Calcitriol

Vitamin D/Nutrient Depletion:

  • AnticonvulsantsAnticonvulsants: In human research, certain anticonvulsant agents (e.g., carbamazepine, phenobarbital, and phenytoin) decreased levels of vitamin D (556; 557; 558; 559) by inducing hepatic conversion of vitamin D to inactive metabolites.
  • AntihypertensivesAntihypertensives: In human research, hypertension treated with angiotensin-converting enzyme inhibitor/angiotensin receptor blocker was associated with low 25-hydroxyvitamin D(3) levels (563).
  • Bile acid sequestrantsBile acid sequestrants: Intestinal absorption of vitamin D may be impaired with the use of bile acid sequestrants (cholestyramine, colestipol) (579; 580; 581; 582).
  • CorticosteroidsCorticosteroids: According to secondary sources, vitamin D levels may be affected when used in combination with corticosteroids.
  • DiureticsDiuretics: Concurrent use of thiazide diuretics (which decrease urinary calcium excretion) and potassium may decrease vitamin D levels and increase the risk of hypercalcemia (615).
  • GlucoseGlucose: According to a clinical review and human research, effects of vitamin D on glucose and insulin metabolism were mixed, with studies showing reduced effects or no effects (368; 369; 370; 37; 371; 372; 373; 374), and in a single study included in one of the reviews, healthy men had significantly increased insulin concentrations (369). In another cohort study, even though diabetes risk decreased with increasing vitamin D supplementation, there was a lack of significant effect of dietary vitamin D on the risk of diabetes (369). In human research, vitamin D reduced fasting glucose levels and insulin resistance in patients with abnormal, but not normal, fasting glucose; effects on HbA1c were lacking (375).
  • LaxativesLaxatives: According to secondary sources, stimulant laxatives may reduce dietary vitamin D absorption.
  • Lipid profileLipid profile: In a systematic review, effects of native vitamin D on cholesterol were lacking, although three of nine of the included studies reported a decrease in triglyceride levels and one of nine reported a reduction in LDL cholesterol (414). In patients with end-stage renal disease, calcitriol reduced triglyceride levels.
  • Mineral oilMineral oil: According to secondary sources, mineral oil may reduce the absorption of vitamin D.
  • Opiate agonistsOpiate agonists: In human research, vitamin D deficiency has been associated with opioid analgesic use among patients with chronic pain (629).
  • OrlistatOrlistat: According to the manufacturer and human research, orlistat may reduce the absorption of fat-soluble vitamins, particularly vitamin D (630). Patients should consider taking a multivitamin with fat-soluble vitamins at least two hours before or after orlistat or at bedtime.
  • ProteinProtein: In human research, the vitamin D analog paricalcitol resulted in a reduction in proteinuria (366).
  • RifampinRifampin: In human research, rifampin increased vitamin D metabolism and reduced vitamin D blood levels, as rifampin increased hepatic metabolism of 25-hydroxyvitamin D (631; 632; 633).
  • SunscreensSunscreens: In human research, sunscreens have been shown to interfere with the cutaneous production of vitamin D3 (635).