Tuesday, January 24, 2012

Macrolide antibiotics for sinus symptoms

Macrolide antibiotics for sinus symptoms

There are over 2,000 macrolides extracted from natural sources besides their several synthetic and semi-synthetic derivations. Macrolide antibiotics, popular antimicrobial agents, have been associated with infectious disease treatment since ages. The agents boast a broad antimicrobial activity spectrum, high safety level on the therapeutic index and effective oral administration. However, macrolides have some limitations too: drug action starts slowly and lower efficacy against Gram +ve bacteria as compared to that of penicillin.  Since gastric acid destroys macrolides, they are sold as enteric-coated tablets. And, the absorption of macrolides depends on type of food consumed.

If patients suffering from H. influenzal sinusitis or streptococcal sinusitis are allergic to penicillin, macrolide antibiotics may be prescribed. Japan pioneered the use of macrolides to treat chronic sinus symptoms. In Japan, macrolide therapy is commonly used to treat chronic sinusitis and the sinusitis related to diffuse panbronchiolitis. Anti-inflammatory activity of macrolide antibiotics helps in treating chronic sinusitis. The macrolides used for treating the sinusitis include erythromycin (EM) and newly developed three macrolides- azithromycin (AZM), clarithromycin (CAM) and roxithromycin (RXM).  McGuire and his colleagues discovered EM derived from Streptomyces erthreus strain in mid of twentieth century. AZM, CAM and RXM are derived from EM.

EM, mainly Gram positive, is a common macrolide resembling penicillin G. Gram positive organisms include streptococci penumonea and pyogenes, B. anthracis and C. diptheriea, clostridia. However, there are also some Gram-negative organisms, such as H. influenzea, M. catarrhalis and N. meningitides.  

Newer AZM, CAM and RXM have long action duration. Administration frequency of these macrolides is low and thereby compliance is good. The macrolides have less impact on gastrointestinal tract (GIT), so these antibiotics are more tolerable. The three new macrolides have wider microorganism range consisting of Myco. Tuberculosis (atypical), Mycoplasma penumonea and H. influenza.

The semi-synthetic macrolide RXM is resistant to acid. Its oral tolerability is good. The drug is more active against G. vaginalis and Br. Catarrhalis. The antibiotic administration is also quite convenient. RXM is preferred for sinusitis, otitis media and pneumonia.

The antimicrobial spectrum of CAM resembles to that of EM. CAM is active against H. pylori, Mycoplasma pneumonia and Myco. avium complex (MAC). GIT irritation associated to CAM is less. Acid stable AZM is effective against N. gonorrhoea, mycoplasma and H. influenzea. The AZM drug is not metabolized.

Controlled clinical studies have shown that AZM and CAM are effective for acute bacterial sinusitis like amoxicillin-clavulanate and amoxicillin. Recent research studies also suggested that calrithromycin and azithromycin are comparable to amoxicillin in terms of efficacy to treat acute maxillary sinusitis. However, erythromycin (EM) is not prescribed for acute sinus symptoms.

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