Pharmacological properties : תכונות פרמקולוגיות

Pharmacodynamic Properties

5.1    Pharmacodynamic properties
Pharmacotherapeutic group: selective β2-agonist, formoterol, ATC code: R03A C13.

Formoterol is a selective β2-adrenergic stimulant that produces relaxation of bronchial smooth muscle. Formoterol thus has a bronchodilating effect in patients with reversible airways obstruction. The bronchodilating effect sets in rapidly, within 1-3 minutes after inhalation and has a mean duration of 12 hours after a single dose.

Pharmacokinetic Properties

5.2    Pharmacokinetic properties
Absorption
Inhaled formoterol is rapidly absorbed and the peak plasma concentration is reached about 10 minutes after inhalation.
In studies the mean lung deposition of formoterol after inhalation via Turbuhaler ranged from 28-49% of the delivered dose (corresponding to 21-37% of the metered dose). The total systemic availability for the higher lung deposition was around 61% of the delivered dose (corresponding to 46% of the metered dose).
OXIS TURBUHALER          31 5. 2012, RH
       Distribution and metabolism
Plasma protein binding is approximately 50%.
Formoterol is metabolised via direct glucuronidation and O-demethylation. The enzyme responsible for O-demethylation has not been identified. Total plasma clearance and volume of distribution has not been determined
Elimination
The major part of the dose of formoterol is eliminated via metabolism. After inhalation, 8-13% of the delivered dose (corresponding to 6-10% of the metered dose) of formoterol is excreted unmetabolised in the urine. About 20% of an intravenous dose is excreted unchanged in the urine. The terminal half-life after inhalation is estimated to 17 hours.
Special populations:
The effect of decreased liver or kidney function on the pharmacokinetics of formoterol and the pharmacokinetics in the elderly is not known. As formoterol is primarily eliminated via liver metabolism an increased exposure can be expected in patients with severe liver cirrhosis.