Cardiovascular drugs: Digoxin and loop diuretics are magnesiuretic drugs and may affect magnesium balance. Magnesium deficiency may enhance digoxin toxicity.
As magnesium and other medicinal products may mutually influence each other's absorption, a time interval of 2 to 3 hours should generally be respected if possible.
This specifically applies to:
• Cellulose sodium phosphate; edetate disodium: concurrent use with magnesium supplements may result in binding of magnesium; patients should be advised not to take magnesium supplements within 1 hour of cellulose sodium phosphate or edentate disodium.
• Fluorides and tetracycline: if they must be used, the doses must be separated by 2 to 3 hours or more to prevent their admixture in the gut.
• Aminoquinolines, quinidine and quinidine derivatives, nitrofurantoin, penicillamine, iron, bisphosphonates (such as alendronate and risedronate), eltrombopag, nitroxoline: to avoid impairment of absorption, magnesium preparations should be taken 3 to 4 hours before or after the administration of those drugs.
Because of increased magnesium losses, a dose adjustment of magnesium may be necessary when taking the following substances:
• Aminoglycoside antibiotics, cisplatin and ciclosporin A
• Diuretics (such as thiazide and furosemide),
• EGF-receptor antagonists (such as cetuximab and erlotinib),
• proton pump inhibitors (such as omeprazole and pantoprazole) and
• viral DNA polymerases-inhibiting foscarnet, pentamidine, rapamycin and amphotericin B
In addition, other electrolyte disturbances, such as hypokalaemia and hypocalcaemia, should be looked for in these patients with hypomagnesaemia.
For further information on mechanisms of drug interactions see section 5.2.