Tobramycin

Tobramycin is an aminoglycoside antibacterial used for selected serious aerobic gram-negative infections. It has useful activity against some Pseudomonas isolates and is available in systemic and ophthalmic formulations. Veterinary systemic use is less common than that of several other aminoglycosides, while local ocular treatment is a familiar application.

Group

Aminoglycoside antibacterial

Mechanism of Action

Tobramycin binds the bacterial 30S ribosomal subunit and disrupts translation, producing abnormal proteins and impaired bacterial function. Interaction with the gram-negative outer membrane also destabilizes membrane structure and assists uptake. These actions produce concentration-dependent killing and a post-antibiotic effect against susceptible aerobic organisms. Local formulations provide high exposure at the treated surface.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Systemic bacterial infection	9–14 mg/kg	SC, IM, IV	Every 24 h
Systemic bacterial infection divided-dose alternative	2 mg/kg	IV, IM, SC	Every 8 h	Older divided schedule; once-daily exposure and therapeutic monitoring may be preferred.
Urinary bacterial infection	1–2 mg/kg	SC	Every 8 h
Sepsis	2–4 mg/kg	IV	Every 8 h
Soft tissue or systemic infection	1–1.7 mg/kg	IV	Every 8 h	Up to 7 days; Therapeutic drug and renal monitoring; source courses no more than about 7 days.
Soft tissue or systemic infection	3–5.1 mg/kg	IV	Every 24 h	Up to 7 days; Therapeutic drug and renal monitoring; source courses no more than about 7 days.
Systemic infection	2 mg/kg	SC	Every 8–12 h	Up to 7 days; Therapeutic drug and renal monitoring; source courses no more than about 7 days.
Systemic infection	4–6 mg/kg	SC	Every 24 h	Up to 7 days; Therapeutic drug and renal monitoring; source courses no more than about 7 days.
Persistent bacteremia	3–5 mg/kg	IV, IM, SC	Every 8 h	Up to 7 days; Therapeutic drug and renal monitoring; source courses no more than about 7 days.
Persistent bacteremia	9–15 mg/kg	IV, IM, SC	Every 24 h	Up to 7 days; Therapeutic drug and renal monitoring; source courses no more than about 7 days.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Systemic bacterial infection	5–8 mg/kg	SC, IM, IV	Every 24 h
Systemic bacterial infection divided-dose alternative	2 mg/kg	IV, IM, SC	Every 8 h	Older divided schedule; once-daily exposure and therapeutic monitoring may be preferred.
Urinary bacterial infection	1–2 mg/kg	SC	Every 8 h
Sepsis	2–4 mg/kg	IV	Every 8 h
Soft tissue or systemic infection	2 mg/kg	IV, IM, SC	Every 12 h	Up to 5 days
Soft tissue or systemic infection	4 mg/kg	IV, IM, SC	Every 24 h	Up to 5 days
Persistent bacteremia	2 mg/kg	IV, IM, SC	Every 8 h	Up to 5 days
Persistent bacteremia	6 mg/kg	IV, IM, SC	Every 24 h	Up to 5 days

Horses

Use / stage	Dose	Route	Schedule	Instructions
Systemic bacterial infection	4 mg/kg	IV, IM	Every 24 h	Reported target for many susceptible organisms.
Higher-MIC bacterial infection	7.2 mg/kg	IV, IM	Every 24 h	Reported exposure target for organisms with MIC 4 mcg/mL.

Llamas

Use / stage	Dose	Route	Schedule	Instructions
Susceptible infection	4 mg/kg	IV	Every 24 h
Susceptible infection	0.75 mg/kg	IV	Every 8 h

Birds

Use / stage	Dose	Route	Schedule	Instructions
Susceptible infection	5 mg/kg	IM	Every 12 h

Reptiles

Use / stage	Dose	Route	Schedule	Instructions
Susceptible infection	2.5 mg/kg	IM	Every 24 h

Indications

Treatment of selected serious tobramycin-susceptible gram-negative infections in veterinary patients, including sepsis, pneumonia or deep soft-tissue infection.
Treatment of selected susceptible Pseudomonas infections.
Local treatment of susceptible bacterial keratitis, conjunctival infection or other ocular surface infection with an ophthalmic formulation.
Specialist inhalational adjunctive treatment of selected resistant bacterial airway infections, with limited veterinary clinical outcome evidence.

Contraindications

Renal disease
Neuromuscular blockade risk with anesthetics.

Interactions

Do not mix with other antibiotics, particularly beta-lactams, in syringes or infusion containers.

Adverse effects

Nephrotoxicity, ototoxicity and vestibular toxicity.

Toxicity

Overexposure increases renal and auditory/vestibular injury risk. Monitor serum drug concentration and renal function; dialysis can remove drug in severe selected cases.

Preparations

Preparation	Form	Strength	Route
Tobramycin injection 40 mg/mL	Injection	40 mg / mL	SC, IM, IV
Tobi nebulizer solution 60 mg/mL Preservative-free nebulization presentation; veterinary numeric regimen unestablished.	Other	60 mg / mL	INHALATION

Monitoring and Administration

Maintain hydration and monitor BUN, creatinine and urinalysis. For once-daily dosing, trough should be below assay detection; clearance estimates can guide dosing.

Nebulized animal doses are not established; human nebulization amounts are not animal regimens. Reconstituted solution stability described as 24 hours ambient or 96 hours refrigerated; discard discoloration.