Pharmacological group and origin
Ergocalciferol (Ergocalciferolum) belongs to the group of agents regulating 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 provitamin of plant origin.
Mechanism of action and bioactivation
The drug itself is pharmacologically inactive. To exert an effect on metabolic processes, it must undergo a complex bioactivation pathway, which consists in the hydroxylation of the initial substances.
The conversion process of inactive forms of vitamin D into active metabolites occurs in two stages:
- Hepatic stage: under the action of the enzyme 25-hydroxylase, the transport (still inactive) form is formed.
- Renal stage: under the action of the enzyme 1-hydroxylase, the final active form is synthesized.
Two conditions are critically important for the successful course of these reactions:
- Presence of ultraviolet irradiation (sunlight exposure).
- Normal activity level 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.
- Insufficiency of sun exposure.
Clinical significance: Impaired 1-hydroxylation in the kidneys is a key cause of osteopenia and osteoporosis (observed in renal failure, menopause, and long-term steroid therapy). In such cases, prescribing inactive ergocalciferol is pointless—the drug simply cannot be activated. Patients with renal pathology require already active metabolites (e.g., alphacalcidol).
Indications and clinical picture of deficiency
The drug is prescribed for the prevention and treatment of hypovitaminosis and avitaminosis D, and to replenish dietary deficiency in individuals with preserved liver and kidney function.
In pediatric practice, vitamin D deficiency manifests with a characteristic symptom complex. Clinical manifestations in childhood include:
- Delayed closure of fontanelles.
- Late tooth eruption.
- Bone skeletal deformities.
- Pronounced muscle weakness.
Topical application (combination forms)
In addition to systemic effects on metabolism, ergocalciferol is used in dermatology and combustiology as part of complex therapy.
It is a component of the combination aerosol Amprovisol.
- Aerosol composition: benzocaine (local anesthetic), menthol, ergocalciferol (vitamin $D_2$), glycerin, propolis, ethanol.
- Indication: local anesthesia and acceleration of regeneration in first- and second-degree thermal and solar burns.
Dosage forms and regimen
For enteral application (orally), ergocalciferol is available in several dosage forms that allow precise titration of the dose:
- Dragees: 500 IU each.
- Oil solution: 0.0625%, 0.125%, and 0.5% (activity in 1 ml is 25,000, 50,000, and 200,000 IU respectively).
- Alcohol solution: 0.5% (200,000 IU per 1 ml).
Dosing regimen: Orally, 10,000 to 100,000 IU once daily, depending on the severity of deficiency and the clinical situation.
Example of prescription writing (oil solution): Rp.: Sol. Ergocalciferoli oleosae 0.125% — 10 ml D.S. Orally, according to the prescribed regimen (in drops). (Note: the exact number of drops is calculated by the physician based on the required dose in IU).
Briefly: answers to topical questions
What are the pharmacokinetic features of absorption and excretion of ergocalciferol?
Absorption of ergocalciferol occurs in the small intestine with the participation of bile acids. After absorption, it is transported by the blood to the liver as part of chylomicrons. Information on the pathways and features of excretion of ergocalciferol itself is absent in the cited sources.
What symptoms develop in case of ergocalciferol overdose and vitamin D hypervitaminosis?
The cited sources associate vitamin D hypervitaminosis with an overdose of active forms of vitamin D; specific manifestations of overdose specifically with ergocalciferol are not indicated in them. The following are described in vitamin D hypervitaminosis:
- In infants in the first year of life — regurgitation, food refusal, weight loss, polyuria, and polydipsia leading to dehydration.
- In older children — headaches, general weakness, arterial hypertension, and convulsive syndrome.
- General manifestations — nausea and fever; with hypercalcemia, convulsive syndrome and arrhythmias are possible.
Complications include ectopic tissue calcification, nephrocalcinosis, angiocalcinosis, and dysmetabolic pyelonephritis. Hypercalciuria promotes the formation of oxalate stones.
ERGOcalciferol — ERGO (plant energy): this is vitamin D2 of plant origin, which requires solar energy (UV) and healthy kidneys to work.
Class and exam questions
What is the fundamental difference between ergocalciferol and cholecalciferol?
Ergocalciferol (vitamin D2) is of plant origin, while cholecalciferol (vitamin D3) is of animal origin. At the same time, both substances are inactive forms and require two-stage bioactivation in the body.
Why is ergocalciferol ineffective for osteoporosis in severe renal failure?
Because the kidneys are responsible for the second, most crucial stage of drug activation (the 1-hydroxylase enzyme operates). In renal pathology, this enzyme does not function, and inactive ergocalciferol cannot convert into the active metabolite.
Which burn medication contains this vitamin?
Ergocalciferol is part of the combination aerosol Amprovisol (along with benzocaine, propolis, and menthol), which is used for first- and second-degree solar and thermal burns.
What else to study on this topic
- Cholecalciferol (vitamin D3): native form of animal origin
- Active metabolites of vitamin D: alfacalcidol and calcitriol
- Bioactivation enzymes: hepatic 25-hydroxylase and renal 1-hydroxylase
- Pathogenesis of rickets and bone deformities in vitamin D deficiency
- Combination drugs with benzocaine (Amprovisol, Menovazin, Anestezol)
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