Drug Interactions between Fosteum and trientine

ADJUST DOSING INTERVAL: The gastrointestinal absorption of trientine may be decreased in the presence of food, resulting in reduced therapeutic effects.

MANAGEMENT: Trientine should be administered on an empty stomach, at least one hour before or two hours after meals and at least one hour apart from any other food, drug, or milk.

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.

GENERALLY AVOID: Concurrent oral administration of mineral supplements or mineral-containing products may block the absorption of trientine, and vice versa. The mechanism is trientine chelation of polyvalent metal ions resulting in a nonabsorbable complex.

MANAGEMENT: In general, mineral supplements or mineral-containing products (e.g., antacids) should not be used in patients treated with trientine. If concomitant use is unavoidable, separation of administration times by at least two hours is advisable.