Magnesium Hydroxide

Products

Magnesium hydroxide is commercially available as suspension, chewable tablets, powder with excipients, pure powder and effervescent powder (Magnesia San Pellegrino, Alucol is a fixed combination with aluminum oxide, pure powder from Hänseler), among others. Magnesium hydroxide has been registered in many countries since 1935. In English, the suspension is called “Milk of Magnesia” because it looks similar to milk. “Milk of Magnesia” is monographed in the US Pharmacopeia (USP). It has been used medicinally since the 19th century.

Structure and properties

Magnesium hydroxide (Mg(OH)2, Mr = 58.3 g/mol) exists as a white, fine, amorphous, odorless, and practically tasteless powder that is virtually insoluble in water. It is a base that dissolves in dilute acids. When mixed with water, it forms a suspension.

Effects

Magnesium hydroxide (ATC A02AA04) has acid-neutralizing (basic) and, in higher doses, laxative properties. It reacts with hydrochloric acid in the stomach to form magnesium chloride, which is readily soluble in water, and water. Compared to carbonates, it has the advantage that the gas carbon dioxide (CO2) is not released in the stomach.

  • Mg(OH)2 (magnesium hydroxide) + 2 HCl (hydrochloric acid) MgCl2 (magnesium chloride) + 2 H2O (water)

In the intestine, magnesium hydroxide in higher doses acts as an osmotic and saline laxative, stimulating intestinal transit and secretion of water and electrolytes. The effects occur within about 6 hours. Up to one-third of the magnesium is absorbed and can produce beneficial effects in the body (see under magnesium).

Indications

  • For the symptomatic treatment of gastric burning, acid regurgitation, and digestive disorders such as flatulence.
  • For the symptomatic treatment of constipation.

Dosage

According to the package leaflet and the technical information. The application depends on the product. For example, for acute stomach burning, adults can take 1/4 teaspoon and up to 2 g of the pure powder suspended in water. Take as needed or after meals. High doses have a laxative effect.

Contraindications

  • Hypersensitivity
  • Severe heart failure or renal insufficiency
  • Inflammatory diseases of the colon
  • Occlusive or subocclusive syndrome
  • Painful abdominal syndromes of unknown origin.
  • Obstruction of the bile ducts

In children under 12 years of age, only if prescribed by a doctor. Full precautions can be found in the drug label.

Interactions

Magnesium hydroxide may inhibit the absorption of other active ingredients and should therefore be taken at least two hours apart. Drug-drug interactions have been described, for example, with antibiotics (tetracyclines, quinolones), anticoagulants, and iron.

Adverse effects

Diarrhea, crampy gastrointestinal symptoms, and flatulence may occur at a high dose or in sensitive individuals. High-dose long-term treatment may rarely cause hypokalemia, which increases the risk of cardiac arrhythmias.