Ipratroium

• An additive effect with the latter drugs is difficult to prove.
• Ipratropium is used in the treatment of asthma and chronic obstructive airways disease.
• Ipratropium is a synthetic quaternary ammonium compound which is a derivative of atropine.
• Ipratropium is presented as an isotonic solution of ipratropium bromide containing 0.25 mg/ml for nebulization or as a metered-dose aerosol delivering 200 micrograms/dose (18 micrograms of which is available to the patient).
• The main action of ipratropium is bronchodilatation.
• Ipratropium acts by competitive inhibition of cholinergic receptors on bronchial smooth muscle, thereby blocking the bronchoconstrictor action of vagal efferent impulses.
• Ipratropium may also inhibit acetylcholine enhancement of mediator release by blocking cholinergic receptors on the surface of mast cells.
• The drug is administered by inhalation of a nebulized solution or aerosol in an adult dose of 100– 500 micrograms 6-hourly or 1–2 puffs 6-hourly, respectively.
• The maximum effect of ipratropium is achieved in 1..5 - 2 hours and lasts 4 - 6 hours.
• Ipratropium has no effect on cardiovascular function when administered by inhalation.
• None of the typical anticholinergic side effects are observed if ipratropium is administered by inhalation.
• The clearance of ipratropium is 11.8 l/hour, and the elimination half-life is 3.2– 3.8 hours.
• The oxygen saturation remains unaltered, following the administration of ipratropium.
• Ipratropium has no effect on the viscosity or volume of secretions or the effectiveness of mucociliary clearance.
• When given orally in large doses, gastric secretion and salivation are decreased by ipratropium.
• Ipratropium is metabolized to eight inactive metabolites.
• Local deposition of the nebulized drug on the eye may cause mydriasis and difficulty with accommodation.
• Between 20 to 30% of patients receiving ipratropium experience transient local effects: dryness or unpleasant taste in the mouth.
• The volume of distribution (VD) of ipratropium is 0.4 l/kg.
• Excretion of ipratropium occurs in approximately equal proportions in the urine and faeces.
• Ipratropium is unable to cross the blood–brain barrier, hence it has no effect on the Central Nervous System (CNS).
• The bioavailability of ipratropium when administered orally is 3–30%, and 5% by the inhaled route.
• When administered intravenously, tachycardia with an increase in blood pressure and cardiac output and a fall in central venous pressure may result.