Medically reviewed on September 10, 2018

Pronunciation

(mag NEE zhum SIT rate)

Index Terms

• Citrate of Magnesia
• Mag Citrate

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Solution, Oral:

Citroma: 1.745 g/30 mL (296 mL) [contains polyethylene glycol, saccharin sodium; lemon flavor]

Citroma: 1.745 g/30 mL (296 mL) [low sodium; lemon flavor]

Citroma: 1.745 g/30 mL (296 mL) [low sodium; contains fd&c red #40, saccharin sodium; cherry flavor]

GoodSense Magnesium Citrate: 1.745 g/30 mL (296 mL) [contains polyethylene glycol, saccharin sodium]

GoodSense Magnesium Citrate: 1.745 g/30 mL (296 mL) [low sodium; contains alcohol, usp, fd&c red #40, saccharin sodium]

GoodSense Magnesium Citrate: 1.745 g/30 mL (296 mL) [low sodium; contains saccharin sodium; lemon flavor]

Generic: 1.745 g/30 mL (296 mL)

Tablet, Oral:

Generic: 100 mg

Brand Names: U.S.

• Citroma [OTC]
• GoodSense Magnesium Citrate [OTC]

Pharmacologic Category

• Laxative, Saline
• Magnesium Salt

Pharmacology

Promotes bowel evacuation by causing osmotic retention of fluid which distends the colon with increased peristaltic activity

Absorption

Oral: Up to 30%

Excretion

Urine (IOM 1997); feces (as unabsorbed drug)

Onset of Action

Laxative effect: Oral solution: 0.5 to 6 hours

Use: Labeled Indications

Occasional constipation: Treatment of occasional constipation

Off Label Uses

Bowel preparation before colonoscopy

Based on the the American Society for Gastrointestinal and Endoscopy (ASGE) guideline for bowel preparation before colonoscopy, routine use of magnesium citrate as a stand-alone colonoscopy preparation is not recommended for routine use due to limited efficacy data and potential toxicity. A randomized, prospective 2-part study supports use of magnesium citrate as an effective and well tolerated low-volume colonoscopy preparation ^{[Berkelhammer 2002]}.

Contraindications

OTC labeling: When used for self-medication, do not use if on low salt diet

Dosing: Adult

Bowel preparation before colonoscopy (off-label use): Note: This preparation should be avoided in patients with renal impairment, heart failure, decompensated cirrhosis, or baseline electrolyte abnormalities (A-Rahim 2018). There is no standard dosing for administration; the following recommendations are suggested by some experts.

Single-dose, same-day (for afternoon procedures): Oral: 1.5 bottles (450 mL or 15 oz) taken 8 hours prior to procedure, followed by clear liquids (at least three 240 mL glasses) over 2 hours. Four hours prior to the procedure, administer a second 1.5 bottle dose followed by clear liquids (three 240 mL glasses) over 1 hour (A-Rahim 2018).

Split-dose (evening before procedure): Oral: 1 to 1.5 bottles (300 to 450 mL or 10 to 15 oz) in the early evening (ie, between 6 and 8 PM) followed by clear liquids (at least three 240 mL glasses) over 2 hours. Patient should also be given a clear liquid diet the day prior to the procedure. Six hours prior to the colonoscopy, administer a second 1 to 1.5 bottle dose followed by clear liquids (three 240 mL glasses) over 1 hour (ASGE [Saltzman 2015]; A-Rahim 2018).

Laxative: Oral: Solution: 195 to 300 mL given once or in divided doses

Dosing: Geriatric

Refer to adult dosing.

Bowel preparation before colonoscopy (off-label use): The ASGE does not recommend use in the elderly (ASGE [Saltzman 2015]); however, some experts suggest that older patients without comorbidities and who cannot tolerate a higher volume preparation may receive magnesium citrate (A-Rahim 2018).

Dosing: Pediatric

Laxative: Oral: Solution:

Children 2 to 6 years: 60 to 90 mL given once or in divided doses (maximum: 90 mL/24 hours)

Children 6 to 12 years: 90 to 210 mL given once or in divided doses

Children ≥12 years and Adolescents: Refer to adult dosing.

