Sulfonamide (medicine)

Sulfonamides, or sulfa drugs, are a class of antibacterial medications typically used to treat certain types of bacterial infections. First developed in the 1930s, sulfa drugs were among the first "miracle drugs" that could be used to save patients suffering from potentially fatal bacterial infections such as pneumonia. Although sulfa drugs were largely replaced by penicillin and other more powerful drugs over time, they played a critical role in the development of antibiotics. In modern medicine, sulfa drugs still are used as antimicrobials in certain circumstances. Most often, sulfa drugs are used in the treatment of urinary tract infections and other types of infections. They also can be used to control seizures and treat other medical problems. Like most medicines, sulfa drugs have a range of side effects, some of which include headache, dizziness, diarrhea, and nausea. Sulfa drugs also can trigger allergic reactions in some patients that can result in rash, hives, difficulty breathing, or swelling.

Brief History

Prior to the 1930s, there were no effective medical treatments for bacterial infections. As a result, such infections could spread with ease. Worse, with no reliable means of helping patients recover, bacterial diseases such as pneumonia and tuberculosis often were fatal. Clearly, a solution to this problem was needed.

The eventual breakthrough in the treatment of bacterial infections came through the work of German physician and researcher Gerhard Domagk. In the early 1930s, Domagk was employed by I.G. Farbenindustrie, a German industrial conglomerate. At the time, he was working on a project that had him tasked with testing various industrial chemicals for possible medical uses. One of the chemicals Domagk tested was a special group of dyes called azo dyes. These dyes could change the color of fabrics by binding some of the proteins found in those fabrics. Domagk supposed that the chemical compounds in azo dyes also might be able to bind bacterial proteins and thus inhibit their action. One such compound, which Domagk and his team called prontosil rubrum, proved to do just that when it was administered to laboratory mice carrying the bacterial infection Streptococcus. When Domagk subsequently patented the compound as Prontosil and published a report on the substance in 1935, the world's first sulfa drug was officially created.

Shortly after Prontosil's debut, scientists studying the compound noticed that its molecules split in two when ingested, leaving the active part of the substance—sulfanilamide—separate from the inactive part. Because the sulfanilamide part of the Prontosil molecule was not covered by Domagk's patent, it could be used to make similar medicinal substances. That cleared the way for the production of a whole range of sulfa drugs, including sulfapyridine, sulfathiazole, and sulfadiazine. With the introduction of these drugs, doctors finally had an effective way to treat pneumonia, Staphylococcus, and other life-threatening bacterial infections.

Although their discovery was a major medical breakthrough, sulfa drugs were used as first-line treatment for bacterial infections for only a short time. In part, this was because they had some serious side effects that often made them difficult to take. More importantly, the eventual development of penicillin and other more effective antibiotics ultimately made sulfa drugs obsolete in most cases.

Overview

Sulfa drugs are a type of medication that prevents the growth of bacteria in the body. Different types of sulfa drugs can be taken orally, topically, or through other routes of administration. Most often, sulfa drugs are prescribed for the treatment of bacterial infections, particularly pneumonia, bacterial meningitis, and urinary tract infections. Sulfa drugs also are commonly used to treat certain types of eye and ear infections and some forms of diarrhea. Some orally administered sulfa drugs can be used to treat inflammatory bowel disease and to prevent seizures. Topical sulfa drugs can be used to treat burns, vaginitis, and eye infections.

One of the major drawbacks of sulfa drugs is their propensity to produce unpleasant and sometimes dangerous side effects. Some of the most common side effects include skin rashes, itching, dizziness, headaches, fatigue, diarrhea, nausea, vomiting, joint pain, and paleness. Patients taking sulfa drugs also may experience increased sensitivity to light. In rare cases, sulfa drugs can have more serious side effects. For example, patients taking sulfa drugs can develop hepatitis, certain types of anemias, and other blood disorders. Overuse of sulfa drugs can result in kidney damage. Some studies indicate that women who take sulfa drugs while pregnant have a greater chance of having a child with birth defects.

Another concern related to sulfa drugs is their potential to cause allergic reactions. Many people are naturally allergic to sulfa and may experience a pronounced reaction in response to exposure to sulfa drugs. The most common signs of an allergic reaction to sulfa include the appearance of hives; swelling of the face, mouth, tongue, and throat; and a sudden drop in blood pressure. In more severe cases, exposure to sulfa can result in anaphylaxis, a severe allergic reaction that requires immediate medical attention. In rare cases, some patients who begin taking sulfa drugs may develop symptoms of serum sickness, which is a type of reaction specifically tied to the immune system's response to certain medicines used to treat immune conditions or to other substances administered to patients to protect them from germs or poisons. Symptoms of this type of reaction may include skin eruptions, hives, fever, drug-induced arthritis, or swollen lymph nodes. A person who is allergic to one particular sulfa drug may not be allergic to all sulfa drugs. Most people with sulfa allergies can take at least some sulfa drugs without having a reaction.

Although they have been largely replaced by more effective antibiotics, sulfa drugs still are prescribed and used on a regular basis. Because they are more affordable than their preferred antibiotic counterparts, sulfa drugs are widely used in developing countries where financial restrictions limit the availability of other drugs. New sulfa drugs are being developed to aid in the treatment of specific types of bacterial infections, including some of those caused by certain strains of Salmonellaand those brought on by Pneumocystis carinii.

Bibliography

"Antibiotic Medications—Sulfa Drugs." University of Maryland Medical Center, www.umm.edu/health/medical/altmed/depletion/antibiotic-medications-sulfa-drugs. Accessed 17 Apr. 2017.

Earl, Lesley. "How Sulfa Drugs Work." National Institutes of Health, 12 Mar. 2012, www.nih.gov/news-events/nih-research-matters/how-sulfa-drugs-work. Accessed 17 Apr. 2017.

"Gerhard Domagk." Chemical Heritage Foundation, www.chemheritage.org/historical-profile/gerhard-domagk. Accessed 17 Apr. 2017.

Kerr, Michael, and Tricia Kinman. "Sulfa Allergies vs. Sulfite Allergies." HealthLine, 4 Aug. 2015, www.healthline.com/health/allergies/sulfa-sulfite. Accessed 17 Apr. 2017.

Lesch, John E. The First Miracle Drugs: How the Sulfa Drugs Transformed Medicine. Oxford University Press, 2007.

Li, James T.C. "I Have a Sulfa Allergy. Do I Need to Avoid Certain Medications?" Mayo Clinic, www.mayoclinic.org/diseases-conditions/drug-allergy/expert-answers/sulfa-allergy/faq-20057970. Accessed 17 Apr. 2017.

Marks, Lynn. "What Are Sulfonamides?" Everyday Health, 1 Dec. 2015, www.everydayhealth.com/sulfonamides/guide/. Accessed 17 Apr. 2017.

Schlecht, Hans P., and Christopher Bruno. "Sulfonamides." Merck Manual, www.merckmanuals.com/professional/infectious-diseases/bacteria-and-antibacterial-drugs/sulfonamides. Accessed 17 Apr. 2017.