Sulfonamides

Definition
Purpose
Description
Recommended dosage
Precautions
Side effects
Interactions

Definition

Sulfonamides are a group of anti-infective drugs that prevent the growth of bacteria in the body by interfering with their metabolism. Bacteria are one-celled disease-causing microorganisms that commonly multiply by cell division.

Purpose

Sulfonamides are used to treat many kinds of infections caused by bacteria and certain other microorganisms. Physicians may prescribe these drugs to treat urinary tract infections, ear infections, frequent or long-lasting bronchitis, bacterial meningitis, certain eye infections, Pneumocystis carinii pneumonia (PCP), traveler’s diarrhea, and a number of other infections. These drugs will, however, not work for colds, flu, and other infections caused by viruses.

Description

Sulfonamides, which are also called sulfa medicines, are available only with a physician’s prescription. They are sold in tablet and liquid forms. Some commonly used sulfonamides are sulfisoxazole (Gantrisin) and the combination drug sulfamethoxazole and trimethoprim (Bactrim, Cotrim, Septra).

Although the sulfonamides have been largely replaced by antibiotics for treatment of infections, some bacteria have developed resistance to antibiotics but can still be treated with sulfonamides because the bacteria have not been exposed to these drugs in the past.

Silver sulfadiazine, an ointment containing a sulfonamide, is valuable for the treatment of infections associated with severe burns. The combination drug trimethoprim/sulfamethoxazole (TMP-SMZ) remains in use for many infections, including those associated with HIV infection (AIDS). TMP-SMZ is particularly useful for prevention and treatment of Pneumocystis carinii pneumonia, which has been the most dangerous of the infections associated with HIV infection.

Recommended dosage

The recommended dosage depends on the type of sulfonamide, the strength of the medication, and the medical problem for which it is being taken. Patients should check the correct dosage with the physician who prescribed the drug or the pharmacist who filled the prescription.

Patients should always take sulfonamides exactly as directed. To make sure the infection clears up completely, the full course of the medicine must be taken. Patients should not stop taking the drug just because their symptoms begin to improve, because the symptoms may return if the drug is stopped too soon.

Sulfonamides 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, sulfa medicines should be

KEY TERMS

Anemia— A deficiency of hemoglobin in the blood. Hemoglobin is the compound in blood that carries oxygen from the lungs throughout the body.

Anticoagulant— A type of medication given to prevent blood from clotting. Anticoagulants are also known as blood thinners.

Bronchitis— Inflammation of the air passages of the lungs.

Diuretic— A type of medication given to increase urinary output.

HIV infection— An infectious disease that impairs the immune system. It is also known as acquired immune deficiency syndrome or AIDS.

Inflammation— A condition in which pain, redness, swelling, and warmth develop in a tissue or organ in response to injury or illness.

Meningitis— Inflammation of tissues that surround the brain and spinal cord.

Pneumocystis carinii pneumonia (PCP)— A lung infection that affects people with weakened immune systems, such as patients with AIDS or people taking medicines that weaken the immune system.

Porphyria— A disorder in which porphyrins build up in the blood and urine.

Porphyrin— A dark red pigment, sensitive to light, that is found in chlorophyll as well as in a substance in hemoglobin known as heme.

Stevens-Johnson syndrome— A severe inflammatory reaction that is sometimes triggered by sulfa medications. It is characterized by blisters and eroded areas in the mouth, nose, eyes, and anus; it may also involve the lungs, heart, and digestive tract. Stevens-Johnson syndrome is also known as erythema multiforme.

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

taken with a full glass of water, and the patient should drink several more glasses of water every day. This precaution is necessary because sulfa drugs do not dissolve in tissue fluids as easily as some other antiinfective medications. Drinking plenty of water will help prevent some of the medicine’s side effects

Precautions

Symptoms should begin to improve within a few days of beginning to take a sulfa drug. If they do not, or if they get worse, the patient should consult the physician who prescribed the medicine.

