METHACHOLINE Drug Interactions: What You Need to Know

INTERACTIONS Beta-Adrenergic Blockers The use of beta-adrenergic blockers may impair reversal of Provocholine-caused bronchoconstriction. Beta-Agonists, Anticholinergics, and Theophylline Beta-agonists, anticholinergics, and theophylline inhibit the response of airways to Provocholine; therefore, hold these drugs before Provocholine use for the following duration:

• Short-acting β-agonists (e.g., albuterol): 6 hours
• Long-acting β-agonists (e.g., salmeterol): 36 hours
• Short-acting anti-cholinergics (e.g., ipratropium): 12 hours
• Long-acting anti-cholinergics (e.g., tiotropium): ≥168 hours
• Oral theophylline: 12-48 hours Oral or Inhaled Corticosteroids, and Inhaled Cromoglycate Regular use of oral or inhaled corticosteroids and inhaled cromoglycate may acutely decrease bronchial responsiveness to Provocholine. However, these drugs may be continued with Provocholine use. Beta-Adrenergic Blockers : May impair reversal of Provocholine-caused bronchoconstriction (7) Beta-Agonists, Anticholinergics, and Theophylline : Inhibit response to Provocholine; therefore, hold these drugs prior to Provocholine use (7) Oral or Inhaled Corticosteroids, and Inhaled Cromyoglycate : May decrease response to Provocholine (7)

Provocholine is contraindicated in the following: 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 <1.5 L (adults) Known hypersensitivity to methacholine chloride or other parasympathomimetic agents (4) Baseline FEV 1 <60% predicted (adults or children) or <1.5 L (adults) (4)

AND PRECAUTIONS Healthcare provider and any other personnel involved in the administration of the methacholine challenge test should take precautions to minimize inhalation of Provocholine powder and nebulized aerosol (5.2)

5.1 Risk of Severe Bronchoconstriction Severe bronchoconstriction can result from Provocholine administration (including the lowest dose). The use of Provocholine is contraindicated in pediatric and adult patients with baseline FEV 1 &lt; 60% predicted or adults with FEV 1 &lt; 1.5 L. Emergency equipment and medication should be immediately available to treat acute respiratory distress. Because of the potential for severe bronchoconstriction, the use of Provocholine in patients with clinically apparent asthma or wheezing is not recommended. If severe bronchoconstriction occurs, reverse immediately by the administration of a rapid-acting inhaled β-agonist. If baseline spirometry is not performed or is measured inaccurately, the initial FEV 1 may be underestimated. In this situation, decreases in FEV 1 may not be detected after escalating Provocholine doses, which may result in administration of unnecessary higher doses and an increase in the risk for excessive bronchoconstriction.

5.2 Risks to Healthcare Providers Administering Provocholine The supplied Provocholine powder or the Provocholine nebulized aerosol may cause bronchoconstriction in healthcare providers administering Provocholine in a methacholine challenge test. Healthcare providers and any other personnel involved in the administration of Provocholine should take the following precautionary steps: Do not inhale the supplied Provocholine powder Do not handle the Provocholine powder if you have asthma or hay fever. Apply a low resistance filter to expiratory ports of dosing apparatus, as necessary, to prevent Provocholine release in the room air

5.3 Coexisting Diseases and Conditions Provocholine is not recommended for patients with uncontrolled hypertension, aortic aneurysm, or history of myocardial infarction or stroke diseases. Patients with epilepsy, vagotonia, peptic ulcer disease, thyroid disease, urinary tract obstruction or other condition that could be adversely affected by a cholinergic agent should undergo methacholine challenge only if the healthcare practitioner considers the benefit to the individual outweighs the potential risks.