Background and Importance Anakinra, a recombinant human IL-1 receptor antagonist, is indicated in rheumatoid arthritis (RA) with a good safety profile, nonetheless its administration has been associated with a severe delayed injection-site reaction without a fully understood pathogenesis. To deal with that several desensitisation schemes have been published in the literature.

Aim and Objectives The aim is to describe the design of a slow desensitisation protocol (SDP) for subcutaneous (SC) anakinra for patients who have failed the rapid desensitisation scheme (RDP).

Material and Methods We introduce a 72 year-old patient diagnosed for RA and treated with SC anakinra after failing other treatment lines who presents severe injection-site reactions after 3 weeks of treatment. An attempt was made to desensitise quickly but it was not tolerated either. As there were no more lines of treatment available, it was decided, in collaboration with allergists, to design a SDP.

It was designed for 56 doses of increasing concentrations (until 100 mg dose). Lower dose was 0,1 mg and dose change was performed every 3-4 days. Solutions were elaborated in the Pharmacy Service. Starting from a mother solution (MS) of 100 mg anakinra in physiologic serum 0,9% (SF) to a final volume of 1mL (1:1 solution) two anakinra dilutions were made: 1:10, 1:5. The MS was prepared from anakinra 100 mg/0,67 ml injection. The dilution 1:10 was made by taking 0,5 ml from the MS and SF until 10 ml (concentration 5 mg/ml). The dilution 1:5 was prepared by diluting 1 ml from 1:10 dilution until 5ml final volume with SF (concentration 1 mg/ml).

To prevent hypersensibility reactions it was needed to add antihistamines during the SDP.

Results Although RDP was not well tolerated, the proposed scheme had satisfactory results. At first the lowest dose (0,1 mg) was not tolerated by the patient, so it was decided to add antihistamines during the process. If any dose could react, the dose change was done instead of 3 after 5-7 days. Actually, the patient has completed the doses until 50 mg without adverse reactions.

Conclusion and Relevance The SDP proposed by allergist in collaboration with hospital pharmacist has allowed the safe administration of anakinra, avoiding a loss of the last therapeutic line possible in a patient with RA.

Conflict of Interest No conflict of interest