D3.02 - A Well-Established Drug and A Rare Reaction: Successful Desensitization to Adalimumab

A 27-year-old male patient treated with adalimumab for Behçet’s disease was referred to our clinic due to a suspected hypersensitivity reaction. Approximately two hours after administration of the 13th dose of adalimumab, a localized reaction characterized by pruritus, swelling, and erythema measuring 7 cm in diameter developed at the injection site. The reaction did not spread to other parts of the body, no accompanying systemic symptoms were observed, and vital signs were stable. As adalimumab was reported to be the only appropriate therapeutic option, skin testing with undiluted adalimumab at a concentration of 50 mg/mL was performed three weeks after the reaction. The test result was negative.

Subsequently, an intradermal test (IDT) was performed starting with a 1/1000 dilution (0.05 mg/mL). The immediate reading at 15 minutes was positive, showing a 5 × 5 mm wheal. Intradermal testing at a 1/100 dilution also yielded a positive result with an 8 × 8 mm wheal (Figure 1). The delayed intradermal reading at 24 hours was negative. A rapid drug desensitization protocol with adalimumab was planned. One hour before initiation of the 8-step subcutaneous desensitization protocol, oral premedication with cetirizine 10 mg, montelukast 10 mg, and famotidine 40 mg was administered. Desensitization was initiated with a starting dose of 0.5 mg (1/100 dilution), and the dose was gradually escalated according to the protocol until a total cumulative dose of 40 mg was administered subcutaneously. The interval between doses was 30 minutes. No reactions were observed during the desensitization procedure (Table 1).

Two weeks later, after the same premedication regimen, adalimumab 40 mg/0.8 mL preparation was divided into two equal doses and administered subcutaneously with a 30-minute interval between injections; no reaction was observed. Finally, two weeks thereafter, the Humira® preparation was administered as a single subcutaneous dose under the same premedication regimen, and no reaction occurred. The patient continues to receive adalimumab 40 mg subcutaneously at two-week intervals without any adverse events.

In contrast to prior reports using weekly dosing, our patient tolerated adalimumab uneventfully at biweekly intervals following desensitization.In this regard, the present case is expected to provide a meaningful contribution to the existing literature.