University of Pennsylvania Medical Center Guidelines for Antibiotic Use

GUIDELINES FOR ONCE DAILY TOBRAMYCIN DOSING FOR CYSTIC FIBROSIS PATIENTS ONLY

for non-cystic fibrosis dosing use this link

 

Background

A recent review of the literature suggests that once daily aminoglycoside dosing in the CF population is as efficacious and safe as traditional aminoglycoside dosing, with the benefit of higher peak concentrations for an antibiotic whose activity is concentration-dependent. After discussion with the pulmonologists, it was felt that the standard therapy should be the use of a once daily aminoglycoside dosing regimen for these patients who are admitted with exacerbations of their disease. The addition of inhaled tobramycin (TOBI) is not recommended during an acute exacerbation. It is recommended that a pharmacokinetics consult be obtained on all of these patients to assist with dosing.

1. Exclusions

Patients treated for suspected or documented endocarditis

Patients with cirrhosis, ascites, or myasthenia gravis

Pregnant patients

Dialysis patients

Patients treated for staphylococcal or enterococcal infections when aminoglycoside is used for synergy

Patients in acute renal failure

2. Dosing

A) Calculate Creatinine Clearance (CrCl)

Males: [(140-AGE) x IBW]/[SrCr x 72]

 

Where AGE= age in years

IBW= ideal body weight in kg

IBW in men = 50 kg + 2.3 kg per inch of height over 60 inches

IBW in women= 45.5 kg + 2.3 kg per inch of height over 60 inches

Ideal Body Weight Table

SrCr =Serum creatinine in mg/dl

Females: CrCl(males) x 0.85

B) Dose as follows

Tobramycin Dosing

Dose according to estimated CrCl

CrCl > 50ml/min = 10 mg/kg/24hrs

CrCl 30-49ml/min = 10 mg/kg/36hrs

CrCl 20-29ml/min = 10 mg/kg/48hrs

CrCl <20ml/min,ARF = 3 mg/kg X 1 & CONSULT KINETICS

For dosing weight, use actual body weight

C) ROUND DOSE to the nearest 50MG.

D) Standard Administration time is 2pm

If first dose is given at non-standard administration time:

Patients with high creatinine clearance (> 70ml/min), 2nd dose may be given > 12 hours from first dose, and then 2 pm the next day.

Example:CrCl 70ml/min- 1st dose-10am, 2nd dose-11pm, 3rd dose-2 pm the next day

Patients with low creatinine clearance (< 70ml/min), 2nd dose must be given 24 hours from the first dose.

Example:CrCl 40ml/min- 1st dose-10am, 2nd dose-10am the next day, 3rd dose-2 pm the next day.

3. Labs

At the time of writing for Once Daily Dosing, please order:

Serum Creatinine/BUN every 2days

Random level (8-14 hours before the next dose)

4. Dosage Increases

If random level (drawn 8-14 hrs before the next dose) is undetectable, consider increasing the tobramycin dosage to 12.5 mg/kg/day

Repeat random level on new doasge

5. Maximum Trobramycin Dosage

Maximum dosage is 15 mg/kg/day

When using this dosages >10 mg/kg/day, order peak levels 90 minutes after the end of the infusion, in addition to radnom levels.

Peak levels must not exceed 50 mg/L (or 50 ug/mL)

6. Use of Other Aminoglycosides

There are insufficient data in CF patients for guiding once daily dosing of other aminoglycosides. If other aminoglycoside use is needed, use conventional dosing guidelines (i.e. every 8 to 12 hours with normal renal function). Because of the rapid clearance of aminoglycosides in CF patients, expert assistance from the pharmacokinetics service is suggested if administration of other aminoglycosides is needed.

 

updated 5/5/04 by Lori LaRosa and Paul Edelstein

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