Tobramycin
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Tobramycin is an aminoglycoside antibiotic derived from Streptomyces tenebrarius and used to treat various types of bacteria infections, particularly Gram-negative infections. It is especially effective against species of Pseudomonas.[1]
Category
Aminoglycoside
US Brand Names
AKTOB®, BETHKIS®, NEBCIN®, TOBI®, TOBRAMYCIN®, TOBREX®, ZYLET®
FDA Package Insert
Description | Clinical Pharmacology | Microbiology | Indications and Usage | Contraindications | Warnings and Precautions | Adverse Reactions | Drug Interactions | Overdosage | Clinical Studies | Dosage and Administration | How Supplied | Labels and Packages
Mechanism of Action
Tobramycin works by binding to a site on the bacterial 30S and 50S ribosome, preventing formation of the 70S complex. As a result, mRNA cannot be translated into protein and cell death ensues.
Administration
Like all aminoglycosides, tobramycin does not pass the gastro-intestinal tract, so for systemic use it can only be given intravenously or intramuscularly. This formulation for injection is branded Nebcin®. Patients with cystic fibrosis will often take an inhalational form (Tobi®) for suppression of Pseudomonas aeruginosa infections. Tobramycin is also combined with dexamethasone as an ophthalmic solution (TobraDex®).
Bausch & Lomb Pharmaceuticals, Inc. makes a sterile Tobramycin Ophthalmic Solution (eye-drops) with a tobramycin concentration of 0.3%, which is available by prescription only in the United States and Canada. (In some countries, such as Italy, it is available over the counter.) It is mixed with 0.01% benzalkonium chloride as a preservative. These concentrations result in 3 mg per ml and 0.1 mg per ml, respectively.
Side effects
Like other aminoglycosides, tobramycin can cause deafness or a loss of equilibrioception (vertigo) in genetically susceptible individuals. These individuals have a normally harmless mutation in their DNA, that allows the tobramycin to affect their cells. The cells of the ear are particularly sensitive to this.
Tobramycin can also be highly toxic to the kidneys, particularly if multiple doses accumulate over a course of treatment.
For these reasons, when tobramycin is given parenterally, it is usually dosed by body weight. Various formulae exist for calculating tobramycin dosage. Also serum levels of tobramycin are monitored during treatment.
References
- ↑ "Tobramycin" (pdf). Toku-E. 2010-01-12. Retrieved 2012-06-11.