Last updated: October 22, 2014

Trade Names: Arcalyst

Drug Class: IL-1 antagonist

Preparations: 220 mg vial for subcutaneous injection

Dose: CAPS: Adults – loading dose of 320 mg as 2 separate subcutaneous injections then once weekly dose of 160 mg. Children 12 to 17  years – loading dose of 4.4 mg/kg (maximum 320 mg) as 2 separate subcutaneous injections then once weekly dose of 2.2 mg/kg (maximum160 mg).

Indications: Cryopyrin-associated periodic syndrome (CAPS)

Mechanism of Action: Acts as a decoy receptor and binds to IL-1 beta preventing interaction with receptors thus blocking the effects of the cytokine.

Contraindications: Hypersensitivity, active or chronic infection

Precautions: Discontinue if patient develops an infection; avoid live vaccines; exclude TB and monitor for new infection

Monitoring: Monitor clinically for infection; CBC after 1-2 months, then periodically

Pregnancy Risk: C

Adverse Effects
Common: Injection site reactions, upper respiratory tract infection, antibody formation
Less common: Infection
Rare: Hypersensitivity

Drug Interactions: Concurrent use of other immunosuppressants may increase risk of infection; do not use with other IL-1 antagonists, TNF-antagonists, biologics, tofacitinib, abatacept

Patient Instructions: Avoid live virus vaccines. Avoid pregnancy. Stop if an infection or a fever develops that lasts more than a few days.

Comments: In clinical studies rilonacept was  more effective than placebo in preventing gout flares in patients starting  allopurinol. Comparative efficacy against far cheaper alternatives such as NSAIDs or colchicine is not known. For the treatment of acute gout rilonacept was less effective than indomethacin; the combination of rilonacept and indomethacin was not significantly more effective than indomethacin alone.

Clinical Pharmacology: Half-life is 9 days. Biologic agents are not metabolized and have few drug interactions.

Cost: $$$$$

Terkeltaub RA, Schumacher HR, Carter JD, et al. Rilonacept i n the treatment of acute gouty arthritis: a randomized, controlled clinicaltrial using indomethacin as the active comparator. Arthritis Res Ther 2013;15:R25. PMID:23375025
Schumacher HR Jr, Sundy JS, Terkeltaub R, et al. Rilonacept (interleukin-1 trap) in the prevention of acute gout flares during initiation of urate-lowering therapy: results of a phase II randomized, double-blind, placebo-controlled trial. Arthritis Rheum 2012;64:876-84. PMID: 22223180.

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