Punol Mechanism of Action

Pharmacology: Pharmacodynamics: lpratropium bromide is an anticholinergic agent. It inhibits vagally mediated reflexes by antagonizing the action of acetylcholine, the transmitter agent released from vagus nerve. The bronchodilation following inhibition of ipratropium bromide is primarily a local effect, not a systemic one.
Fenoterol hydrobromide is a sympathomimetic agent, selective stimulating beta-2 receptors in the therapeutic dose range. The stimulation of beta-1 receptor comes into effect at higher dose range. Concurrent use of two bronchodilators affect different pharmacological sites of action.
Pharmacokinetics: Ipratropium bromide: Following oral inhalation, ipratropium bromide is only minimally absorbed into systemic circulation from the surface of the lungs or from the GI tract. Following oral inhalation via nebulization of 400 - 600 mcg of ipratropium bromide, bronchodilation usually is evident within 15 - 30 minutes with peak effect in approximately 1-2 hours. Following concomitant administration via nebulization of a β₂-adrenergic agonist and ipratropium in patients with chronic obstructive pulmonary disease (COPD), bronchodilalion persists for 5 - 7 hours compared with 3 - 4 hours in patients given a β₂-adrenergic agonist alone. Distribution of ipratropium bromide into human tissues and body fluids has not been elucidated. Quaternary ammonium antimuscarinics arc completely ionized and possess poor lipid solubility; accordingly, they do not readily penetrate the CNS. Ipratropium bromide reportedly is 0 - 9% bound to plasma albumin and α₁-acid glycoproteins in vitro.
It is not known whether ipratropium bromide crosses the placenta or is distributed into milk. An elimination half-life of about 2 - 4 hours. The drug is partially metabolized to at least 8 metabolites. The main metabolites appear to be N-isopropylnortropium rnethobromide, α-phenylacrylic acid-N-isopropylnortropine-ester methobromide and phenylacetic acid-N-isopropylnortropine-ester methobromide. In vitro, these metabolites have minimal or no antimuscarinic activity. After oral inhalation of ipratropium bromide, most of the dose is excreted in feces, principally as unchanged drugs.
Fenoterol hydrobromide: When drug is administered by inhalation, as much as 90% of the dose is swallowed. Fenoterol undergoes extensive first-pass metabolism. The half-life is 7 hours. Although maximum effect of inhaled fenoterol is not achieved for 1 to 2 hours, 60% of the maximal response is seen within the first few minutes. The duration of action is about 4 - 6 hours. Less than 2% of the dose is eliminated unchanged in the urine. The balance is excreted as acid conjugates in the urine and feces (40%).