Pharmacological Group and Origin
Ergocalciferol (Ergocalciferolum) is part of the group of agents that regulate metabolic processes (vitamin D preparations). It is important to understand the classification: this substance represents the inactive form of vitamin $D_2$. Unlike cholecalciferol (vitamin $D_3$), which is of animal origin, ergocalciferol is a plant-derived provitamin.
Mechanism of Action and Bioactivation
The drug itself is pharmacologically inactive. To influence metabolic processes, it must undergo a complex path of bioactivation involving the hydroxylation of parent compounds.
The conversion of inactive vitamin D forms into active metabolites occurs in two steps:
- Hepatic step: under the action of the enzyme 25-hydroxylase, the transport form (still inactive) is produced.
- Renal step: under the action of the enzyme 1-hydroxylase, the final active form is synthesized.
Two conditions are critical for these reactions to succeed:
- Presence of ultraviolet radiation (sunlight exposure).
- Normal activity of hydroxylase enzymes in the liver and kidneys.
Factors reducing the synthesis of active forms:
- Renal pathologies (the most frequent and clinically significant cause).
- Liver diseases.
- Insufficient sunlight exposure (insolation).
Clinical Significance: Impaired 1-hydroxylation in the kidneys is a key cause of osteopenia and osteoporosis (observed in renal failure, menopause, prolonged steroid therapy). In such cases, administering inactive ergocalciferol is pointless—the drug simply cannot be activated. Patients with renal pathology require already active metabolites (e.g., alfacalcidol).
Indications and Clinical Manifestations of Deficiency
The drug is prescribed for the prevention and treatment of hypovitaminosis and avitaminosis D, as well as to correct dietary deficiencies in individuals with preserved hepatic and renal function.
In pediatric practice, vitamin D deficiency manifests with a characteristic symptom complex. Clinical presentations in childhood include:
- Delayed closure of the fontanelles.
- Delayed tooth eruption.
- Bone skeletal deformities.
- Pronounced muscle weakness.
Topical Application (Combination Formulations)
In addition to its systemic effects on metabolism, ergocalciferol is used in dermatology and combustiology as part of combination therapy.
It is a component of the combination aerosol Amprovisol.
- Aerosol composition: benzocaine (local anesthetic), menthol, ergocalciferol (vitamin $D_2$), glycerin, propolis, ethanol.
- Indications: local anesthesia and acceleration of regeneration in first- and second-degree thermal and solar burns.
Formulations and Dosing Regimen
For enteral administration (oral use), ergocalciferol is available in several dosage forms that allow precise dose titration:
- Dragees: 500 IU.
- Oil solution: 0.0625%, 0.125%, and 0.5% (activity per 1 mL is 25,000, 50,000, and 200,000 IU, respectively).
- Alcohol solution: 0.5% (1 mL contains 200,000 IU).
Dosing Regimen: Administered orally from 10,000 to 100,000 IU once daily, depending on the severity of the deficiency and the clinical situation.
Prescription Example (oil solution): Rp.: Sol. Ergocalciferoli oleosae 0.125% — 10 ml D.S. Oral drops, as directed. (Note: the exact number of drops is calculated by the physician based on the required dose in IU).