Calcidol Disease Interactions

The amine ergot alkaloids, ergonovine and methylergonovine, can cause serious cardiovascular complications because of their vasospastic effects. Hypertension (more often with ergonovine) has been most commonly reported, particularly when administered IV undiluted or at an excessive rate or when used in conjunction with regional anesthesia or vasoconstrictors. Headaches, seizures, cerebrovascular accidents and death have been associated with the hypertensive episodes. Other, less common adverse effects include acute myocardial infarction, transient chest pains, thrombophlebitis, tachycardia and palpitations. Therapy with ergot alkaloids should generally be avoided, except under special circumstances, in patients with chronic hypertension, preeclampsia or eclampsia, cardiovascular disease, cerebrovascular disease, or peripheral vascular disease. Caution is advised when these agents are administered to patients with venoatrial shunts, mitral valve stenosis, or sepsis. Close monitoring of cardiovascular status is highly recommended during therapy.

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.