Pegzilarginase

No UK SPC was retrieved — dose taken from the US prescribing information for LOARGYS (pegzilarginase-nbln) for hyperargininemia in ARG1-D; verify against the UK SPC before use. Obtain a baseline plasma arginine concentration before starting. Titration: aim for a pre-dose plasma arginine near the upper limit of normal (normal range 40-115 micromolar). After four weeks of treatment measure pre-dose plasma arginine (168 hours after the prior dose); if two consecutive weekly pre-dose measurements are outside the desired range, adjust the weekly dose — below 50 micromolar reduce by 0.05 mg/kg, above 150 micromolar increase by 0.05 mg/kg. Monitor plasma arginine weekly for 2 weeks after any dose adjustment and as clinically indicated. Arginine must be collected into the manufacturer's Nor-NOHA blood collection tubes and measured with the manufacturer's arginine assay. Missed dose: administer as soon as possible, but never two doses on the same day or within four days of another dose — maintain a minimum of four days between doses. Administer under the supervision of a healthcare provider knowledgeable in managing hypersensitivity reactions including anaphylaxis, in a setting with appropriate monitoring and cardiopulmonary resuscitation equipment; consider pre-medication with antihistamines. Severe hypersensitivity — discontinue and treat immediately including epinephrine; mild to moderate — consider antihistamines and/or corticosteroids and, for intravenous use, temporarily holding or slowing the infusion. Dilute for intravenous administration; do not dilute for subcutaneous administration.

The US label states no separate paediatric dosage — the same actual-body-weight dosage applies. Safety and effectiveness established under accelerated approval in paediatric patients 2 years of age and older with ARG1-D in conjunction with dietary protein restriction (§8.4); paediatric patients aged 2-17 years in the pivotal trial received intravenous dosages up to 0.2 mg/kg once weekly. Not established in patients under 2 years of age. US labelling — verify against the UK SPC and a children's formulary before prescribing.