Drug Name

Rocaltrol (Calcitriol)

Drug Uses

This is a form of vitamin D, a fat-soluble vitamin stored in the body. Vitamin D is necessary for normal bone development. This medication is used as a dietary supplement to help prevent and treat rickets (a vitamin D deficiency). It is also used to prevent and treat muscle cramps and certain types of calcium and phosphate disorders (such as with chronic dialysis), and to regulate parathyroid hormone.

How to use

Capsules must be swallowed whole. Do not crush or chew them. If you are prescribed the liquid form, use as directed. Follow dosing instructions closely. Do not increase your dose without doctor's approval. Do not take this medication with mineral oil or magnesium containing antacids which may reduce its effects.

Drug Class and Mechanism

Rocaltrol (calcitriol) is a synthetic vitamin D analog which is active in the regulation of the absorption of calcium from the gastrointestinal tract and its utilization in the body. All dosage forms contain butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) as antioxidants. The capsules contain a fractionated triglyceride of coconut oil, and the oral solution contains a fractionated triglyceride of palm seed oil. Gelatin capsule shells contain glycerin, parabens (methyl and propyl) and sorbitol.

The two known sites of action of calcitriol are intestine and bone. A calcitriol receptor-binding protein appears to exist in the mucosa of human intestine.

Additional evidence suggests that calcitriol may also act on the kidney and the parathyroid glands.

Calcitriol is the most active known form of vitamin D3 in stimulating intestinal calcium transport. In acutely uremic rats calcitriol has been shown to stimulate intestinal calcium absorption. The kidneys of uremic patients cannot adequately synthesize calcitriol, the active hormone formed from precursor vitamin D. Resultant hypocalcemia and secondary hyperparathyroidism are a major cause of the metabolic bone disease of renal failure. However, other bone-toxic substances which accumulate in uremia (eg, aluminum) may also contribute. The beneficial effect of Rocaltrol in renal osteodystrophy appears to result from correction of hypocalcemia and secondary hyperparathyroidism. It is uncertain whether Rocaltrol produces other independent beneficial effects. Rocaltrol treatment is not associated with an accelerated rate of renal function deterioration. No radiographic evidence of extraskeletal calcification has been found in predialysis patients following treatment.

The duration of pharmacologic activity of a single dose of calcitriol is about 3 to 5 days.

Missed Dose

Take the missed dose as soon as you remember; do not take if it is almost time for the next dose. Instead, skip the missed dose and resume your usual dosing schedule. Do not "double-up" the dose to catch up.

Storage

Store at room temperature (77 degrees F/25 degrees C).

Warnings/Precautions

Tell your doctor if you have: heart disease, kidney disease or kidney stones, coronary artery disease (hardening of the arteries). This drug should be used only if clearly needed during pregnancy. It is not known if this medication appears in breast milk; consult your doctor before breast-feeding.

Possible Side Effects

Vitamin D is generally well tolerated. However, notify your doctor if you experience: nausea, vomiting, loss of appetite, constipation, diarrhea, stomach pain, thirst, weakness, headache, bone pain, dry mouth, increased urination. If you notice other effects not listed above, contact your doctor or pharmacist.

More Information

Foods rich in vitamin D include: fortified dairy products, eggs, sardines, cod liver oil, chicken livers and fresh-water fish. Vitamin D is also obtained from periodic exposure to the sun. It is important to maintain a well-balanced diet while taking this medication. Calcium supplements may be recommended in addition to this medication. Discuss this with your doctor.