magnesium citrate: mag-NEE-zhum SI -trate

magnesium hydroxide: mag-NEE-zhum hye-DROX-ide

• As a:
  • Laxative,
  • Bowel evacuant in preparation for surgical/radiographic procedures.

• 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
• Active labor or within 2 hr of delivery (unless used for preterm labor).

Use Cautiously in:

• Any degree of renal insufficiency.

GI: diarrhea.

Derm: flushing, sweating.

Drug-Drug:

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

• 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.
• 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 citrate: Citrate of Magnesia, Citroma

magnesium hydroxide: Dulcolax Magnesia Tablets, Phillips Magnesia Tablets, Phillips Milk of Magnesia, MOM

magnesium citrate: Citromag

Therapeutic Classification: laxatives

Magnesium Citrate

(generic available)

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

( 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.

• Constipation (Indications).

• Advise patient not to take this medication within 2 hr of taking other medications, especially fluoroquinolones, nitrofurantoin, and tetracyclines.
• 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.

• Passage of a soft, formed bowel movement, usually within 3–6 hr.