Drug information of Tobramycin

Tobramycin

Drug group: Aminoglycosides

It is used to treat bacterial infections.

Mechanism of effect

Tobramycin binds irreversibly to one of two aminoglycoside binding sites on the 30 S ribosomal subunit, inhibiting bacterial protein synthesis. Tobramycin may also destabilize bacterial memebrane by binding to 16 S 16 S r-RNA. An active transport mechanism for aminoglycoside uptake is necessary in the bacteria in order to attain a significant intracellular concentration of tobramycin.

Pharmacodynamic

Tobramycin, an aminoglycoside antibiotic obtained from cultures of Streptomyces tenebrarius, is used in combination with other antibiotics to treat urinary tract infections, gynecologic infections, peritonitis, endocarditis, pneumonia, bacteremia and sepsis, respiratory infections including those associated with cystic fibrosis, osteomyelitis, and diabetic foot and other soft-tissue infections. It acts primarily by disrupting protein synthesis, leading to altered cell membrane permeability, progressive disruption of the cell envelope, and eventual cell death. Tobramycin has in vitro activity against a wide range of gram-negative organisms including Pseudomonas aeruginosa.

Pharmacokinetics

absorption:
The bioavailability of tobramycin may vary because of individual differences in nebulizer performance and airway pathology.

half-life:
The elimination half-life of tobramycin from serum is approximately 2 hours after intravenous (IV) administration.

Dosage

Serious infections: 1 mg/kg IM or IV infusion (over 20 to 60 minutes) every 8 hours
-Duration of therapy: 7 to 10 days

Drug contraindications

Hypersensitivity to this drug

Alerts

Neurotoxicity, manifested as both bilateral auditory and vestibular ototoxicity, can occur in patients with preexisting renal damage and in patients with normal renal function treated at higher doses and/or for periods longer than those recommended; high-frequency deafness usually occurs first and can be detected only by audiometric testing; vertigo may occur and may be evidence of vestibular injury
Patients who develop cochlear damage may not have symptoms during therapy to warn them of eighth-nerve toxicity, and partial or total irreversible bilateral deafness may continue to develop after the drug has been discontinued
When feasible, recommended that serial audiograms be obtained in patients old enough to be tested, particularly high-risk patients; evidence of impairment of renal, vestibular, or auditory function requires discontinuation of drug or dosage adjustment
Aminoglycosides are potentially nephrotoxic; risk is greater in patients with impaired renal function and in those who receive high doses or prolonged therapy; rarely, nephrotoxicity may not become apparent until the first few days after cessation of therapy
Use with caution in premature infants and neonates because of renal immaturity and the resulting prolongation of serum half-life of the drug
Neuromuscular blockade and respiratory paralysis have been reported following parenteral injection, topical instillation (as in orthopedic and abdominal irrigation or in local treatment of empyema), and oral use of aminoglycosides, especially when given soon after anesthesia or muscle relaxants; if blockage occurs, calcium salts may reverse these phenomena, but mechanical respiratory assistance may be necessary
Avoid concurrent or sequential use of neurotoxic and/or nephrotoxic drugs including other aminoglycosides (eg, amikacin, streptomycin, neomycin, kanamycin, gentamicin, paromomycin
Cumulative listing of drugs to avoid from all aminoglycoside package inserts includes amphotericin B, bacitracin, cephaloridine, cisplatin, colistin, polymyxin B, vancomycin, and viomycin. Avoid potent diuretics (eg, ethacrynic acid, furosemide) because they increase risk of ototoxicity. When administered intravenously, diuretics may enhance aminoglycoside toxicity by altering antibiotic concentrations in serum and tissue

Pregnancy level

Not assigned

Total irreversible bilateral congenital deafness reported in children whose mother received another aminoglycoside (streptomycin) during pregnancy
Serious side effects to fetus/infant not reported following use of aminoglycoside but potential for harm exists

Breast feeding warning

Drug is present in breast milk following injection; aminoglycosides have poor oral bioavailability; may consider breastfeeding following injection

Ask a Pharmacist


User's questions
    No comments yet.