Although major side effects are rare, some people have had severe and life-threatening reactions to sulfonamides. These include sudden and severe liver damage; serious blood problems; breakdown of the outer layer of the skin; and a condition called Stevens-Johnson syndrome (erythema multiforme), in which people get blisters around the mouth, eyes, or anus. The patient may be unable to eat and may develop ulcerated areas in the eyes or be unable to open the eyes. It is important to consult a dermatologist and an ophthalmologist as quickly as possible if a patient develops Stevens-Johnson syndrome, to prevent lasting damage to the patient’s eyesight. In addition, the syndrome is sometimes fatal.

A physician should be called immediately if any of these signs of a dangerous reaction occur:

• skin rash or reddish or purplish spots on the skin;
• such other skin problems as blistering or peeling;
• fever;
• sore throat;
• •cough;
• shortness of breath;
• joint pain;
• pale skin; or
• yellow skin or eyes.

Sulfa drugs may also cause dizziness. Anyone who takes sulfonamides should not drive, use machines or do anything else that might be dangerous until they have found out how these drugs affect them.

Sulfonamides may cause blood problems that can interfere with healing and lead to additional infections. Patients should try to avoid minor injuries while taking these medicines, and be especially careful not to injure the mouth when brushing or flossing the teeth or using a toothpick. They should not have dental work done until their blood is back to normal.

Sulfa medications 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.

Babies under two months should not be given sulfonamides unless their physician has specifically ordered these drugs.

Older people may be especially sensitive to the effects of sulfonamides, increasing the chance of such unwanted side effects as severe skin problems and blood disorders. Patients who are taking water pills (diuretics ) at the same time as sulfonamides may also be more likely to have these problems.

Special conditions

People with certain medical conditions or who are taking other medicines may have problems if they take sulfonamides. Before taking these drugs, the patient must inform the doctor about any of these conditions:

ALLERGIES. Anyone who has had unusual reactions to sulfonamides, diuretics, diabetes medicines, or glaucoma medications in the past should let his or her physician know before taking sulfonamides. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.

PREGNANCY. Some sulfonamides have been found to cause birth defects in studies of laboratory animals. The drugs’ effects on human fetuses have not been studied. Pregnant women are advised not to use sulfa drugs around the time of labor and delivery, because they can cause side effects in the baby. Women who are pregnant or who may become pregnant should check with their physicians about the safety of using sulfonamides during pregnancy.

LACTATION. Sulfonamides pass into breast milk and may cause liver problems, anemia, and other problems in nursing babies whose mothers take the medicine. Because of those problems, women should not breast-feed their babies when they are under treatment with sulfa drugs. Women who are breast-feeding but require treatment with sulfonamides should check with their physicians to find out how long they should stop breast-feeding.

OTHER MEDICAL CONDITIONS. People with any of the following medical problems should make sure their physicians are aware of their conditions before they take sulfonamides:

• anemia or other blood problems;
• kidney disease;
• liver disease;
• asthma or severe allergies;
• alcohol abuse;
• poor nutrition;
• abnormal intestinal absorption;
• porphyria;
• folic acid deficiency; and
• deficiency of an enzyme known as glucose-6-phosphate dehydrogenase (G6PD).

Side effects

The most common side effects are mild diarrhea, nausea, vomiting, dizziness, headache, loss of appetite, and tiredness. These problems usually go away as the body adjusts to the drug and do not require medical treatment.

More serious side effects are not common, but may occur. If any of the following side effects occur, the patient should check with a physician immediately:

• itching or skin rash;
• reddish or purplish spots on the skin;
• such other skin problems as redness, blistering, or peeling;
• severe, watery or bloody diarrhea;
• muscle or joint aches;
• fever;
• sore throat;
• cough;
• shortness of breath;
• unusual tiredness or weakness;
• unusual bleeding or bruising;
• pale skin;
• yellow eyes or skin; or
• swallowing problems.

