Drug Dosing Management

Drug Dosing for Management of Acute Pulmonary Exacerbations

Many adult patients with cystic fibrosis (CF) are colonized with Pseudomonas aeruginosaS aureus is also frequently present.  A minority of patients grow Burkholderia cepacia.  Other organisms that are occasionally seen include: Stenotrophomonas maltophilia and Achromobacter xylosoxidans, non-tuberculous mycobacterium, and Aspergillus.

Patients with CF pulmonary exacerbations may be admitted for 2-3 weeks for IV antibiotics.  Treatment of pulmonary infection due to either P aeruginosa or B cepacia requires the use of two antibiotics. Antibiotics are selected based on previous response to therapy, sputum cultures, and known antibiotic intolerances or allergies. Doses of antibiotics are higher in patients with CF because they have altered pharmacokinetics.

Drug Dosing Notes

IV Antibiotics

   

Amikacin#

30mg/kg/day IV divided q8h

Monitor levels to adjust dose*

Aztreonam

2g IV q6h

Special Access (Health Canada)

Cefipime

2g IV q8h

Non-formulary at SPH

Maximum 6-8 g/day

Ceftazidime 2g IV q6h (or 3g IV q8h for home IV)

Maximum 8-12 g/day

Ceftriaxone

2g IV q12h

 

Chloramphenicol

50-100mg/kg IV divided q6h

 

Ciprofloxacin

400 mg IV q8h

 

Colymycin                    

5-8 mg/kg/day IV divided q8h

Maximum 480 mg/day

Cotrimoxazole

(TMP/SMX)                

20mg/kg/day IV divided q6h

Dosed on TMP, serious infection dosing

Imipenem

1g IV q6h

 
Meropenem

2g IV q8h

Preferred carbapenem

Piperacillin/Tazobactam

4.5g IV q4h

Maximum 18-24 g piperacillin/day

Ticarcillin/clavulanate

3.1g IV q4h or 6.2g IV q6h

Maximum 24-30 g ticarcillin/day

Tobramycin#

10 mg/kg IV once daily

12mg/kg/day IV divided q8h

Monitor levels to adjust dose*

Vancomycin

See dosing guidelines on PHC Connect: “Vancomycin – How to Prescribe”

Monitor levels to adjust dose*

PO Antibiotics (outpatients)

   

Cephalexin

1 g PO QID

 

Cloxacillin

2 g PO QID

 

Cotrimoxazole

(TMP/SMX)

2 DS (double-strength) tabs PO BID

 
Ciprofloxacin

750 mg PO TID

≤40 kg: 750 mg PO BID

Doxycycline

200 mg PO daily

 

Levofloxacin

750mg PO daily

 

Linezolid

600 mg PO BID

Requires Special Authority

Minocycline

100mg PO BID

 

 

*Levels: Peak (mg/L) Trough (mg/L)
Amikacin 25-30 < 10
Tobramycin once daily 20-30 < 1
Tobramycin conventional 10-12 < 2
Vancomycin n/a 15-20

# Most CF patients admitted to SPH have previous treatments with aminoglycosides.  Doses would have been adjusted to their pharmacokinetics.  Thus when they are admitted, we try to start them on the dose used in the previous admission (ie. empiric dosing is not used). 

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