From the FDA Drug Label
Azithromycin Tablets, USP contain the active ingredient azithromycin, an azalide, a subclass of macrolide antibiotics, for oral administration Azithromycin has the chemical name (2R,3S,4R,5R,8R,10R,11R,12S,13S,14R)-13-[(2,6-dideoxy-3-C-methyl-3-O-methyl-α-L-ribo-hexopyranosyl) oxy]-2-ethyl-3,4,10-trihydroxy-3,5,6,8,10,12,14-heptamethyl-11-[[3,4,6-trideoxy-3- (dimethylamino)-β-D-xylo-hexopyranosyl]oxy]-1-oxa-6-azacyclopentadecan-15-one
Azithromycin is not a sulfonamide (sulfa), it is a macrolide antibiotic, specifically an azalide. The chemical structure and classification of azithromycin are clearly described in the drug label, and there is no mention of sulfonamide or sulfa groups 1.
- Key points:
- Azithromycin is a macrolide antibiotic
- It is an azalide, a subclass of macrolide antibiotics
- The chemical structure does not indicate the presence of sulfonamide or sulfa groups
From the Research
No, azithromycin is not a sulfa drug, as it belongs to the macrolide class of antibiotics, which work by inhibiting bacterial protein synthesis, whereas sulfa drugs inhibit bacterial folic acid synthesis. This distinction is crucial because patients with sulfa allergies can typically take azithromycin safely, as there is no cross-reactivity between the two classes of antibiotics 2. Azithromycin is commonly used to treat respiratory, skin, and sexually transmitted infections, and its mechanism of action involves binding to the 50S subunit of the bacterial ribosome, thus inhibiting translation of mRNA 3. In contrast, sulfa drugs, such as sulfamethoxazole, work by inhibiting the synthesis of folic acid in bacteria, which is essential for their growth and survival. The most recent and highest quality study on azithromycin, published in 2022, confirms its efficacy in treating various infections, including those caused by Mycoplasma genitalium, and emphasizes the importance of macrolide resistance-guided therapy 4.
Some key points to consider when prescribing azithromycin include:
- Its effectiveness against a wide range of bacterial infections, including respiratory, skin, and sexually transmitted infections
- Its safety profile, which is generally favorable, with a low risk of adverse effects
- The importance of informing healthcare providers about all allergies, including sulfa allergies, before starting azithromycin therapy
- The potential for cross-reactivity between azithromycin and other macrolide antibiotics, but not with sulfa drugs
Common sulfa antibiotics include sulfamethoxazole (often combined with trimethoprim as co-trimoxazole or Bactrim), whereas common macrolides include azithromycin (Zithromax), erythromycin, and clarithromycin 5. Overall, azithromycin is a valuable antibiotic that can be used safely and effectively in patients with sulfa allergies, and its use should be guided by the most recent and highest quality evidence available 4.