A sufficient calcitriol dose is affected by various factors, including the age of the patient being treated and the condition that the drug is being used to treat. The dosage also is altered by the method of administration of the drug, with intravenous administration requiring twice the dose but not as often. An oral calcitriol dose for hypocalcemia is 0.25 micrograms per day, which can be increased by 0.25 micrograms per dosage at four- to eight-week intervals. If the drug is administered intravenously, 0.5 micrograms is given three times per week, and it can be increased much more quickly. For rickets, the recommended oral dose is 1 micrograms per day.
Calcitriol can be thought of as an active vitamin D supplement. Ordinary vitamin D, commonly found in food and sunlight, is made active by the kidneys so it can be used by the body. If a patient has kidney disease, his or her body cannot change the vitamin D from his or her diet into its active form, which can lead to diminishing levels of calcium and phosphorus within the body. The drug is vitamin D already in its active form, so it can be administered to patients who are suffering from kidney disease to keep up their vitamin D supplies and to fight hypocalcemia. The drug also can be used to treat hypoparathyroidism and rickets.
The correct calcitriol dose can be determined if one knows the condition that it is being used to treat, the age and weight of the patient being treated and the method of administration of the drug. Most conditions, including hypocalcemia, renal osteodystrophy and hypoparathyroidism, respond to a 0.25-microgram dose once per day. This dosage can be increased by 0.25 micrograms every four to eight weeks, with the exception of the treatment of hypoparathyroidism, in which case it can be increased every two to four weeks. Secondary hypoparathyroidism sufferers take only 0.25 micrograms per day, and people who have rickets can take 1 microgram per day.
Generally, only rickets and hypoparathyroidism require a calcitriol dose in children, and the rickets dosage is the same as it is for adults who have the condition. The daily recommended dosage for hypoparathyroidism in babies who are less than 1 year old is 0.04-0.08 micrograms per 2.2 pounds (1 kg) of weight. For children who are more than 1 year old, the dose goes up to 0.25 micrograms, and it can be increased every two to four weeks. In most cases, no more than 2 micrograms per day will be needed.