Drug Interactions between Calcium 600 D and mycophenolic acid

ADJUST DOSING INTERVAL: Administration with food may increase the absorption of calcium. However, foods high in oxalic acid (spinach or rhubarb), or phytic acid (bran and whole grains) may decrease calcium absorption.

MANAGEMENT: Calcium may be administered with food to increase absorption. Consider withholding calcium administration for at least 2 hours before or after consuming foods high in oxalic acid or phytic acid.

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.

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 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.

ADJUST DOSING INTERVAL: Administration of enteric coated mycophenolic acid with meals may alter its pharmacokinetics relative to administration in the fasting state. When mycophenolic acid 720 mg was administered with a high-fat meal, there was a 33% decrease in the peak plasma concentration (Cmax); a 3.5-hour increase in delay time for the rise of plasma mycophenolic acid; and a 5-hour delay in the time to reach peak plasma concentration (Tmax). However, no effect was observed on the systemic exposure of mycophenolic acid.

MANAGEMENT: To avoid variability in drug absorption between doses, enteric coated formulations of mycophenolic acid should be taken on an empty stomach, one hour before or two hours after food intake. The tablets should be swallowed whole and not crushed, chewed or divided in order to maintain the integrity of the enteric coating.