Vitamin D has three main isoforms - vitamins D1, D2, and D3. Vitamin D is fat soluble and helps maintain calcium and phosphate levels. It is produced in the skin from exposure to UV light and is hydroxylated in the liver and kidneys to form active calcitriol. Calcitriol enhances absorption of calcium and phosphate from the intestine and bone and promotes renal reabsorption of calcium and phosphate. Vitamin D deficiency can lead to rickets in children and osteomalacia in adults by inhibiting bone mineralization. Treatment depends on the type of deficiency and may involve supplements of vitamin D, calcium, or analogues like calcitriol or alfacalcidol.

1. Ajith.A

2.  Fat soluble ,maintanence of plasma
calcium and phosphate level ,
thermostabile
ISOFORMS
• Vitamin D1
• Vitamin D2 ( calciferol )
• Vitamin D3 ( cholecalciferol )

3. 7-Dehydro cholesterol Ergosterol
UV light
CalciferolCholecalciferol
25- Hydroxy
cholecalciferol
25-Hydroxy calciferol
Liver
microsomes
Calcitriol 1,25- Di Hydroxy calciferol
Kidney
Mitochondria
Active forms

4.  Calcitriol enhances absorption of calcium
and phosphate from intestine.
 It enhances resorption of calcium &
phosphate from bone
 Calcitriol enhances tubular reabsorption
of calcium & phosphate in kidney

5. RDA
5µgm (200IU) or 400 IU/day if there is no
synthesis in body
PREPARATIONS
 CALCIFEROL
as solution in oil, filled in gelatin
capsules 25,000 and 50,000 IU caps.
 CHOLECALCIFEROL
as granules for oral ingestion and oily
solution for i.m injection

6.  CALCITRIOL
0.25 – 1 µgm orally daily or on alternate
days
0.5 – 1 µgm I.v on alternate days
 ALFACALCIDOL
It is 1α – OHD3, a prodrug that is rapidly
hydroxylated in the liver to calcitriol
1-2µgm/day in adults
for children<20 kg 0.5µgm/ day
 DIHYDROTACHYSTEROL
synthetic vit D2 analogue
0.25 – 0.5 mg/ day

7. Absorption Intestine in presence of bile salts
Storage Adipose tissues
t1/2 1-18 Days
Excretion Bile

8. Inadequate absorption
Plasma calcium & phosphate
Secretion of PTH
Calcium mobilization from bone to restore plasma Ca
2+
Mineralization of bone fails in newly laid area & becomes soft
Rickets in children
Oestomalacia in adults

9.  Prophylaxis (400 IU/ day)
 Treatment of nutritionalVit D deficiency
(3000-4000 IU/day) or
(3,00,000 – 6,00,000 IU) orally or i.m
once in 2-6 mnths
 Metabolic rickets
A.) Vit D resistant ricket
administration of phosphate with
calcitriol or alfacalcidol

10. B.)Vit D dependent rickets
administration of calcitriol or
alfacalcidol
C.) Renal rickets
alfacalcidol or calcitriol
 Senile or post menopausal osteoporosis
Vit D3 + Calcium
 Hypoparathyroidism
Dihydrotachysterol is given
 Fanconi syndrome

11. > 50,000 IU/ day
Excess ingestion of vit D leads to
• Hypercalcemia
• Weakness
• Fatigue
• Vomiting

12.  Diarrhoea
 sluggishness
 Polyuria
 Albuminuria
 Renal stones
 hypertension

13. Thank you