Posology
The dosage of One-Alpha Injection is the same as for One-Alpha in its oral presentations.
Initial dose for all indications:
Adults and children over 20 kg bodyweight: | 1 microgram/day |
Elderly: | 0.5 microgram/day |
Neonates and premature infants: | 0.05-0.1 microgram/kg/day |
Children under 20 kg bodyweight: | 0.05 microgram/kg/day |
The dose of One-Alpha should be adjusted thereafter to avoid hypercalcaemia according to the biochemical response.
Indices of response include plasma levels of calcium (ideally corrected for protein binding), alkaline phosphatase, parathyroid hormone, as well as radiographic and histological investigations.
Maintenance doses are generally in the range of 0.25 to 1 microgram per day.
When administered as intravenous injection to patients undergoing haemodialysis the initial dosage for adults is 1 microgram per dialysis. The maximum dose recommended is 6 micrograms per dialysis and not more than 12 micrograms per week. The injection should be administered into the return line from the haemodialysis machine at the end of each dialysis.
(a) Renal bone disease:
Patients with relatively high initial plasma calcium levels may have autonomous hyperparathyroidism, often unresponsive to One-Alpha. Other therapeutic measures may be indicated.
Before and during treatment with One-Alpha, phosphate binding agents should be considered to prevent hyperphosphataemia. It is particularly important to make frequent plasma calcium measurements in patients with chronic renal failure because prolonged hypercalcaemia may aggravate the decline of renal function.
(b) Hyperparathyroidism:
In patients with primary or tertiary hyperparathyroidism about to undergo parathyroidectomy, pre-operative treatment with One-Alpha for 2-3 weeks alleviates bone pain and myopathy without aggravating pre-operative hypercalcaemia. In order to decrease post-operative hypocalcaemia, One-Alpha should be continued until plasma alkaline phosphatase levels fall to normal or hypercalcaemia occurs.
(c) Hypoparathyroidism:
In contrast to the response to parent vitamin D, low plasma calcium levels are restored to normal relatively quickly with One-Alpha. Severe hypocalcaemia is corrected more rapidly with higher doses of One-Alpha (e.g. 3-5 micrograms) together with calcium supplements.
(d) Neonatal hypocalcaemia:
Although the normal starting dose of One-Alpha is 0.05-0.1 microgram/kg/day (followed by careful titration), in severe cases, doses of up to 2 microgram/kg/day may be required. Whilst ionised serum calcium levels may provide a guide to response, measurement of plasma alkaline phosphatase activity may be more useful. Levels of alkaline phosphatase approximately 7.5 times above the adult range indicates active disease.
(e) Nutritional and malabsorptive rickets and osteomalacia:
Nutritional rickets and osteomalacia can be cured rapidly with One-Alpha. Malabsorptive osteomalacia (responding to large doses of IM or IV parent vitamin D) will respond to small doses of One-Alpha.
(f) Pseudo-deficiency (D-dependent) rickets and osteomalacia:
Although large doses of parent vitamin D would be required, effective doses of One- Alpha are similar to those required to heal nutritional vitamin D deficiency rickets and osteomalacia.
(g) Hypophosphataemic vitamin D-resistant rickets and osteomalacia:
Neither large doses of parent vitamin D nor phosphate supplements are entirely satisfactory. Treatment with One-Alpha at normal dosage rapidly relieves myopathy when present and increases calcium and phosphate retention. Phosphate supplements may also be required in some patients.
Method of administration
One-Alpha Injection should be administered intravenously as a bolus over approximately 30 seconds. Shake the ampoule for a minimum of 5 seconds before use.