Mag-Tab SR Special Precautions

Patients with renal disease should not take Mag-Tab SR without the advice and direct supervision of their physician. While there are no contraindications to Mag-Tab SR, it should not be prescribed to patients with existing hypermagnesemia. Also some clinicians suggest that when used as laxatives, magnesium supplements are contraindicated in patients with GI obstruction and ileus. The unique lactate formulation produces a low incidence of GI distress or diarrhea. To date, placebo controlled trials of Mag-Tab SR report an incidence of GI side effects no greater than placebo.
Magnesium salts should be used with caution in dehydrated patients, since continued administration may lead to severe dehydration due to fluid loss via the GI tract.
Oral magnesium salts are classified as "pregnancy category B" and oral Mg++ salts are distributed into breast milk. Problems with Mag-Tab SR in pregnancy have not been demonstrated with normal daily recommended dosages. One study in France of 22 pregnant women receiving 2 g/day of magnesium lactate for one month reported no mention of any symptoms of intolerance. It should be noted that IV magnesium has long been the standard of care for pregnant women with eclampsia and no adverse effects have been reported in the medical literature.
Concerning Lactose: Some patients and clinicians have mistakenly been concerned about lactose intolerance with Mag-Tab SR. There is no chemical relationship between lactate and lactose. Lactose is a disaccharide composed of glucose and galactose. The intolerance to lactose is due to the deficiency of the enzyme, lactase. In patients with this deficiency, lactose accumulates in the lumen of the small intestine because there is no mechanism for the absorption of the disaccharide. The large osmotic effect of the unabsorbed lactose leads to an influx of fluid into the small intestine, which leads to the clinical symptoms.
As noted previously, lactate (or lactic acid) is produced during gluconeogenesis by active skeletal muscle and erythrocytes and is a normal body constituent. The lactate is then converted by the enzyme lactic dehydrogenase into glucose by the liver.
Lactose is not used in the manufacture of Mag-Tab SR and thus there should be no problem with patients with lactose intolerance consuming Mag-Tab SR.