Infusion-related reactions to infliximab in patients with rheumatoid arthritis in a clinical practice setting: relationship to dose, antihistamine pretreatment, and infusion number.

Objective: We describe infusion-related reactions to infliximab (during infusion or within 1 hour postinfusion) in patients with active rheumatoid arthritis (RA) treated in a quaternary care center.

Methods: We followed 113 patients for a mean of 60.6 +/- 28.9 weeks, obtaining 10.5 +/- 4.9 infusions per patient.

Results: We observed 1183 infusions resulting in 104 infusion reactions (8.8%). All reactions resolved within several hours following cessation of the infusion and none was serious enough to warrant hospitalization. Reactions included allergic reactions (pruritus, urticaria) in 4.2% of infusions, cardiopulmonary (hypotension, hypertension, tachycardia) in 3.0%, and miscellaneous reactions (headache, nausea, vomiting) in 2.0%. Reactions occurred in 8.0% of 3 mg/kg infusions and in 10.3% of 5 mg/kg infusions. Reactions occurred in 13.2% of infusions that involved antihistamine pretreatment compared to only 7.5% of infusions that involved no pretreatment. At both infliximab doses, there was a similar frequency of infusion reactions in patients pretreated due to a previous infusion (12.6%) compared to those pretreated strictly based on infusion number (14.7%). A number of the reactions involving antihistamine pretreatment may be explained by known side effects of diphenhydramine, including headache, dizziness, nausea, and palpitations.

Conclusion: Infusion-related reactions to infliximab were infrequent, rarely severe, and easily manageable. The frequency of reactions was equivalent in patients treated with 3 mg/kg compared to 5 mg/kg. Reactions were significantly more frequent in infusions where patients were pretreated with the antihistamine diphenhydramine, compared to those not involving pretreatment.