Methacholine Chloride

What it is and how it works

Mechanism of Action Methacholine chloride is a cholinergic agonist. Bronchial smooth muscle contains significant parasympathetic (cholinergic) innervation. Methacholine chloride agonizes the muscarinic receptors which eventually induce bronchoconstriction.

Indications

Provocholine, used in a methacholine challenge test, is indicated for the diagnosis of bronchial airway hyperreactivity in adults and pediatric patients five years of age and older who do not have clinically apparent asthma. Provocholine, a cholinergic agonist used in a methacholine challenge test, is indicated for the diagnosis of bronchial airway hyperreactivity in adults and pediatric patients five years of age and older who do not have clinically apparent asthma

Dosage and administration (summary)

The methacholine challenge test should be conducted in a pulmonary function laboratory or clinic, by adequately trained personnel, for safety and accuracy Determine baseline FEV1 values to assess whether a patient is able to undergo the methacholine challenge test See the Full Prescribing Information for the required reconstitution and dilution procedures prior to use .

Contraindications

Provocholine is contraindicated in patients with: Hypersensitivity to methacholine or other parasympathomimetic agents. Reactions have included rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. Baseline FEV 1 < 60% predicted (adults or pediatric patients) or <L (adults) hypersensitivity to methacholine chloride or other parasympathomimetic agents Baseline FEV 1 <60% predicted (adults or pediatric patients) or <L (adults)

Warnings and precautions

. Risk of Severe Bronchoconstriction: Severe bronchoconstriction can result from Provocholine administration. Do not use Provocholine in pediatric and adult patients with baseline FEV1 <60% predicted or adults with FEV1 <L. Not recommended in patients with clinically apparent asthma or wheezing. If severe bronchoconstriction occurs, reverse with administration of rapid-acting inhaled β2-agonist.

Pregnancy

Pregnancy Risk Summary The available data from published literature on Provocholine use in pregnant women are insufficient to evaluate for a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes.

Storage and supply

Provocholine (methacholine chloride) for Inhalation Solution: Powder: 100 mg of methacholine chloride as a white to off-white powder in amber glass vial. Each carton contains six vials (NDC 64281-100-06). Store the supplied powder at 59°F to 86°F (15°C to 30°C).

Source: Methacholine Chloride (Provocholine) — US FDA prescribing information, 2026-07-15, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.