BNF for Children 2011-2012

474 9.5.2 Phosphorus BNFC 2011–20129 Nutrition and bloodChild 1 month–12 years 0.2 mmol/kg Mg 2þ(50 mg/kg magnesium sulphate) 12 hourly asnecessaryChild 12–18 years 4 mmol Mg 2þ (1 g magnesiumsulphate) 12 hourly as necessaryTorsade de pointes (consult local guidelines). By intravenous injection over 10–15 minutesChild 1 month–18 years 0.1–0.2 mmol/kg (25–50 mg/kg magnesium sulphate); max. 8 mmol (2 gmagnesium sulphate); dose repeated once ifnecessaryPersistent pulmonary hypertension section 2.5.1Severe acute asthma section 3.1Administration Dilute to 10% (100 mg in 1 mL) withGlucose 5 or 10%, Sodium Chloride 0.45 or 0.9% orGlucose and Sodium Chloride combinations. Up to20% solution may be given in fluid restriction. Rate ofadministration should not exceed 10 mg/kg/minuteof magnesium sulphateNote Magnesium sulphate 1 g equivalent to Mg 2þ approx.4 mmolMagnesium Sulphate (Non-proprietary) AInjection, magnesium sulphate 20% (Mg 2þ approx.0.8 mmol/mL), net price 20-mL (4-g) amp = £2.75;50% (Mg 2þ approx. 2 mmol/mL), 2-mL (1-g) amp =£2.39, 4-mL (2-g) prefilled syringe = £7.39; 5-mL (2.5-g) amp = £3.00, 10-mL (5-g) amp = 69p; 10-mL (5-g)prefilled syringe = £4.95Brands include Minijet c Magnesium Sulphate 50%MAGNESIUM-L-ASPARTATECautions see under Magnesium SulphateRenal impairment avoid or reduce dose; increasedrisk of toxicitySide-effects see under Magnesium Sulphate; alsodiarrhoeaLicensed use classified as a Food for Special MedicalPurposes for use in children over 2 yearsIndication and doseHypomagnesaemia. By mouthChild 1 month–2 years initially 0.2 mmol/kg ofMg 2þ 3 times daily dissolved in water, doseadjusted as requiredChild 2–10 years half a sachet (5 mmol Mg 2þ )daily dissolved in 100 mL of water, dose adjustedas requiredChild 10–18 years one sachet (10 mmol Mg 2þ )daily dissolved in 200 mL of water, dose adjustedas requiredMagnaspartate c (KoRa)Oral powder, magnesium-L-aspartate 6.5 g (10 mmolMg 2þ )/sachet, net price 10-sachet pack = £7.95Excipients include sucroseMAGNESIUM GLYCEROPHOSPHATECautions see under Magnesium SulphateRenal impairment avoid or reduce dose; increasedrisk of toxicitySide-effects see under Magnesium Sulphate; alsodiarrhoeaLicensed use not licensedIndication and doseHypomagnesaemia. By mouthChild 1 month–12 years initially 0.2 mmol/kgMg 2þ 3 times daily, dose adjusted as requiredChild 12–18 years initially 4–8 mmol Mg 2þ 3times daily, dose adjusted as requiredAdministration tablets may be dispersed in waterMagnesium Glycerophosphate (Non-proprietary)Tablets, magnesium glycerophosphate 1 g (approximatelymagnesium 97 mg or Mg 2þ 4 mmol)Available from ‘special-order’ manufacturers or specialistimporting companies, see p. 809Liquid, magnesium glycerophosphate 250 mg/mL(approximately magnesium 24.25 mg or Mg 2þ1 mmol/mL)Available from ‘special-order’ manufacturers or specialistimporting companies, see p. 809Extemporaneous formulations available seeExtemporaneous Preparations, p. 69.5.2 Phosphorus9.5.2.1 Phosphate supplements9.5.2.2 Phosphate-binding agents9.5.2.1 Phosphate supplementsOral phosphate supplements may be required in additionto vitamin D in children with hypophosphataemicvitamin D-resistant rickets (section 9.6.4). Diarrhoea is acommon side-effect and should prompt a reduction indosage.Phosphate infusion is occasionally needed in phosphatedeficiency arising from use of parenteral nutrition deficientin phosphate supplements; phosphate depletionalso occurs in severe diabetic ketoacidosis. It is difficultto provide detailed guidelines for the treatment of severehypophosphatemia because the extent of total bodydeficits and response to therapy are difficult to predict.High doses of phosphate may result in a transient serumelevation followed by redistribution into intracellularcompartments or bone tissue; excessive doses maycause hypocalcaemia and metastatic calcification. It isessential to monitor plasma concentrations of calcium,phosphate, potassium and other electrolytes. It isrecommended that severe hypophosphataemia be treatedintravenously as large doses of oral phosphate maycause diarrhoea; intestinal absorption may be unreliableand dose adjustment may be necessary.