phosphate supplements

CLINICAL USE

Hypophosphataemia

DOSE IN NORMAL RENAL FUNCTION

Oral: According to response; maximum oral dose =100 mmol in 24 hoursIV: 9–30 mmol/day (maximum 500 micromols/kg in critically ill patients); see ‘Other Information’

PHARMACOKINETICS

Molecular weight :94–97 (Phosphate)

%Protein binding :No data

%Excreted unchanged in urine : High

Volume of distribution (L/kg) :No data

half-life – normal/ESRD (hrs) :No data

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function

10 to 20 : Dose as in normal renal function

<10 : Dose as in normal renal function

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Dialysed. Dose as in normal renal function

HD :Dialysed. Dose as in normal renal function

HDF/high flux :Dialysed. Dose as in normal renal function

CAV/VVHD :Dialysed. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugsAvoid insoluble incompatibilities, e.g. calcium salts

ADMINISTRATION

Reconstition

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Route

IV, oral

Rate of Administration

Usually over 6–12 hours

Comments

Phosphate polyfusor: give undiluted over 24 hours, peripherallyAddiphos: peripherally – give each vial (20 mL) diluted to 250–500 mL with glucose 5% over 6–12 hours, minimum volume 100 mL (UK Critical Care Group, Minimum Infusion Volumes for fluid restricted critically ill patients, 3rd Edition, 2006); centrally – 20 mL vial made up to 60 mL with glucose 5% over 6–8 hours via syringe driver

OTHER INFORMATION

Oral dosing: Phosphate Sandoz – 16.1 mmol phosphate, 20.4 mmol sodium, 3.1 mmol potassium per tabletIV dosing: (i) Phosphate Polyfusor (500 mL) containing: 50 mmol phosphate, 81 mmol sodium, 9.5 mmol potassium. (ii) Addiphos (20 mL) containing: 40 mmol phosphate, 30 mmol sodium, 30 mmol potassium

HD : patients usually need 15–20 mmol/ day in TPNCAV/VVHD patients usually need 30– 40 mmol/dayDuring IV phosphate replacement, serum calcium, potassium and phosphate should be monitored 6–12 hourly. Repeat the dose within 24 hours if an adequate level has not been achieved. Urinary output should also be monitoredThere is experience giving 15 mmol over 2 hours up to 3 times a dayExcessive doses of phosphate may cause hypocalcaemia and metastatic calcification

See how to identify renal failure stages according to GFR calculation

See how to diagnose irreversible renal disease

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