Fluoroquinolones

Definition

Fluoroquinolones are medicines that kill bacteria or prevent their growth.

Purpose

Fluoroquinolones are antimicrobials, medicines 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.

Description

Fluoroquinolones are available only with a physician's prescription and 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).

In the wake of the anthrax terrorist attacks in the United States in 2001, ciprofloxacin received extensive media attention because it was the only drug labeled as approved by the Food and Drug Administration (FDA) for both prophylaxis and treatment of inhalation anthrax (the most serious form of the disease). However, in late October 2001, the FDA issued a notice clarifying that the antibiotic doxycycline is also approved for anthrax prophylaxis and that doxycycline and amoxicillin are also approved for treatment for all forms of anthrax. The FDA encouraged companies to update labeling of these products with this previously unspecified information.

Recommended dosage

The recommended dosage depends on the type and strength of fluoroquinolone, and the kind of infection for which it is being taken. Check with the physician who prescribed the drug or the pharmacist who filled the prescription for the correct dosage.

To make sure the infection clears up completely, take the medicine for as long as it has been prescribed. Do not stop taking the drug just because symptoms begin to improve. Symptoms may return if the drug is stopped too soon.

Fluoroquinolones work best when they are at constant levels in the blood. To help keep levels constant, take the medicine in doses spaced evenly through the day and night. Do not miss any doses. For best results, take this medicine with a full glass of water and drink several more glasses throughout the day, every day during treatment with the drug. The extra water will help prevent some side effects. Some fluoroquinolones should be taken on an empty stomach; others may be taken with meals. Check package directions or ask the physician or pharmacist for instructions on how to take the medicine.

Precautions

An important precaution for any antibiotic is that unnecessary use or abuse of antibiotics can encourage drug-resistant strains of bacteria to develop and proliferate. 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. Following the U.S. 2001 anthrax attacks, for example, the American Medical Association urged its members not to prescribe ciprofloxacin unnecessarily. One fear is that the overuse of the drug could reduce its effectiveness against infections such 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 this medicine 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. Call a physician immediately if any of these signs of a dangerous reaction occur:

• swelling of the face and throat
• swallowing problems
• shortness of breath
• rapid heartbeat
• tingling of fingers or toes
• itching or hives
• loss of consciousness

Some fluoroquinolones may weaken the tendons in the shoulder, hand, or heel, making the tendons more likely to tear. Anyone who notices pain or inflammation in these or other tendon areas should stop taking the medicine immediately and call a physician. Rest and avoid exercise until the physician determines whether the tendons are damaged. If the tendons are torn, surgery may be necessary to repair them.

These medicines 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 might be dangerous until they have found out how the drugs affect them.

This medicine may increase sensitivity to sunlight. Even brief exposure to sun can cause a severe sunburn or a rash. While being treated with fluoroquinolones, avoid being in direct sunlight, especially 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 sun block lipstick; and do not use tanning beds, tanning booths, or sunlamps.

Do 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, take them at least two hours before or two hours after taking norfloxacin or ofloxacin, at least four hours before or two hours after taking ciprofloxacin. Follow the same instructions for taking sucralfate (Carafate), a medicine used to treat stomach ulcers and other irritation in the digestive tract and mouth.

Anyone who has had unusual reactions to fluoroquinolones or related medicines such 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.

Before using fluoroquinolones, people with any of these medical problems should make sure their physicians are aware of their conditions:

• kidney disease
• liver disease with kidney disease
• diseases of the brain or spinal cord, including hardening of the arteries in the brain, epilepsy, and other seizure disorders

Taking fluoroquinolones with certain other drugs may affect the way the drugs work or may increase the chance of side effects.

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 problems 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, check with a physician immediately:

• skin rash or other skin problems such as itching, peeling, hives, or redness
• fever
• agitation or confusion
• hallucinations
• shakiness or tremors
• seizures or convulsions
• tingling of fingers or toes
• pain where the medicine was injected (lasting after the injection)
• pain in the calves, spreading to the heels
• swelling of the calves or lower legs
• swelling of the face or neck
• swallowing problems
• rapid heartbeat
• shortness of breath
• loss of consciousness

Other rare side effects may occur. Anyone who has unusual symptoms after taking fluoroquinolones should get in touch with his or her physician.

