PURPOSE: To show that administration of adalimumab combined with injectable lidocaine pre-mixed in the syringe decreases the pain of injection and results in improved tolerance and acceptance of this therapy.
METHODS: Pediatric and adult rheumatology patients at our institution treated with adalimumab since 2006 were included in our study. Potential patients were prospectively identified when initiating adalimumab therapy. Patients with prior injection site pain, younger age, or injection anxiety symptoms were offered this innovation when using adalimumab therapy. 0.2 ml of lidocaine was added directly to the pre-filled syringe containing 0.8 ml of adalimumab. These agents were combined at room temperature and no precipitation occurred. There is no documented incompatibility of lidocaine with adalimumab. Patients were asked to rate the level of injection discomfort prior to and following the use of lidocaine and to base their answers on a 1-10 pain scale. Laboratory markers of inflammation, the CRP and ESR, and joint counts were reviewed to assess and ensure the continued efficacy of the adalimumab/lidocaine admixture. Results were compared before and after the addition of lidocaine.
RESULTS: Approximately 30 patients in the combined rheumatology practices were prescribed adalimumab therapy. Of this group, 15 patients used the mixture of lidocanie and adalimumab. Pain at the injection site was diminished following the addition of lidocaine. Patients report increased comfort level using this method. There were no significant changes in ESR/CRP or joint counts following the addition of the lidocaine. We noted no change in reports of infections or site reactions between the two groups.
CONCLUSTIONS: In order for adalimumab to be available in a pre-filled formulation, the addition of a preservative is required. This lowers the pH to 5.2 producing significant injection site discomfort for some patients. This is a major factor in patient/family willingness to initiate and continue therapy with this agent. With the addition of lidocaine, none of our patients discontinued the adalimumab due to this side effect. We have concluded that the addition of injectable lidocaine to the pre-filled adalimumab syringe is safe and results in decreased pain without sacrificing effectiveness of the drug. Patients using this combination are more willing to continue their therapy
