Tobramycin

Uses

What is tobramycin used for?

Tobramycin is part of a class of antibiotics known as aminoglycosides. Aminoglycosides work by binding to the 30S and 50S subunits of bacterial ribosomes. This binding interferes with bacterial protein synthesis, resulting in reduced growth, defective bacterial cell membrane, and eventual bacterial cell death.

Aminoglycosides have the same mechanism as penicillin, however, have enhanced resistance against β-lactamases.

Tobramycin is a broad-spectrum antibiotic mainly indicated for:

• Susceptible infections
• Mild-to-moderate urinary tract infections (UTIs)
• Cystic fibrosis
• Ocular infections

The antimicrobial spectrum of activity of tobramycin includes:

Aerobic and facultative Gram-positive bacteria

• Staphylococcus aureus

Aerobic and facultative Gram-negative bacteria

• Citrobacterspp
• Enterobacterspp
• Escherichia coli
• Klebsiellasp
• Morganella morganii
• Pseudomonas aeruginosa
• Proteus mirabilis, P. vulgaris
• Providenciaspp
• Serratiaspp

How should I take tobramycin?

Tobramycin is commercially available as an ophthalmic (eye) drop and ointment preparations. The eye drops should be instilled into the affected eye(s) as directed. Do not touch the tip of the dropper with your finger or eye. For the ointment, apply a ribbon of ointment direction onto the affected eye(s) as directed.

Parenteral and inhalational dosage forms are used for certain conditions, however, are not commonly used.

How do I store tobramycin?

This drug should be stored at room temperature (20-25°C) and be protected from light and moisture. Always check the label before using this product. For safety, keep out of the reach of children and pets.

Do not use if the printed expiration date has passed, the product seal has been broken, or the product has changed in color, odor, or consistency. Keep reconstituted solutions in the refrigerator (<20°C) for up to 10 days. Do not freeze this product.

Do not dispose of this product by pouring it down the drain, toilet, or into the environment. Ask your pharmacist regarding the proper way and location of disposal.

Precautions & warnings

What should I know before using tobramycin?

Before using this medication, inform your doctor if:

• You have ever had an allergic reaction to tobramycin or other aminoglycosides
• You have a history of allergy to other medications, food, or other substances
• You are taking other medications
• You have underlying health conditions

Is it safe during pregnancy or breastfeeding?

This drug is a pregnancy category B drug in the ophthalmic preparation form and category D in parenteral and inhalational dosage forms. There are no adequate and well-controlled studies using tobramycin in pregnant women. This drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus, as determined by your doctor.

This drug may be excreted in breast milk. This drug should be used while breastfeeding only if the potential benefit justifies the potential risk to the child, as determined by your doctor.

Side effects

What side effects can occur when using tobramycin?

All drugs have the potential to elicit side effects even with normal use. Many side effects are dose-related and will resolve when it is adjusted or at the end of therapy.

Potential side effects while using this drug include:

• Localized ocular toxicity
• Conjunctival erythema (redness)
• Punctate keratitis
• Increased lacrimation (tear production)

Rare, serious adverse reactions:

• Neurotoxicity
• Nephrotoxicity
• Anaphylactic reaction
• Exfoliative dermatitis
• Toxic epidermal necrolysis (TEN)
• Stevens-Johnson syndrome (SJS)
• Erythema multiforme
• Neuromuscular blockage or respiratory paralysis

You may experience some, none, or other side effects not mentioned above. If you experience serious adverse reactions, you must stop taking the drug immediately. If you have any concerns about a side effect or it becomes bothersome, consult your doctor or pharmacist.

Interactions

What drugs may interact with tobramycin?

This drug may interact with other medications. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist.

This drug is incompatible with the following:

• Allopurinol
• Amphotericin B cholesteryl sulfate complex
• Azithromycin
• Heparin
• Hetastarch in NS
• Indomethacin
• Pantoprazole
• Pemetrexed
• Piperacillin (with or without tazobactam)
• Propofol
• Sargramostim

If you experience an adverse drug interaction, stop taking this drug and continue taking your other medication. Inform your doctor immediately to reevaluate your treatment plan. Your dose may need to be adjusted, substituted with another drug, or discontinue using the drug.

Does food or alcohol interact with tobramycin?

This drug can be taken with or without meals, as there is no notable interaction. There are no notable reactions with alcohol.

Inform your doctor or pharmacist if you have any concerns regarding food-drug interactions.

What health conditions may interact with tobramycin?

This drug should be taken with caution if you have any of the following conditions or risk factors:

• History of hypersensitivity to aminoglycosides
• Neuromuscular disorders
  • Myasthenia gravis
  • Parkinson’s disease
• Renal impairment

Inform your doctor or pharmacist if you have any concerns regarding specific health conditions.

Dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using tobramycin.

What is the dose of tobramycin for an adult?

For treating ocular infections

• As 0.3% eye drops: instill 1 drop into the conjunctival sac once in the morning and evening.
  • For severe infections, instill 4 times on the first day, then two times a day for the succeeding days.
• As 0.3% ointment: apply a half-inch ribbon into the affected eye(s) 2 to 3 times per day.
  • For severe infections, apply every 3 to 4 hours

What is the dose of tobramycin for a child?

For treating ocular infections

• For ages >1 year: same as the adult dose
• For ages <1 year: do not give this medication

How is tobramycin available?

This drug is available in the following brands, dosage forms, and strengths:

• Celsus eye drops 0.3% (3 mg/mL)
• Sensomed eye drops 0.3% (3 mg/mL)
• Tobrex eye drops 3 mg/mL
• Tobrex eye ointment 3 mg/g
• Tomracin eye drops 3 mg/mL

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of this drug, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose. Avoid missing doses to prevent antibiotic resistance and treatment failure.