Dosing: Renal Impairment

No dosage adjustment provided in manufacturer’s labeling; however, magnesium is renally excreted. Use caution; accumulation of magnesium in renal impairment may lead to magnesium toxicity.

Administration

Oral: To increase palatability, chill the solution prior to administration. Administer each dose with 8 oz (240 mL) of water.

Dietary Considerations

Some products may contain potassium and/or sodium.

Storage

Store at 15°C to 30°C (59°F to 86°F).

Oral solution: Discard remaining medication within 24 hours of opening.

Drug Interactions

Alfacalcidol: May increase the serum concentration of Magnesium Salts. Consider therapy modification

Alpha-Lipoic Acid: Magnesium Salts may decrease the absorption of Alpha-Lipoic Acid. Alpha-Lipoic Acid may decrease the absorption of Magnesium Salts. Consider therapy modification

Aluminum Hydroxide: Citric Acid Derivatives may increase the absorption of Aluminum Hydroxide. Monitor therapy

Bisphosphonate Derivatives: Magnesium Salts may decrease the serum concentration of Bisphosphonate Derivatives. Management: Avoid administration of oral magnesium salts within: 2 hours before or after tiludronate/clodronate/etidronate; 60 minutes after oral ibandronate; or 30 minutes after alendronate/risedronate. Exceptions: Pamidronate; Zoledronic Acid. Consider therapy modification

Calcitriol (Systemic): May increase the serum concentration of Magnesium Salts. Management: Consider using a non-magnesium-containing antacid or phosphate-binding product in patients also receiving calcitriol. If magnesium-containing products must be used with calcitriol, serum magnesium concentrations should be monitored closely. Consider therapy modification

Calcium Channel Blockers: May enhance the adverse/toxic effect of Magnesium Salts. Magnesium Salts may enhance the hypotensive effect of Calcium Channel Blockers. Monitor therapy

Calcium Polystyrene Sulfonate: Laxatives (Magnesium Containing) may enhance the adverse/toxic effect of Calcium Polystyrene Sulfonate. More specifically, concomitant use of calcium polystyrene sulfonate with magnesium-containing laxatives may result in metabolic alkalosis or with sorbitol may result in intestinal necrosis. Management: Avoid concomitant use of calcium polystyrene sulfonate (rectal or oral) and magnesium-containing laxatives. Avoid combination

Deferiprone: Magnesium Salts may decrease the serum concentration of Deferiprone. Management: Separate administration of deferiprone and oral medications or supplements that contain polyvalent cations by at least 4 hours. Consider therapy modification

Dolutegravir: Magnesium Salts may decrease the serum concentration of Dolutegravir. Management: Administer dolutegravir at least 2 hours before or 6 hours after oral magnesium salts. Administer the dolutegravir/rilpivirine combination product at least 4 hours before or 6 hours after oral magnesium salts. Consider therapy modification

Doxercalciferol: May enhance the hypermagnesemic effect of Magnesium Salts. Management: Consider using a non-magnesium-containing antacid or phosphate-binding product in patients also receiving doxercalciferol. If magnesium-containing products must be used with doxercalciferol, serum magnesium concentrations should be monitored closely. Consider therapy modification

Eltrombopag: Magnesium Salts may decrease the serum concentration of Eltrombopag. Management: Administer eltrombopag at least 2 hours before or 4 hours after oral administration of any magnesium-containing product. Consider therapy modification

Gabapentin: Magnesium Salts may enhance the CNS depressant effect of Gabapentin. Specifically, high dose intravenous/epidural magnesium sulfate may enhance the CNS depressant effects of gabapentin. Magnesium Salts may decrease the serum concentration of Gabapentin. Management: Administer gabapentin at least 2 hours after use of a magnesium-containing antacid. Monitor patients closely for evidence of reduced response to gabapentin therapy. Monitor for CNS depression if high dose IV/epidural magnesium sulfate is used. Consider therapy modification

Levothyroxine: Magnesium Salts may decrease the serum concentration of Levothyroxine. Management: Separate administration of oral levothyroxine and oral magnesium salts by at least 4 hours. Consider therapy modification

