What is Slow-mag (magnesium supplements)?

What is Slow-Mag?

Slow-Mag is a sustained-release magnesium chloride supplement (71.5 mg elemental magnesium per tablet) designed to provide magnesium supplementation while minimizing gastrointestinal side effects through its slow-release formulation.

Product Characteristics

• Slow-Mag contains magnesium chloride in a sustained-release formulation that releases magnesium gradually over time 1
• Each tablet typically provides approximately 71.5 mg of elemental magnesium 1
• The slow-release mechanism is designed to reduce common gastrointestinal side effects like diarrhea and abdominal cramping that occur with standard magnesium supplements 1, 2
• Liquid or dissolvable magnesium products are generally better tolerated than pills for some patients, though sustained-release formulations like Slow-Mag offer an alternative approach 1

Clinical Context for Magnesium Supplementation

Magnesium is the fourth most abundant mineral in the body and serves as a cofactor for over 300 enzymatic reactions 3, 4, 5. Approximately 50% of total body magnesium resides in bone, with most of the remainder inside cells—only 1% circulates in blood 3, 6.

Common Indications for Supplementation

• Chronic idiopathic constipation: The American Gastroenterological Association conditionally recommends magnesium oxide for adults who have failed other therapies, starting at lower doses and increasing based on response 1
• Short bowel syndrome: Patients, particularly those with jejunostomy, experience significant magnesium losses requiring 12-24 mmol daily (480-960 mg elemental magnesium), preferably administered at night when intestinal transit is slowest 1
• Cardiac arrhythmias: For torsades de pointes and polymorphic ventricular tachycardia, IV magnesium 1-2 g bolus is recommended, and maintaining serum magnesium >2 mg/dL helps prevent drug-induced arrhythmias 7, 8
• Refractory hypokalemia: Magnesium deficiency causes dysfunction of potassium transport systems, making hypokalemia resistant to treatment until magnesium is corrected 1

Dosing Considerations

• The Recommended Dietary Allowance is 320 mg/day for women and 420 mg/day for men 1
• The Tolerable Upper Intake Level from supplements is 350 mg/day to avoid adverse effects 1
• For therapeutic use in conditions like short bowel syndrome, doses of 480-960 mg elemental magnesium daily may be required 1
• Divided doses throughout the day help maintain stable levels and reduce gastrointestinal side effects 1

Important Precautions

• Renal insufficiency: Avoid magnesium supplementation in patients with creatinine clearance <20 mL/min due to hypermagnesemia risk 1
• Common side effects: Diarrhea, abdominal distension, and gastrointestinal intolerance are the most frequent adverse effects 1
• Drug interactions: Magnesium can affect absorption of certain medications and should be spaced appropriately 2
• Monitoring: Serum magnesium levels do not accurately reflect total body stores (which are 99% intracellular), so clinical symptoms and response to therapy guide management 8, 6

Clinical Pitfall

The most common error is attempting to correct hypokalemia or treating conditions like short bowel syndrome without first addressing volume depletion and secondary hyperaldosteronism, which causes ongoing renal magnesium wasting despite supplementation 1. Rehydration with IV saline must precede magnesium replacement in these scenarios 1.