A Study to Evaluate the Safety and Effectiveness of Doxercalciferol Capsules in Participants With Moderate to Severe Psoriasis

Inclusion Criteria

• Participant had moderate to severe chronic plaque psoriasis defined by a body surface area (BSA) involvement greater than or equal to (>=) 10 percent (%) and plaques with at least a slight elevation above the surrounding normal skin at the Day 1 visit
• Participant had a static Physician's Global Assessment (PGA) of moderate or severe at the Day 1 visit
• Participant had a minimum PASI score of 10 at the Day 1 visit
• Participant was a candidate to receive systemic psoriasis therapy in the opinion of the Investigator
• Participant of childbearing potential, was willing to use an effective contraceptive method throughout the study, which included barrier methods, hormones, or intrauterine devices

Exclusion Criteria

• Used vitamin D analogues, multivitamin supplements containing greater than (>) 400 international unit (IU) vitamin D, topical retinoids, topical pimecrolimus, and topical tacrolimus within 14 days prior to the Day 1 visit
• Used drugs known to influence serum calcium (such as lithium, digoxin, thiazide diuretics, teriparatide, bisphosphonates, and calcitonin) and multivitamin supplements containing calcium and/or calcium-containing antacids exceeding a total of 1 gram/day within 14 days prior to the Day 1 visit
• Used keratolytics or coal tar (except shampoo containing coal tar or salicylic acid) within 14 days prior to the Day 1 visit
• Used low potency topical corticosteroids (Classes VI and VII), except on the groin, scalp, palms, soles and face, within 14 days prior to the Day 1 visit
• Used medium potency topical corticosteroids (Classes III - V) or high potency topical corticosteroids (Classes I and II) within 14 days prior to the Day 1 visit
• Used systemic retinoids, systemic corticosteroids, methotrexate, cyclosporine, azathioprine, thioguanine or other systemic immunosuppressant agents within 28 days prior to the Day 1 visit
• Used phototherapy, including Ultraviolet B within 14 days or Psoralen plus Ultraviolet A within 28 days prior to the Day 1 visit
• Used a biological agent (including, but not limited to, etanercept, adalimumab, efalizumab, infliximab, or alefacept) within 5 half-lives of the drug prior to the Day 1 visit
• Used systemic antibiotics within 14 days prior to the Day 1 visit. Antibiotic treatment of infections during the Treatment Period was not excluded
• Used investigational drugs within 28 days prior to the Day 1 visit
• Current erythrodermic, guttate, generalized pustular, unstable psoriasis or other chronic active skin conditions that may interfere with the study
• Screening visit laboratory result exceeded the following limits: alanine transaminase (ALT) or aspartate transaminase (AST) >1.5 times the upper limit of normal (ULN); bilirubin >ULN; serum creatinine, calcium, or phosphorus >ULN; spot urine calcium/creatinine ratio >0.4
• History of nephrolithiasis
• Chronic kidney disease as evidenced by a calculated glomerular filtration rate (GFR) less than (<) 60 milliliter/minute/1.73 square meter (mL/min/1.73 m^2) at the screening visit
• Symptomatic coronary or cerebral vascular disease, human immunodeficiency virus, active viral hepatitis, or any other clinically significant, unstable medical condition that would interfere with the completion of the study
• Clinically significant electrocardiogram (EKG) abnormality at screening
• Any evidence of active malignancy except for basal cell carcinoma of the skin. A history of malignancy was not an exclusion
• Active ethanol or drug abuse, excluding tobacco use
• Active severe psychiatric illness that could interfere with the conduct of the study
• Pregnant or breast-feeding women
• Known allergy or hypersensitivity to vitamin D or other ingredients in the study drug formulation