An aminoglycoside antibiotic
Tobramycin
A powerful aminoglycoside antibiotic given into a vein, inhaled or as eye drops for specific infections.
What is Tobramycin?
Tobramycin is an aminoglycoside antibiotic used for serious bacterial infections. It can be given into a vein, breathed in (often in cystic fibrosis) or used as eye drops, depending on the infection. Because it can affect hearing, balance and the kidneys, the injected form needs careful blood-level and kidney monitoring.
Education and reference only. This is a plain-language guide to Tobramycin — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Tobramycin is an aminoglycoside antibiotic used against certain serious infections, including those caused by Pseudomonas. In hospital it is given into a vein; an inhaled form is used to manage chest infection in cystic fibrosis, and eye drops treat bacterial eye infections. It is reserved for situations where its power is needed because of its potential side effects.
How it works
Tobramycin enters bacteria and binds to their ribosomes, the machinery that builds proteins. This jams protein production and causes the bacteria to make faulty proteins, killing them. It is especially useful against certain stubborn Gram-negative bacteria, but the same potency means careful use is needed to protect the patient.
Company & origin
Originated / developed by: Available from several manufacturers, including inhaled forms branded as Tobi..
Introduced in the 1970s and used in the UK for serious infections and in cystic fibrosis.
Practical use
How to take Tobramycin
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- The injected form is given by a nurse or doctor in hospital, with monitoring.
- For the inhaled form, use the nebuliser or device exactly as shown, on the schedule given.
- For eye drops, wash your hands and avoid touching the dropper to your eye.
- Report any ringing in the ears, hearing change or dizziness without delay.
- Drink enough fluids unless you have been told otherwise.
- Complete the full course as directed, even if you feel better.
Weighing it up
Advantages & disadvantages of Tobramycin
Advantages
- Highly effective against certain serious Gram-negative infections, including Pseudomonas.
- Inhaled form delivers the antibiotic directly to the lungs in cystic fibrosis.
- Eye drops treat bacterial eye infections with little absorbed into the body.
Disadvantages
- The injected form can damage hearing and balance, sometimes permanently.
- It can harm the kidneys, so needs blood-level and kidney monitoring.
- Must be used cautiously in myasthenia gravis because it can worsen muscle weakness.
Practical use
Good to know
When tobramycin is given into a vein it can harm hearing and balance and can affect the kidneys, so your team will check blood levels and kidney function during treatment. Tell them straight away about ringing in the ears, hearing changes or dizziness. It should be used with particular caution in people with myasthenia gravis, as it can worsen muscle weakness.
Who should not take it / use with caution
- People who are allergic to tobramycin or other aminoglycosides.
- People with myasthenia gravis, unless there is no safer option and care is taken.
- People with significant kidney or hearing problems need very careful assessment.
Monitoring
- Blood levels of tobramycin to keep them effective but not toxic.
- Kidney function before and during injected treatment.
- Hearing and balance, with prompt review if symptoms appear.
Side effects
- Hearing loss, ringing in the ears or problems with balance.
- Effects on the kidneys, shown by blood and urine tests.
- With inhaled use, cough, throat irritation or a temporary change in voice.
Key interactions
- Other medicines that affect the kidneys or hearing increase the risk of harm.
- Certain water tablets (diuretics) can add to ear and kidney effects.
- Tell your team about all medicines, as some muscle relaxants and others interact.
Available as: Available as an injection/infusion, an inhaled solution or powder, and eye drops.
Answers
Tobramycin: frequently asked questions
Why are blood tests needed with tobramycin?
The injected form has a narrow safe range. Blood levels guide your team to keep it effective while avoiding kidney and hearing damage.
Can tobramycin affect my hearing?
Yes. Aminoglycosides can affect hearing and balance, sometimes permanently. Report any ringing in the ears, hearing change or dizziness straight away.
Why is it used in cystic fibrosis?
An inhaled form delivers the antibiotic directly to the lungs to manage chronic Pseudomonas chest infection, with less reaching the rest of the body.
Is it safe with myasthenia gravis?
It must be used with great caution, as it can worsen the muscle weakness of myasthenia gravis. Your team will weigh up the risks carefully.
How are the eye drops different?
The eye drops treat bacterial eye infections locally, with very little absorbed, so the serious whole-body risks of the injection are far less of a concern.
The wider class
About Aminoglycosides
Tobramycin belongs to the aminoglycosides class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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