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Aminoglycoside antibiotic Pregnancy: UK SPC §4.6 (inhaled product), verbatim: 'Tobramycin 300 mg/5 ml Nebuliser solution should not be used during pregnancy or lactation unless the benefits to the mother outweigh the risks to the foetus or baby.' Pregnancy: 'There are no adequate data from the use of tobramycin administered by inhalation in pregnant women. Animal studies do not indicate a teratogenic effect of tobramycin. However, aminoglycosides can cause foetal harm (e.g., congenital deafness) when high systemic concentrations are achieved in a pregnant woman. If [it] is used during pregnancy, or if the patient becomes pregnant while taking [it], she should be informed of the potential hazard to the foetus.' Lactation: 'Systemic tobramycin is excreted in breast milk. It is not known if administration of [the nebuliser solution] will result in serum concentrations high enough for tobramycin to be detected in breast milk. Because of the potential for ototoxicity and nephrotoxicity with tobramycin in infants, a decision should be made whether to terminate nursing or discontinue [it].' Fertility: 'No effect on male or female fertility was observed in animal studies after subcutaneous administration.' The US injection label's pregnancy section was not captured in this bundle.

Tobramycin

Brand names: TOBI, Bramitob, Tobi Podhaler

Tobramycin is an aminoglycoside antibacterial used intravenously for serious Gram-negative infection, and given by nebuliser to suppress chronic Pseudomonas infection in cystic fibrosis and bronchiectasis.

Adult dose

Dose: Serious infections: 1 mg/kg every 8 hours (total 3 mg/kg/day). Life-threatening infections: up to 5 mg/kg/day in 3 or 4 equal doses (1.66 mg/kg every 8 hours), reduced to 3 mg/kg/day as soon as clinically indicated.
Route: Intramuscular or intravenous — 'Tobramycin may be given intramuscularly or intravenously. Recommended dosages are the same for both routes.' For IV: 'the usual volume of diluent (0.9% Sodium Chloride Injection or 5% Dextrose Injection) is 50 to 100 mL for adult doses. The diluted solution usually should be infused over a period of 20 to 60 minutes. Infusion periods of less than 20 minutes are not recommended because peak serum levels may exceed 12 mcg/mL.' 'Tobramycin Injection, USP should not be physically premixed with other drugs.'
Frequency: Every 8 hours (3 equal doses per day); life-threatening infections may be given in 3 or 4 equal doses. 'The usual duration of treatment is 7 to 10 days.'
It comes from the US injection label, because the UK SPC in this bundle is the INHALED nebuliser product and explicitly states it 'is not for parenteral use'. Confirm the systemic regimen against a UK SPC for tobramycin injection before prescribing. || No once-daily / extended-interval regimen appears anywhere in the fetched sources; the US label gives 8-hourly divided dosing only, verbatim: 'Adults with Serious Infections: 3 mg/kg/day in 3 equal doses every 8 hours'; 'Adults with Life-Threatening Infections: Up to 5 mg/kg/day may be administered in 3 or 4 equal doses. The dosage should be reduced to 3 mg/kg/day as soon as clinically indicated.' || WHY maxDose IS EMPTY: the only ceiling in the source is expressed per kilogram — 'To prevent increased toxicity due to excessive blood levels, dosage should not exceed 5 mg/kg/day unless serum levels are monitored' — so it cannot go in the maxDose field. Treat 5 mg/kg/day as the ceiling, monitored. || OBESITY, verbatim: 'The appropriate dose may be calculated by using the patient's estimated lean body weight plus 40% of the excess as the basic weight on which to figure mg/kg.' Pre-treatment body weight should be obtained for the dose calculation. || SYSTEMIC DOSING IN CYSTIC FIBROSIS, verbatim: 'In patients with severe cystic fibrosis, an initial dosing regimen of 10 mg/kg/day in 4 equally divided doses is recommended. This dosing regimen is suggested only as a guide. The serum levels of tobramycin should be measured directly during treatment due to wide interpatient variability.' || INHALED CF REGIMEN (different route — recorded here, not published as the headline dose). UK SPC §4.2, verbatim: 'The recommended dose for adults and children is one ampoule twice daily for 28 days. The dose interval should be as close as possible to 12 hours and not less than 6 hours. After 28 days of therapy, patients should stop... therapy for the next 28 days. A cycle of 28 days of active therapy and 28 days of rest from treatment should be maintained. Dosage is not adjusted for weight.' One ampoule = 300 mg in 5 ml (strength pinned by the product name). Administration: 'by inhalation over approximately a 15-minute period using a hand-held PARI LC PLUS reusable nebuliser', compressors delivering '4-6 L/min and/or a back pressure of 110-217 kPa'; order of therapies 'bronchodilator, chest physiotherapy, other inhaled medicinal products, and finally' the nebulised tobramycin. Not studied in patients under 6 years, FEV1 25% or 75% predicted, or Burkholderia cepacia colonisation. 'The maximum tolerated daily dose... has not been established.' || OPHTHALMIC ROUTE: the page also lists 'Ophthalmic: 1-2 drops QDS'. NOTHING in this bundle doses the eye route — no ophthalmic product, strength or regimen appears in either label. Do not publish it from here.

