TOBI PODHALER

Clinical safety rating: caution

Comprehensive clinical and safety monograph for TOBI PODHALER (TOBI PODHALER).

How it works

Tobramycin is an aminoglycoside antibiotic that binds to the 30S ribosomal subunit of susceptible bacteria, causing misreading of mRNA, inhibition of protein synthesis, and cell death. It is bactericidal against Pseudomonas aeruginosa.

What the body does with it

Metabolism	Tobramycin is not significantly metabolized; it is primarily excreted unchanged by the kidneys via glomerular filtration.
Excretion	Renal: approximately 90% of absorbed dose excreted unchanged in urine within 24 hours. Biliary/fecal: minimal (<5%).
Half-life	Terminal elimination half-life: approximately 3-4 hours in patients with cystic fibrosis. Clinically, following inhalation, systemic half-life does not directly guide dosing frequency due to local action in airways.
Protein binding	Tobramycin is 0-10% bound to plasma proteins.
Volume of Distribution	0.26-0.42 L/kg in cystic fibrosis patients, indicating distribution primarily into extracellular fluid.
Bioavailability	Inhalation: absolute bioavailability is approximately 11.5% of the delivered dose (deposited in lungs); systemic absorption is minimal compared to intravenous tobramycin.
Onset of Action	Inhalation: clinical improvement (e.g., lung function) observed within 1-2 weeks of continuous therapy, but local antimicrobial effect begins immediately upon deposition.
Duration of Action	Inhalation: duration of antimicrobial effect at airway surface fluid is approximately 12 hours, supporting twice-daily dosing. Clinical trials show sustained improvement over 28-day cycles.

Classification & Brands

Dosing & administration

Inhalation of 4 capsules (112 mg) twice daily using the Podhaler device, 12 hours apart, for 28 days on/28 days off cycles.

Dosage form	POWDER
Renal impairment	No dose adjustment recommended for mild to moderate renal impairment. Insufficient data for severe renal impairment (CrCl < 30 mL/min); use with caution.
Liver impairment	No specific dose adjustment guidelines for hepatic impairment. Use with caution in severe hepatic impairment (Child-Pugh class C) due to limited data.
Pediatric use	Approved for children aged 6 years and older. Weight-based dosing not required; same as adult dose: 4 capsules (112 mg) inhaled twice daily.
Geriatric use	No specific dose adjustment; use same as adult dose. Monitor for adverse effects due to potential age-related decline in renal function and comorbidities.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for TOBI PODHALER (TOBI PODHALER).

Breastfeeding	Excretion into human milk unknown. Because many drugs are excreted in milk, caution advised. M/P ratio not established. Consider developmental benefits of breastfeeding vs mother's need for drug and potential infant exposure.
Teratogenic Risk	FDA Pregnancy Category C. Animal studies at 2 times the maximum recommended human dose showed embryofetal toxicity including reduced fetal weights and increased resorptions. No adequate human studies. Risk cannot be ruled out. Use only if potential benefit justifies potential risk. First trimester: defer if possible. Second/third trimesters: consider risk/benefit.

Warnings & precautions

■ FDA Black Box Warning

Warning: Risk of nephrotoxicity and ototoxicity, especially in patients with renal impairment or those receiving other nephrotoxic/ototoxic drugs. Also, neuromuscular blockade risk, particularly with anesthetics or neuromuscular blocking agents.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to tobramycin or any aminoglycoside","Known or suspected neuromuscular disorders (e.g., myasthenia gravis, parkinsonism) due to risk of neuromuscular blockade"]

Clinical Precautions

Precautions

["Nephrotoxicity: Monitor renal function; risk increased with high doses, prolonged therapy, or concomitant nephrotoxic drugs.","Ototoxicity: Can cause irreversible bilateral vestibular and cochlear damage; monitor for dizziness, tinnitus, hearing loss.","Neuromuscular blockade: May exacerbate muscle weakness; avoid in myasthenia gravis or other neuromuscular disorders.","Bronchospasm: Can occur with inhalation; use with caution in patients with reactive airway disease.","Superinfection: Prolonged use may result in overgrowth of nonsusceptible organisms."]

Clinical Tips & Counseling

Drug interactions

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TOBI PODHALER

Clinical safety rating: caution

Comprehensive clinical and safety monograph for TOBI PODHALER (TOBI PODHALER).

How it works

What the body does with it

Metabolism	Tobramycin is not significantly metabolized; it is primarily excreted unchanged by the kidneys via glomerular filtration.
Excretion	Renal: approximately 90% of absorbed dose excreted unchanged in urine within 24 hours. Biliary/fecal: minimal (<5%).
Half-life	Terminal elimination half-life: approximately 3-4 hours in patients with cystic fibrosis. Clinically, following inhalation, systemic half-life does not directly guide dosing frequency due to local action in airways.
Protein binding	Tobramycin is 0-10% bound to plasma proteins.
Volume of Distribution	0.26-0.42 L/kg in cystic fibrosis patients, indicating distribution primarily into extracellular fluid.
Bioavailability	Inhalation: absolute bioavailability is approximately 11.5% of the delivered dose (deposited in lungs); systemic absorption is minimal compared to intravenous tobramycin.
Onset of Action	Inhalation: clinical improvement (e.g., lung function) observed within 1-2 weeks of continuous therapy, but local antimicrobial effect begins immediately upon deposition.
Duration of Action	Inhalation: duration of antimicrobial effect at airway surface fluid is approximately 12 hours, supporting twice-daily dosing. Clinical trials show sustained improvement over 28-day cycles.

Classification & Brands

Dosing & administration

Inhalation of 4 capsules (112 mg) twice daily using the Podhaler device, 12 hours apart, for 28 days on/28 days off cycles.

Dosage form	POWDER
Renal impairment	No dose adjustment recommended for mild to moderate renal impairment. Insufficient data for severe renal impairment (CrCl < 30 mL/min); use with caution.
Liver impairment	No specific dose adjustment guidelines for hepatic impairment. Use with caution in severe hepatic impairment (Child-Pugh class C) due to limited data.
Pediatric use	Approved for children aged 6 years and older. Weight-based dosing not required; same as adult dose: 4 capsules (112 mg) inhaled twice daily.
Geriatric use	No specific dose adjustment; use same as adult dose. Monitor for adverse effects due to potential age-related decline in renal function and comorbidities.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for TOBI PODHALER (TOBI PODHALER).

Breastfeeding	Excretion into human milk unknown. Because many drugs are excreted in milk, caution advised. M/P ratio not established. Consider developmental benefits of breastfeeding vs mother's need for drug and potential infant exposure.
Teratogenic Risk	FDA Pregnancy Category C. Animal studies at 2 times the maximum recommended human dose showed embryofetal toxicity including reduced fetal weights and increased resorptions. No adequate human studies. Risk cannot be ruled out. Use only if potential benefit justifies potential risk. First trimester: defer if possible. Second/third trimesters: consider risk/benefit.

Warnings & precautions

■ FDA Black Box Warning

Side Effect Profile

Serious Effects

Absolute Contraindications

["Hypersensitivity to tobramycin or any aminoglycoside","Known or suspected neuromuscular disorders (e.g., myasthenia gravis, parkinsonism) due to risk of neuromuscular blockade"]