In Canada—

• Dermatitis herpetiformis suppressant

Sulfapyridine (sul-fa-PEER-i-deen) is a sulfa medicine. It is used to help control dermatitis herpetiformis (Duhring's disease), a skin problem. It may also be used for other problems as determined by your doctor. However, this medicine will not work for any kind of infection as other sulfa medicines do.

This medicine may cause some serious side effects. Before using this medicine, be sure to talk to your doctor about these problems, as well as the good this medicine will do.

Sulfapyridine is available only with your doctor's prescription, in the following dosage form:

Oral
• Tablets (U.S. and Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For sulfapyridine, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to sulfa medicines, furosemide (e.g., Lasix) or thiazide diuretics (water pills), oral antidiabetics (diabetes medicine you take by mouth), glaucoma medicine you take by mouth (acetazolamide [e.g., Diamox], dichlorphenamide [e.g., Daranide], methazolamide [e.g., Neptazane]), or pyrimethamine (e.g., Daraprim). Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Studies have not been done in humans. Studies in rats and mice have shown that some sulfa medicines, given by mouth in high doses, cause birth defects, including cleft palate and bone problems. In addition, sulfa medicines may cause liver problems in newborn infants. Therefore, use is not recommended during pregnancy.

Breast-feeding—Sulfapyridine passes into the breast milk. This medicine may cause liver problems in nursing babies. In addition, it may cause blood problems in nursing babies with glucose-6-phosphate dehydrogenase (G6PD) deficiency (lack of G6PD enzyme). Therefore, use is not recommended in nursing women.

Children—Use of this medicine is not recommended since dermatitis herpetiformis usually does not occur in children.

Older adults—Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing the use of sulfapyridine in the elderly with use in other age groups.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking sulfapyridine, it is especially important that your health care professional know if you are taking any of the following:

• Acetaminophen (e.g., Tylenol) (with long-term, high-dose use) or
• Amiodarone (e.g., Cordarone) or
• Anabolic steroids (nandrolone [e.g., Anabolin], oxandrolone [e.g., Anavar], oxymetholone [e.g., Anadrol], stanozolol [e.g., Winstrol]) or
• Androgens (male hormones) or
• Antithyroid agents (medicine for overactive thyroid) or
• Carbamazepine (e.g., Tegretol) or
• Carmustine (e.g., BiCNU) or
• Chloroquine (e.g., Aralen) or
• Dantrolene (e.g., Dantrium) or
• Daunorubicin (e.g., Cerubidine) or
• Disulfiram (e.g., Antabuse) or
• Divalproex (e.g., Depakote) or
• Estrogens (female hormones) or
• Etretinate (e.g., Tegison) or
• Gold salts (medicine for arthritis) or
• Hydroxychloroquine (e.g., Plaquenil) or
• Mercaptopurine (e.g., Purinethol) or
• Naltrexone (e.g., Trexan) (with long-term, high-dose use) or
• Oral contraceptives (birth control pills) containing estrogen or
• Other anti-infectives by mouth or by injection (medicine for infection) or
• Phenothiazines (acetophenazine [e.g., Tindal], chlorpromazine [e.g., Thorazine], fluphenazine [e.g., Prolixin], mesoridazine [e.g., Serentil], perphenazine [e.g., Trilafon], prochlorperazine [e.g., Compazine], promazine [e.g., Sparine], promethazine [e.g., Phenergan], thioridazine [e.g., Mellaril], trifluoperazine [e.g., Stelazine], triflupromazine [e.g., Vesprin], trimeprazine [e.g., Temaril]) or
• Plicamycin (e.g., Mithracin) or
• Valproic acid (e.g., Depakene)—Use of sulfapyridine with these medicines may increase the chance of side effects affecting the liver

• Acetohydroxamic acid (e.g., Lithostat) or
• Dapsone or
• Furazolidone (e.g., Furoxone) or
• Nitrofurantoin (e.g., Furadantin) or
• Primaquine or
• Procainamide (e.g., Pronestyl) or
• Quinidine (e.g., Quinidex) or
• Quinine (e.g., Quinamm) or
• Sulfoxone (e.g., Diasone) or
• Vitamin K (e.g., AquaMEPHYTON, Synkayvite)—Use of sulfapyridine with these medicines may increase the chance of side effects affecting the blood