Paediatric dose

Route: Intramuscular or intravenous (US injection label). For IV in children, 'the volume of diluent should be proportionately less than that for adults'; infuse over 20 to 60 minutes.
Frequency: Every 6 or 8 hours in patients over 1 week of age; every 12 hours in premature or full-term neonates 1 week of age or less.
dosePerKg is deliberately NULL — the source gives an AGE-BANDED rule with different frequencies, and the per-dose figure is a range, so no single per-kg per-dose number is valid across the paediatric range. Feeding the over-1-week figure to a neonate would exceed the neonatal ceiling by roughly half. || VERBATIM US LABEL: 'Pediatric Patients (Greater than 1 Week of Age): 6 to 7.5 mg/kg/day in 3 or 4 equally divided doses (2 to 2.5 mg/kg every 8 hours or 1.5 to 1.89 mg/kg every 6 hours).' 'Premature or Full-Term Neonates 1 Week of Age or Less: Up to 4 mg/kg/day may be administered in 2 equal doses every 12 hours.' Severe cystic fibrosis: 'an initial dosing regimen of 10 mg/kg/day in 4 equally divided doses is recommended... The serum levels of tobramycin should be measured directly during treatment due to wide interpatient variability.' || PRODUCT STRENGTHS mentioned in the bundle: a paediatric injection presentation, 'Tobramycin Injection, USP, 10 mg/mL (Pediatric)'; the adult table implies 40 mg/mL for the standard injection (120 mg = 3 mL); the UK nebuliser ampoule is 300 mg in 5 ml. concentration is left null rather than guessing which presentation a given unit stocks. || INHALED (UK SPC §4.2): 'The recommended dose for adults and children is one ampoule twice daily for 28 days'; 'The safety and efficacy... in children aged less than 6 years have not yet been established. Currently available data are described in section 5.1 but no recommendation on a posology can be made.' || Verify every paediatric and neonatal tobramycin dose against a children's formulary and local therapeutic-drug-monitoring policy before prescribing; serum levels govern the dose.

Dose adjustments

Renal

SYSTEMIC (US injection label), verbatim: 'Whenever possible, serum tobramycin concentrations should be monitored during therapy. 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.' Reduced dosage at 8-hour intervals: 'When the creatinine clearance rate is 70 mL or less per minute or when the serum creatinine value is known, the amount of the reduced dose can be determined by multiplying the normal dose from Table 3 by the percent of normal dose from the accompanying nomogram. An alternate rough guide... is to divide the normally recommended dose by the patient's serum creatinine.' Normal dosage at prolonged intervals: 'a dosage frequency in hours... can be determined by multiplying the patient's serum creatinine by 6.' Both methods 'are suggested as guides to be used when serum levels of tobramycin cannot be measured directly' and 'Neither method should be used when dialysis is being performed.' The nomogram itself was not captured in the bundle. INHALED (UK SPC §4.2): 'There are no data in this population to support a recommendation for or against dose adjustment'; patients with serum creatinine 2 mg/dL (176.8 micromol/L) were excluded from the trials, and 'Current clinical practice suggests baseline renal function should be assessed.' ELDERLY (UK §4.2): 'There are insufficient data in this population to support a recommendation for or against dose adjustment.'

Hepatic

UK SPC §4.2, verbatim: 'No studies have been performed on patients with hepatic impairment. As tobramycin is not metabolized, an effect of hepatic impairment on the exposure to tobramycin is not expected.' The US injection label carries no hepatic-impairment dosing statement in any fetched section.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION Tobramycin may be given intramuscularly or intravenously. Recommended dosages are the same for both routes. This insert is for a Pharmacy Bulk Package and is intended for preparing I.V. admixtures only. Dosage recommendations for intramuscular use are for informational purposes only. The patient’s pretreatment body weight should be obtained for calculation of correct dosage. It is desirable to measure both peak and trough serum concentrations (see WARNINGS box and PRECAUTIONS ). Administration for Patients with Normal Renal Function— Adults with Serious Infections : 3 mg/kg/day in 3 equal doses every 8 hours (see Table 3). Adults with Life-Threatening Infections : …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2023-02-27. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Contraindications

  • US injection label: 'A hypersensitivity to any aminoglycoside is a contraindication to the use of tobramycin. A history of hypersensitivity or serious toxic reactions to aminoglycosides may also contraindicate the use of any other aminoglycoside because of the known cross-sensitivity of patients to drugs in this class.'
  • UK nebuliser SPC §4.3: 'Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.' (This is the only contraindication in the UK SPC.)
  • Not a contraindication but a §4.4 caution: 'should be used with caution in patients with known or suspected renal, auditory, vestibular or neuromuscular dysfunction, or with severe, active haemoptysis.'
  • Not a contraindication but a §4.4 caution: neuromuscular disorders — 'should be used with great caution in patients with known or suspected neuromuscular disorders such as parkinsonism or other conditions characterised by myasthenia, including myasthenia gravis, as aminoglycosides may aggravate muscle weakness due to a potential curare-like effect on neuromuscular function.'
  • Not a contraindication but a §4.6 restriction: 'should not be used during pregnancy or lactation unless the benefits to the mother outweigh the risks to the foetus or baby.'

