ATS Pulmonary Function Laboratory Manual

CHAPTER  12

INDICATIONS AND CONTRAINDICATIONS Indications for the methacholine challenge test are provided in Table 12.1, with a list of relative contraindications presented in Table 12.2.

EQUIPMENT AND SUPPLIES 1.

Methacholine (acetyl- β methylcholine chloride) 1.1.

Methacholine (Provocholine ® ) approved by the Food and Drug Administration (FDA) and/or United States Pharmacopieia (USP) can be obtained in 100-mg pre-measured sealed containers from: Methapharm, Inc. 19 Isabel Drive

RR 4, Brantford, ON N3T 5L7, CANADA 1-800-287-7686 www.methapharm.com

1.2. Industrial methacholine is available in bulk quantities from chemical supply companies, but is not FDA approved. While industrial methacholine has been shown to be clinically and structurally similar to the FDA-approved product (12), its use is not recommended by the most current ATS/ERS guideline (10). 1.3. Where methacholine is formulated locally, the laboratory must be assured that it meets good manu- facturing practices for quality, purity, and consistency. 1.4. Sealed prepackaged vials of Provocholine have a shelf life of 2 to 3 years when stored at ambient temperature.

Table 12.1

Indications for Methacholine Challenge Testing (10)

Clinical Indications for Testing Include Evaluation of: • Confirm or exclude a suspected diagnosis of asthma • Screening applicants for situations where asthma would present a high safety risk (e.g., commercial diving, submarine service, and some occupational exposures) • Assess response to therapeutic interventions

Table 12.2

Relative Contraindications for Performing Methacholine Challenge Testing (10)

Relative Contraindications for Testing Include: • Low FEV 1

(Less than 60% of predicted or 1.5 L in adults) • Inability to perform acceptable and repeatable spirometry (11) • Uncontrolled hypertension, recent heart attack or stroke, arterial hypoxemia • Recent eye surgery, or any condition where raised intracranial pressure (caused by forced exhalation) is a contraindication • Pregnancy and nursing mothers: methacholine is a pregnancy category C drug, meaning no animal reproduc- tive studies have been performed to determine if methacholine chloride is associated with fetal abnormalities, or whether it is excreted in breast milk. • Current use of cholinesterase inhibitor medication (e.g., myasthenia gravis)

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