Multivitamins/Fluoride (with ADE): Magnesium Salts may decrease the serum concentration of Multivitamins/Fluoride (with ADE). Specifically, magnesium salts may decrease fluoride absorption. Management: To avoid this potential interaction separate the administration of magnesium salts from administration of a fluoride-containing product by at least 1 hour. Consider therapy modification

Mycophenolate: Magnesium Salts may decrease the serum concentration of Mycophenolate. Management: Separate doses of mycophenolate and oral magnesium salts. Monitor for reduced effects of mycophenolate if taken concomitant with oral magnesium salts. Consider therapy modification

Neuromuscular-Blocking Agents: Magnesium Salts may enhance the neuromuscular-blocking effect of Neuromuscular-Blocking Agents. Monitor therapy

PenicillAMINE: Magnesium Salts may increase the serum concentration of PenicillAMINE. Management: Separate the administration of penicillamine and oral magnesium salts by at least 1 hour. Consider therapy modification

Phosphate Supplements: Magnesium Salts may decrease the serum concentration of Phosphate Supplements. Management: Administer oral phosphate supplements as far apart from the administration of an oral magnesium salt as possible to minimize the significance of this interaction. Exceptions: Sodium Glycerophosphate Pentahydrate. Consider therapy modification

Quinolones: Magnesium Salts may decrease the serum concentration of Quinolones. Management: Administer oral quinolones several hours before (4 h for moxi/pe/spar-, 2 h for others) or after (8 h for moxi-, 6 h for cipro/dela-, 4 h for lome/pe-, 3 h for gemi-, and 2 h for levo-, nor-, or ofloxacin or nalidixic acid) oral magnesium salts. Exceptions: LevoFLOXacin (Oral Inhalation). Consider therapy modification

Raltegravir: Magnesium Salts may decrease the serum concentration of Raltegravir. Management: Avoid the use of oral / enteral magnesium salts with raltegravir. No dose separation schedule has been established that adequately reduces the magnitude of interaction. Avoid combination

Sodium Polystyrene Sulfonate: Laxatives (Magnesium Containing) may enhance the adverse/toxic effect of Sodium Polystyrene Sulfonate. More specifically, concomitant use of sodium polystyrene sulfonate with magnesium-containing laxatives may result in metabolic alkalosis or with sorbitol may result in intestinal necrosis. Management: Avoid concomitant use of sodium polystyrene sulfonate (rectal or oral) and magnesium-containing laxatives. Avoid combination

Tetracyclines: Magnesium Salts may decrease the absorption of Tetracyclines. Only applicable to oral preparations of each agent. Exceptions: Eravacycline. Consider therapy modification

Trientine: May decrease the serum concentration of Magnesium Salts. Magnesium Salts may decrease the serum concentration of Trientine. Consider therapy modification

Test Interactions

Increased magnesium; decreased protein, decreased calcium (S), decreased potassium (S)

Adverse Reactions

Frequency not defined: Gastrointestinal: Abdominal pain, diarrhea, flatulence, nausea, vomiting

Warnings/Precautions

Disease-related concerns:

• Constipation (self-medication, OTC use): Appropriate use: For occasional use only; serious side effects may occur with prolonged use. For use only under the supervision of a physician in patients with kidney dysfunction, sodium- or magnesium-restricted diets, abdominal pain/nausea/vomiting, with a sudden change in bowel habits which has persisted for >2 weeks, or use of a laxative for >1 week. If rectal bleeding develops or a bowel movement does not occur after use, discontinue use and consult a health care provider.

• Neuromuscular disease: Use with extreme caution in patients with myasthenia gravis or other neuromuscular disease.

• Renal impairment: Use with caution in patients with renal impairment; accumulation of magnesium may lead to magnesium intoxication.

Pregnancy Considerations

Magnesium crosses the placenta; serum concentrations in the fetus are similar to those in the mother (Idama 1998; Osada 2002). The American Gastroenterological Association considers the use of magnesium citrate as a laxative to be low risk in pregnancy, but long term use should be avoided (not the preferred treatment of chronic constipation) (Mahadevan 2006).

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience flatulence. Have patient report immediately to prescriber severe abdominal pain or severe diarrhea (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.

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