fluoroquinolone antibiotics (such as trovafloxacin and moxifloxacin) to avoid significantly reduced antibiotic absorption 3, 4
• When trovafloxacin was given 30 minutes after Maalox, bioavailability was reduced by 66%, but when given 2 hours before Maalox, bioavailability was preserved at 104% 4

Special Population Precautions

• Elderly patients may require dose reduction due to increased risk of side effects with aluminum-containing antacids 3
• Patients with renal impairment should use caution, as aluminum can accumulate with chronic use 3

Safety Profile

Common Adverse Effects

• Diarrhea is the most common side effect, occurring in approximately 12 patients per treatment group at higher maintenance doses 2
• The twice-daily maintenance regimen (3 tablets b.i.d.) led to withdrawal in 12 patients due to adverse events, compared to fewer withdrawals with lower doses 2

Monitoring

• Serum magnesium concentrations remain unchanged with standard dosing 2
• Aluminum concentrations may be slightly elevated at 6 and 12 months but differences are not clinically significant 2