Alfacalcidol is an active metabolite of Vitamin D, which performs important functions in regulation of the calcium balance and the bone metabolism. Alfacalcidol is Vitamin D-hormone analog which is activated by the enzyme 25-hydroxylase in the liver for systemic and in osteoblasts for local D-hormone actions. It possesses a unique pattern of pleiotropic effects on, e.g. gut, bone, pararthyroids, muscle and brain. Alfacalcidol is superior to plain vitamin D (cholecalciferol) because the final kidney activation of the latter is regulated by a negative feedback mechanism. Although alfacalcidol is widely used in the treatment of osteoporosis, its mechanism of action in bone is not fully understood. Alfacalcidol stimulates intestinal calcium (Ca) absorption, increases urinary Ca excretion and serum Ca levels, and suppresses parathyroid hormone (PTH) secretion.
What indications has this product?
One-Alpha is indicated in all conditions where there is a disturbance of calcium metabolism due to impaired 1-α 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
How should I take this product?
Take it exactly as it's been prescibed by your doctor. It comes as a capsule to take by mouth, with food.
Adult- PO- The recommended starting dose is 1mcg/day. Maintenance: 0.25-1 mcg/day. Adult- IV- The recommended initial dose is 1 mcg per dialysis two to three times a week.
Contraindications
Hypersensitivity to the active substance or to any of the excipients, hypercalcaemia, metastatic calcification.
What should you know before using this medication?
During treatment with One-Alpha, serum calcium and serum phosphate levels should be monitored regularly especially in children, patients with renal impairment and patients receiving high doses. PTH, alkaline phosphatase and calcium phosphates should be monitored as clinically indicated.
Hypercalcaemia might appear in patients treated with One-Alpha. For this reason, patients should be informed about the clinical symptoms connected with hypercalcaemia. Signs of hypercalcaemia are muscle and bone pain, muscle weakness, confusion, dehydration, anorexia, fatigue, nausea and vomiting, constipation, polyuria, sweating, headache, polydipsia, hypertension and somnolence.
Hypercalcaemia can be rapidly corrected by stopping treatment until plasma calcium levels return to normal (in about one week). One-Alpha may then be restarted at a reduced dose (half the previous dose) with monitoring of calcium.
Prolonged hypercalcaemia may aggravate arteriosclerosis, cardiac valve sclerosis or nephrolithiasis and therefore prolonged hypercalcaemia should be avoided when One-Alpha is used in these patients. Transient or even long-lasting deterioration of kidney function has been observed. One-Alpha should also be used with caution in patients with calcification of pulmonary tissue as this may result in cardiac disease.
In patients with renal bone disease or severely reduced renal function, a phosphate binding agent could be used simultaneously with alfacalcidol to prevent increased serum phosphate and potential metastatic calcification.
One-Alpha should be used with caution in patients with granulomatous diseases such as sarcoidosis where the sensitivity to vitamin D is increased due to increased hydroxylation activity.
Concurrent use of digitalis glycosides in the presence of hypercalcaemia due to vitamin D administration increases the potential for cardiac arrhythmias.
One-Alpha capsules contain sesame oil as an excipient. Sesame oil may rarely cause severe allergic reactions.
Pregnancy
There is a limited amount of data from the use of alfacalcidol in pregnant women. Studies in animals have shown reproductive toxicity at high doses. Therefore, One-Alpha is not recommended during pregnancy and in women of child-bearing potential not using contraception.
Breast-feeding
Although it has not been established, it is likely that increased amounts of 1,25-dihydroxyvitamin D will be found in the milk of lactating mothers treated with One-Alpha. This may influence calcium metabolism in the infant. Consequently, breast-fed infants of alfacalcidol-using mothers should be monitored closely for hypercalcaemia.
Fertility
There are no clinical studies on the effect of One-Alpha on fertility. A pre-clinical study did not show an effect on fertility in rats.
What are the posible side effects?
Hypercalcemia - Early symptoms of hypercalcemia, include nausea and vomiting, weakness, headache, somnolence, dry mouth, constipation, metallic taste, muscle pain and bone pain. Late symptoms and signs of hypercalcemia, include polyuria, polydipsia, anorexia, weight loss, nocturia, conjunctivitis, pancreatitis, photophobia, rhinorrhea, pruritis, hyperthermia, decreased libido, elevated BUN, albuminuria, hypercholesterolemia, elevated ALT (SGPT) and AST (SGOT), ectopic calcification, nephrocalcinosis, hypertension and cardiac arrhythmias.
Gastrointestinal : Loss of appetite, nausea, vomiting, diarrhea and increased thirst.
Central Nervous System : Headache, fainting and lack of energy.
Skin : Increased sweating, itching, rash and hives.
Alfacalcidol has no or negligible direct influence on the ability to drive and use machines. However, the patient should be informed that dizziness may occur during treatment and take this into account while driving or using machines.
What should I know in case of an overdose?
Excessive intake of One-Alpha may lead to the development of hypercalcaemia, however, the effect is reversed rapidly on withdrawal. In severe cases of hypercalcaemia general supportive measures should be undertaken. Keep the patient well hydrated by i.v. infusion of saline (force diuresis), measure electrolytes, calcium and renal function indices, assess electrocardiographic abnormalities, especially in patients using digitalis. More specifically, treatment with glucocorticosteroids, loop diuretics, bisphosphonates, calcitonin and eventually haemodialysis with low calcium content should be considered.
What are the storage conditions for Alfacalcidol?
Capsules: Store it at room temperature (25°C), and in an airtight container.
