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Drug Details

ONE-ALPHA

• Drug Class Description
  Vitamin D analogues (vitamins).
• Generic Name
  Alfacalcidol Note: One-Alpha Drops have replaced One-Alpha Solution. The concentration of the drops is 10 times that of the solution.
• Presentation
  One-Alpha® Capsules 1 microgram: brown soft gelatin capsules. One-Alpha® Capsules 0.25 microgram: white soft gelatin capsules. One-Alpha® Capsules 0.5 microgram: red soft gelatin capsules.
• Description
  One-Alpha® Capsules 1 microgram: alfacalcidol (1-? hydroxyvitamin D3) 1 µg. One-Alpha® Capsules 0.25 microgram: alfacalcidol (1-? hydroxyvitamin D3) 0.25 ?g. One-Alpha® Capsules 0.5 microgram: alfacalcidol 0.5 ?g.
• Indications
  

  One-Alpha® is indicated in all conditions where there is a disturbance of calcium metabolism due to impaired 1-? hydroxylation such as when there is reduced renal function. The main indications are:

  a) Renal osteodystrophy

  b) Hyperparathyroidism (with bone disease)

  c) Hypoparathyroidism

  d) Neonatal hypocalcaemia

  e) Nutritional and malabsorptive rickets and osteomalacia

  f) Pseudo-deficiency (D-dependent) rickets and osteomalacia

  g) Hypophosphataemic vitamin D resistant rickets and osteomalacia

• Adult Dosage
  

  Route of administration: oral

  Initial dose for all indications:

  Adults	1 microgram/day
  Dosage in the 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
  Children over 20 kg bodyweight	1 microgram/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.

  Plasma levels should initially be measured at weekly intervals. The daily dose of One-Alpha^® may be increased by increments of 0.25 - 0.5 microgram. When the dose is stabilised, measurements may be taken every 2 - 4 weeks.

  Most adult patients respond to doses between 1 and 3 micrograms per day. When there is biochemical or radiographic evidence of bone healing, (and in hypoparathyroid patients when normal plasma calcium levels have been attained), the dose generally decreases. Maintenance doses are generally in the range of 0.25 to 1 microgram per day. If hypercalcaemia occurs, One-Alpha^® should be stopped until plasma calcium returns to normal (approximately 1 week) then restarted at half the previous dose.

  (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.

  A dose of 0.1 microgram/kg/day of One-Alpha^® has proven effective as prophylaxis against early neonatal hypocalcaemia in premature infants.

  (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.

• Child Dosage
  One-Alpha and One-Alpha Drops: Neonates and premature infants, initially 0.05 - 0.1 microgram/kg daily; under 20 kg, initially 0.05 microgram/kg daily; over 20 kg, initially 1 microgram daily. Half-drop doses should be rounded up to the next whole number of drops. See data sheet. One-Alpha Injection: As for oral presentations. Given by intravenous injection. Adjust doses according to response.
• Contra Indications
  

  Hypercalcaemia, metastatic calcification.

  Hypersensitivity to alfacalcidol or any of the other ingredients.

• Special Precautions
  

  One-Alpha^® should be used with caution for:

  • patients being treated with cardioactive glycosides or digitalis as hypercalcaemia may lead to arrhythmia in such patients

  • patients with nephrolithiasis

  During treatment with One-Alpha^® serum calcium and serum phosphate should be monitored regularly especially in children, patients with renal impairment and patients receiving high doses. To maintain serum phosphate at an acceptable level in patients with renal bone disease a phosphate binding agent may be used.

  Hypercalcaemia may appear in patients treated with One-Alpha^®, the early symptoms are as follows:

  • polyuria

  • polydipsia

  • weakness, headache, nausea, constipation

  • dry mouth

  • muscle and bone pain

  • metallic taste

  Hypercalcaemia can be rapidly corrected by stopping treatment until plasma calcium levels return to normal (in about one week). One-Alpha^® treatment may then be restarted at a reduced dose (half the previous dose).

• Interactions
  

  Patients taking barbiturates or anticonvulsants may require larger doses of One-Alpha^® to produce the desired effect due to the induction of hepatic detoxification enzymes.

  Concomitant administration of colestyramine may interfere with the intestinal absorption of alfacalcidol.

  Use with caution in patients being treated with thiazide diuretics as they may have an increased risk of developing hypercalcaemia.

• Adverse Drug Reactions
  

  The most frequently reported undesirable effects are hypercalcaemia and various skin reactions. Hypercalcaemia can be rapidly corrected by stopping treatment until plasma calcium levels return to normal (about 1 week). One-Alpha^® treatment may then be re-started at half the previous dose.

  Based on data from post-market use the total undesirable effect “reporting rate” is rare or very rare being approximately 1:10,000 patients treated.

  Metabolism and Nutrition Disorders

  Hypercalcaemia

  Hyperphosphataemia

  Skin and Subcutaneous Tissue Disorders

  Pruritis

  Rash

  Urticaria

  Renal and Urinary Disorders

  Nephrocalcinosis

  Renal impairment