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

Interactions

Sulfonamides may interact with a large number of 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 sulfonamides should give the physician a list of all other medicines that he or she is taking. Among the drugs that may interact with sulfonamides are:

• acetaminophen (Tylenol);
• medicines to treat an overactive thyroid gland;
• male hormones (androgens);
• female hormones (estrogens);
• other medicines used to treat infections;
• birth control pills;
• such medicines for diabetes as glyburide (Micronase);
• warfarin (Coumadin) and other anticoagulants;
• disulfiram (Antabuse), a drug used to treat alcohol abuse;
• amantadine (Symmetrel), used to treat influenza and also Parkinson’s disease;
• hydrochlorothiazide (HCTZ, HydroDIURIL) another diuretics;
• the anticancer drug methotrexate (Rheumatrex); and
• valproic acid (Depakote, Depakene) and other anti-seizure medications.

The list above does not include every drug that may interact with sulfonamides. Patients should be careful to check with a physician or pharmacist before combining sulfonamides with any other prescription or nonprescription (over-the-counter) medicine. This precaution includes herbal preparations. Some herbs, such as bearberry, parsley, dandelion leaf, and sarsaparilla, have a diuretic effect and should not be used while taking sulfa drugs. Basil, which is commonly used in cooking to flavor salad dressings, stews, and tomato recipes, is reported to affect the absorption of sulfonamides.

Resources

BOOKS

Cohen J., and W. G. Powderly. Infectious Diseases, 2nd ed. St. Louis: Mosby, 2003.

Gershon A. A., P. J. Hotez, and S. L. Katz. Krugman’s Infectious Diseases of Children, 11th ed. St. Louis:Mosby, 2003.

Long S. S., L. K. Pickering, and C. G. Prober. Principles and Practice of Pediatric Infectious Diseases, 3rd ed. London: Churchill Livingstone, 2008.

Mandell G. L., J. E. Bennett, and R. Dolin. Principles and Practice of Infectious Diseases, 6th ed. London: Churchill Livingstone, 2004.

ORGANIZATIONS

American Society of Health-System Pharmacists, 7272 Wisconsin Avenue, Bethesda, MD, 20814, (301) 657-3000, http://www.ashp.org.

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

Nancy Ross-Flanigan

Sam Uretsky, Pharm.D.

Surgical debridement seeDebridement

Sulfonamides

Definition

Sulfonamides are a group of anti-infective drugs that prevent the growth of bacteria in the body by interfering with their metabolism. Bacteria are one-celled disease-causing microorganisms that commonly multiply by cell division.

Purpose

Sulfonamides are used to treat many kinds of infections caused by bacteria and certain other microorganisms. Physicians may prescribe these drugs to treat urinary tract infections, ear infections, frequent or long-lasting bronchitis, bacterial meningitis, certain eye infections, Pneumocystis carinii pneumonia (PCP), traveler's diarrhea, and a number of other infections. These drugs will, however, not work for colds, flu, and other infections caused by viruses.

Description

Sulfonamides, which are also called sulfa medicines, are available only with a physician's prescription. They are sold in tablet and liquid forms. Some commonly used sulfonamides are sulfisoxazole (Gantrisin) and the combination drug sulfamethoxazole and trimethoprim (Bactrim, Cotrim, Septra).

Although the sulfonamides have been largely replaced by antibiotics for treatment of infections, some bacteria have developed resistance to antibiotics but can still be treated with sulfonamides because the bacteria have not been exposed to these drugs in the past.

Silver sulfadiazine, an ointment containing a sulfonamide, is valuable for the treatment of infections associated with severe burns. The combination drug trimethoprim/sulfamethoxazole (TMP-SMZ) remains in use for many infections, including those associated with HIV infection (AIDS). TMP-SMZ is particularly useful for prevention and treatment of Pneumocystis carinii pneumonia, which has been the most dangerous of the infections associated with HIV infection.

