Metacolina Lofarma (Methacholine Chloride)

• Metacolina Lofarma is employed in diagnostic testing of the bronchial airway and related respiratory conditions.
• Asthma diagnostic testing: enables controlled bronchoconstriction to confirm airway hyperresponsiveness.
• Airway hyperresponsiveness assessment: quantifies bronchial sensitivity in patients with suspected reactive airway disease.
• Clinical research on bronchial reactivity: provides a standardized agent for inhalation challenge protocols.

• Methacholine chloride acts as a selective muscarinic receptor agonist in airway smooth muscle. By binding to M3 receptors, it triggers intracellular calcium release, leading to contraction of bronchial smooth muscle and resultant bronchoconstriction. This pharmacologic response is deliberately provoked during inhalation challenge tests to evaluate the degree of airway hyperresponsiveness in suspected asthma patients.

Adverse reactions may occur during or after inhalation of methacholine.

Common Side Effects

• Cough: transient irritation of the airway.
• Throat irritation: mild discomfort during inhalation.
• Dyspnea: shortness of breath that resolves with bronchodilator use.
• Wheezing: audible airway narrowing.
• Chest tightness: sensation of constriction in the chest.
• Nausea: occasional gastrointestinal upset.

Serious or Rare Side Effects

• Severe bronchospasm: marked airway obstruction requiring emergency intervention.
• Anaphylaxis: rare systemic allergic reaction.
• Respiratory arrest: extremely rare, life‑threatening cessation of breathing.
• Hypotension: significant drop in blood pressure.
• Cardiac arrhythmia: irregular heart rhythm.
• Pulmonary edema: fluid accumulation in the lungs.

• Careful patient assessment and preparation are essential before performing a methacholine challenge.
• Patient selection: avoid in individuals with severe obstructive lung disease or recent asthma exacerbation.
• Baseline lung function: obtain spirometry measurements prior to the test.
• Rescue medication: ensure short‑acting bronchodilator is immediately available.
• Monitoring: observe the patient continuously during and after inhalation.
• Contraindications: do not use in patients with known hypersensitivity to methacholine.
• Store at room temperature: keep in the original container, protect from moisture and light.

Methacholine may have interactions that affect test outcomes or patient safety.

Major Interactions (Avoid)

• Beta‑agonists: can blunt the bronchoconstrictive response.
• Anticholinergics: may reduce methacholine‑induced bronchoconstriction.
• Recent inhaled corticosteroid use: can alter test sensitivity.

Moderate Interactions (Monitor Closely)

• ACE inhibitors: may increase cough frequency.
• Theophylline: can modify airway reactivity.
• Smoking: may affect the magnitude of the bronchial response.