A pilot trial in 24 patients randomized to 3 groups to receive 0, 1, or 2 mcg of paricalcitol orally for 1 month.
At 1 month, the treatment/baseline ratio of high sensitivity C-reactive protein was 1.5 (95% CI: 1.1 to 2.1; ) with placebo, 0.8 (95% CI: 0.3 to 1.9; ) with the 1 mcg dose, and 0.5 (95% CI: 0.3 to 0.9; ) with a 2 mcg dose of paricalcitol. The treatment/baseline ratio of 24-hour albumin excretion rate was 1.35 (95% CI: 1.08 to 1.69; ) with placebo, 0.52 (95% CI: 0.40 to 0.69; ) with a 1-mcg dose, and 0.54 (95% CI: 0.35 to 0.83; ) with a 2 mcg dose ( between group changes).
A study in 10 healthy volunteers; peripheral blood mononuclear cells (PBMC) were cultured for 48 hours in presence or not of lipopolysaccharide (LPS) and in the presence or not of paricalcitol. TNF-alpha and IL-8 produced by PBMC were measured.
Basal TNF-alpha concentration and IL-8 concentrations were reduced by paricalcitol. Paricalcitol also blunted the TNF-alpha concentration increase induced by LPS. Paricalcitol reduced to its basal level the IL-8 concentration increase by LPS. The in vitro inhibition of TGF-alpha and IL-8 by paricalcitol confirms the immunomodulatory properties of this vitamin D analogue.
