Aztreonam

Usual Dosing (Adults)

[Mild infection] (i.e. UTI): 500mg to 1 gram IV q8-12h.
[Usual dose]: 1-2 grams IV q8-12h.
[Severe/life threatening infection]: 2 grams IV q6-8h.

[Maximum dose]: 8 grams/day.

DOSAGE AND ADMINISTRATION
Dosage in Adult Patients
AZACTAM may be administered intravenously or by intramuscular injection. Dosage and route of administration should be determined by susceptibility of the causative organisms, severity and site of infection, and the condition of the patient. The intravenous route is recommended for patients requiring single doses greater than 1 g or those with bacterial septicemia, localized parenchymal abscess (eg, intra-abdominal abscess), peritonitis or other severe systemic or life-threatening infections.

The duration of therapy depends on the severity of infection. Generally, AZACTAM should be continued for at least 48 hours after the patient becomes asymptomatic or evidence of bacterial eradication has been obtained. Persistent infections may require treatment for several weeks. Doses smaller than those indicated should not be used.

AZACTAM DOSAGE GUIDELINES
Type of Infection	Dose	Frequency (hours)
ADULTS*
Urinary tract infections	500 mg or 1 g	8 or 12
Moderately severe systemic infections	1 g or 2 g	8 or 12
Severe systemic or life-threatening infections	2 g	6 or 8
*Maximum recommended dose is 8 g per day.

Because of the serious nature of infections due to Pseudomonas aeruginosa, dosage of 2 g every 6 or 8 hours is recommended, at least upon initiation of therapy, in systemic infections caused by this organism in adults.

Renal Dosing

IV:
[CRCL >30 ml/min]: no change.

[10-30 ml/min]: Loading dose: 1-2 grams x 1, then give 50% of the usual dose (e.g. 0.5 – 1 gm) q6-12h.

[<10 ml/min]: 1–2 grams x 1, then 25% of usual dose (e.g. 250-500 mg) q6-12 hours.

Renal Impairment in Adult Patients
Prolonged serum levels of aztreonam may occur in patients with transient or persistent renal insufficiency. Therefore, the dosage of AZACTAM should be halved in patients with estimated creatinine clearances between 10 mL/min/1.73 m2 and 30 mL/min/1.73 m2 after an initial loading dose of 1 g or 2 g.

When only the serum creatinine concentration is available, the following formula (based on sex, weight, and age of the patient) may be used to approximate the creatinine clearance (Clcr). The serum creatinine should represent a steady state of renal function.

Males: Clcr = [weight (kg) × (140-age)]/ 72× serum creatinine (mg/dL)
Females: 0.85 × above value

In patients with severe renal failure (creatinine clearance less than 10 mL/min/1.73 m2), such as those supported by hemodialysis, the usual dose of 500 mg, 1 g or 2 g should be given initially. The maintenance dose should be one-fourth of the usual initial dose given at the usual fixed interval of 6, 8 or 12 hours. For serious or life-threatening infections, in addition to the maintenance doses, one-eighth of the initial dose should be given after each hemodialysis session.

Hemodialysis

Hemodialysis:
1 – 2 grams x 1, then 25% of usual dose q6-12h. (e.g., 250-500 mg q6-12 hours).
For serious or life-threatening infections, give an additional 125mg after each hemodialysis session (1/8th of the usual dose).

PD:
1 – 2 grams x 1, then 25% of usual dose q6-12h. (e.g., 250-500 mg q6-12 hours).

Reference(s)

National Institutes of Health, U.S. National Library of Medicine, DailyMed Database.
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