old abx new uses

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http://www.postgradmed.com/issues/1997/04_97/cunha_1.htm

New uses for older antibiotics

The 'rediscovery' of four beneficial and cost-effective antimicrobials

Burke A. Cunha, MD

VOL 101 / NO 4 / APRIL 1997 / POSTGRADUATE MEDICINE

This page is best viewed with a browser that supports tables This is the first of three articles on antimicrobial therapy

Preview: For years, the antibiotic marketplace has been in a state of eruption, sending forth an impressive array of -cillins, -mycins, and other familiar options. But in this era of managed care, many physicians are re-examining some of the old standbys, especially since these agents share an important trait: cost-effectiveness. In this article, Dr Cunha reviews established and growing uses for doxycycline, minocycline hydrochloride, trimethoprim-sulfamethoxazole, and metronidazole.

Several antibiotics that have been around for years are now the subject of renewed interest and are enjoying a dramatic increase in use. Several factors account for this comeback. For one thing, more cases are emerging of certain infectious diseases against which these older agents are especially effective, such as ehrlichiosis, Lyme disease, and methicillin-resistant Staphylococcus aureus (MRSA) infection. Other factors are the agents' beneficial pharmacokinetic profiles and their generic availability, which makes them extremely cost-effective compared with their newly released counterparts. Another feature of the older agents that is very important in light of the economic pressures arising from managed care is that oral administration is as effective as intravenous administration for a wide variety of infectious diseases. Intravenous therapy can be largely eliminated except in the most critically ill patients, and even patients who are started on an intravenous regimen can be switched to oral therapy as soon as clinical improvement occurs, which is usually within 3 days. The cost savings of this factor alone are tremendous for the institution and the healthcare system. Patients who start on oral therapy or switch to it soon after admission avoid infections originating at the intravenous line and have a shorter hospital stay, which means less likelihood of contracting phlebitis or nosocomial infections. This article describes traditional applications as well as new uses for four of the older antibiotics: doxycycline (Doryx, Vibramycin), minocycline hydrochloride (Minocin), trimethoprim-sulfamethoxazole (TMP-SMX) (Bactrim, Cotrim, Septra), and metronidazole (Flagyl, Protostat).

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Summary

Because of its intracellular mechanism of activity, excellent safety profile, and low cost, doxycycline is one of the most extensively used antibiotics in the world, and its use will increase as new applications are found. One of its most important uses is in treatment of bacterial community-acquired pneumonias, but it is also useful against atypical pneumonias and sexually transmitted disease. As zoonotic infections continue to increase around the world, doxycycline will occupy an increasingly prominent place. Minocycline shares doxycycline's favorable attributes and also has tissue-penetration characteristics that are important when therapeutic alternatives are few, as in MRSA. TMP-SMX is widely used to treat urinary and respiratory tract infections and for prophylaxis and treatment of P carinii infection. As the AIDS epidemic continues, its use will continue to grow, because it is also effective against other pathogens associated with AIDS. TMP-SMX is relatively underused for treating gram-negative bacteremias, especially nosocomial infections caused by nonaeruginosa pseudomonads. Metronidazole is a cost-effective antianaerobic component in treatment of intra-abdominal and pelvic infections, especially when it is combined with a once-a-day antibiotic.