|
Clinical Pharmacology
CLINICAL PHARMACOLOGY
Combivent Inhalation Aerosol is a combination of the anticholinergic bronchodilator, ipratropium bromide, and the beta 2 -adrenergic bronchodilator, albuterol sulfate. Ipratropium Bromide: Text Continues Below
Mechanism of Action Ipratropium bromide is an anticholinergic (parasympatholytic) agent which, based on animal studies, appears to inhibit vagally mediated reflexes by antagonizing the action of acetylcholine, the transmitter agent released from the vagus nerve. Anticholinergics prevent the increases in intracellular concentration of cyclic guanosine monophosphate (cyclic GMP) which are caused by interaction of acetylcholine with the muscarinic receptor on bronchial smooth muscle. Pharmacokinetics The bronchodilation following inhalation of ipratropium bromide is primarily a local, site-specific effect, not a systemic one. Much of an administered dose is swallowed as shown by fecal excretion studies. Ipratropium bromide is a quaternary amine. It is not readily absorbed into the systemic circulation either from the surface of the lung or from the gastrointestinal tract as confirmed by blood level and renal excretion studies. Plasma levels of ipratropium bromide were below the assay sensitivity limit of 100 pg/ mL. The half-life of elimination is about 2 hours after inhalation or intravenous administration. Ipratropium bromide is minimally bound (0 to 9% in vitro) to plasma albumin and 1-acid glycoprotein. It is partially metabolized to inactive ester hydrolysis products. Following intravenous administration, approximately one-half of the dose is excreted unchanged in the urine. Studies in rats have shown that ipratropium bromide does not penetrate the blood-brain barrier. The pharmacokinetics of Combivent Inhalation Aerosol or ipratropium bromide have not been studied in patients with hepatic or renal insufficiency or in the elderly (See PRECAUTIONS). Page: 1 | 2 | 3 | 4 | 5 | Next >>
|
.gif)
