tobramycin: clinical use

Prescribing considerations

• Confirm organism susceptibility and the formulation-specific licensed indication.
• Review renal function, hydration, age, previous aminoglycoside exposure and concurrent nephrotoxic or ototoxic medicines.
• For inhaled treatment, assess bronchospasm and tolerance around the first supervised administration; review significant haemoptysis and baseline respiratory status.
• Consider auditory assessment with hearing or vestibular dysfunction, previous prolonged exposure or other ototoxicity risks.
• Ask about maternal-family hearing loss or known MT-RNR1 variants. Testing may be appropriate before recurrent or long-term treatment but should not delay urgent therapy.

Contraindications and cautions

• Hypersensitivity to tobramycin or another aminoglycoside.
• Intrathecal administration of the selected injection.
• The selected nebuliser solution is contraindicated with potent ototoxic diuretics such as furosemide or ethacrynic acid.
• Use caution with renal, auditory, vestibular or neuromuscular dysfunction and severe active haemoptysis.

Monitoring

• For systemic treatment, monitor serum tobramycin concentrations, renal function, fluid status and relevant laboratory parameters.
• Monitor hearing and vestibular function when clinically indicated, particularly with additional risk factors.
• With nebulised treatment, obtain serum concentrations if systemic accumulation or toxicity is suspected. Use venous samples because skin contamination can produce falsely high finger-prick results.
• Monitor respiratory tolerance, clinical response, sputum microbiology and possible emerging resistance during inhaled therapy.

Clinical pharmacology

A bactericidal aminoglycoside acting mainly at the bacterial 30S ribosomal subunit. It disrupts protein synthesis and cell-envelope integrity. It is not appreciably metabolised; systemically absorbed drug is eliminated mainly unchanged by glomerular filtration. Inhaled formulations give high local airway exposure with relatively low systemic exposure.

Formulation and product differences

• Nebuliser solution comes in single-use containers and requires a compatible, personally maintained nebuliser. It must not be injected or mixed with other inhaled medicines.
• Inhalation-powder capsules are used only with the dedicated Podhaler device, are not swallowed and may cause more cough than nebuliser solution.
• Injection is administered intravenously or intramuscularly for serious systemic infection and has greater systemic kidney, hearing and neuromuscular toxicity concerns.
• Licensing, contraindications, administration devices, storage and excipients are product-specific and not interchangeable.

Inhaled preparation

Route: Inhaled

Strengths: 170 mg, 300 mg/5 mL

Capsule

Route: Oral

Strengths: 28 mg

Injection

Route: Parenteral

Strengths: 40 mg/mL