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Tobramycin information from DrugsUpdate  

See Available Brands of Tobramycin in India

P - Contraindicated in pregnancy
L - Caution when used during lactation

Tobramycin sulfate is an aminoglycoside antibiotic used to treat various types of bacterial infections, particularly Gram-negative infections.

Pharmacodynamics

Pharmacokinetics

Tobramycin acts by binding to 30S ribosomal subunits thus interfering with bacterial protein synthesis. It is active against many aerobic gram-negative bacteria and some aerobic gram-positive bacteria but inactive against Chlamydia, fungi, viruses, and most anaerobic bacteria.

Absorption
Rapid and complete absorption (IM); peak plasma concentrations after 30-90 minutes (IM). Poor oral absorption.

Distribution
Crosses the placenta.

Excretion
Via the urine; elimination half-life: 2-3 hours.

Tobramycin Indications / Tobramycin Uses

Information Not Available

Tobramycin Adverse Reactions / Tobramycin Side Effects

Nausea, vomiting, dizziness or vertigo, acute renal failure, interstitial nephritis, acute tubular necrosis, electrolyte imbalances, purpura, encephalopathy, convulsions, mental depression, hallucinations, ototoxicity, blood dyscrasias, increased LFT and bilirubin concentrations. Topical: Ocular toxicity and hypersensitivity reactions (e.g. itching and oedema of the eyelid), conjunctival erythema, punctate keratitis and tearing.

Potentially Fatal: Neuromuscular blockade, respiratory paralysis, anaphylaxis.

Precautions

Warnings
Renal and eight nerve function closely monitored in patients with suspected renal dysfunction. Monitor peak and trough concentration.

Dosage adjustments required in renal impairment.

Nephrotoxicity
Usually reversible.

Neurotoxicity

Manifests as both auditory and vestibular ototoxicity, and primarily occurs in patients with preexisting renal damage or with prolonged therapy. Partial or total irreversible deafness may continue to develop after drug is stopped. Other features of neurotoxicity include paresthesias, twitching, and seizures.

Overdosage

If orally ingested, toxicity is less likely as it is poorly absorbed from an intact GI tract. In parenteral overdose, nephrotoxicity may occur if trough blood concentrations fail to fall below 2 mcg/ml. Auditory and vestibular toxicities may occur in patients treated for >10 days; abnormal renal function; dehydrated patients; or receiving medications with additive auditory toxicities. Ototoxicity signs and symptoms (e.g. dizziness, tinnitus, vertigo, loss of high-tone acuity) may manifest even after the drug has been discontinued. Neuromuscular blockade, respiratory failure and prolonged respiratory paralysis may also occur. Treatment is supportive and symptomatic. Neuromuscular blockade may be reversed by the admin of calcium salts. Monitor fluid balance, creatinine clearance and tobramycin plasma levels until the serum tobramycin level falls below 2 mcg/ml. Ensure adequate hydration in patients with normal renal function. In patients with abnormal renal function, aggressive therapy e.g. haemodialysis may be beneficial.

Special Precautions

Preexisting renal and auditory or vestibular impairment; dehydration; neuromuscular blockade, muscular disorders (e.g. myasthenia gravis, parkinsonism); neonates; elderly; lactation. Avoid peak plasma concentrations > 10 mcg/ml or trough concentrations >2 mcg/ml when used parenterally.

Other Drug Interactions

Increased nephrotoxicity or ototoxicity with etacrynic acid, furosemide, other aminoglycosides, cefalotin, cisplatin, vancomycin, piperacillin, ciclosporin, amphotericin B. Decrease serum tobramycin levels with miconazole.

Potentially Fatal: Increased neuromuscular-blocking activity with magnesium and other neuromuscular-blocking agents.

Other Interactions

Information Not Available

Dosage

Parenteral
Susceptible infections
Adult: 3-5 mg/kg/day, to be given in 3-4 divided doses for 7-10 days. Dose may be given via IM/IV infusion in 50-100 ml of 0.9% sodium chloride or 5% glucose over 20-60 minutes.
Child: IM/IV infusion over 20-60 minutes: 6-7.5 mg/kg daily in 3-4 divided doses; premature and full-term neonates: 2 mg/kg bid. Treatment is given for 7-10 days.

Renal impairment: Initial loading dose of 1 mg/kg, subsequent dosage or frequency of admin adjusted based on serum concentration.

Parenteral

Mild to moderate urinary tract infections
Adult: 2-3 mg/kg once daily for 7-10 days. Dose to be given via IM/IV infusion in 50-100 ml of 0.9% sodium chloride or 5% glucose over 20-60 minutes.

Renal impairment: Initial loading dose of 1 mg/kg, subsequent dosage or frequency of admin adjusted based on serum concentration.

Ophthalmic
Ocular infections
Adult: As 0.3% eye drop: Mild to moderate infections: Instill 1-2 drops into affected eye every 4 hours. Severe infections: Instill 2 drops into affected eye every 30-60 minutes initially until improvement, reduce treatment frequency before discontinuation. As 0.3% eye ointment: Mild to moderate infections: Apply a half-inch ribbon bid-tid into affected eye. Severe infections: Apply a half-inch ribbon into the affected eye every 3-4 hours until improvement, reduce treatment frequency before discontinuation.

Inhalation
Cystic fibrosis
Adult: 300 mg every 12 hours inhaled from a suitable nebuliser for 28 days, then stop for 28 days and repeat in cycles of 28 days as needed. Do not give doses <6 hours apart.

Incompatibility
Inactivated by b-lactam-type antibiotics (e.g. penicillins or cephalosporins).

Food(before/after)

Information Not Available

List of Contraindications

Tobramycin and Pregnancy

Contraindicated in pregnancy

Category B: Either animal-reproduction studies have not demonstrated a foetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the 1st trimester (and there is no evidence of a risk in later trimesters).
                   
Category D: There is positive evidence of human foetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).

Tobramycin and Lactation

Caution when used during lactation

Tobramycin and Children

Use parenteral form cautiously in premature infants and newborns due to renal immaturity.

Tobramycin and Geriatic

There is a higher risk of developing nephrotoxicity and ototoxicity while receiving Tobramycin. Monitoring of renal function during treatment with aminoglycosides is particularly important.

Tobramycin and Other Contraindications

Hypersensitivity to aminoglycosides; pregnancy

Storage

Ophthalmic
Store at 8-27°C (46-80°F).

Parenteral
Store between 15-30°C (59-86°F).

Lab interference

Ophthalmic
Store at 8-27°C (46-80°F).

Parenteral
Store between 15-30°C (59-86°F).

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