Vitamins and Trace Elements 385Retinoids: They influence a wide variety
of biological activities including cellular
proliferation, cellular differentiation,
immune function, inflammation. e.g.
tretinoin, isotretinoin, etretinate.
Isotretinoin is a retinoid, recently
approved for use in capsule form (10-20 mg).
It decreases the amount of sebum that
sebaceous glands produce. Isotretinoin exhibits
antiproliferative and antiandrogenic effects on
the sebaceous glands. It also interacts with the
formation of androgens in sebaceous glands.
It is indicated in the treatment of severe
nodular acne, acne conglobata and recalcitrant
acne. It is available in International market
under the brand name ‘ACCUTANE’ by
Roche pharmaceuticals.
Deficiency symptoms: Bitot’s spots,
xerosis, night blindness, keratomalacia,
diarrhoea, follicular hyperkeratosis,
papular eruptions, drying of epidermis,
urinary calculi, degeneration of testis,
impaired spermatogenesis, sterility,
abortion, impairment of smell and taste.
It is indicated in night blindness, vitamin
A deficiency (in infants, in pregnancy,
lactation, malabsorption syndrome), for
prophylaxis of vitamin A deficiency, acne,
ichthyosis, psoriasis, xerophthalmia, Bitot’s
spots (especially children).
Dosage:
Severe deficiency with
xerophthalmia: 50,000 IU per day for three
days followed by 50,000 IU per day for two
weeks.
Severe deficiency: 100,000 IU per day
for three days followed by 50,000 IU per
day for two weeks.
Children: 5,000 to 10,000 IU per day
for two weeks.
VITAMIN D
The term vitamin D is used for a range
of compounds which possess the property
of preventing or curing rickets. They include
ergocalciferol (calciferol, vitamin D 2 ), chole-
calciferol (vitamin D 3 ), dihydrotachysterol,
alfacalcidol (1α-hydroxycholecalciferol) and
calcitriol (1,25-dihydroxycholecalciferol).
It plays an important role in calcium
metabolism. It regulates calcium
homeostasis and maintains normal levels of
plasma calcium and phosphate.
Deficiency symptoms: Rickets occurs
in patients who are having deficiency of
vitamin D. The bones are unusually soft
and due to stress and strain of weight
bearing produce characteristic deformities.
It is indicated in prophylaxis and
treatment of rickets, postmenopausal
osteoporosis, Fanconi syndrome and
hypoparathyroidism.
Adverse effects include headache,
weakness, nausea, vomiting, dry mouth,
muscle pain, constipation, somnolence,
ectopic calcification, hypertension,
nephrocalcinosis and weight loss.ALFACALCIDOL
It regulates calcium metabolism by
increasing calcium and phosphate
absorption from the intestinal tract and also
mobilises minerals from the bone.
After oral administration it is absorbed
in the small intestine and undergoes rapid
metabolism to 1,25 (OH) 2 D 3 in liver and
further distribution to bone and intestine is
nearly similar to its physiological distribution.