Background/Purpose: Repository Corticotropin Injection (RCI) is an adrenocorticotropin hormone in 16% gelatin with a prolonged release after intramuscular (IM) or subcutaneous injection. Adverse effects of RCI are primarily related to its steroidogenic effects including decrease in BMD. However, there is recent renewed interest in RCI’s role as an alternative to high dose glucocorticoids and as last resort therapy for SLE.

Methods: This retrospective case series looks at the bone density changes of 5 adult female patients with mean age of 59 years on RCI vs. glucocorticoids at a Rheumatology practice. A list of 73 patients on RCI was populated using the EMR. Chart review was performed and patients were selected with the following criteria: on RCI for at least 6 months, history of SLE, verifiable DXA scan results from before and after starting RCI. Patients were then excluded if they had been on bone sparing agents during this time interval. The bone with the lowest density on the DXA report post-RCI is selected for comparison to the pre-RCI BMD. The lowest significant change of each BMD value is operator dependent and is within 95% confidence interval based on the certified technologist’s past DXAs. The same technologist performed all of the above DXAs. An example is as follows: for this particular technologist, her range of lowest significant change (at 95% confidence interval) in measurement of the femoral neck is plus or minus 0.010 gm/cm^2. If the difference in BMD of the femoral neck falls outside of this range on a latter DXA, then there is indeed a significant change.

Results: Two of the 5 patients had nonsignificant changes to their BMD before and after starting RCI. Two patients had a decrease in BMD that were significant but were noted to have been on higher doses of Prednisone (10mg and/or 20mg a day) and received more IM glucocorticoid injections. One patient had an increased BMD, although for her, RCI was started just 3 months prior to her latter DXA. Her third DXA scan 2 years later did show a significant decrease in BMD but she, too, had received more glucocorticoid IM injections.

Conclusion: These cases illustrate the possibility that RCI by itself does not contribute to significant BMD decrease. Rather, significant decrease in BMD is seen in those patients who have concurrently received more oral, IM or intra-articular glucocorticoids while on RCI. Although RCI may be understood to have similar side effects as glucocorticoids, we see a possible difference in side effects such as BMD decrease as compared to glucocorticoids.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/case-series-comparison-of-repository-corticotropin-injection-h-p-acthar-gel-versus-glucocorticoids-on-bone-density-in-sle-patients/