1.1 Septicemia

Tobramycin for Injection is indicated for the treatment of septicemia caused by susceptible isolates of P. aeruginosa, E. coli, and Klebsiella spp., in adult and pediatric patients.

1.2 Lower Respiratory Tract Infections

Tobramycin for Injection is indicated for the treatment of lower respiratory tract infections caused by susceptible isolates of P. aeruginosa, Klebsiella spp., Enterobacter spp., Serratia spp., E. coli, and S. aureus in adult and pediatric patients.

1.3 Central Nervous System Infections (Meningitis)

Tobramycin for Injection is indicated for the treatment of bacterial meningitis caused by susceptible bacteria in adult and pediatric patients.

1.4 Intra-abdominal Infections

Tobramycin for Injection is indicated for the treatment of intra-abdominal infections, including peritonitis, caused by susceptible isolates of E. coli, Klebsiella spp., and Enterobacter spp. in adult and pediatric patients.

1.5 Skin and Skin Structure Infections

Tobramycin for Injection is indicated for the treatment of skin and skin structure infections caused by susceptible isolates of P. aeruginosa, Proteus spp., E. coli, Klebsiella spp., Enterobacter spp., and S. aureus in adult and pediatric patients.

1.6 Bone Infections

Tobramycin for Injection is indicated for the treatment of bone infections caused by susceptible isolates of P. aeruginosa, Proteus spp., E. coli, Klebsiella spp., Enterobacter spp., and S. aureus in adult and pediatric patients

1.7 Complicated and Recurrent Urinary Tract Infections

Tobramycin for Injection is indicated for the treatment of complicated urinary tract infections caused by susceptible isolates of P. aeruginosa, Proteus spp., (indole-positive and indole-negative), E. coli, Klebsiella spp., Enterobacter spp., Serratia spp., S. aureus, Providencia spp., and Citrobacter spp. in adult and pediatric patients

1.8 Usage

To reduce the development of drug-resistant bacteria and maintain the effectiveness of Tobramycin for Injection and other antibacterial drugs, Tobramycin for Injection 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.

2.1 Important Preparation and Administration Instructions

2.2 Dosage for Adult Patients with Normal Renal Function

Tobramycin for Injection may be given intramuscularly or intravenously. Recommended dosages are the same for both routes. The recommended dosage is as follows:

2.3 Dosage for Pediatric Patients

2.4 Duration of Treatment for Adult and Pediatric Patients

The usual duration of treatment for adult and pediatric patients is 7 to10 days. A longer course of therapy may be necessary in complicated infections. In such cases, monitoring of renal, auditory, and vestibular functions is advised, because neurotoxicity is more likely to occur when treatment is extended longer than 10 days.

2.5 Dosage in Patients with Cystic Fibrosis or Burns

In patients with cystic fibrosis, altered pharmacokinetics may result in reduced serum concentrations of aminoglycosides. An initial dosing regimen of 10 mg/kg/day in 4 equally divided doses is suggested as a guide. The serum concentrations of tobramycin should be monitored during treatment due to wide inter-patient variability.

Similarly, altered pharmacokinetics may result in reduced serum concentrations in patients with extensive burns. Monitoring tobramycin serum concentration in these patients is especially important as a basis for determination of appropriate dosage [see Dosage and Administration (2.9].

2.6 Dosage for Patients with Renal Impairment

Following a loading dose of 1 mg/kg, subsequent dosage in these patients must be adjusted, either with reduced doses administered at 8-hour intervals or with normal doses given at prolonged intervals. Both of these methods are suggested as guides and dose should be adjusted based on serum concentration. The dosage adjustment for patients with renal impairment are based on either the creatinine clearance level or the serum creatinine level of the patient because these values correlate with the half-life of tobramycin. The dosage schedule derived from either method should be used in conjunction with careful clinical and laboratory observations of the patient and serum tobramycin concentration monitoring and should be modified as necessary. Neither method should be used when dialysis is being performed.

Reduced dosage at 8-hour intervals

When the creatinine clearance rate is less than or equal to 70 mL per minute or when the serum creatinine value is known, the amount of the reduced dose can be determined by multiplying the normal dose in adult patients from Table 1 by the percent of the normal dosage from the accompanying nomogram in Figure 1 below.

Figure 1: NOMOGRAM

2.7 Dosage in Obese Patients

The appropriate dose may be calculated by using the patient's estimated lean body weight plus 40% of the excess as the weight on which to determine the dose in mg/kg.

