Reslizumab

Reslizumab is a humanised monoclonal antibody against interleukin-5, given by intravenous infusion as add-on treatment for severe eosinophilic asthma in adults. Its use is limited by the need for infusion and the anaphylaxis warning.

Classification. Anti-interleukin-5 biologic, humanised IgG4 monoclonal antibody.

Mechanism. Binds circulating interleukin-5 and lowers blood and tissue eosinophils.

Pharmacokinetics. Intravenous only. Half-life about 24 days. Cleared by proteolytic catabolism.

Specialist, severe eosinophilic asthma, adults 18 years and over. Blood eosinophils of 400 cells/microlitre or more and uncontrolled asthma despite high-dose inhaled corticosteroid with a LABA. Dose is 3 mg/kg intravenously every 4 weeks, infused over 20 to 50 minutes. Dose is by actual body weight at each visit. Assess response at 16 weeks.

Alternative. Subcutaneous anti-interleukin-5 agents when injection at home is preferred.

Emergency. Not used.

Titration and loading. No loading dose and no titration.

Boxed-warning-level risk. Anaphylaxis (about 0.3%), which can occur during or soon after infusion, including after earlier uneventful doses. Give only where resuscitation capability is available, with the patient observed during and after the infusion.

Contraindications. Hypersensitivity. Not for acute bronchospasm.

Serious adverse effects. Anaphylaxis, malignancy signal (not established as causal), raised creatine kinase with myopathy, helminth worsening.

Common adverse effects. Oropharyngeal pain, myalgia, injection-related reactions.

Interactions. None of clinical importance.

Common prescribing errors. Giving as an intravenous push. Dosing by ideal rather than actual body weight. Using a vial without the required filter.

Special groups.

• Pregnancy: limited data; use only if needed. Breastfeeding: probably compatible.

• Children: not licensed under 18 years.

• Older adults: no adjustment.

• Kidney and liver impairment: not studied; no adjustment expected.

• East Africa: treat existing helminth infection before starting. Availability is very limited.

Formulations. Vial 100 mg/10 mL (10 mg/mL).

Preparation. Draw up the dose and add to 50 mL of sodium chloride 0.9%. Infuse through a 0.22 micrometre low-protein-binding filter over 20 to 50 minutes. Flush with sodium chloride 0.9% after the infusion. Do not give as a push or bolus and do not mix with other drugs.

Baseline. Blood eosinophils, weight, control score, creatine kinase if myalgia occurs, stool examination in helminth-endemic areas.

Monitoring. Observe during and after each infusion. Exacerbations, control score and oral corticosteroid dose at 16 weeks and every 6 to 12 months.

Stop and reduce rules. Stop the infusion and treat for any hypersensitivity. Stop permanently after anaphylaxis. Stop if there is no benefit at 16 weeks. Therapeutic drug monitoring is not used.

Referral and escalation. Initiation is by a severe asthma specialist.