31.1 Antacids

Antacids are your stomach's best friend when it comes to taming that fiery heartburn. These over-the-counter heroes work by neutralizing excess stomach acid, providing quick relief from the burn. But not all antacids are created equal.

Different antacid ingredients have their own superpowers and quirks. Some work fast but don't last long, while others take their time but stick around. It's important to know the pros and cons of each to find your perfect acid-fighting match.

Antacids for Treating Hyperacidity and Gastrointestinal Disorders

Mechanism of action and common ingredients in antacids

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• Antacids neutralize excess stomach acid (HCl) by raising the pH of stomach contents providing symptomatic relief from hyperacidity and related conditions (heartburn, dyspepsia, peptic ulcers)
• Common ingredients include:
  • Calcium carbonate (CaCO3) found in Tums, Rolaids, Maalox
  • Magnesium hydroxide (Mg(OH)2) found in Milk of Magnesia, Maalox
  • Aluminum hydroxide (Al(OH)3) found in Maalox, Mylanta, Gaviscon
  • Sodium bicarbonate (NaHCO3) found in Alka-Seltzer, baking soda

Advantages and disadvantages of different antacid formulations

• Calcium carbonate antacids have rapid onset of action, high acid-neutralizing capacity, and provide calcium supplementation but may cause acid rebound, constipation, and hypercalcemia with excessive use
• Magnesium hydroxide antacids have rapid onset of action and laxative effect useful for patients with constipation but may cause acid rebound and diarrhea
• Aluminum hydroxide antacids have prolonged duration of action and minimal systemic absorption but slow onset of action, may cause constipation and phosphate depletion with long-term use
• Combination antacids (Maalox, Mylanta) balance side effects of individual components (constipation, diarrhea) but may cause drug interactions and altered absorption of other medications

Drug interactions and adverse effects of antacids

• Antacids can alter absorption of many drugs by changing stomach pH or binding to them (tetracyclines, fluoroquinolones, iron supplements, levothyroxine)
  • Separate administration of antacids and other medications by at least 2 hours to minimize interactions
• Adverse effects include:
  • Constipation (calcium carbonate, aluminum hydroxide)
  • Diarrhea (magnesium hydroxide)
  • Electrolyte imbalances with excessive use
    1. Hypercalcemia (calcium carbonate)
    2. Hypermagnesemia (magnesium hydroxide)
    3. Hypokalemia and hypochloremic metabolic alkalosis (sodium bicarbonate)
  • Aluminum toxicity with long-term use in patients with renal impairment

Patient education for administering antacids

• Timing of administration: take antacids at least 1 hour after meals and at bedtime for optimal symptom relief, take antacids at least 2 hours apart from other drugs
• Dosage: follow product label instructions or healthcare provider's recommendations, do not exceed recommended daily dose to avoid adverse effects
• Additional education:
  • Encourage lifestyle modifications to reduce hyperacidity symptoms (avoid trigger foods, eat smaller meals, elevate head of bed)
  • Advise patients to seek medical attention if symptoms persist or worsen despite antacid use as this may indicate a more serious underlying condition
  • Inform patients about potential side effects and when to report them to their healthcare provider