Recommended dosage

The recommended dosage depends on the type of sulfonamide, the strength of the medication, and the medical problem for which it is being taken. Patients should check the correct dosage with the physician who prescribed the drug or the pharmacist who filled the prescription.

Patients should always take sulfonamides exactly as directed. To make sure the infection clears up completely, the full course of the medicine must be taken. Patients should not stop taking the drug just because their symptoms begin to improve, because the symptoms may return if the drug is stopped too soon.

Sulfonamides 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, sulfa medicines should be taken with a full glass of water, and the patient should drink several more glasses of water every day. This precaution is necessary because sulfa drugs do not dissolve in tissue fluids as easily as some other anti-infective medications. Drinking plenty of water will help prevent some of the medicine's side effects.

Precautions

Symptoms should begin to improve within a few days of beginning to take a sulfa drug. If they do not, or if they get worse, the patient should consult the physician who prescribed the medicine.

Although major side effects are rare, some people have had severe and life-threatening reactions to sulfonamides. These include sudden and severe liver damage; serious blood problems; breakdown of the outer layer of the skin; and a condition called Stevens-Johnson syndrome (erythema multiforme), in which people get blisters around the mouth, eyes, or anus. The patient may be unable to eat and may develop ulcerated areas in the eyes or be unable to open the eyes. It is important to consult a dermatologist and an ophthalmologist as quickly as possible if a patient develops Stevens-Johnson syndrome, to prevent lasting damage to the patient's eyesight. In addition, the syndrome is sometimes fatal.

A physician should be called immediately if any of these signs of a dangerous reaction occur:

• skin rash or reddish or purplish spots on the skin
• such other skin problems as blistering or peeling
• fever
• sore throat
• cough
• shortness of breath
• joint pain
• pale skin
• yellow skin or eyes

Sulfa drugs may also cause dizziness. Anyone who takes sulfonamides should not drive, use machines or do anything else that might be dangerous until they have found out how these drugs affect them.

Sulfonamides may cause blood problems that can interfere with healing and lead to additional infections. Patients should try to avoid minor injuries while taking these medicines, and be especially careful not to injure the mouth when brushing or flossing the teeth or using a toothpick. They should not have dental work done until their blood is back to normal.

Sulfa medications 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.

Babies under two months should not be given sulfonamides unless their physician has specifically ordered these drugs.

Older people may be especially sensitive to the effects of sulfonamides, increasing the chance of such unwanted side effects as severe skin problems and blood disorders. Patients who are taking water pills (diuretics ) at the same time as sulfonamides may also be more likely to have these problems.

Special conditions

People with certain medical conditions or who are taking other medicines may have problems if they take sulfonamides. Before taking these drugs, the patient must inform the doctor about any of these conditions:

allergies. Anyone who has had unusual reactions to sulfonamides, diuretics, diabetes medicines, or glaucoma medications in the past should let his or her physician know before taking sulfonamides. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.

pregnancy. Some sulfonamides have been found to cause birth defects in studies of laboratory animals. The drugs' effects on human fetuses have not been studied. Pregnant women are advised, however, not to use sulfa drugs around the time of labor and delivery, because they can cause side effects in the baby. Women who are pregnant or who may become pregnant should check with their physicians about the safety of using sulfonamides during pregnancy.

lactation. Sulfonamides pass into breast milk and may cause liver problems, anemia, and other problems in nursing babies whose mothers take the medicine. Because of those problems, women should not breastfeed their babies when they are under treatment with sulfa drugs. Women who are breastfeeding but require treatment with sulfonamides should check with their physicians to find out how long they should stop breastfeeding.

other medical conditions. People with any of the following medical problems should make sure their physicians are aware of their conditions before they take sulfonamides:

• anemia or other blood problems
• kidney disease
• liver disease
• asthma or severe allergies
• alcohol abuse
• poor nutrition
• abnormal intestinal absorption
• porphyria
• folic acid deficiency
• deficiency of an enzyme known as glucose-6-phosphate dehydrogenase (G6PD)

Side effects

The most common side effects are mild diarrhea, nausea, vomiting, dizziness, headache, loss of appetite, and tiredness. These problems usually go away as the body adjusts to the drug and do not require medical treatment.