2.8 Instructions for Preparation and Intravenous Administration

Tobramycin is supplied as a dry powder in a pharmacy bulk package vial that contains the equivalent of 1.2 g of tobramycin. The contents of the vial must be reconstituted and diluted prior to intravenous administration as follows:

• Reconstitute the contents of the pharmacy bulk package vial aseptically with 30 mL of Sterile Water for Injection, USP to provide a reconstituted solution containing 40 mg of tobramycin per mL.
• Dilute the reconstituted pharmacy bulk vial prior to intravenous administration by adding a specified volume of the reconstituted solution to 50 to 100 mL (for adult doses) of diluent (0.9% Sodium Chloride Injection or 5% Dextrose Injection) for each patient. For pediatric patients, the volume of diluent should be proportionately less than for adults.
• After penetration, entire contents of pharmacy bulk vial should be dispensed within 24 hours.
• Visually inspect for particulate matter and discoloration prior to administration
• The diluted solution should be intravenously infused over a period of 20 to 60 minutes. Intravenous infusion periods of less than 20 minutes are not recommended because peak serum concentrations may exceed 12 mcg/mL [see Dosage and Administration (2.9)].

2.9 Measurement of Serum Concentrations of Tobramycin

Measure peak and trough serum tobramycin concentrations periodically during therapy to assure adequate concentrations and to avoid potentially toxic concentrations in all patients, especially in patients with renal impairment [see Dosage and Administration (2.6)]. Avoid peak serum concentrations above 12 mcg/mL. Rising trough concentrations (above 2 mcg/mL) may indicate tissue accumulation. Such accumulation may result in ototoxicity and nephrotoxicity [Warnings and Precautions (5.1, 5.2].

A useful guideline is to measure serum concentrations after 2 or 3 doses, so that the dosage could be adjusted if necessary, and at 3- to 4-day intervals during therapy. In the event of changing renal function, obtain more frequent serum tobramycin concentrations and adjust the dosage or dosage interval according to the guidelines provided [see Dosage and Administration (2.6)].

In order to measure the peak concentration, a serum sample should be drawn about 30 minutes following intravenous infusion or 1 hour after an intramuscular injection. Trough concentrations are measured by obtaining serum samples at 8 hours or just prior to the next dose of tobramycin. These suggested time intervals are intended only as guidelines and may vary according to institutional practices. It is important, however, that there be consistency within the individual patient program unless computerized pharmacokinetic dosing programs are available in the institution. These serum-concentration assays may be especially useful for monitoring the treatment of severely ill patients with changing renal function or of those infected with less susceptible organisms or those receiving maximum dosage.

2.10 Drug Incompatibilities

Tobramycin should not be physically premixed with other drugs but should be administered separately according to the recommended dose and route.

5.1 Nephrotoxicity

Systemic exposure to Tobramycin for Injection and other aminoglycosides can cause nephrotoxicity, primarily manifested as acute tubular necrosis. Signs of nephrotoxicity include rising blood urea nitrogen (BUN) and creatinine (Cr), decreased urinary output, and sodium, potassium, bicarbonate, magnesium, phosphate and calcium urinary losses. Aminoglycoside-induced nephrotoxicity may occur during therapy but may not become apparent until the first few days after cessation of therapy and usually is reversible. The risk for nephrotoxicity increases with tobramycin accumulation (indicated by rising trough levels above 2 mcg/mL), excessive peak concentrations (above 12 mcg/mL), total cumulative dose, advanced age, volume depletion, concurrent or sequential use of other nephrotoxic drugs and in patients with diabetes. Monitor serum tobramycin concentrations in all patients and avoid peak levels above 12 mcg/mL and trough levels above 2 mcg/mL [see Dosage and Administration (2.9)]. Monitor renal function, serum electrolytes, potassium, sodium, magnesium, calcium and phosphate, urine output and urinalysis during therapy in all patients. Reduce the dose or discontinue treatment if renal impairment occurs.

5.2 Ototoxicity

Tobramycin for Injection can cause both auditory and vestibular eighth nerve damage. The auditory changes are irreversible, are usually bilateral, and may be partial or total. Symptoms of ototoxicity can include dizziness, vertigo, tinnitus, roaring in the ears and hearing loss. Ototoxicity symptoms may manifest during therapy or after tobramycin has been discontinued. The risk of ototoxicity increases with higher peak and trough serum tobramycin concentrations, in patients who receive high doses or prolonged or prior treatment with tobramycin or other aminoglycosides, in patients with renal impairment, patients receiving with other nephrotoxic or ototoxic drugs and in the extremes of age. To decrease the risk of ototoxicity, use as short a duration of therapy as clinically appropriate, adequately hydrate patients, limit the use of other ototoxic drugs, and closely monitor tobramycin concentrations during therapy [see Dosage and Administration (2.9)]. Monitor patients for signs and symptoms of auditory or vestibular toxicity and consider serial audiograms in high-risk patients. Discontinue tobramycin in patients with evidence of auditory or vestibular toxicity.

