Cholecalciferol Flashcards
What class does cholecalciferol belong to?
vitamins (single agents)
What are other drugs in this class?
ascorbic acid folic acid nicotinic acid calcium folinate ergocalcfierol
What is cholecalciferol?
Cholecalciferol is a compound belong to the Vitamin D and derivatives. These are compounds containing a secosteroid backbone which is usually secorgostane or secocholestane.
What is cholecalciferol indicated for?
It is marketed as Cal. D. Forte.
FOr the prevention and reatment of vitamin D deficiency states
What is the dose of cholecalciferol used in osteoporosis?
initially 250ng daily or on alternate days.
This can be increased if necessary in steps of 250ng at intervals of 2-4 weeks.
THe usual dose is 0.5-1microgram daily.
How is cholecalciferol taken?
tablet
what are the characteristic pharmacokinetic/pharmacodynamic parameters associated with cholecalciferol use?
onset of action: 12-24 hours, although therapeutic effect may take 10-14 days
Duration of action up to 6 months. Repeated doses will have a cumulative action.
Presence of bile essential for absorption.
Bound to specific alpha globulins.
Can be stored in adipose and muscle tissue for long periods
hydroxylated in liver to the active calcitriol form.
excreted mainly in bile and faeces, small amounts appearing in urine.
Some Vit D substances may be distributed into breast milk.
What is the mechanism of action of cholecalciferol?
Cholecalciferol regulates serum Ca concentrations by increasing serum Ca
and Phosphate concentrations as needed.
- stimulates Ca and
phosphate absorption from the small intestine - mobilises Ca from bone.
Colecalciferol is transferred to the liver where it is converted to calcifediol (25-
hydroxycolecalciferol), which is then transferred to the kidneys and converted to
calcitriol (1,25-dihyroxycolecalciferol, thought to be the most active form) and 24,25-
dihydroxycolecalciferol (physiologic role not determined).
What is the mechanism of action of calcitriol?
Calcitriol binds to a specific receptor in the cytoplasm of the
intestinal mucosa and is subsequently incorporated into the nucleus, leading to formation of the Ca-binding protein resulting in increased
absorption of Ca from the intestine.
Also regulates the transfer of
Ca ion from bone and stimulate reabsorption of Ca in the distal renal tubule, thereby affecting Ca homeostasis in the extracellular fluid.
What are the precautions associated with Cholecalciferol use?
monitor plasma Ca concentrations in paitnts receiving high doses and in renal impairment
Not in pregnancy category; High doses are teratogenic in animals
Breastfeeding: take cuation in high doses, may cause hypercalcaemia in infant, monitor serum Ca concentration.
What are the contraindications associated with cholecalciferol use?
hypercalcaemia, metastatic calcification
What are the drug interactions associated with cholecalciferol use?
Vitamin D requirements possibly increased when given with carbamazepine, phenobarbital, phenytoin
Increased risk of hypercalcaemia when vitamin D is given with thiazides and related diuretics
What are the alarm bells associated with cholecalciferol?
If patient has severe renal impairment, they cannot metabolise the drug into the active form of vitamin D. Give calcitriol instead.
monitor plasma Ca concentrations initially once ortwice/weekly, and then whenever nausea or vomiting occur
what are the adverse effects associated with cholecalciferol use?
symptoms of overdosage
anorexia, lassitude, nausea and vomiting, diarrhoea, constipiation, weight loss, polyuria, sweating, headache, thirst, vertigo, raised concentrations of C and Phosphate in plasma and urine.
