Erythromycin gastrointestinal system

A combination of neomycin and nonabsorbable erythromycin base given orally prior to colorectal surgery can markedly reduce the incidence of postoperative wound infection. Orally administered neomycin is sometimes used to suppress the facultative flora of the gut in patients with hepatic encephalopathy. It is unclear how this improves coma, but one theory is that it reduces systemic absorption of the bacterial metabo-htes that allegedly cause hepatic encephalopathy. Although more than 95% of an oral dose of neomycin is excreted unchanged in the stool of normal subjects, the bioavaUabUity of neomycin may be much higher in patients with an abnormal gastrointestinal mucosa. 

Erythromycin can be used for patients who reqnire systemic antibiotics, but cannot tolerate tetracyclines, or who acqnire hacterial strains resistant to tetracyclines. The dosage is nsnally 1 g/day with meals to minimize gastrointestinal intolerance. Zinc combination products possibly enhance penetration of erythromycin into the pilosebaceous unit. Erythromycin s efficacy is similar to tetracycline, but it induces higher rates of bacterial resistance. - Development of erythromycin resistance by P. acnes may be rednced by combination therapy with BPO. 

Oral pH sensitive drug delivery systems are gaining importance because they are able to deliver the drag at specific part of the gastrointestine. Antibiotics, especially macrolide ones like erythromycin, enzymes and proteins are rapidly degraded by gastric juices. Others, such as acidic drugs like NSAID s (e.g., diclofenac, valproic acid, or acetylsalicylic acid) cause a local irritation of the stomach mucosa. 

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