5.3 Embryo-Fetal Toxicity

Aminoglycosides, including Tobramycin for Injection, can cause fetal harm when administered to a pregnant woman. Aminoglycosides cross the placenta. Streptomycin has been associated with several reports of total, irreversible, bilateral congenital deafness in pediatric patients whose mothers received streptomycin during pregnancy. Apprise patients of potential hazard to the fetus if Tobramycin for Injection is used during pregnancy or if the patient becomes pregnant while taking Tobramycin for Injection. [see Use in Specific Populations (8.1)].

5.4 Allergic Reactions

Serious and fatal allergic reactions including anaphylaxis and dermatologic reactions including exfoliative dermatitis, toxic epidermal necrolysis, erythema multiforme, and Stevens-Johnson Syndrome have been reported in patients on tobramycin therapy [see Contraindications (4) and Adverse Reactions (6)].

If an allergic reaction occurs, discontinue Tobramycin for Injection and institute appropriate therapy. A history of hypersensitivity to other aminoglycosides is a contraindication to the use of Tobramycin for Injection, because cross-allergenicity among aminoglycosides has been demonstrated [see Contraindications (4)].

5.5 Neuromuscular Blockade and Other Neurologic Adverse Reactions

Neuromuscular blockade with respiratory paralysis and respiratory failure may occur following administration of aminoglycosides. Neuromuscular blockade, respiratory failure, and prolonged respiratory paralysis may occur more commonly and be more severe in patients with myasthenia gravis or Parkinson's disease and in patients concomitantly receiving neuromuscular blocking agents such as succinylcholine. If neuromuscular blockade occurs following the administration of Tobramycin for Injection, it may be reversed by the administration of calcium salts but mechanical assistance may be necessary.

Other manifestations of neurotoxicity may include numbness, skin tingling, muscle twitching, and convulsions.

5.6 Clostridioides difficile-Associated Diarrhea (CDAD)

Clostridioides difficile-associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including Tobramycin for Injection, USP, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile.

C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antibacterial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibacterial use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents.

If CDAD is suspected or confirmed, ongoing antibacterial use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibacterial treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.

5.7 Risk of Development of Drug-Resistant Bacteria

Prescribing Tobramycin for Injection, USP in the absence of a proven or strongly suspected bacterial infection is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.

5.8 Macular Necrosis

Tobramycin for Injection is not approved for intraocular and/or subconjunctival use. Macular necrosis has been reported following intraocular and/ or subconjunctival administration of aminoglycosides, including tobramycin,

5.9 Inactivation by Beta-Lactam Antibacterials

The inactivation of tobramycin and other aminoglycosides by ß-lactam-type antibacterials (penicillins, cephalosporins) has been demonstrated in vitro and in patients with severe renal impairment. Such inactivation has not been found in patients with normal renal function who have been given the drugs by separate routes of administration.

7.1 Drugs with Nephrotoxic or Ototoxic Potential

Avoid concurrent and/or sequential use of Tobramycin for Injection with other drugs with nephrotoxic and/or ototoxic potential.

7.2 Diuretics

Some diuretics can enhance aminoglycoside toxicity by altering concentrations in serum and tissue and causing dehydration. Monitor serum concentrations, renal function, serum electrolytes, sodium, magnesium, calcium and phosphate, urine output and urinalysis, and signs of auditory or vestibular toxicity in patients concomitantly administered diuretics.

7.3 Drugs with Neuromuscular Blockade or Neurotoxic Potential

Prolonged respiratory paralysis may occur in patients concomitantly receiving neuromuscular blocking agents with Tobramycin for Injection [see Boxed Warning, Warnings and Precautions (5.5)]. If neuromuscular blockade occurs, it may be reversed by the administration of calcium salts but mechanical assistance may be necessary. In addition, avoid concurrent and/or sequential use of Tobramycin for Injection with other neurotoxic drugs.

8.1 Pregnancy

8.3 Nursing Mothers

It is not known whether tobramycin is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions such as nephrotoxicity and neurotoxicity, in nursing infants from tobramycin, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

8.4 Pediatric Use

Use Tobramycin for Injection with caution in premature infants and neonates because of their renal immaturity and the resulting prolongation of serum half-life. For pediatric dosing information [see Dosage and Administration (2.3)]. Similar to adults, monitor renal function and serum tobramycin concentrations in pediatric patients receiving Tobramycin for Injection.

