Furosemide pharmacokinetics following intratracheal instillation in the guinea pig

Inhaled furosemide has been shown to attenuate bronchospasm in asthmatics and to increase lung compliance in infants with bronchopulmonary dysplasia (BPD). The reports involving BPD used a dose of 1 mg/kg and some have failed to show an effect with that dose. We determined the pharmacokinetics of furosemide administered directly to the airway in 7 young adult male guinea pigs who received intravenous and intratracheal doses of furosemide. Each animal received a 3 mg/kg i.v. bolus, 1, 3 and 6 mg/kg i.t. in 2 ml/kg normal saline and 3 mg/kg i.t. in 2 ml/kg bovine extract surfactant. Blood was sampled multiple times after each dose. The mean fraction of the intratracheal dose absorbed was 0.50-0.60 for all doses. Surfactant delayed the absorption of furosemide but did not alter the fraction absorbed.