Aztreonam Dosing for Patients on Hemodialysis
For patients on hemodialysis, the recommended dose of aztreonam is a standard loading dose (500 mg, 1 g, or 2 g) followed by a maintenance dose of one-fourth the usual initial dose given at the usual fixed interval of 6,8, or 12 hours. For serious or life-threatening infections, an additional one-eighth of the initial dose should be given after each hemodialysis session. 1
Dosing Algorithm for Aztreonam in Hemodialysis Patients
Initial Dosing
- Give standard loading dose based on infection severity 1:
- Urinary tract infections: 500 mg or 1 g
- Moderately severe systemic infections: 1 g or 2 g
- Severe systemic or life-threatening infections: 2 g
Maintenance Dosing
- Administer one-fourth of the initial dose at the usual dosing interval (6,8, or 12 hours) 1, 2
- For example:
- If initial dose was 1 g, maintenance dose would be 250 mg
- If initial dose was 2 g, maintenance dose would be 500 mg
Post-Hemodialysis Supplementation
- For serious or life-threatening infections, give an additional one-eighth of the initial dose after each hemodialysis session 1
- For example:
- If initial dose was 2 g, post-dialysis supplement would be 250 mg
Pharmacokinetic Considerations
- Aztreonam has a significantly prolonged half-life in patients with renal failure 2
- The serum half-life increases from 1.5-2.1 hours in patients with normal renal function to approximately 7.9 hours between dialysis sessions 2, 3
- During hemodialysis, the half-life decreases to about 2.7 hours 2
- A single 4-hour hemodialysis session removes approximately 38.2% (range 27-58%) of the antibiotic 2
Administration Timing
- Administer all doses after hemodialysis on dialysis days 1, 2
- This approach:
- Prevents premature removal of the drug
- Facilitates directly observed therapy
- Avoids underdosing
Monitoring Recommendations
- Consider monitoring serum drug concentrations to 1:
- Ensure adequate drug absorption
- Prevent excessive accumulation
- Avoid toxicity
- Be aware that SQ 26,992 (a metabolite of aztreonam) can accumulate in patients with severe renal impairment, though this has not been associated with adverse effects 4
Important Considerations and Caveats
- Aztreonam is primarily eliminated through the kidneys, necessitating dose adjustment in renal impairment 3, 5
- The relationship between creatinine clearance and aztreonam clearance should be considered when individualizing therapy 2, 6
- For patients with peritoneal dialysis, limited data exists - consider starting with hemodialysis recommendations and adjusting based on serum concentration monitoring 2
- Aztreonam has a strictly gram-negative aerobic spectrum, which may limit its use as a single empiric agent 3, 5