A LOW DOSE REGIME OF 1α HYDROXYVITAMIN D₃ IN THE MANAGEMENT OF SENILE OSTEOPOROSIS: A PILOT STUDY

Abstract

A comparison has been made between themetabolic consequences of daily administration for 6 weeks of 1.0 micrograms and 0.5 micrograms 1 alpha hydroxyvitamine D3 (1 alpha(OH)D3) in twenty patients with senile osteoporosis. There was no significant difference in the increase of calcium absorption which occurred in the two treatment groups between the beginning and end of the trial period. Serum and urinary calcium rose significantly in those receiving 1.0 micrograms 1 alpha(OH)D3 but not in the lower dosage group. Serum parathyroid hormone levels were suppressed in the higher dosage group only. There was a significantly greater rise of serum inorganic phosphate, and fall of serum magnesium, on the higher dosage, but no significant change in serum creatinine occurred in either group. It is, therefore, suggested that in long term therapy regimes for osteoporosis incorporating 1 alpha(OH)D3, 0.5 micrograms may be a more suitable daily dose than 1.0 micrograms 1 alpha(OH)D3.

Vitamin D and its Metabolites and Analogs in the Management of Osteoporosis

“…Thus, its biochemical effects are very similar to those of calcitriol. Urine calcium excretion increases [204,205,208,209] and several groups have observed suppression of circulating PTH concentrations with doses of 1 μg/day or more [204,206]. This is associated with increases in serum calcium concentrations when a dose of 1 μg/day or more is used [204,206] and some authors have noted increases in serum calcium levels with doses of only 0.5 μg/day [204,207,208].…”

“…It is different from calcitriol in that it has not been hydroxylated at position 25, but this conversion takes place rapidly in the liver following oral or parenteral administration of alfacalcidol in humans [203]. This is associated with increases in serum calcium concentrations when a dose of 1 μg/day or more is used [204,206] and some authors have noted increases in serum calcium levels with doses of only 0.5 μg/day [204,207,208]. For example, it stimulates intestinal calcium absorption [204,205].…”

Osteoporosis

“…A major concern is that excessive amounts of 1‐hydroxylated metabolites could produce hypercalcemia and hypercalciuria and possibly impair renal function. Such effects have been observed with doses as low as 1 μg/day of la‐OH vitamin D or 1,25(OH) 2 , vitamin D 118,119 . However, hypercalcemia is transient when these agents are used, in contradistinction to the prolonged toxicity that can occur with an excess of vitamin D itself.…”