Magnesium sulfate

Magnesium repletion during electrolyte correction appears in the AEMPS Sulfato de Magnesio Altan label: hypomagnesaemia and the acute hypokalaemia that goes with it. The link runs both ways – while magnesium stays low, potassium is not retained and a potassium drip achieves nothing. The same label limits the intravenous route: mild to moderate deficiency (1.2–1.7 mg/dL) is covered by diet and oral salts, and the vein is kept for emergencies. Oral magnesium sulfate is rarely used for repletion, because at that dose diarrhoea comes first – citrate, lactate or glycinate serve for longer courses. Common causes of deficiency: loop and thiazide diuretics, months of proton pump inhibitors, alcohol, diarrhoea, refeeding syndrome.

ICD-10: E83.4 · ICD-11: 5C64.41

Eclampsia sits among the indications of the AEMPS Sulfato de Magnesio Altan label. Magnesium goes in intravenously and works not as an antihypertensive but as an anticonvulsant: it stops a fit under way and keeps it from returning. The 2010 Cochrane review compared magnesium with diazepam and phenytoin and found fewer recurrent seizures on magnesium, and in severe pre-eclampsia half as many progressions to eclampsia. Blood pressure is brought down by separate drugs. During the infusion knee reflexes, respiratory rate and urine output are watched: their fading precedes respiratory arrest. The antidote in overdose is intravenous calcium gluconate, which the label states outright. With impaired renal function the dose drops and serum magnesium is checked more often.

ICD-10: O14/O15 · ICD-11: JA24/JA25

In a severe asthma exacerbation, when nebulised salbutamol, ipratropium and a systemic corticosteroid are already in and breathing has not improved, the emergency department adds a single intravenous magnesium sulfate infusion. The 2014 Cochrane review in adults found fewer hospital admissions and better lung function in exactly that subgroup, with no difference in mild to moderate attacks. The Spanish label carries no such indication: it lists torsade de pointes, hypomagnesaemia, parenteral nutrition and eclampsia, so this use sits outside the label and belongs in hospital. The infusion runs under blood pressure monitoring: the label requires it during intravenous administration, and in a breathless patient a falling pressure is easy to miss.

ICD-10: J98.0 · ICD-11: CA23.2

The AEMPS Sulfato de Magnesio Altan label opens its indications with curative treatment of torsade de pointes. This is a particular ventricular tachycardia on a long QT background, and magnesium breaks it even when serum magnesium is normal: it suppresses the early afterdepolarisations that trigger the run. The 2022 ESC guidelines on ventricular arrhythmias hold the same line, adding withdrawal of the QT-prolonging drug, potassium repletion and overdrive pacing for pause-dependent episodes. In monomorphic ventricular tachycardia without QT prolongation magnesium does not do this. The label warns separately about patients on cardiac glycosides: there magnesium goes in with particular caution, above all alongside intravenous calcium salts.

ICD-10: I47.2 · ICD-11: BC71.0