Efficacy and Safety of Calcifediol vs Placebo in Subjects With Vitamin D Deficiency

Inclusion Criteria: * Male or female subjects ≥ 18 years of age. * Evidence of serum 25-OH-D levels \< 20 ng/mL or ≤ 10 ng/mL, for each cohort. * Written informed consent. * For females of childbearing potential only: willing to perform pregnancy tests, must agree to use highly effective methods of birth control throughout the study. Exclusion Criteria: * Subjects receiving any treatment with calcifediol, vitamin D analogues, vitamin complexes or vitamin D supplements. * Subjects taking drugs that could modify vitamin D levels. * Subjects taking calcium supplements. * Uncorrected hypercalcaemia, known hypercalciuria or nephrolithiasis. * Severe renal impairment. * Subjects diagnosed with liver or biliary failure, congestive heart failure, malabsorption, primary hyperparathyroidism, hypothyroidism, prolonged immobilisation, sarcoidosis, tuberculosis or other granulomatous diseases or hyperthyroidism. * Any present or previous malignancy. * Known contraindications or sensitivities to the use of the IP or any of its components. * Pregnant woman, breastfeeding woman or woman planning a pregnancy. * Subject has received an IP within 30 days before the start of the screening or is currently enrolled in an investigational interventional study. * Any condition that may jeopardise the clinical trial conduct according to the protocol. * Employees of the investigator or clinical trial site, as well as family members of the employees or the principal investigator. * Person committed to an institution by virtue of an order issued either by judicial or other authorities.