Antimicrobial agents/therapy metronidazole

Many antimicrobial agents have similar pharmacokinetic properties when given orally or parenterally (ie, tetracyclines, trimethoprim-sulfamethoxazole, quinolones, chloramphenicol, metronidazole, clindamycin, rifampin, linezolid and fluconazole). In most cases, oral therapy with these drugs is equally effective, is less costly, and results in fewer complications than parenteral therapy. 

In most instances patients demonstrate significant improvement of clinical symptomatology and physical signs in the first 2 to 3 weeks. Many patients, however, require chronic therapy and demonstrate exacerbations of the disease during its course. Metronidazole (MetroGel) is a topical gel developed to treat the skin of the facial area in patients with chronic disease and thus reduce the reliance on oral antimicrobial agents. It is applied twice daily. Although not yet an approved use, metronidazole gel applied to the eyelids was found to be an effective treatment of ocular rosacea. 

Naturally resistant strains. Some bacteria are innately resistant to certain classes of antimicrobial agent, e.g. coliforms and many other Gramnegative bacteria possess outer cell membranes which protect their cell walls from the action of certain penicillins and cephalosporins. Facultatively anaerobic bacteria (such as Escherichia colt) lack the ability to reduce the nitro group of metronidazole which therefore remains in an inactive form. In the course of therapy, naturally sensitive organisms are eliminated and those naturally resistant proliferate and occupy the biological space newly created by the drug. 

The major types of drug therapy used in IBD include aminosalicylates, glucocorticoids, immunosuppressive agents (azathioprine, mercaptopu-rine, cyclosporine, and methotrexate), antimicrobials (metronidazole and ciprofloxacin), and agents to inhibit tumor necrosis factor-a (TNF-a) (anti-TNF-a antibodies). 

---