Side effects

  • Neurotoxicity (US label): 'Adverse effects on both the vestibular and auditory branches of the eighth nerve have been noted, especially in patients receiving high doses or prolonged therapy, in those given previous courses of therapy with an ototoxin, and in cases of dehydration. Symptoms include dizziness, vertigo, tinnitus, roaring in the ears, and hearing loss. Hearing loss is usually irreversible and is manifested initially by diminution of high-tone acuity.'
  • Nephrotoxicity (US label): 'Renal function changes, as shown by rising BUN, NPN, and serum creatinine and by oliguria, cylindruria, and increased proteinuria, have been reported, especially in patients with a history of renal impairment who are treated for longer periods or with higher doses than those recommended. Adverse renal effects can occur in patients with initially normal renal function.'
  • Inhaled route, UK §4.8 very common: lung disorder; rhinitis; dysphonia; sputum discoloured; pulmonary function test decreased.
  • Inhaled route, UK §4.8 common: malaise; tinnitus; myalgia; laryngitis.
  • Inhaled route, UK §4.8: 'Dysphonia and tinnitus were the only undesirable effects reported in significantly more patients treated with tobramycin; (12.8% tobramycin vs. 6.5% placebo) and (3.1% tobramycin vs. 0% placebo) respectively. These episodes of tinnitus were transient and resolved without discontinuation of tobramycin therapy, and were not associated with permanent loss of hearing on audiogram testing.'
  • Bronchospasm with the inhaled route, UK §4.4: 'Bronchospasm can occur with inhalation of medicinal products and has been reported with nebulised tobramycin.' Evidence of bronchospasm despite bronchodilator therapy 'may indicate an allergic response'; discontinue if suspected.

Monitoring

  • Serum concentrations (US label): 'It is desirable to measure both peak and trough serum concentrations.' Infusions shorter than 20 minutes are not recommended 'because peak serum levels may exceed 12 mcg/mL'.
  • UK SPC §4.4: 'Serum tobramycin concentrations should be monitored in patients with known or suspected auditory or renal dysfunction. If oto- or nephrotoxicity occurs in a patient receiving [nebulised] tobramycin therapy should be discontinued until serum concentration falls below 2 micrograms/mL.'
  • UK SPC §4.4: 'Serum concentrations of tobramycin should be monitored in patients receiving concomitant parenteral aminoglycoside therapy (or other medications that can affect renal excretion).'
  • Sampling technique, UK §4.4: 'The serum concentration of tobramycin should only be monitored through venipuncture and not finger prick blood sampling. Contamination of the skin of the fingers with tobramycin may lead to falsely increased measurements... This contamination cannot be completely avoided by hand washing before testing.'
  • Renal, auditory and vestibular function (US label): 'A longer course of therapy may be necessary in difficult and 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.'
  • Renal baseline and follow-up (UK §4.4): 'Current clinical practice suggests baseline renal function should be assessed. Urea and creatinine levels should be reassessed after every 6 complete...'
  • First inhaled dose (UK §4.4): 'The first dose... should be given under supervision, using a pre-nebulisation bronchodilator if this is part of the current regimen for the patient. FEV1 should be measured before and after nebulisation.'
  • This list may be incomplete — check the full SPC.

Clinical monograph

How it works

It binds the bacterial 30S ribosomal subunit, inhibiting protein synthesis and producing a concentration-dependent bactericidal effect, principally against aerobic Gram-negative organisms.

Prescribing in practice

  • Nephrotoxicity and ototoxicity (both auditory and vestibular, and potentially irreversible) are the key hazards, so therapeutic drug monitoring and renal monitoring are essential.
  • Avoid concurrent use with other nephrotoxic or ototoxic drugs wherever possible, and adjust dosing in renal impairment.
  • Use with caution in myasthenia gravis and other neuromuscular disorders, as aminoglycosides may impair neuromuscular transmission.

Monitoring

Monitor serum drug concentrations to guide dosing, together with renal function; assess auditory and vestibular function during prolonged courses and review hydration status. Limit the duration of treatment in keeping with antimicrobial stewardship.

Counselling the patient

  • Report any hearing loss, ringing in the ears, dizziness or unsteadiness without delay.
  • Report a marked reduction in urine output or new swelling.
  • Attend for the blood tests arranged to check drug levels and kidney function.

Evidence & guidelines

An established aminoglycoside in UK practice; dosing and monitoring should follow local antimicrobial guidance.

Reference: NICE NG78; UKHSA; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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