Interactions

Fluoroquinolones may interact with other medicines. When this happens, 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 let the physician know all other medicines he or she is taking. Among the drugs that may interact with fluoroquinolones are:

• antacids that contain aluminum, calcium, or magnesium
• medicines that contain iron or zinc, including multivitamin and mineral supplements
• sucralfate (Carafate)
• caffeine
• blood thinning drugs such as warfarin (Coumadin)
• airway opening drugs (bronchodilators ) such as aminophylline, theophylline (Theo-Dur and other brands), and oxtriphylline (choledyl and other brands)
• didanosine (Videx), used to treat HIV infection.

The list above does not include every drug that may interact with fluoroquinolones. Be sure to check with a physician or pharmacist before combining fluoroquinolones with any other prescription or nonprescription (over-the-counter) medicine.

Resources

OTHER

"Fluoroquinolones (Systemic)." National Library of medicine. 〈http://www.nlm.nih.gov/medlineplus/druginfo/fluoroquinolonessystemic202656.html〉.

KEY TERMS

Bacteria— Tiny, one-celled forms of life that cause many diseases and infections.

Bronchitis— Inflammation of the air passages of the lungs.

Digestive tract— The stomach, intestines, and other parts of the body through which food passes.

Inflammation— Pain, redness, swelling, and heat that usually develop in response to injury or illness.

Microorganism— An organism that is too small to be seen with the naked eye.

Pneumonia— A disease in which the lungs become inflamed. Pneumonia may be caused by bacteria, viruses, or other organisms, or by physical or chemical irritants.

Prostate— A donut-shaped gland in males below the bladder that contributes to the production of semen.

Sexually transmitted disease (STD)— A disease that is passed from one person to another through sexual intercourse or other intimate sexual contact.

Tendon— A tough band of tissue that connects muscle to bone.

Tuberculosis— An infectious disease that usually affects the lungs, but may also affect other parts of the body. Symptoms include fever, weight loss, and coughing up blood.

Urinary tract— The passage through which urine flows from the kidneys out of the body.

Fluoroquinolones

Definition
Purpose
Description
Recommended dosage
Precautions
Side effects
Interactions

Definition

Fluoroquinolones are a subgroup of quinolones, which are medications that kill bacteria or prevent their growth. The parent drug of the group is nalidixic acid (NegGram), a synthetic drug used to treat urinary tract infections caused by gram-negative bacteria. Bacteria are one-celled disease-causing microorganisms that commonly multiply by cell division.

Purpose

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. Some fluoroquinolones, such as enrofloxacin (Baytril), were developed for use in veterinary practice to treat infections in household pets and farm animals but are not given to humans.

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. Fluoro-quinolones have also been studied for their usefulness in eye surgery and surgery of the biliary tract.

Description

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), and sparfloxacin (Zagam).

Newer (so-called fourth-generation) fluoroquinolones include gatifloxacin (Zymar) and gemifloxacin (Factive). Another new drug in this class, prulifloxacin, is still in clinical trials as of early 2008.

Recommended dosage

The recommended dosage depends on the type and strength of the specific 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.

Precautions

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, 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.

KEY TERMS

Bacterium (plural, bacteria)— A microscopic one-celled form of life that causes many diseases and infections.

Biliary tract— The part of the digestive system that conveys or stores bile, consisting of the bile ducts and the gallbladder.

Bronchitis— Inflammation of the air passages in the lungs.

Digestive tract— The stomach, intestines, and other parts of the body through which food passes.

Inflammation— A condition characterized by pain, redness, swelling, and warmth. Inflammation usually develops in response to an injury or infection.

Microorganism— An organism that is too small to be seen with the naked eye.

Pneumonia— A disease characterized by inflammation of the lungs. Pneumonia may be caused by bacteria, viruses, or other organisms, or by physical or chemical irritants.

Prophylaxis— A medical intervention intended to prevent disease.

