Drug Interactions between budesonide and ergocalciferol

MONITOR: Additive effects and possible toxicity (e.g., hypercalcemia, hypercalciuria, and/or hyperphosphatemia) may occur when patients using vitamin D and/or vitamin D analogs ingest a diet high in vitamin D, calcium, and/or phosphorus. The biologically active forms of vitamin D stimulate intestinal absorption of calcium and phosphorus. This may be helpful in patients with hypocalcemia and/or hypophosphatemia. However, sudden increases in calcium or phosphorus consumption due to dietary changes could precipitate hypercalcemia and/or hyperphosphatemia. Patients with certain disease states, such as impaired renal function, may be more susceptible to toxic side effects like ectopic calcification. On the other hand, if dietary calcium is inadequate for the body's needs, the active form of vitamin D will stimulate osteoclasts to pull calcium from the bones. This may be detrimental in a patient with reduced bone density.

MONITOR: Grapefruit or grapefruit juice may alter the plasma concentrations of vitamin D analogs due to CYP450 3A4 inhibition. For analogs partially metabolized by CYP450 3A4, such as calcitriol, inhibitors can increase plasma concentrations, thereby elevating the risk of adverse effects like hypercalcemia and hyperphosphatemia. For prodrug analogs, such as calcifediol and doxercalciferol, CYP450 3A4 inhibition may affect activation and metabolic pathways, leading to variable net effects depending on the specific agent and individual patient factors. The effects of CYP450 3A4 inhibition on native vitamin D (cholecalciferol and ergocalciferol) are not noted. Clinical manifestations of such interactions may include alterations in serum calcium, phosphate, and parathyroid hormone (PTH) levels. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition. Pharmacokinetic interactions involving grapefruit juice are also subject to a high degree of interpatient variability, thus the extent to which a given patient may be affected is difficult to predict.

MANAGEMENT: Given the narrow therapeutic index of vitamin D and vitamin D analogs, the amounts of calcium, phosphorus, and vitamin D present in the patient's diet, as well as grapefruit consumption may need to be taken into consideration. Specific dietary guidance should be discussed with the patient and regular lab work should be monitored as indicated. Calcium, phosphorus, and vitamin D levels should be kept within the desired ranges, which may differ depending on the patient's condition. Patients should also be counseled on the signs and symptoms of hypervitaminosis D, hypercalcemia, and/or hyperphosphatemia.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations and systemic effects of orally administered budesonide. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. According to the manufacturer, the systemic exposure of oral budesonide approximately doubles after extensive intake of grapefruit juice.

MANAGEMENT: Patients receiving budesonide should avoid the regular consumption of grapefruits and grapefruit juice to prevent undue increases in plasma budesonide levels and systemic effects.

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

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

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 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 calcitriol (active form) may be considered in patients with compromised hepatic function.

Prolonged use of corticosteroids may cause posterior subcapsular cataracts and elevated intraocular pressure, the latter of which may lead to glaucoma and/or damage to the optic nerves. Therapy with corticosteroids should be administered cautiously nonetheless in patients with a history of cataracts, glaucoma, or increased intraocular pressure. Although adverse effects of corticosteroids may be minimized by local rather than systemic administration, the risks are not entirely abolished. Inhaled and nasally applied drug may be absorbed into the circulation, especially when large doses are used. It is important that the recommended dosages of the individual products not be exceeded and that the lowest effective dosage be used.

Prolonged use of corticosteroids may cause posterior subcapsular cataracts and elevated intraocular pressure, the latter of which may lead to glaucoma and/or damage to the optic nerves. Therapy with corticosteroids should be administered cautiously nonetheless in patients with a history of cataracts, glaucoma, or increased intraocular pressure. Although adverse effects of corticosteroids may be minimized by local rather than systemic administration, the risks are not entirely abolished. Inhaled and nasally applied drug may be absorbed into the circulation, especially when large doses are used. It is important that the recommended dosages of the individual products not be exceeded and that the lowest effective dosage be used.

The use of corticosteroids may rarely precipitate or aggravate conditions of hyperadrenocorticism. Although adverse effects of corticosteroids may be minimized by local rather than systemic administration, the risks are not entirely abolished. Inhaled and nasally applied drug may be absorbed into the circulation, especially when large doses are used. It is important that the recommended dosages of the individual products not be exceeded and that the lowest effective dosage be used. The development of symptoms such as menstrual irregularities, acneiform lesions, cataracts and cushingoid features during inhaled or nasal corticosteroid therapy may indicate excessive use.

The immunosuppressant and anti-inflammatory effects of corticosteroids, particularly in higher dosages, may decrease host resistance to infectious agents, decrease the ability to localize infections, and mask the symptoms of infection. Secondary infections may be more likely to develop. Therapy with corticosteroids should be administered cautiously in patients with an infection, particularly active or quiescent tuberculosis or in hepatitis B carriers. Monitor patients for any new or worsening infection and use with caution in these patients. A serious or even fatal course of chickenpox and measles can occur in susceptible patients. It is important that the recommended dosages of the individual products not be exceeded and that the lowest effective dosage be used.

Some inhaled corticosteroid formulations contain lactose and may cause adverse reactions including cough, wheezing and bronchospasm in patients with severe milk protein allergy or intolerance. Caution is advised.

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 calcitriol (active form) may be considered in patients with compromised hepatic function.

Corticosteroids are predominantly cleared by hepatic metabolism and impairment of the liver function may lead to their accumulation. Patients with hepatic disease should be closely monitored.

Pharmacologic dosages of corticosteroids may increase the risk of corneal perforation in patients with ocular herpes simplex. Therapy with inhaled and nasal corticosteroids should be administered cautiously in such patients.

Prolonged use of inhaled corticosteroids may be associated with a reduction in bone density. This effect appears to be dose-related and has been reported primarily with high dosages (800 mcg/day or more of beclomethasone or equivalent for 1 year or greater). Reduced levels of total body calcium have also been demonstrated in patients receiving lower dosages. Long-term therapy with inhaled and nasal corticosteroids should be administered cautiously in patients with osteoporosis. It is important that the recommended dosages of the individual products not be exceeded and that the lowest effective dosage be used.

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.

Ergocalciferol and cholecalciferol 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.

The immunosuppressant and anti-inflammatory effects of corticosteroids, particularly in higher dosages, may decrease host resistance to infectious agents, decrease the ability to localize infections, and mask the symptoms of infection. Secondary infections may be more likely to develop. Therapy with corticosteroids should be administered cautiously in patients with an infection, particularly active or quiescent tuberculosis or in hepatitis B carriers. Monitor patients for any new or worsening infection and use with caution in these patients. A serious or even fatal course of chickenpox and measles can occur in susceptible patients. It is important that the recommended dosages of the individual products not be exceeded and that the lowest effective dosage be used.