PLASMA-LYTE

What it is

PLASMA-LYTE is a magnesium chloride hexahydrate injection supplied as a clear, colourless, sterile solution containing 480 milligrams of magnesium chloride anhydrous in each 5 mL vial, providing 1 mmol (2 mEq) of magnesium ions and 2 mmol (2 mEq) of chloride ions per mL. It is administered intravenously, usually by slow intravenous infusion.

Approved indications

— Acute hypomagnesaemia. — Prevention of hypomagnesaemia in patients receiving total parenteral nutrition.

Dosing overview

For acute hypomagnesaemia in adults, a dose of 3.3 to 7.2 grams of magnesium chloride anhydrous (70 to 150 mEq of magnesium) is given by slow intravenous infusion on the first day, followed by 2.4 grams of magnesium chloride anhydrous (50 mEq of magnesium) daily until hypomagnesaemia is corrected. For total parenteral nutrition in adults, a dose of 0.2 to 1.2 grams magnesium chloride anhydrous (4 to 24 mEq of magnesium) daily may be administered. For infants receiving total parenteral nutrition, a dose of 0.1 to 0.5 grams magnesium chloride anhydrous (2 to 10 mEq of magnesium) daily may be administered. Intravenous doses should be diluted in glucose 5%, with a maximum of 1.9 grams of magnesium chloride anhydrous (40 mEq of magnesium) diluted in 250 mL of 5% glucose and infused at a rate not to exceed 3 mL per minute (0.5 mEq/min). The total adult daily dose should not exceed 18.7 grams of magnesium chloride anhydrous per day.

Key safety warnings

Respiration rate should be determined and should be at least 16 per minute prior to each dose of magnesium, as respiratory depression is the most critical side effect of the medication. Urine output should be monitored and should be at least 100 mL during the four hours preceding dosing to ensure adequate excretion of magnesium. The patellar reflex should be tested prior to administering repeat doses of magnesium chloride, as suppression of the reflex is an indication of magnesium intoxication. An intravenous preparation of a calcium salt (such as calcium gluconate) should be readily available when magnesium chloride is given. Excessive administration of magnesium chloride may result in hypermagnesaemia, with signs including nausea, vomiting, flushing, hypotension, muscle weakness, muscle paralysis, blurred or double vision, and CNS depression, with more severe cases resulting in respiratory depression, respiratory paralysis, renal failure, coma, cardiac arrhythmias, and cardiac arrest.

Contraindications

PLASMA-LYTE is contraindicated in patients with heart block, since magnesium may exacerbate this condition. It is contraindicated in patients with renal failure (creatinine clearance less than 20 mL/min), as there is an increased risk of hypermagnesaemia in these patients. PLASMA-LYTE should not be given to a pregnant woman within two hours preceding delivery, as there is a risk of respiratory depression due to hypermagnesaemia in the neonate.

Regulatory history

PLASMA-LYTE was first approved on 8 October 1991. The brand was initially registered on the ARTG with two formulations (PLASMA-LYTE 148 and 5% Glucose 1000 mL injection bag and PLASMA-LYTE 56 in 5% Glucose 1000 mL injection bag) on 30 September 1991. Two additional formulations (PLASMA-LYTE 148 at approximately pH 7.4 in both 500 mL and 1000 mL injection bags) were listed on the ARTG on 11 December 2014.