Carlson D Disease Interactions

Vitamin D analogs function to increase serum calcium concentrations and can exacerbate arrhythmias, particularly in patients receiving cardiac glycosides. Therapy with vitamin D analogs should be administered cautiously in patients with or predisposed to cardiac arrhythmias. Clinical monitoring of serum electrolyte concentrations and cardiac function is recommended.

Vitamin D analogs administered in the presence of hyperphosphatemia can result in precipitation of calcium-phosphate deposits within the vascular or renal systems or other soft tissue calcifications. A solubility product (Serum Calcium X Phosphate) should not exceed 70. Serum electrolyte concentrations should be corrected prior to vitamin D analog therapy and monitored during therapy.

Vitamin D analogs such as calciferol and ergocalciferol should not be given to patients with hypercalcemia, malabsorption syndrome, or evidence of vitamin D toxicity.

Ergocalciferol, cholecalciferol, and calcifediol undergo renal biotransformation during metabolic activation. Renal impairment can alter metabolic and therapeutic activity of certain vitamin D analogs. Alternative vitamin D analogs such as dihydrotachysterol (hepatic activation) and calcitriol (active form) may be considered in patients with compromised renal function.

Vitamin D analogs are fat soluble and oral formulations require bile for adequate intestinal absorption. Hepatic and/or biliary dysfunction decrease the absorption of vitamin D analogs. Metabolites of vitamin D analogs are primarily excreted in bile and feces. Ergocalciferol, cholecalciferol, and dihydrotachysterol undergo hepatic hydroxylation during metabolic activation. Hepatic impairment can alter the metabolic and therapeutic activity of certain vitamin D analogs. Alternative vitamin D analogs such as calcifediol (requires renal activation) and calcitriol (active form) may be considered in patients with compromised hepatic function.