Tobramycin

C difficile risk
Low
Oral Bioavailability
N/A
Cost
$26.70/day

Dosing

For patients greater than 30% above their Ideal Body weight (IBW), aminoglycosides should be dosed based on an adjusted /obese body weight (OBW). See Policy PHA-161 or Contact Pharmacy for details.

Once Daily/Extended Interval DosingMultiple Daily DosingSynergyCystic Fibrosis5-7mg/kg IV q24h

7 mg/kg preferred however 5 mg/kg is commonly used in OBS/GYN1.5 mg/kg IV q8hTobramycin is not indicated for synergy in Gram positive infectionsCF TEAM CONSULTATION RECOMMENDED

Dosing varies but most commonly used regimens in normal renal function are 10 mg/kg IV q24h or 5 mg/kg IV q12h

IBW = Ideal Body Weight
ABW = Actual Body Weight
OBW = Obese Body weight (aka dosing weight)

Males
IBW in kg = 50 + 0.9 (height in cm - 150)

Females
IBW in kg = 45.5 + 0.9 (height in cm - 150)

See nomogram section for IBW table

Use the Following Weights for Dosing Purposes
(Round all doses to the nearest 25 mg)

If ABW is < 30% above IBW : Use ABW
If ABW is > 30% above IBW: Calculate OBW

OBW in kg = IBW + 0.4(ABW - IBW)

Male, Height = 170cmIBW = 50 + 0.9(170-150) = 68 kg

If ABW = 100 kg
OBW = 68 + 0.4 (100 -68) = 81 kg

If ABW = 60 kg , he is non-obese and ABW of 60 kg should be used for dosing.

eGFR less than 20 eGFR 20-39eGFR 40-59eGFR 60 and aboveConsult PharmacyInitial dosing regimen: 5-7 mg/kg q48h

Trough level 6 hrs prior to second dose
DESIRED RESULT : Less than 1 mg/LInitial dosing regimen: 5-7 mg/kg q36h

Trough level 6 hrs prior to second dose
DESIRED RESULT : Less than 1 mg/LInitial dosing regimen: 5-7 mg/kg q24h

Trough level 6 hrs prior to second dose
DESIRED RESULT : Less than 1 mg/L

eGFR < 10 eGFR 10 - 20 eGFR 20-40eGFR 40-50 mL/mineGFR >50 mL/minPharmacist Consult Recommended

Estimated dose: 1.5mg/kg of calculated dosing weight q48-72h (Round dose to nearest 20 mg)Pharmacist Consult Recommended

Estimated dose: 1.5mg/kg of calculated dosing weight q24h (Round dose to nearest 20 mg)Pharmacist Consult Recommended

Estimated dose: 1.5 mg/kg of calculated dosing weight q12-24h (Round dose to nearest 20 mg)Estimated dose: 1.5 mg/kg of calculated dosing weight q12h (Round dose to nearest 20 mg)Estimated dose: 1.5 mg/kg of calculated dosing weight q8-12h (Round dose to nearest 20 mg)

Initially : 1 mg/kg of appropriate weight after each dialysis session
Subject to change following high or low serum trough levels or evidence of toxicity or treatment failure.

Trough should be collected prior to start of HD session
Desired result: < 3 mg/L (See "Additional Information")

PHARMACIST CONSULT RECOMMENDED
Dosing and drug clearance highly dependant on type of renal replacement therapy being used

Usual Dosing
2-3mg/kg load then 1-2mg/kg IV q24-48h

Height Males Females
150.0 cm 50.0 kg 45.5 kg
152.5 cm 52.3 kg 47.8 kg
155.0 cm 54.6 kg 50.1 kg
157.5 cm 56.9 kg 52.4 kg
160.0 cm 59.2 kg 54.7 kg
162.5 cm 61.5 kg 57.0 kg
165.0 cm 63.8 kg 59.3 kg
167.5 cm 66.1 kg 61.6 kg
170.0 cm 68.4 kg 63.9 kg
172.5 cm 70.7 kg 66.2 kg
175.0 cm 73.0 kg 68.5 kg
177.5 cm 75.3 kg 70.8 kg
180.0 cm 77.6 kg 73.1 kg
182.5 cm 79.9 kg 75.4 kg
185.0 cm 82.2 kg 77.7 kg
187.5 cm 84.5 kg 80.0 kg
190.0 cm 86.8 kg 82.3 kg

General Information

Tobramycin is not indicated for synergy in Gram positive infections

Pseudomonal and other gram negative infections.

Inhaled form used in cystic fibrosis.

Serum creatinine whenever initiating any aminoglycoside.

Creatinine and trough level should be monitored AT LEAST twice weekly; more often if unstable renal function or addition
of nephrotoxic medications.

Order appropriate trough level for dosage regimen used

Once Daily/Extended Interval Dosing
Order 6 hour pre-dose level
Target level: less than 1 mg/L

Multiple Daily Dosing
Order tobramycin trough level (0-60 min before a dose)
Desired result: less than 2 mg/L

Tobramycin Peaks
Are not used in once daily/extended interval regimens

For multiple daily dosing regimens, Peaks not commonly measured but if required are collected 30-60 min after dose infused

Nephrotoxicity

  • ¬†Avoid concomitant nephrotoxins

  • ¬†Less common with once daily dosing

  • ¬†Greater toxicity with longer duration and supratherapeutic trough levels
    KEEP DURATION TO MINIMUM POSSIBLE FOR INDICATION BEING TREATED

Vestibulocochlear toxicity

  • Irreversible

  • Require audiology testing if prolonged use

Other

  • ¬†Can exacerbate neuromuscular blockade

  • ¬†Contraindicated in patients with myasthenia gravis.

Increased nephrotoxicity

  • ¬†Amphotericin B

  • ¬†Cyclosporine

  • ¬†Cisplatin

  • ¬†NSAIDS

  • ¬†Contrast dye

  • ¬†Vancomycin

Increased ototoxicity

  • ¬†Furosemide

Neuromuscular blockade agents - Respiratory paralysis.

IV Administration
Dilute in 100 mL D5W or NS and administer over 30-60 min. (*60 min for extended interval dosing)

EH Prescribing Restrictions
None (Pharmacist review of therapy)

Community IV Formulary (Metro area
YES

See EH Intranet for Full Aminoglycoside dosing policy:
PHA-124: Aminoglycoside Antibiotic Monitoring (Adult)

IV: N/A
Nebules: generic are open benefit
TOBI brand require Special Authorization (CF)

Antimicrobial class: Aminoglycoside

Pregnancy category: D

Average serum half life: 3 hours

Urine penetration: Therapeutic

Lung penetration: Therapeutic

CSF penetration: Poor

Biliary penetration: Moderate

Route of Elimination: Renal