More serious side effects are not common, but may occur. If any of the following side effects occur, the patient should check with a physician immediately:

• itching or skin rash
• reddish or purplish spots on the skin
• such other skin problems as redness, blistering, or peeling
• severe, watery or bloody diarrhea
• muscle or joint aches
• fever
• sore throat
• cough
• shortness of breath
• unusual tiredness or weakness
• unusual bleeding or bruising
• pale skin
• yellow eyes or skin
• swallowing problems

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

Interactions

Sulfonamides may interact with a large number of 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 sulfonamides should give the physician a list of all other medicines that he or she is taking. Among the drugs that may interact with sulfonamides are:

• acetaminophen (Tylenol)
• medicines to treat an overactive thyroid gland
• male hormones (androgens)
• female hormones (estrogens)
• other medicines used to treat infections
• birth control pills
• such medicines for diabetes as glyburide (Micronase)
• warfarin (Coumadin) and other anticoagulants
• disulfiram (Antabuse), a drug used to treat alcohol abuse
• amantadine (Symmetrel), used to treat influenza and also Parkinson's disease
• hydrochlorothiazide (HCTZ, HydroDIURIL) and other diuretics
• the anticancer drug methotrexate (Rheumatrex)
• valproic acid (Depakote, Depakene) and other antiseizure medications

The list above does not include every drug that may interact with sulfonamides. Patients should be careful to check with a physician or pharmacist before combining sulfonamides with any other prescription or nonprescription (over-the-counter) medicine. This precaution includes herbal preparations. Some herbs, such as bearberry, parsley, dandelion leaf, and sarsaparilla, have a diuretic effect and should not be used while taking sulfa drugs. Basil, which is commonly used in cooking to flavor salad dressings, stews, and tomato recipes, is reported to affect the absorption of sulfonamides.

Resources

books

"Antibacterial Drugs: Sulfonamides." Section 13, Chapter 153 in The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 1999.

Brody, T. M., J. Larner, K. P. Minneman, and H. C. Neu. Human Pharmacology: Molecular to Clinical, 2nd ed. St. Louis: Mosby Year-Book, 1995.

"Inflammatory Reactions: Erythema Multiforme." Section 10, Chapter 118 in The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. Whitehouse Station, NJ: Merck Research Laboratories, 1999.

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

Pelletier, Kenneth R., MD. The Best Alternative Medicine, Part I, Chapter 6, "Western Herbal Medicine." New York: Simon & Schuster, 2002.

Reynolds, J. E. F., ed. Martindale: The Extra Pharmacopoeia, 31st ed. London, UK: The Pharmaceutical Press, 1996.

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

<http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202540.html>.

Nancy Ross-Flanigan Sam Uretsky, PharmD

Sulfonamides

Definition

Sulfonamides are medicines that prevent the growth of bacteria in the body.

Purpose

Sulfonamides are used to treat many kinds of infections caused by bacteria and certain other microorganisms. Physicians may prescribe these drugs to treat urinary tract infections, ear infections, frequent or long-lasting bronchitis, bacterial meningitis, certain eye infections, Pneumocystis carinii pneumonia, traveler's diarrhea, and a number of other kinds of infections. These drugs will not work for colds, flu, and other infections caused by viruses.

Description

Sulfonamides, also called sulfa medicines, are available only with a physician's prescription. They are sold in tablet and liquid forms. Some commonly used sulfonamides are sulfisoxazole (Gantrisin) and the combination drug sulfamethoxazole and trimethoprim (Bactrim, Cotrim).

Recommended dosage

The recommended dosage depends on the type of sulfonamide, the strength of the medicine, and the medical problem 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.

Always take sulfonamides exactly as directed. 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.

