We report the efficacy and safety of IM ergocalciferol in a small series of patients with SSc and a low vitamin D level that was refractory to oral supplementation.
To our knowledge, it is the first shared experience of normalizing vitamin D levels with IM injection in patients having a connective tissue disease and a poor vitamin D status refractory to oral supplementation. Such a route of administration was reported in vitamin D-deficient diabetic patients [13]. We thought to use it on our first patient in 2018; the good response and safety led us to try the same treatment on other patients.
The limitations of this study include a retrospective observation with small sample size, a short follow-up, and restricted clinical data. Although the poor vitamin D status was subclinical, we thought, based on literature data on the possible interaction between low vitamin D and disease status, that raising rapidly the level would be theoretically beneficial. We have investigated the improvement of vitamin D levels only, without other scleroderma-related manifestations which would have carried more weight to this study. Furthermore, the patients were not thoroughly investigated for the precise cause of low vitamin D like abnormal gastrointestinal absorption, renal disease, menopausal status, concomitant medication, or poor drug compliance. Finally, higher doses of oral vitamin D are recommended in patients with malabsorption, like after bariatric surgery; up to 6000IU of daily vitamin D3 are preferred to up to 50.000IU of 3 times weekly vitamin D2 [14]. We could have tested this recommendation on our patients, but we considered the IM route safer and of lower cost.
The most efficient replacement therapy has been the subject of years of debate [15]. If a choice can be made, recent guidance prefers vitamin D3 to vitamin D2 in oral supplementation [16]. Equal efficacy and safety were shown in daily, weekly, or monthly dosing regimens [17]. Compared to the IM route, higher and earlier peaks are observed with the oral route [18, 19]. Compared to IM cholecalciferol, lower peaks were seen with IM ergocalciferol. For our patients, ergocalciferol was the only IM vitamin D available. The vial dose was divided into two halves at a 15-day interval to reduce the risk of side effects.
IM vitamin D injections have shown promising results. In healthy Korean adults with vitamin D deficiency, a single injection of 200,000 IU of vitamin D3 raised, within 12 weeks, the 25(OH)D levels above 20 ng/mL and 30 ng/mL in around 90% and 50% of individuals, respectively [20]. Moreover,10 adults with a variety of past and present medical conditions received 600 000 IU of IM vitamin D3; blood samples showed a peak of 25(OH)D at 4 weeks for most participants and the levels were still remarkably higher than baseline at 24 weeks [11]. Similarly, Wylon et al. compared the pharmacokinetic evolution of a single 100 000 IU IM dose of cholecalciferol to that of an 84-day oral supplementation; serum 25(OH)D level peaked one week after the first dose of oral cholecalciferol and 4 weeks after the IM injection. Unlike the IM route, the fast rise with the oral route was transitory. The sustained levels following IM injection were explained by a delayed release along with the storage capacity of vitamin D in the adipose tissue [18]. Likewise, Gupta et al. compared the mean serum 25(OH)D levels in 2 healthy groups with vitamin D deficiency. Twenty weekly received 60,000 IU of cholecalciferol for 5 weeks and twenty others received a single IM injection of 300,000 IU of cholecalciferol. At 12 weeks, levels were significantly higher in the second group (25.46 ± 1.37 vs. 16.66 ± 1.36 ng/mL; p < 0.001), hence showing a sustained increase from baseline [5].
In conclusion, the IM administration of vitamin D2 showed promising results in correcting a refractory low level, though subclinical, in patients with systemic sclerosis. Based on the response of our patients and the results of other studies of IM vitamin D in healthy subjects, close monitoring of 25(OH)D in the blood can help define the frequency of supplementation. Moreover, extrapolating this route of delivery to other diseases with subclinical malabsorption is expected to be promising. This case series is not the strongest source of evidence; however, it provides descriptive data that contributes to generating more precise hypotheses to test.