Tobramycin clinical pharmacology: Difference between revisions
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==Clinical Pharmacology== | |||
TOBI® is specifically formulated for administration by inhalation. When inhaled, tobramycin is concentrated in the airways. | |||
====Pharmacokinetics==== | |||
<ref name="dailymed.nlm.nih.gov">{{Cite web | last = | first = | title = TOBI (TOBRAMYCIN) SOLUTION [NOVARTIS PHARMACEUTICALS CORPORATION] | url =http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=94f9e516-6bf6-4e30-8dde-8833c25c2560 | publisher = | date = | accessdate = }}</ref> | TOBI® contains tobramycin, a cationic polar molecule that does not readily cross epithelial membranes.(1) The bioavailability of TOBI® may vary because of individual differences in nebulizer performance and airway pathology.(2) Following administration of TOBI®, tobramycin remains concentrated primarily in the airways. | ||
Sputum Concentrations: Ten minutes after inhalation of the first 300-mg dose of TOBI®, the average concentration of tobramycin was 1237 µg/g (ranging from 35 to 7417 µg/g) in sputum. Tobramycin does not accumulate in sputum; after 20 weeks of therapy with the TOBI® regimen, the average concentration of tobramycin at ten minutes after inhalation was 1154 µg/g (ranging from 39 to 8085 µg/g) in sputum. High variability of tobramycin concentration in sputum was observed. Two hours after inhalation, sputum concentrations declined to approximately 14% of tobramycin levels at ten minutes after inhalation. | |||
Serum Concentrations: The average serum concentration of tobramycin one hour after inhalation of a single 300-mg dose of TOBI® by cystic fibrosis patients was 0.95 µg/mL. After 20 weeks of therapy on the TOBI® regimen, the average serum tobramycin concentration one hour after dosing was 1.05 µg/mL. | |||
Elimination: The elimination half-life of tobramycin from serum is approximately 2 hours after intravenous (IV) administration. Assuming tobramycin absorbed following inhalation behaves similarly to tobramycin following IV administration, systemically absorbed tobramycin is eliminated principally by glomerular filtration. Unabsorbed tobramycin, following TOBI® administration, is probably eliminated primarily in expectorated sputum.<ref name="dailymed.nlm.nih.gov">{{Cite web | last = | first = | title = TOBI (TOBRAMYCIN) SOLUTION [NOVARTIS PHARMACEUTICALS CORPORATION] | url =http://dailymed.nlm.nih.gov/dailymed/lookup.cfm?setid=94f9e516-6bf6-4e30-8dde-8833c25c2560 | publisher = | date = | accessdate = }}</ref> | |||
==References== | ==References== | ||
Latest revision as of 20:03, 6 January 2014
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Clinical Pharmacology
TOBI® is specifically formulated for administration by inhalation. When inhaled, tobramycin is concentrated in the airways.
Pharmacokinetics
TOBI® contains tobramycin, a cationic polar molecule that does not readily cross epithelial membranes.(1) The bioavailability of TOBI® may vary because of individual differences in nebulizer performance and airway pathology.(2) Following administration of TOBI®, tobramycin remains concentrated primarily in the airways.
Sputum Concentrations: Ten minutes after inhalation of the first 300-mg dose of TOBI®, the average concentration of tobramycin was 1237 µg/g (ranging from 35 to 7417 µg/g) in sputum. Tobramycin does not accumulate in sputum; after 20 weeks of therapy with the TOBI® regimen, the average concentration of tobramycin at ten minutes after inhalation was 1154 µg/g (ranging from 39 to 8085 µg/g) in sputum. High variability of tobramycin concentration in sputum was observed. Two hours after inhalation, sputum concentrations declined to approximately 14% of tobramycin levels at ten minutes after inhalation.
Serum Concentrations: The average serum concentration of tobramycin one hour after inhalation of a single 300-mg dose of TOBI® by cystic fibrosis patients was 0.95 µg/mL. After 20 weeks of therapy on the TOBI® regimen, the average serum tobramycin concentration one hour after dosing was 1.05 µg/mL.
Elimination: The elimination half-life of tobramycin from serum is approximately 2 hours after intravenous (IV) administration. Assuming tobramycin absorbed following inhalation behaves similarly to tobramycin following IV administration, systemically absorbed tobramycin is eliminated principally by glomerular filtration. Unabsorbed tobramycin, following TOBI® administration, is probably eliminated primarily in expectorated sputum.[1]
References
Adapted from the FDA Package Insert.