Sulfonamides 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 the medicine with a full glass of water and drink several more glasses of water every day. This will help prevent some of the medicine's side effects.

Precautions

Symptoms should begin to improve within a few days of beginning to take this medicine. If they do not, or if they get worse, check with the physician who prescribed the medicine.

Although such side effects are rare, some people have had severe and life-threatening reactions to sulfonamides. These include sudden, severe liver damage, serious blood problems, breakdown of the outer layer of the skin, and a condition called Stevens-Johnson syndrome, in which people get blisters around the mouth, eyes, or anus. Call a physician immediately if any of these signs of a dangerous reaction occur:

• skin rash or reddish or purplish spots on the skin
• other skin problems, such as blistering or peeling
• fever
• sore throat
• cough
• shortness of breath
• joint pain
• pale skin
• yellow skin or eyes

This medicine may cause dizziness. Anyone who takes sulfonamides should not drive, use machines or do anything else that might be dangerous until they have found out how the drugs affect them.

Sulfonamides may cause blood problems that can interfere with healing and lead to additional infections. Avoid injuries while taking this medicine. Be especially careful not to injure the mouth when brushing or flossing the teeth or using a toothpick. Do not have dental work done until the blood is back to normal.

This medicine may increase sensitivity to sunlight. Even brief exposure to sun can cause a severe sunburn or a rash. While being treated with this medicine, 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.

Babies under 2 months should not be given sulfonamides unless their physician has ordered the medicine.

Older people may be especially sensitive to the effects of sulfonamides, increasing the chance of unwanted side effects, such as severe skin problems and blood problems. Patients who are taking water pills (diuretics ) at the same time as sulfonamides may also be more likely to have these problems.

Special conditions

People with certain medical conditions or who are taking certain other medicines can have problems if they take sulfonamides. Before taking these drugs, be sure to let the physician know about any of these conditions:

ALLERGIES. Anyone who has had unusual reactions to sulfonamides, water pills (diuretics), diabetes medicines, or glaucoma medicine in the past should let his or her physician know before taking sulfonamides. The physician should also be told about any allergies to foods, dyes, preservatives, or other substances.

PREGNANCY. In studies of laboratory animals, some sulfonamides cause birth defects. The drugs' effects on human fetuses have not been studied. However, pregnant women are advised not to use this medicine around the time of labor and delivery, because it can cause side effects in the baby. Women who are pregnant or who may become pregnant should check with their physicians about the safety of using sulfonamides during pregnancy.

BREASTFEEDING. Sulfonamides pass into breast milk and may cause liver problems, anemia, and other problems in nursing babies whose mothers take the medicine. Because of those problems, women should not breastfeed when they are under treatment with this drug. Women who are breastfeeding and who need to take this medicine should check with their physicians to find out how long they need to stop breastfeeding.

OTHER MEDICAL CONDITIONS. Before using sulfonamides, people with any of these medical problems should make sure their physicians are aware of their conditions:

• anemia or other blood problems
• kidney disease
• liver disease
• asthma or severe allergies
• alcohol abuse
• poor nutrition
• abnormal intestinal absorption
• porphyria
• folic acid deficiency
• deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD)

USE OF CERTAIN MEDICINES. Taking sulfonamides 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, dizziness, headache, loss of appetite, and tiredness. These problems usually go away as the body adjusts to the drug and do not require medical treatment.

More serious side effects are not common, but may occur. If any of the following side effects occur, check with a physician immediately:

• itching or skin rash
• reddish or purplish spots on the skin
• other skin problems, such as redness, blistering, peeling
• severe, watery or bloody diarrhea
• muscle or joint aches
• fever
• sore throat
• cough
• shortness of breath
• unusual tiredness or weakness
• unusual bleeding or bruising
• pale skin
• yellow eyes or skin
• swallowing problems

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

Interactions

Sulfonamides may interact with a large number of 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 sulfonamides should let the physician know all other medicines he or she is taking. Among the drugs that may interact with sulfonamides are:

