CHICAGO – Compressing the usual 3-day course of intravenous azithromycin into a single high dose appears to be a safe, efficacious alternative for treating community-acquired pneumonia in adult outpatients.
In an open-label, randomized trial, investigators in Austria compared the same total dose of azithromycin either split over 3 days or given as a single infusion among 72 outpatients with community-acquired pneumonia (CAP).
Trial results, reported at the annual Interscience conference on Antimicrobial Agents and Chemotherapy, showed that the two regimens had similar efficacy and adverse effect profiles. In both groups, nearly 90% of patients were cured.
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A single dose of IV azithromycin for community-acquired pneumonia (shown in x-ray above) assures patient compliance and is similar in efficacy to the standard three-dose regimen.
The single-dose strategy ensures high levels of the drug independent of patient compliance, according to presenting author Dr. Rainer Gattringer of the Elisabethinen Hospital and Analyse BioLab, both in Linz, Austria. Additionally, it may reduce treatment costs.
"I think maybe physicians are a little bit afraid because it’s not written in the description of the drug that you can use it at 1.5 g as a single dose," he proposed in an interview. "They say, I have no experience with it, and they don’t know about side effects and so on."
But the drug appeared safe and well tolerated with the protocol used in the trial: administration in a liter of infusion solution given over an extended period of 4 hours. "That [protocol] is I think the main thing," Dr. Gattringer said. "So don’t be afraid, try it."
The patients studied were 45 years old, on average, and 65% were men, according to data reported in a poster session. They were fairly healthy, Dr. Gattringer noted; the CRB-65 (confusion, respiratory rate, blood pressure, and age 65 years or older) score was 0, 1, and 2 in 33.3%, 51.4%, and 15.3%, respectively. Overall, 18% had previously received oral antibiotic therapy.
The most common pathogens identified were Streptococcus pneumoniae (22.2% of patients), Mycoplasma pneumoniae (6.9%), Legionella pneumophila (6.9%), Coxiella burnetii (1.4%), and Cytomegalovirus (1.4%). No pathogen was identified in 59.7% of cases.
The patients received either a single IV dose of 1.5 g azithromycin (diluted in 1 L of lactated Ringer solution and given as a 4-hour infusion) or the conventional dose schedule of 500 mg azithromycin IV once daily for 3 days.
Azithromycin is especially useful in patients who have an allergy to beta-lactam antibiotics, and the intravenous formulation is attractive given that oral macrolides, including azithromycin, have low bioavailability, Dr. Gattringer noted at the conference, which was sponsored by the American Society for Microbiology.
The rate of clinical cure – defined as resolution of fever within 72 hours; disappearance of other clinical and laboratory signs of inflammation, including achievement of C-reactive protein level of less than 1 mg/dL; and no need for additional antimicrobial therapy at 10 days – was statistically indistinguishable between the single-dose group and the conventional-regimen group (87.2% vs. 87.9%).
With the single-dose strategy, "you can send the patient home and you can achieve the right level of the drug in the patient," he concluded.
Dr. Gattringer reported having no conflicts of interest related to the trial. The trial was supported by a grant from Pfizer Research, manufacturer of Zithromax (azithromycin).