Loargys is an enzyme replacement therapy for arginase 1 deficiency (ARG1-D). Understanding its indication scope and the full-process precautions for medication is the foundation for safe and effective treatment.

I. Indication Scope

1. Target Population

(1) It is indicated for adult and pediatric patients aged 2 years and older with a confirmed diagnosis of arginase 1 deficiency (ARG1-D).

(2) This disease is an inborn error of metabolism characterized by persistently elevated plasma arginine due to arginase 1 deficiency.

2. Therapeutic Positioning

(1) This drug is used for the treatment of hyperargininemia and must be used in conjunction with dietary protein restriction.

(2) Both components are indispensable. Drug therapy cannot replace dietary management, and dietary management alone cannot fully substitute for the drug effect.

II. Pre-Medication Preparations

1. Baseline Testing Requirements

(1) Plasma arginine concentration must be measured before the first dose to establish an individualized baseline value.

(2) This value serves as the core reference for subsequent dose adjustments and efficacy assessments.

2. Medical Setting Requirements

(1) The first and subsequent administrations must be performed in a medical facility equipped with anaphylaxis resuscitation capabilities, including cardiopulmonary resuscitation equipment.

(2) The entire process must be supervised by medical personnel experienced in managing anaphylactic shock.

3. Premedication Considerations

(1) Pre-treatment with antihistamines may be considered prior to infusion.

(2) For patients with a history of hypersensitivity reactions, corticosteroids may be added to reduce risk.

4. Special Blood Collection and Testing Requirements

(1) Plasma arginine testing must use dedicated blood collection tubes (containing enzyme inhibitors) and companion assay methods provided by the specified manufacturer, to prevent in vitro degradation of arginine by the drug after sampling that could lead to falsely low results.

(2) Related consumables are available only to participants in designated research projects.

III. Full-Process Medication Precautions

1. Route and Timing of Administration

(1) Initiate therapy with intravenous infusion once weekly, with each infusion lasting no less than 30 minutes.

(2) After completing 8 weeks of intravenous therapy, switch to subcutaneous injection at the same dose.

(3) Subcutaneous injection sites include the abdomen, lateral thigh, or back of the upper arm; rotate sites and avoid scars and erythematous areas.

2. Management of Missed Doses

(1) If a dose is missed, administer it as soon as possible.

(2) However, do not administer two injections on the same day or with an interval of less than four days between consecutive injections; maintain at least a four-day interval between doses.

3. Drug Preparation and Storage

(1) For intravenous administration: dilute with 0.9% sodium chloride injection to a final concentration not exceeding 0.5 mg/mL, mix gently, and avoid vigorous shaking.

(2) For subcutaneous administration: use the undiluted original solution for direct injection.

(3) After preparation, use immediately; if stored temporarily, keep at room temperature for no more than 2 hours or under refrigeration for no more than 4 hours.

(4) Store the original packaging under refrigeration (2–8°C), protect from light, and do not freeze or shake.

4. Visual Inspection Before Administration

(1) The solution should be clear to slightly opalescent, colorless to slightly yellow or slightly pink.

(2) If particulates or discoloration are observed, do not use.

5. Conditions for Home Subcutaneous Injection

(1) After the patient tolerates subcutaneous administration well, the transition to home injection may be performed under medical supervision.

(2) Maintain the same dose during the initial transition period; do not change without authorization.

(3) If a dose is missed or delayed, contact medical personnel; subsequent injections may need to be administered back in the medical facility.

6. Maintenance of Combination Therapy

During treatment, the existing ARG1-D‑related dietary regimen and ammonia-lowering medications should be continued; do not discontinue or alter them without medical advice.