Fluoroquinolones are medications that kill bacteria or prevent their growth. Bacteria are one-celled diseasecausing microorganisms that commonly multiply by cell division.
Fluoroquinolones are a class of antimicrobials, which are medications used to treat infections caused by microorganisms. Physicians prescribe these drugs for bacterial infections in many parts of the body. For example, they are used to treat bone and joint infections, skin infections, urinary tract infections, inflammation of the prostate, serious ear infections, bronchitis, pneumonia, tuberculosis, some sexually transmitted diseases (STDs), and some infections that affect people with AIDS.
Although fluoroquinolones are normally used only to treat infections, and not for prophylaxis (prevention of infection), some of these compounds have been used before surgery, particularly if the patient is allergic to the antibiotic that is usually given. Fluoroquinolones have also been studied for their usefulness in eye surgery and surgery of the biliary tract.
Fluoroquinolones are available only with a physician's prescription; they are sold in tablet and injectable forms. Examples of these medicines are moxifloxacin (Avelox), ciprofloxacin (Cipro), ofloxacin (Floxin), levofloxacin (Levaquin), lomefloxacin (Maxaquin), norfloxacin (Noroxin), enoxacin (Penetrex), gatifloxacin (Tequin), and sparfloxacin (Zagam).
The recommended dosage depends on the type and strength of fluoroquinolone, and the kind of infection for which it is being taken. Patients should consult the physician who prescribed the drug or the pharmacist who filled the prescription for the correct dosage.
To make sure an infection clears up completely, patients should take the full course of fluoroquinolone that their doctor prescribed. It is important to not stop taking the drug just because the symptoms begin to diminish.
Fluoroquinolones work best when they are at constant levels in the blood. To help keep blood levels constant, patients should take the medicine in doses spaced evenly through the day and night without missing any doses. For best results, these medications should be taken with a full glass of water, and the patient should drink several more glasses of water every day. Drinking plenty of water will help prevent some of the medicine's side effects. Some fluoroquinolones should be taken on an empty stomach; others may be taken with meals. Patients should read the directions on the package very carefully or ask the physician or pharmacist for instructions on the best way to take a specific medicine.
The precautions described below are primarily applicable to the use of fluoroquinolones when they are prescribed to treat an infection for several days. Other than allergic reactions, few patients experience significant problems when they are given a single dose of a fluoroquinolone for surgical prophylaxis. The external use of these drugs—for example as eye drops—is also generally safe.
An important precaution to observe with any antimicrobial drug is that the unnecessary use or abuse of these medications can encourage drug-resistant strains of bacteria to develop and spread. These drug-resistant strains then become difficult or even impossible to treat. Bacteria found in hospitals appear to have become especially resilient, and are causing increasing difficulty for patients and the doctors treating them. One fear is that the overuse of fluoroquinolone medications could reduce their effectiveness against such infections as typhoid fever, hospital-acquired pneumonia, and others.
Research suggests that fluoroquinolones may cause bone development problems in children and teenagers. Infants, children, teenagers, pregnant women, and women who are breastfeeding should not take these drugs unless directed to do so by a physician.
Although such side effects are rare, some people have had severe and life-threatening reactions to fluoroquinolones. Patients should call their physician at once if they have any of the following signs:
Some fluoroquinolones may weaken the tendons in the shoulder, hand, or heel, making these fibrous bands of tissue more likely to tear. Anyone who notices pain or inflammation in these or other joints should stop taking the medicine immediately and call their physician. They should rest and avoid athletic activity or vigorous exercise until the physician determines whether the tendons have been damaged. Tendons that are torn may require surgical repair.
Fluoroquinolones make some people feel drowsy, dizzy, lightheaded, or less alert. Anyone who takes these drugs should not drive, use machines or do anything else that requires a high level of alertness until they have found out how the drugs affect them.
Fluoroquinolones may increase the skin's sensitivity to sunlight. Even brief exposure to sun can cause a severe sunburn or a rash. During treatment with these drugs, patients should avoid exposure to direct sunlight, especially high sun between 10 A . M . and 3 P . M .; wear a hat and tightly woven clothing that covers the arms and legs; use a sunscreen with a skin protection factor (SPF) of at least 15; protect the lips with a lip balm containing sun block; and avoid the use of tanning beds, tanning booths, or sunlamps.
Patients should not take antacids that contain aluminum, calcium, or magnesium at the same time as fluoroquinolones. The antacids may keep the fluoroquinolones from working as they should. If antacids are needed, they should be taken at least 2 hours before or 2 hours after taking norfloxacin or ofloxacin, and at least 4 hours before or 2 hours after taking ciprofloxacin. Patients who are taking sucralfate (Carafate), a medicine used to treat stomach ulcers and other irritations in the digestive tract and mouth, should follow the same instructions as for taking antacids.
Anyone who has had unusual reactions to fluoroquinolones or such related compounds as cinoxacin (Cinobac) or nalidixic acid (NegGram) in the past should let his or her physician know before taking the drugs again. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.
People with any of these medical problems should make sure their physicians are aware of their conditions before using fluoroquinolones:
Taking fluoroquinolones with certain other drugs may affect the way the drugs work or may increase the chance of side effects.
The most common side effects are mild diarrhea, nausea, vomiting, stomach or abdominal pain, dizziness, drowsiness, lightheadedness, nervousness, sleep problems, and headache. These side effects occur in about 5% of patients taking fluoroquinolones. They usually go away as the body adjusts to the drug and do not require medical treatment unless they are bothersome.
More serious side effects are not common, but may occur. If any of the following side effects occur, the patient should consult a physician immediately:
Other rare side effects may occur. Anyone who has unusual symptoms after taking fluoroquinolones should consult his or her physician at once.
Fluoroquinolones may interact with other medicines. When an interaction occurs, the effects of one or both of the drugs may change or the risk of side effects may be greater. Anyone who takes fluoroquinolones should give the doctor a list of all other medications that they take on a regular basis, including over-the-counter drugs, herbal preparations, and traditional Chinese or other alternative medicines . Drugs that may interact with fluoroquinolones include:
The list above does not include every drug that may interact with fluoroquinolones. Patients should check with a physician or pharmacist before combining fluoroquinolones with any other prescription or nonprescription (over-the-counter) medicine.
"Antibacterial Drugs: Fluoroquinolones." Section 13, Chapter 153 in The Merck Manual of Diagnosis and Therapy , edited by Mark H. Beers, MD, and Robert Berkow, MD. White-house Station, NJ: Merck Research Laboratories, 1999.
Reynolds, J. E. F., ed. Martindale: The Extra Pharmacopoeia , 31st ed. London, UK: The Pharmaceutical Press, 1996.
Wilson, Billie Ann, RN, PhD, Carolyn L. Stang, PharmD, and Margaret T. Shannon, RN, PhD. Nurses Drug Guide 2000 . Stamford, CT: Appleton and Lange, 1999.
American Society of Health-System Pharmacists (ASHP). 7272 Wisconsin Avenue, Bethesda, MD 20814. (301) 657-3000. http://www.ashp.org .
United States Food and Drug Administration (FDA). 5600 Fishers Lane, Rockville, MD 20857-0001. (888) INFO-FDA. http://www.fda.gov .
"Fluoroquinolones (Systemic)." National Library of medicine. http://www.nlm.nih.gov/medlineplus/druginfo/fluoroquinolonessystemic202656.html .
Rosalyn Carson-DeWitt, MD
Samuel Uretsky, PharmD