magnesium chloride (12% Mg; 9.8 mEq Mg/g): mag-NEE-zhum KLOR-ide

magnesium citrate (16.2% Mg; 4.4 mEq Mg/g): mag-NEE-zhum SI-trate

Magnesium Gluconate (5.4% Mg; 4.4 mEq/g): mag-NEE-zhum GLOO-con-ate

magnesium hydroxide (41.7% Mg; 34.3 mEq Mg/g): mag-NEE-zhum hye-DROX-ide

magnesium oxide (60.3% Mg; 49.6 mEq Mg/g): mag-NEE-zhum OX-ide

• Treatment/prevention of hypomagnesemia.
• As a:
  • Laxative,
  • Bowel evacuant in preparation for surgical/radiographic procedures.
• Milk of Magnesia has also been used as an antacid.

• Essential for the activity of many enzymes.
• Play an important role in neurotransmission and muscular excitability.
• Are osmotically active in GI tract, drawing water into the lumen and causing peristalsis.

• Replacement in deficiency states.
• Evacuation of the colon.

Absorption: Up to 30% may be absorbed orally.

Distribution: Widely distributed. Cross the placenta and are present in breast milk.

Metabolism/Excretion: Excreted primarily by the kidneys.

Half-life: Unknown.

Contraindicated in:

• Hypermagnesemia
• Hypocalcemia
• Anuria
• Heart block
• OB: Unless used for preterm labor, use during active labor or within 2 hr of delivery may ↑ potential for magnesium toxicity in newborn.

Use Cautiously in:

• Any degree of renal insufficiency.

GI: diarrhea.

Derm: flushing, sweating.

Drug-Drug:

• Potentiates neuromuscular blocking agents.
• May ↓ absorption of fluoroquinolones, nitrofurantoin, and tetracyclines and penicillamine.

Prevention of Deficiency (in mg of Magnesium)

• PO (Adults and Children >10 yr): Adolescent and adult men — 270–400 mg/day; adolescent and adult women — 280–300 mg/day; pregnant women — 320 mg/day; breast-feeding women — 340–355 mg/day.
• PO (Children 7–10 yr): 170 mg/day.
• PO (Children 4–6 yr): 120 mg/day.
• PO (Children birth–3 yr): 40–80 mg/day.

Treatment of Deficiency (Expressed as mg of Magnesium)

• PO (Adults): 200–400 mg/day in 3–4 divided doses.
• PO (Children 6–11 yr): 3–6 mg/kg/day in 3–4 divided doses.

Laxative

• PO (Adults): Magnesium citrate — 240 mL; magnesium hydroxide (Milk of Magnesia) — 30–60 mL single or divided dose or 10–20 mL as concentrate.
• PO (Children 6–12 yr): Magnesium citrate — 100 mL; magnesium hydroxide (Milk of Magnesia) — 15–30 mL single or divided dose.
• PO (Children 2–5 yr): magnesium hydroxide (Milk of Magnesia) — 5–15 mL single or divided dose.

• PO: To prevent tablets entering small intestine in undissolved form, they must be chewed thoroughly before swallowing. Follow with ½ glass of water.
  • Magnesium citrate: Refrigerate solutions to ensure they retain potency and palatability. May be served over ice. Magnesium citrate in an open container will lose carbonation upon standing; this will not affect potency but may reduce palatability.
  • Magnesium hydroxide: Shake solution well before administration.
• Antacid: Administer 1–3 hr after meals and at bedtime.
  • Powder and liquid forms are considered more effective than tablets.
• Laxative: Administer on empty stomach for more rapid results. Follow all oral laxative doses with a full glass of liquid to prevent dehydration and for faster effect. Do not administer at bedtime or late in the day.

magnesium chloride (12% Mg; 9.8 mEq Mg/g): Chloromag, Slo-Mag

magnesium citrate (16.2% Mg; 4.4 mEq Mg/g): Citrate of Magnesia, Citroma

Magnesium Gluconate (5.4% Mg; 4.4 mEq/g): Magtrate, Magonate

magnesium hydroxide (41.7% Mg; 34.3 mEq Mg/g): Dulcolax Magnesia Tablets, Phillips Magnesia Tablets, Phillips Milk of Magnesia, MOM

magnesium oxide (60.3% Mg; 49.6 mEq Mg/g): Mag-Ox 400, Uro-Mag

magnesium citrate (16.2% Mg; 4.4 mEq Mg/g): Citromag

Therapeutic Classification: mineral and electrolyte replacements/supplements, laxatives

Pharmacologic Classification: salines

Magnesium Chloride

(generic available)

• Sustained-release tablets: 535 mg (64 mg magnesium)^OTC;
• Enteric-coated tablets: 833 mg (100 mg magnesium)^OTC;

Magnesium Citrate

(generic available)

• Oral solution: 240-; 296-; and 300-mL bottles (77 mEq magnesium/100 mL)^OTC;

Magnesium Gluconate

(generic available)

• Tablets: 500 mg^OTC;
• Liquid: 54 mg/5 mL^OTC;

Magnesium Hydroxide

(generic available)

• Liquid: 400 mg/5 mL (164 mg magnesium/5 mL)^OTC;
• Concentrated liquid: 800 mg/5 mL (328 mg magnesium/5 mL)^OTC;
• Chewable tablets: 300 mg (130 mg magnesium)^OTC; 600 mg (260 mg magnesium)^OTC;

Magnesium Oxide

(generic available)

• Tablets: 400 mg (241.3 mg magnesium)^OTC;
• Capsules: 140 mg (84.5 mg magnesium)^OTC;

(laxative effect)

• Laxative: Assess patient for abdominal distention, presence of bowel sounds, and usual pattern of bowel function.
  • Assess color, consistency, and amount of stool produced.
• Antacid: Assess for heartburn and indigestion as well as location, duration, character, and precipitating factors of gastric pain.

• Constipation (Indications).

• Advise patient not to take this medication within 2 hr of taking other medications, especially fluoroquinolones, nitrofurantoin, and tetracyclines.
• Antacids: Caution patient to consult health care professional before taking antacids for more than 2 wk if problem is recurring, if relief is not obtained, or if symptoms of gastric bleeding (black, tarry stools; coffee-ground emesis) occur.
• Laxatives: Advise patient that laxatives should be used only for short-term therapy. Long-term therapy may cause electrolyte imbalance and dependence.
  • Encourage patient to use other forms of bowel regulation, such as increasing bulk in the diet, fluid intake, and mobility. Normal bowel habits are individualized; frequency of bowel movement may vary from 3 times/day to 3 times/wk.
  • Advise patient to notify health care professional if unrelieved constipation, rectal bleeding, or symptoms of electrolyte imbalance (muscle cramps or pain, weakness, dizziness) occur.

• Relief of gastric pain and irritation.
• Passage of a soft, formed bowel movement, usually within 3–6 hr.
• Prevention and treatment of magnesium deficiency.