Mechanism of action and pharmacokinetics
The structure of beclometasone is based on a steroid nucleus (cyclopentanoperhydrophenanthrene). The drug contains a chlorine atom at the 9-alpha position, making it a halogenated steroid with enhanced glucocorticoid activity.
The main issue with inhaled steroids is the risk of resorptive (systemic) effects. The drug may be cleared from the airways by mucociliary clearance, reach the oral cavity, be swallowed, and be absorbed from the gastrointestinal tract into the bloodstream.
To minimize systemic effects, beclometasone has intensive presystemic elimination. The fraction of the drug that enters the gastrointestinal tract is rapidly degraded during the first pass through the liver and does not reach the systemic circulation in an active form. Unlike systemic agents (prednisolone, dexamethasone), beclometasone acts topically.
Pharmacological effects
The drug exerts pronounced anti-inflammatory, anti-allergic, and anti-edematous effects on the respiratory mucosa.
- Reduces eosinophilic infiltration of the lung tissue.
- Decreases bronchial hyperreactivity.
- Improves pulmonary function test (PFT) parameters.
- Exerts a permissive effect: restores the sensitivity of bronchial receptors to bronchodilators, which is critical in severe asthma.
Indications for use
The drug's action develops gradually, which is why it is intended solely for regular, systematic (baseline) treatment rather than emergency relief.
- Pulmonology: steroid-dependent bronchial asthma (most severe course). Used as aerosol inhalations.
- ENT pathology: vasomotor and allergic rhinitis. Prescribed intranasally (as nasal sprays).
Side effects and contraindications
Due to pharmacokinetic features, systemic effects are practically absent. Side effects are predominantly local in nature:
- Vocal apparatus: dysphonia (hoarseness).
- Irritant effects: cough, sneezing, throat tickling, or burning in the pharynx or larynx.
- Infectious complications: prolonged use may cause oral candidiasis (oral thrush) and upper respiratory tract infections.
- Specific reaction: paradoxical bronchospasm occurs rarely. It is managed by intravenous administration of theophylline.
Contraindications: active pulmonary tuberculosis and the first trimester of pregnancy.
Prescribing specifics and formulation
The drug is available as metered-dose aerosols (including those with a dose counter/optimizing device) and powder inhalers (with a dosing device or Diskus).
The maintenance dose is 100–200 mcg. Frequency of administration is 2–4 times a day.
Prescription example: Rp.: Aeros. Beclomethasoni 0.00005 - 1 dose D.t.d. N. 1 S. Inhalation. 2 inhalations twice daily.
Briefly: answers to topical questions
What is the molecular mechanism of the anti-inflammatory action of beclometasone?
The molecular mechanism of the anti-inflammatory action of beclometasone involves the inhibition of the enzyme phospholipase A2.
- Induction of synthesis — the drug stimulates the production of lipocortin proteins (annexins), specifically lipocortin-1.
- Enzyme inhibition — lipocortins block the activity of phospholipase A2, halting the hydrolysis of cell membrane phospholipids.
- Substrate deficiency — the release of arachidonic acid is prevented.
- Blockade of inflammatory pathways — synthesis of mediators via the cyclooxygenase (prostaglandins) and lipoxygenase (leukotrienes) pathways is halted.
Additionally, there is repression of genes responsible for the synthesis of pro-inflammatory cytokines.
How can oral candidiasis be prevented when using beclometasone?
To prevent oral candidiasis when using beclometasone, it is necessary to rinse the mouth after inhalation.
Oral and pharyngeal candidiasis is a local side effect of inhaled corticosteroids, including beclometasone, especially with prolonged use.
What are the contraindications to the use of beclometasone?
Contraindications to the use of beclometasone include:
- first trimester of pregnancy;
- active pulmonary tuberculosis.
Beclometasone means No Relief of acute symptoms. The drug acts as BASELINE therapy, with a slow onset of action (maximum by days 5–7), making it useless during an acute asthma attack.
Class and exam questions
Why doesn't beclometasone cause severe systemic side effects like prednisolone?
Beclometasone undergoes high presystemic elimination. The fraction of the dose that is swallowed and absorbed in the GI tract is rapidly degraded during the first pass through the liver without entering the systemic circulation.
What is the permissive effect of beclometasone?
This is the ability of the drug to restore the sensitivity of bronchial receptors to bronchodilators. Due to this effect, bronchodilators start working again in patients with severe asthma.
Why does oral candidiasis develop upon inhalation of beclometasone?
This local infectious complication occurs because part of the drug deposits in the oral cavity and pharynx, exerting local immunosuppressive effects during prolonged use.
How does beclometasone differ from budesonide and flunisolide?
Beclometasone is a halogenated steroid (contains chlorine) used 2–4 times a day. Budesonide is non-halogenated, acts longer (1–2 times a day), but its effect develops more slowly. Flunisolide has higher systemic absorption (bioavailability up to 40%).
What else to study on this topic
- Comparative pharmacokinetics of ICS: beclometasone, budesonide, flunisolide.
- Mechanism of paradoxical bronchospasm and the role of theophylline in its treatment.
- Presystemic elimination: physiological basis of the first-pass effect through the liver.
- Systemic glucocorticoids (prednisolone, dexamethasone) in the treatment of severe bronchial asthma.
- Mucociliary clearance as a pathway for the removal of inhaled medicinal substances.
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