Drug Interactions between cycloserine and Vitamin D3

GENERALLY AVOID: Coadministration with alcohol may potentiate some of the central nervous system adverse effects of cycloserine and its prodrug, terizidone. These effects may include dizziness, drowsiness, depression, anxiety, psychoses, memory impairment, confusion, and convulsions.

MANAGEMENT: Patients should be advised to avoid the consumption of alcohol during treatment with cycloserine or terizidone. The use of these medications is contraindicated in patients with chronic alcohol consumption or alcoholism.

MONITOR CLOSELY: Coadministration with caffeine may potentiate some of the central nervous system adverse effects of cycloserine and its prodrug, terizidone. These effects may include insomnia, excitability, irritability, anxiety, tremor, psychoses, and convulsions.

MANAGEMENT: Caution is advised when cycloserine or terizidone is used with caffeine. Consumption of certain beverages or stimulants with very high caffeine levels should be avoided as a precautionary measure.

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.