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Methacholine Dosage

Applies to the following strengths: 100 mg

Usual Adult Dose for:

Usual Pediatric Dose for:

Additional dosage information:

Usual Adult Dose for Diagnostic

The inhalation challenge is performed by giving patients ascending serial concentrations of this drug to inhale:

Serial Concentration One: 0.025 mg/mL
Cumulative Units per Concentration: 0.125
Total Cumulative Units: 0.125

Serial Concentration Two: 0.25 mg/mL
Cumulative Units per Concentration: 1.25
Total Cumulative Units: 1.375

Serial Concentration Three: 2.5 mg/mL
Cumulative Units per Concentration: 12.5
Total Cumulative Units: 13.88

Serial Concentration Four: 10 mg/mL
Cumulative Units per Concentration: 50
Total Cumulative Units: 63.88

Serial Concentration Five: 25 mg/mL
Cumulative Units per Concentration: 125
Total Cumulative Units: 188.88

-At each concentration, 5 breaths are administered by a nebulizer that permits intermittent delivery time of 0.6 seconds by a breath-actuated timing device (dosimeter).
-Cumulative units are calculated by multiplying the number of breaths by the concentration administered.
-Total cumulative units equates to the sum of cumulative units for each concentration administered.

MAXIMUM DOSE: 188.88 total cumulative units

DURATION OF THERAPY:
-FEV1 reductions of 20% or greater compared with baseline, or if FEV1 has been reduced by 14% or less after 188.88 total cumulative units have been administered: End the challenge.
-FEV1 reductions of 15% to 19% compared with baseline: Repeat the challenge at that concentration, or a higher concentration may be given as long as the dosage does not exceed 188.88 total cumulative units.

Comments:
-Baseline pulmonary function tests must be performed prior to challenge initiation.
-A patient must have an FEV1 of at least 70% of the predicted value to undergo this challenge.

Use: Diagnosis of bronchial airway hyperreactivity in subjects who do not have clinically apparent asthma.

Usual Pediatric Dose for Diagnostic

Age 5 years and older:
The inhalation challenge is performed by giving patients ascending serial concentrations of this drug to inhale:

Serial Concentration One: 0.025 mg/mL
Cumulative Units per Concentration: 0.125
Total Cumulative Units: 0.125

Serial Concentration Two: 0.25 mg/mL
Cumulative Units per Concentration: 1.25
Total Cumulative Units: 1.375

Serial Concentration Three: 2.5 mg/mL
Cumulative Units per Concentration: 12.5
Total Cumulative Units: 13.88

Serial Concentration Four: 10 mg/mL
Cumulative Units per Concentration: 50
Total Cumulative Units: 63.88

Serial Concentration Five: 25 mg/mL
Cumulative Units per Concentration: 125
Total Cumulative Units: 188.88

-At each concentration, 5 breaths are administered by a nebulizer that permits intermittent delivery time of 0.6 seconds by a breath-actuated timing device (dosimeter).
-Cumulative units are calculated by multiplying the number of breaths by the concentration administered.
-Total cumulative units equates to the sum of cumulative units for each concentration administered.

MAXIMUM DOSE: 188.88 total cumulative units

DURATION OF THERAPY:
-FEV1 reductions of 20% or greater compared with baseline, or if FEV1 has been reduced by 14% or less after 188.88 total cumulative units have been administered: End the challenge.
-FEV1 reductions of 15% to 19% compared with baseline: Repeat the challenge at that concentration, or a higher concentration may be given as long as the dosage does not exceed 188.88 total cumulative units.

Comments:
-Baseline pulmonary function tests must be performed prior to challenge initiation.
-A patient must have an FEV1 of at least 70% of the predicted value to undergo this challenge.

Use: Diagnosis of bronchial airway hyperreactivity in subjects who do not have clinically apparent asthma.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Precautions

US BOXED WARNING(S):
SEVERE BRONCHOCONSTRICTION:
-Severe bronchoconstriction may occur, including at the lowest dose.
-Use in contraindicated in all patients with baseline forced expiratory volume (FEV1) less than 60% of predicted or in adults with FEV1 under 1.5 L.
-Use is not recommended in clinically apparent asthma or wheezing due to the potential for severe bronchoconstriction.
-Have emergency equipment and medication immediately available to treat acute respiratory distress.
-Severe bronchoconstriction should be immediately reversed with a rapid-acting bronchodilator agent (beta-agonist).
-Initial FEV1 may be underestimated if baseline spirometry is not performed or inaccurately measured, and FEV1 decreases may not be detected after administration of escalating doses of this drug, resulting in unnecessary higher doses and increased risk of excessive bronchoconstriction.

CONTRAINDICATIONS:
-Hypersensitivity to methacholine or other parasympathetic agents. Reactions include rash, itching/swelling (especially of face/tongue/throat), severe dizziness, and trouble breathing.
-All patients with baseline FEV1 less than 60% of predicted or in adults with FEV1 under 1.5 L.

Safety and efficacy have not been established in patients younger than 5 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration Advice:
-Consult the manufacturer product information for instructions on the standardized inhalation procedure.
-At each inhalation of a serial concentration, patients should begin at functional residual capacity (FRC) and slowly and completely inhale the dose delivered.
-An inhaled beta-agonist may be administered after the challenge to expedite the return of the FEV1 to baseline and to relieve the discomfort of the subject. Most patients revert to normal pulmonary function within 5 minutes following use of bronchodilators or within 30 to 45 minutes without any bronchodilator.

Storage Requirements:
-Unreconstituted Powder: 59 to 86 degrees Fahrenheit (15 to 30 degrees Celsius).
-Reconstituted Solution/Dilutions: Consult the manufacturer product information.

Reconstitution/Preparation Techniques:
-Consult manufacturer product information.

General:
-The target level for a positive challenge is a 20% reduction in the FEV1 compared with the baseline value after inhalation.
-FEV1 values are determined within 5 minutes.
-Serious toxic reactions should be treated with 0.5 mg to 1 mg of atropine sulfate, administered IM or IV.
-The acute (24 hour) oral LD50 of this drug is 1100 mg/kg in mice and 750 mg/kg in rats.
-People with asthma or hay fever should not handle this drug.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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