8.5 Geriatric Use

Elderly patients may be at a higher risk of developing nephrotoxicity and ototoxicity while receiving tobramycin [see Warnings and Precautions (5.1)].

Tobramycin is known to be substantially excreted by the kidney, and the risk of adverse reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function and serum tobramycin levels [see Dosage and Administration (2.6) and Warnings and Precautions (5.1)].

8.6 Patients with Renal Impairment

The dosage schedule should be adjusted according to the degree of renal impairment and serum concentration [see Dosage and Administration (2.6)]. In patients undergoing hemodialysis, 25% to 70% of the administered dose may be removed, depending on the duration and type of dialysis.

10.1 Signs and Symptoms

Acute overdosage with Tobramycin for Injection can result in more severe manifestations of the types of toxicities known to occur with recommended doses, e.g., renal damage, ototoxicity, neuromuscular blockade. The severity of the signs and symptoms following a tobramycin overdose are dependent on the dose administered, the patient's renal function, state of hydration, age and whether or not other medications with similar toxicities are being administered concurrently. [see Warnings and Precautions (5.1, 5.2, 5.5)] for signs and symptoms related to neurotoxicity, nephrotoxicity and neuromuscular blockade; and Adverse Reactions (6)].

If tobramycin were ingested, toxicity would be less likely because aminoglycosides are minimally absorbed from an intact gastrointestinal tract.

10.2 Treatment

In all cases of suspected overdosage, call your Regional Poison Control Center or the National Poison Control center at 1-800-222-1222 or www.poison.org to obtain the most up-to-date information about the treatment of overdose. This recommendation is made because, in general, information regarding the treatment of overdosage may change more rapidly than the package insert.

Management of tobramycin overdosage is symptomatic and supportive. Maintain airway, provide adequate hydration and monitor renal function, serum electrolytes, and tobramycin concentrations until the serum tobramycin level falls below 2 mcg/mL. Tobramycin is removed by hemodialysis.

12.1 Mechanism of Action

Tobramycin sulfate is an aminoglycoside antibacterial drug [see Microbiology (12.4)].

12.3 Pharmacokinetics

In patients with normal renal function, except neonates, tobramycin administered every 8 hours does not accumulate in serum. The serum elimination half-life in patients with normal renal function is 2 hours. However, in patients with renal impairment and in neonates, serum concentrations of the antibacterial are usually higher and can be measured for longer periods of time than in adults with normal renal function. Thus, the dosage of tobramycin for patients with renal impairment and neonates must be adjusted accordingly [see Dosage and Administration (2.3, 2.6)].

12.4 Microbiology

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Subcutaneous administration of up to 100 mg/kg of tobramycin (3.2x an adult human dose of 5 mg/kg/day based on body surface area) did not affect mating behavior or cause impairment of fertility in male or female rats.

16.1 How Supplied

Tobramycin for Injection, USP is supplied as a sterile dry powder containing tobramycin sulfate equivalent to 1.2 g tobramycin in a 50 mL Pharmacy Bulk Package Vial packaged in trays of 6.

Vial stoppers do not contain natural rubber latex.

16.2 Storage and Handling

Prior to reconstitution, the vial should be stored at 20°C to 25°C (68° to 77°F) [see USP Controlled Room Temperature]. After reconstitution, the solution should be kept in a refrigerator and used within 96 hours. If kept at room temperature, the solution must be used within 24 hours [see Dosage and Administration (2.1, 2.8)].

Serious Allergic Reactions

Advise patients that serious allergic reactions could occur. Advise patients to report fever, swelling, difficulty breathing, wheezing, decrease blood pressure or dizziness, or skin rash. If an allergic reaction occurs, discontinue the drug and institute appropriate therapy immediately.

Impairment of Kidney Function

Advise patients that tobramycin may cause impairment in kidney function and that periodic blood draws are required to monitor kidney function and tobramycin drug levels.

Hearing Loss and Impaired Balance

Advise patients that tobramycin may cause serious and irreversible hearing loss and impaired balance. Advise patients to report hearing loss, ringing or roaring in the ears, dizziness or imbalance.

Antibacterial Resistance

Counsel patients that antibacterial drugs, including Tobramycin for Injection, USP should be used to treat bacterial infections only. They do not treat viral infections (e.g., the common cold). When Tobramycin for Injection, USP is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be administered exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by Tobramycin for Injection, USP or other antibacterial drugs in the future.

Diarrhea

Counsel patients that diarrhea is a common problem caused by antibacterials, and it usually ends when the antibacterial is discontinued. Sometimes after starting treatment with antibacterials, patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as 2 or more months after having taken their last dose of the antibacterial. If this occurs, patients should contact their physician as soon as possible.

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