• acetaminophen (Tylenol)
• medicine for overactive thyroid
• male hormones (androgens)
• female hormones (estrogens)
• other medicines used to treat infections
• birth control pills
• medicines for diabetes such as glyburide (Micronase)
• anticoagulants such as warfarin (Coumadin)
• disulfiram (Antabuse), used to treat alcohol abuse
• amantadine (Symmetrel), used to treat flu and also Parkinson's disease
• water pills (diuretics) such as hydrochlorothiazide (HCTZ, HydroDIURIL)
• the anticancer drug methotrexate (Rheumatrex)
• antiseizure medicines such as valproice acid (Depakote, Depakene)

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

KEY TERMS

Anemia— A lack of hemoglobin—the compound in blood that carries oxygen from the lungs throughout the body and brings waste carbon dioxide from the cells to the lungs, where it is released.

Bronchitis— Inflammation of the air passages of the lungs.

Fetus— A developing baby inside the womb.

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

Meningitis— Inflammation of tissues that surround the brain and spinal cord.

Pneumocystis carinii pneumonia— A lung infection that affects people with weakened immune systems, such as people with AIDS or people taking medicines that weaken the immune system.

Porphyria— A disorder in which porphyrins build up in the blood and urine.

Porphyrin— A type of pigment found in living things.

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

Sulfonamides

Definition

Sulfonamides, sometimes called sulfa drugs, are medicines that prevent the growth of bacteria in the body. The sulfonamides have largely been replaced by the antibiotics which generally are safer and more effective.

Description

Sulfonamides are used to treat many kinds of infections caused by bacteria and certain other microorganisms. Physicians may prescribe these drugs to treat urinary tract infections, ear infections, frequent or long lasting bronchitis , bacterial meningitis , certain eye infections, Pneumocystis carinii pneumonia , traveler's diarrhea , and a number of other kinds of infections. These drugs will not work for colds, flu, and other infections caused by viruses.

Description

Although there were many sulfonamides, relatively few are in use as of 2004:

• Sulfisoxazole (Gantrisin) is used to treat urinary tract infections. In combination with erythromycin, sulfisoxazole may be used to treat ear infections in children.
• Trimethoprim/sulfamethoxazole (Bactrim, Septra) is a combination of two sulfonamides used together. The combination is more effective than giving either drug alone in a larger dose. The combination is commonly used to treat urinary tract infections and other infections that cannot be treated with antibiotics.
• Sulfadiazine may be used to protect people with rheumatic fever from infections. It is used to treat toxoplasmosis . An ointment containing silver sulfadiazine is widely used for treatment of burns.
• Sulfasalazine (Azulfadine) is used to treat infections of the colon and intestine.

General use

The most common use for sulfonamides in adults is treatment of urinary tract infections. In children, sulfonamides have more limited use. Sulfisoxazole may be used for prophylaxis of ear infections and prevention of meningococcal infections. Sulfasakazube is used to treat children over the age of two years with ulcerative colitis.

Precautions

Sulfonamides should never be used in infants under the age of two months. They should also be used with extreme care in patients with liver problems, kidney problems, and some types of anemia.

Side effects

Although such side effects are rare, some people have severe and life-threatening reactions to sulfonamides. These include sudden, severe liver damage; serious blood problems; breakdown of the outer layer of the skin; and a condition called Stevens-Johnson syndrome, in which people get blisters around the mouth, eyes, or anus. People should call a physician immediately if any of the following signs of a dangerous reaction occur:

• skin rash or reddish or purplish spots on the skin
• other skin problems, such as blistering or peeling
• fever
• sore throat
• cough
• shortness of breath
• joint pain
• pale skin
• yellow skin or eyes

This medicine may cause dizziness . Sulfonamides may also cause blood problems that can interfere with healing and lead to additional infections. This medicine may increase sensitivity to sunlight. Even brief exposure to sun can cause severe sunburn or rash. While being treated with this medicine, people should avoid being in direct sunlight. Very rarely, systemic sulfonamides may even cause kidney stones.

