TOBI
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TOBI (TOBI).
Aminoglycoside antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, causing misreading of mRNA and incorporation of incorrect amino acids into the bacterial polypeptide chain.
| Metabolism | Not metabolized; excreted unchanged in urine via glomerular filtration (over 90% within 24 hours). |
| Excretion | Renal excretion of unchanged drug accounts for >90% of elimination; biliary/fecal excretion is minimal (<5%). |
| Half-life | Terminal elimination half-life is approximately 2 hours in patients with normal renal function; may be prolonged to 8-12 hours in renal impairment. |
| Protein binding | Low (<20%), primarily to albumin. |
| Volume of Distribution | 0.2-0.3 L/kg in adults, concentrated in respiratory secretions. |
| Bioavailability | Inhaled: approximately 10-15% systemic bioavailability; IV: 100%. |
| Onset of Action | Inhaled: 30-60 minutes for peak sputum concentration; IV: immediate upon administration. |
| Duration of Action | Inhaled: Typical dosing interval is 8-12 hours; clinical effect persists for 12 hours post-inhalation. |
4 to 6 mL of 300 mg/5 mL solution nebulized twice daily, 28 days on, 28 days off. Administer via PARI LC PLUS reusable nebulizer.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for renal impairment; tobramycin systemic exposure minimal with inhalation. |
| Liver impairment | No dose adjustment required for hepatic impairment; tobramycin pharmacokinetics not significantly affected. |
| Pediatric use | Children 6 years and older: 4 to 6 mL of 300 mg/5 mL solution nebulized twice daily, 28 days on, 28 days off. Safety and efficacy not established in children under 6 years. |
| Geriatric use | No specific dose adjustment; monitor for bronchospasm, renal function, and hearing loss due to potential increased susceptibility to adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for TOBI (TOBI).
| Breastfeeding | Tobramycin is excreted into human milk in low concentrations. M/P ratio is not reported. The systemic absorption from inhalation is minimal; however, caution is advised due to potential for infant gut microbiota alteration and ototoxicity/nephrotoxicity. Use only if benefit outweighs risk. |
| Teratogenic Risk | FDA Pregnancy Category B. No evidence of teratogenicity in animal studies; no adequate well-controlled studies in pregnant women. Inhaled tobramycin is minimally absorbed systemically, reducing fetal exposure. Use only if clearly needed. |
■ FDA Black Box Warning
Nephrotoxicity, ototoxicity, neuromuscular blockade; monitor renal function and drug levels; avoid concurrent use with nephrotoxic or ototoxic drugs.
| Serious Effects |
["Hypersensitivity to tobramycin or any aminoglycoside","Pre-existing severe renal impairment (CrCl < 30 mL/min) for inhaled TOBI? (Note: inhaled TOBI has less systemic absorption; however, caution is advised in renal impairment due to potential accumulation.)"]
| Precautions | ["Nephrotoxicity: monitor renal function (BUN, serum creatinine, creatinine clearance) and adjust dose accordingly.","Ototoxicity: vestibular and cochlear damage may occur; monitor for tinnitus, vertigo, hearing loss.","Neuromuscular blockade: may exacerbate weakness in patients with neuromuscular disorders; use with caution.","Bronchospasm: monitor pulmonary function during inhaled therapy.","Superinfection: prolonged use may result in overgrowth of nonsusceptible organisms."] |
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| Fetal Monitoring |
| Monitor pulmonary function, serum tobramycin levels (if systemic absorption suspected), renal function (serum creatinine, BUN), and auditory function (audiometry) in pregnant patients. Fetal ultrasound for growth and anatomy. |
| Fertility Effects | No specific data on fertility impairment from inhaled tobramycin. Systemic aminoglycosides may affect male fertility (sperm motility). However, minimal systemic absorption of inhaled tobramycin suggests low risk. |