Zithromax (Azithromycin) for Injection
Zithromax I.V. (500 mg IV qd for at least 2 days, followed by 500 mg qd PO to complete 7 to 10 days of therapy) is indicated for community-acquired pneumonia (CAP) due to Chlamydia pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Mycoplasma pneumoniae, Legionella pneumophila, Staphylococcus aureus, and Streptococcus pneumoniae.
In a randomized, multicenter study, the efficacy and safety of Zithromax I.V. (500 mg IV qd for 2 to 5 days, followed by 500 mg PO qd to complete 7 to 10 days of therapy) were compared to the combination of cefuroxime (750 mg IV tid for 2 to 7 days, followed by 500 mg PO bid to complete 7 to 10 days of therapy) plus erythromycin in 145 patients with CAP. In this study, Zithromax I.V. demonstrated comparable clinical cure rates* (91%) with the combination of cefuroxime and erythromycin (91%).
In pooled data from 2 separate clinical trials (1 comparative, 1 noncomparative) evaluating the efficacy and safety of Zithromax (500 mg IV qd for 2 to 5 days, followed by 500 mg PO qd to complete 7 to 10 days of therapy) in 414 patients with CAP, Zithromax I.V. also produced favorable outcomes in patients with pneumococcal bacteremia, with 19/24 patients (79%) clinically cured.
Zithromax has a unique pharmacokinetic profile, which makes it an optimal treatment for CAP. Zithromax concentrates more highly in white blood cells (WBCs) than in serum.† This rapid and extensive uptake of Zithromax by WBCs brings concentrated power to the site of infection and inflammation.
Zithromax I.V. also offers excellent tolerability, with a low incidence of adverse events. The most common side effects of Zithromax I.V./PO in adult patients are diarrhea/loose stools (4.3%), nausea (3.9%), abdominal pain (2.7%), and vomiting (1.4%). The most common side effects related to I.V. infusion are pain at the injection site (6.5%) and local inflammation (3.1%). Zithromax has not demonstrated an inhibitory effect on the cytochrome P450 system. Zithromax is designated pregnancy category B.
Zithromax is contraindicated in patients with known hypersensitivity to any macrolide antibiotic. If an allergic reaction occurs, the drug should be discontinued and appropriate therapy instituted. Physicians should be aware that reappearance of the allergic symptoms may occur when symptomatic therapy for the allergic reaction is discontinued.
Pseudomembranous colitis has been reported with nearly all antibacterial agents. It is important to consider this diagnosis in patients who present with diarrhea.
*Clinical cure was defined as resolution of signs and symptoms at end of therapy.
†High tissue concentrations should not be interpreted to be quantitatively related to efficacy.
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