The most serious adverse effects of sulfonamides cannot be predicted. Some steps can minimize some of the less severe adverse effects. Because sulfonamides are not very soluble, they should always be taken with a full glass of water. Moreover, sulfonamides increase sensitivity to sunlight and increase the risk of sunburn. People taking sulfonamides by mouth should avoid direct sunlight and stay covered up. They should not rely on sunscreens . This risk does not apply, however, to people using sulfonamide eye or ear drops. Oral sulfonamides should always be taken in evenly spaced doses to maintain a steady blood level throughout the day.

Interactions

Sulfonamides may interact with a large number of other medicines. When interaction occurs, the effects of one or both of the drugs may change or the risk of side effects may be greater. People who take sulfonamides should let their physician know all other medicines they are taking. Among the drugs that may interact with sulfonamides are:

• acetaminophen (Tylenol)
• medicine for overactive thyroid
• other medicines used to treat infections
• birth control pills
• medicines for diabetes, such as glyburide (Micronase)
• anticoagulants, such as warfarin (Coumadin)
• amantadine (Symmetrel)
• water pills (diuretics) such as hydrochlorothiazide (HCTZ, HydroDIURIL)
• the anticancer drug methotrexate (Rheumatrex)
• antiseizure medicines such as valproic acid (Depakote, Depakene)

The list above does not include every drug that may interact with sulfonamides but is limited to drugs that might be used in treatment of children and adolescents. Parents should be sure to check with a physician or pharmacist before combining sulfonamides with any other prescription or nonprescription (over-the-counter) medicine.

Parental concerns

Parents giving their children eye or ear drops should be sure they know the proper way to administer these drops. Parents should review the technique with a physician or nurse to be sure the medication is given properly. If children are taking sulfonamides by mouth, parents should be sure that the children are drinking a full glass of water with each dose. Because some of the adverse effects of sulfonamides may be very serious, parents should report any suspicious symptoms to their physician promptly.

See also Cystitis; Penicillins; Tetracyclines.

Resources

BOOKS

Beers Mark H., and Robert Berkow, eds. The Merck Manual, 2nd ed. home edition. West Point, PA: Merck & Co., 2004.

Marx, John A. Rosen's Emergency Medicine: Concepts and Clinical Practice, 5th ed. St. Louis, MO: Mosby & Co, 2002.

Mcevoy, Gerald K., et al. AHFS Drug Information 2004. Bethesda, MD: American Society of Healthsystems Pharmacists, 2004.

Siberry, George K., and Robert Iannone, eds. The Harriet Lane Handbook, 15th ed. Philadelphia: Mosby Publishing, 2000.

PERIODICALS

American Academy of Pediatrics, Committee on Quality Improvement, Subcommittee on Urinary Tract Infection. "Practice parameter: the diagnosis, treatment, and evaluation of the initial urinary tract infection in febrile infants and young children." Journal of Pediatrics 105, no. 2 (February 2000): 463–464.

Halasa, Natasha B., et al. "Differences in antibiotic prescribing patterns for children younger than five years in the three major outpatient settings." Journal of Pediatrics 144, no. 2 (February 2004): 200–205.

Witman, P. M. "Pediatric oral medicine." Dermatolgic Clinics of North America 21, no. 1 (January 2003): 157–170.

ORGANIZATIONS

American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007–1098. Web site: <www.aap.org>.

WEB SITES

"Med Chem Group 7—Antibiotics." University of Michigan, College of Pharmacy. Available online at <http://sitemaker.umich.edu/medchemgroup7/files/sulfonamides_clinical_pharmacology.htm> (accessed September 29, 2004).

"Sulfonamides (Ophthalmic)." MedlinePlus. Available online at <www.nlm.nih.gov/medlineplus/druginfo/uspdi/202539.html> (accessed September 29, 2004).

Nancy Ross-Flanigan Samuel Uretsky, PharmD