Prostate— A donut-shaped gland in males below the bladder that contributes to the production of semen.

Sexually transmitted disease (STD)— A disease that is passed from one person to another through sexual intercourse or other intimate sexual contact.

Tendon— A tough band of tissue that connects muscle to bone.

Tuberculosis (TB)— An infectious disease that usually affects the lungs, but may also affect other parts of the body. Its symptoms include fever, weight loss, and coughing up blood.

Urinary tract— The passage through which urine flows from the kidneys to the outside of the body.

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. Several drugs in this class have been withdrawn in the United States because of severe reactions. One drug, temafloxacin (Omniflox), was withdrawn less than six months after its approval in 1992 because of three patient deaths related to liver damage and destruction of red blood cells. Another fluoroquinolone, trovafloxacin (Trovan), was withdrawn from the market in 2000 when it was found to cause liver damage. The tablet form of gatifloxacin, sold under the trade name Tequin, was withdrawn in 2006 after a Canadian study published in the New England Journal of Medicine showed that it could produce diabetes as a side effect. Gatifloxacin is presently available only in the form of eye drops (Zymar).

Patients should call their physician at once if they have any of the following signs:

• swelling of the face and throat
• problems swallowing
• shortness of breath
• rapid heartbeat
• tingling in the fingers or toes
• itching or hives
• loss of consciousness

Some fluoroquinolones may weaken the tendons in the shoulder, hand, or heel, making these fibrous bands of tissue more likely to tear. In 2004, the Food and Drug Administration (FDA) upgraded the warnings included in package inserts for these drugs to note the possibility of tendon damage or peripheral nerve damage. Anyone who notices pain or inflammation in the shoulder, heel, 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 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 two hours before or two hours after taking norfloxacin or ofloxacin, and at least four hours before or two 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.

People who have had unusual reactions to fluoroquinolones or such related compounds as cinoxacin (Cinobac) or nalidixic acid (NegGram) in the past should let their 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:

• kidney disease
• liver disease together with kidney disease
• diseases that affect the brain or spinal cord, including hardening of the arteries in the brain; epilepsy; and other seizure disorders

Taking fluoroquinolones with certain other drugs may affect the way the drugs work or may increase the chance of side effects.

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:

• skin rash or such other skin problems as itching, peeling, hives, or redness
• fever
• agitation or confusion
• hallucinations
• shakiness or tremors
• seizures or convulsions

• tingling in the fingers or toes
• pain at the injection site that persists after the drug was injected
• pain in the calves that spreads to the heel area
• swelling of the calves or lower legs
• swelling of the face or neck
• difficulty swallowing
• rapid heartbeat
• shortness of breath
• loss of consciousness

Other rare side effects may occur. People who have unusual symptoms after taking fluoroquinolones should consult their physician at once.

Interactions

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 (OCT) drugs, herbal preparations, and traditional Chinese or other alternative medicines. Drugs that may interact with fluoroquinolones include:

• antacids containing aluminum, calcium, or magnesium
• medicines that contain iron or zinc, including multivitamin and mineral supplements
• sucralfate (Carafate)
• caffeine
• such blood-thinning drugs as warfarin (Coumadin)
• drugs given to open the airway (bronchodilators), including aminophylline, theophylline (Theo-Dur and other brands), and oxtriphylline (Choledyl and other brands)
• didanosine (Videx), a drug used to treat HIV infection

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.

Resources

BOOKS

Abrams, Anne Collins, Carol Barnett Lammon, and Sandra Smith Pennington. Clinical Drug Therapy: Rationales for Nursing Practice. Philadelphia: Lippincott Williams and Wilkins, 2007.

Karch, A. M. Lippincott’s Nursing Drug Guide. Springhouse, PA: Lippincott Williams & Wilkins, 2003.

Neal, Michael J. Medical Pharmacology at a Glance, 5th ed. Malden, MA: Blackwell Publishing, 2005.

PERIODICALS

Bayes, M., X. Rabasseda, and J. R. Prous. “Gateways to Clinical Trials.” Methods and Findings in Experimental and Clinical Pharmacology 29 (October 2007): 547–583.

