Mechanism of Action
The action of retinol and its active metabolites is mediated at the genetic level through interaction with specific nuclear receptors. Pharmacology distinguishes two main types of such receptors: RAR (retinoic acid receptors) and RXR (retinoid X receptors). Activation of these receptors triggers gene expression regulation by stimulating transcription, thereby influencing cell proliferation and differentiation.
Pharmacological Effects
The biological role and pharmacodynamics of retinol encompass several key areas:
- Visual function: The substance is essential for the synthesis of the visual pigment rhodopsin, which ensures normal scotopic (dim-light) vision.
- Effect on epithelium: The drug directly participates in the synthesis of glycoproteins and glycosaminoglycans, ensuring normal function, trophic support, and regeneration of skin and mucosal epithelia (exhibiting a marked antixerophthalmic effect).
- Metabolism: Participation in redox processes and regulation of lipid metabolism.
Indications for Use
According to reference data, retinol is prescribed as part of complex pharmacotherapy for various pathological conditions:
- Replacement therapy: Prevention and treatment of vitamin A deficiency and hypovitaminosis A.
- Ophthalmology: Nyctalopia ("night blindness") and associated scotopic vision disorders, corneal lesions.
- Dermatology and traumatology: Psoriasis, burns, trophic ulcers (to stimulate epithelialization and skin tissue restoration).
- Gastroenterology: Chronic inflammatory diseases of the gastrointestinal tract (enteritis, enterocolitis).
- Other pathologies: Hepatitis, pulmonary diseases.
Adverse Effects and Hypervitaminosis
Overdose leads to acute poisoning (hypervitaminosis A), affecting various organs and systems:
- CNS: Lethargy, somnolence, severe headache.
- Dyspeptic syndrome: Nausea, vomiting.
- Skin and appendages: Characteristic skin peeling, alopecia (hair loss).
Contraindications include individual hypersensitivity and the risk of overdose.
Administration and Pharmacy
The drug is available in diverse dosage forms for differentiated use:
- Dragees of 0.001 g (3,300 IU) and 0.01 g (33,000 IU), as well as tablets of 3,300 IU (for oral administration).
- Oily solutions for oral administration with varying potency per 1 mL: 100,000, 200,000, and 250,000 IU.
- Oily solution in 0.86% ampoules of 1 mL (25,000 IU) and oil-based solutions for intramuscular injection with concentrations per 1 mL of 25,000, 50,000, and 100,000 IU.
Retinol is a member of the first generation of retinoids, along with its esters (retinyl acetate, retinyl palmitate) and carotene.