OPT-D 1 Lac IU CAP
DESCRIPTION
Opt-D® capsules contain Cholecalciferol, a Vitamin D analogue also referred to as Vitamin D3. It is a fat soluble vitamin and is a precursor of the active hormone 1, 25-dihydroxy cholecalciferol, also known as Calcitriol. Chemically it is (3β, 5Z, 7E)-9, 10-secocholesta-5, 7, 10(19)-trien-3-ol and molecular formula is C27H44O.
CLINICAL PHARMACOLOGY
Mechanism of Action Cholecalciferol is produced within the skin under the influence of UV radiation including sunlight. In its biologically active form, cholecalciferol stimulates intestinal calcium absorption, incorporation of calcium into the osteoid, and release of calcium from bone tissue. In the small intestine it promotes rapid and delayed calcium uptake. The passive and active transport of phosphate is also stimulated. In the kidney, it inhibits the excretion of calcium and phosphate by promoting tubular resorption. The production of parathyroid hormone (PTH) in the parathyroids is inhibited directly by the biologically active form of cholecalciferol. PTH secretion is inhibited additionally by the increased calcium uptake in the small intestine under the influence of biological- ly active cholecalciferol.
Pharmacokinetics
Absorption Cholecalciferol from nutritional sources is almost completely absorbed from within the gastro-intestinal tract in the presence of dietary lipids and bile acids.
Distribution & Metabolism
Cholecalciferol is stored in fat cells. Cholecalciferol is metabolized by microsomal hydroxylase to form 25-hydroxycholecalciferol (25(OH) D3, calcidiol), the primary storage form of vitamin D3. 25(OH) D3 undergoes a secondary hydroxylation within the kidney to form the predominant active metabolite 1, 25-hydroxycholecalciferol (1, 25(OH)2D3, calcitriol). The metabolites circulate in the blood bound to a specific α-globin. After a single oral dose of cholecalciferol, the maximum serum concentra- tions of the primary storage form are reached after approximately 7 days. Elimination Cholecalciferol and its metabolites are excreted mainly in bile and faeces. 25(OH) D3 is slowly eliminated with an apparent half-life in serum of about 50 days.
INDICATIONS
Opt-D® (Cholecalciferol) capsules are indicated in: • Prevention of Vitamin D deficiency • Treatment of Vitamin D deficiency • Osteomalacia due to hepatobiliary disease • Osteomalacia due to malabsorption • Hypoparathyroidism • Osteodystrophy DOSAGE AND
ADMINISTRATION
Adult dosage:
Prevention of Vitamin-D deficiency: 25,000 IU capsule / month Higher doses may be needed in certain population e.g. hospitalized individuals, dark skinned individuals, individuals with limited effective sun exposure, obese individuals, patients being evaluated for osteoporosis, patients using certain concomitant medications (e.g., anticonvulsant medications, glucocorticoids), patients with malabsorption, including inflammatory bowel disease and coeliac disease. In such populations monitoring of serum Vitamin D levels 25(OH)D is also recommended.
Treatment of Vitamin D deficiency:
50,000 IU (2 capsules of 25,000 IU) per week initially for 7 weeks. Followed by maintenance therapy with 2 capsules of 25,000 IU per month. OR 1 capsule of 100,000 IU once every 3 months. Follow-up 25(OH) D measurements should be made approximately three to four months after initiating maintenance therapy to confirm that the target level has been achieved)