Park-Wyllie, Laura Y., David N. Juurlink, Alexander Kopp, et al. “Outpatient Gatifloxacin Therapy and Dysglycemia in Older Adults.” New England Journal of Medicine 354 (March 30, 2006): 1352–1361.

Petersen, Melody. “Unforeseen Side Effects Ruined One Blockbuster.”New York Times, August 27, 2000, p. 3

Prats, G., et al. “Prulifloxacin: A New Antibacterial Fluoroquinolone.” Expert Review of Anti-Infective Therap. 4 (February 2006): 27–41.

Zhanel, G. G., S. Fontaine, H. Adam, et al. “A Review of New Fluoroquinolones: Focus on their Role in Respiratory Tract Infections.” Treatments in Respiratory Medicine 5 (2006): 437–465.

ORGANIZATIONS

American Society of Health-System Pharmacists (ASHP). 7272 Wisconsin Avenue, Bethesda, MD 20814. (866) 279-0681. http://www.ashp.org (accessed March 22, 2008).

United States Food and Drug Administration (FDA). 5600 Fishers Lane, Rockville, MD 20857-0001. (888) INFO-FDA. http://www.fda.gov (accessed March 22, 2008).

OTHER

Food and Drug Administration (FDA). Press release, June 5, 1992. Recall of temafloxacin (Omniflox) tablets. http://www.fda.gov/bbs/topics/NEWS/NEW00279.html [cited January 8, 2008, accessed March 22, 2008].

Rosalyn Carson-DeWitt, MD

Samuel Uretsky, PharmD

Rebecca Frey, PhD

Fluoroquinolones

Definition

Fluoroquinolones are medications that kill bacteria or prevent their growth. Bacteria are one-celled diseasecausing microorganisms that commonly multiply by cell division.

Purpose

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.

Description

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).

Recommended dosage

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.

Precautions

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:

• swelling of the face and throat
• problems swallowing
• shortness of breath
• rapid heartbeat
• tingling in the fingers or toes
• itching or hives
• loss of consciousness

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:

• kidney disease
• liver disease together with kidney disease
• diseases that affect the brain or spinal cord, including hardening of the arteries in the brain; epilepsy; and other seizure disorders

Taking fluoroquinolones with certain other drugs may affect the way the drugs work or may increase the chance of side effects.

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:

• skin rash or such other skin problems as itching, peeling, hives, or redness
• fever
• agitation or confusion
• hallucinations
• shakiness or tremors
• seizures or convulsions
• tingling in the fingers or toes
• pain at the injection site that persists after the drug was injected
• pain in the calves that spreads to the heel area
• swelling of the calves or lower legs
• swelling of the face or neck
• difficulty swallowing
• rapid heartbeat
• shortness of breath
• loss of consciousness

Other rare side effects may occur. Anyone who has unusual symptoms after taking fluoroquinolones should consult his or her physician at once.

Interactions

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:

• antacids containing aluminum, calcium, or magnesium
• medicines that contain iron or zinc, including multivitamin and mineral supplements
• sucralfate (Carafate)
• caffeine
• such blood-thinning drugs as warfarin (Coumadin)
• drugs given to open the airway (bronchodilators), including aminophylline, theophylline (Theo-Dur and other brands), and oxtriphylline (Choledyl and other brands)
• didanosine (Videx), a drug used to treat HIV infection

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.

Resources

books

"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.

organizations

American Society of Health-System Pharmacists (ASHP). 7272 Wisconsin Avenue, Bethesda, MD 20814. (301) 657-3000. <www.ashp.org>.

United States Food and Drug Administration (FDA). 5600 Fishers Lane, Rockville, MD 20857-0001. (888) INFO-FDA. <www.fda.gov>.

other

"Fluoroquinolones (Systemic)." National Library of medicine. <www.nlm.nih.gov/medlineplus/druginfo/fluoroquinolonessystemic202656.html>.

Rosalyn Carson-DeWitt, MD

Samuel Uretsky, PharmD