WARNINGS
Patients treated with Tobramycin Injection and other aminoglycosides should be under close clinical observation, because these drugs have an inherent potential for causing ototoxicity and nephrotoxicity.
Neurotoxicity, manifested as both auditory and vestibular ototoxicity, can occur. The auditory changes are irreversible, are usually bilateral, and may be partial or total. Eighth-nerve impairment and nephrotoxicity may develop, primarily in patients having pre-existing renal damage and in those with normal renal function to whom aminoglycosides are administered for longer periods or in higher doses than those recommended. Other manifestations of neurotoxicity may include numbness, skin tingling, muscle twitching, and convulsions. The risk of aminoglycoside-induced hearing loss increases with the degree of exposure to either high peak or high trough serum concentrations. 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. Rarely, nephrotoxicity may not become apparent until the first few days after cessation of therapy. Aminoglycoside-induced nephrotoxicity usually is reversible.
Renal and eighth-nerve function should be closely monitored in patients with known or suspected renal impairment and also in those whose renal function is initially normal but who develop signs of renal dysfunction during therapy. Peak and trough serum concentrations of aminoglycosides should be monitored periodically during therapy to assure adequate levels and to avoid potentially toxic levels. Prolonged serum concentrations above 12 mcg/mL should be avoided. Rising trough levels (above 2 mcg/mL) may indicate tissue accumulation. Such accumulation, excessive peak concentrations, advanced age, and cumulative dose may contribute to ototoxicity and nephrotoxicity (see PRECAUTIONS). Urine should be examined for decreased specific gravity and increased excretion of protein, cells, and casts. Blood urea nitrogen, serum creatinine, and creatinine clearance should be measured periodically. When feasible, it is 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 the drug or dosage adjustment.
Tobramycin should be used with caution in premature and neonatal infants because of their renal immaturity and the resulting prolongation of serum half-life of the drug.
Concurrent and sequential use of other neurotoxic and/or nephrotoxic antibiotics, particularly other aminoglycosides (e.g., amikacin, streptomycin, neomycin, kanamycin, gentamicin, and paromomycin), cephaloridine, viomycin, polymyxin B, colistin, cisplatin, and vancomycin, should be avoided. Other factors that may increase patient risk are advanced age and dehydration.
Aminoglycosides should not be given concurrently with potent diuretics, such as ethacrynic acid and furosemide. Some diuretics themselves cause ototoxicity, and intravenously administered diuretics enhance aminoglycoside toxicity by altering antibiotic concentrations in serum and tissue.
Aminoglycosides can cause fetal harm when administered to a pregnant woman (see PRECAUTIONS).
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TOBRAMYCIN SUMMARY
TOBRAMYCIN
INJECTION, USP
Tobramycin sulfate, a water-soluble antibiotic of the aminoglycoside group, is derived from the actinomycete Streptomyces tenebrarius. Tobramycin Injection, USP is a clear and colorless sterile aqueous solution for parenteral administration. Each mL contains tobramycin sulfate equivalent to 10 mg tobramycin; sodium metabisulfite added as an antioxidant, 1.5 mg; and edetate disodium added as a stabilizer, 0.1 mg. Contains sulfuric acid and may contain sodium hydroxide for pH adjustment. pH 4.5 (3.0 to 6.5). Tobramycin sulfate is O -3-amino-3-deoxy-α-D-glucopyranosyl-(1→4)- O -[2,6-diamino-2,3,6-trideoxy-α-D- ribo -hexopyranosyl-(1→6)]-2-deoxy-,L-streptamine sulfate (2:5)(salt) and has the chemical formula (C18H37N5O9)2• 5H2SO4.
To reduce the development of drug-resistant bacteria and maintain the effectiveness of tobramycin and other antibacterial drugs, tobramycin should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.
Tobramycin is indicated for the treatment of serious bacterial infections caused by susceptible strains of the designated microorganisms in the diseases listed below:
Septicemia in the pediatric patient and adult caused by P aeruginosa, E coli, and Klebsiella sp
Lower respiratory tract infections caused by P aeruginosa, Klebsiella sp, Enterobacter sp, Serratia sp, E coli, and S aureus (penicillinase and non-penicillinase-producing strains)
Serious central-nervous-system infections (meningitis) caused by susceptible organisms
Intra-abdominal infections, including peritonitis, caused by E coli, Klebsiella sp, and Enterobacter sp
Skin, bone, and skin-structure infections caused by P aeruginosa, Proteus sp, E coli, Klebsiella sp, Enterobacter sp, and S aureus
Complicated and recurrent urinary tract infections caused by P aeruginosa, Proteus sp (indole-positive and indole-negative), E coli, Klebsiella sp, Enterobacter sp, Serratia sp, S aureus, Providencia sp, and Citrobacter sp
Aminoglycosides, including tobramycin, are not indicated in uncomplicated initial episodes of urinary tract infections unless the causative organisms are not susceptible to antibiotics having less potential toxicity. Tobramycin may be considered in serious staphylococcal infections when penicillin or other potentially less toxic drugs are contraindicated and when bacterial susceptibility testing and clinical judgment indicate its use.
Bacterial cultures should be obtained prior to and during treatment to isolate and identify etiologic organisms and to test their susceptibility to tobramycin. If susceptibility tests show that the causative organisms are resistant to tobramycin, other appropriate therapy should be instituted. In patients in whom a serious life-threatening gram-negative infection is suspected, including those in whom concurrent therapy with a penicillin or cephalosporin and an aminoglycoside may be indicated, treatment with tobramycin may be initiated before the results of susceptibility studies are obtained. The decision to continue therapy with tobramycin should be based on the results of susceptibility studies, the severity of the infection, and the important additional concepts discussed in the WARNINGS box above.
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