• Anticoagulants (blood thinners) or
• Ethotoin (e.g., Peganone) or
• Mephenytoin (e.g., Mesantoin)—Use of sulfapyridine with these medicines may increase the chance of side effects of these medicines

• Antidiabetics, oral (diabetes medicine you take by mouth)—Use of oral antidiabetics with sulfapyridine may increase the chance of side effects affecting the blood and/or the side effects or oral antidiabetics

• Methotrexate (e.g., Mexate)—Use of methotrexate with sulfapyridine may increase the chance of side effects affecting the liver and/or the side effects of methotrexate

• Methyldopa (e.g., Aldomet)—Use of methyldopa with sulfapyridine may increase the chance of side effects affecting the liver and/or the blood

• Phenytoin (e.g., Dilantin)—Use of phenytoin with sulfapyridine may increase the chance of side effects affecting the liver and/or the side effects of phenytoin

• Blood problems or
• Glucose-6-phosphate dehydrogenase deficiency (lack of G6PD enzyme)—Patients with these problems may have an increase in side effects affecting the blood

• Kidney disease or
• Liver disease—Patients with kidney disease or liver disease may have an increased chance of side effects

• Porphyria—Use of sulfapyridine may cause an attack of porphyria

Each dose of sulfapyridine should be taken with a full glass (8 ounces) of water. Several additional glasses of water should be taken every day, unless otherwise directed by your doctor. Drinking extra water will help to prevent some unwanted effects (e.g., kidney stones) of the sulfa medicine.

For patients taking sulfapyridine for dermatitis herpetiformis :

• Your doctor may want you to follow a strict, gluten-free diet.
• You may have to use this medicine regularly for 6 months to a year before you can reduce the dose of sulfapyridine or stop it altogether. If you have any questions about this, check with your doctor.

Dosing—

The dose of sulfapyridine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of sulfapyridine. Your dose may be different if you have kidney disease. If your dose is different, do not change it unless your doctor tells you to do so.

• For dermatitis herpetiformis:
  • Adults and adolescents: 250 milligrams to 1 gram four times a day until improvement occurs. After improvement has occurred, the dose should then be reduced by 250 to 500 milligrams every three days until there are no symptoms; that dose should be taken once daily.
  • Children: Use is not recommended, because children usually do not get this condition.

Missed dose—

For patients taking sulfapyridine for dermatitis herpetiformis: You may skip a missed dose if this does not make your symptoms return or get worse. If your symptoms do return or get worse, take the missed dose as soon as possible. Then go back to your regular dosing schedule.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

It is very important that your doctor check your progress at regular visits. This medicine may cause blood problems, especially if it is taken for a long time.

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

Sulfapyridine may cause blood problems. These problems may result in a greater chance of certain infections, slow healing, and bleeding of the gums. Therefore, you should be careful when using regular toothbrushes, dental floss, and toothpicks. Dental work should be delayed until your blood counts have returned to normal. Check with your medical doctor or dentist if you have any questions about proper oral hygiene (mouth care) during treatment.

Sulfapyridine may cause your skin to be more sensitive to sunlight than it is normally. Exposure to sunlight, even for brief periods of time, may cause a skin rash, itching, redness or other discoloration of the skin, or a severe sunburn. When you begin taking this medicine:

• Stay out of direct sunlight, especially between the hours of 10:00 A.M. and 3:00 P.M., if possible.
• Wear protective clothing, including a hat. Also, wear sunglasses.
• Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your health care professional.
• Apply a sun block lipstick that has an SPF of at least 15 to protect your lips.
• Do not use a sunlamp or tanning bed or booth.

You may still be more sensitive to sunlight or sunlamps for many months after stopping this medicine. If you have a severe reaction from the sun, check with your doctor.

Tell the doctor in charge that you are taking this medicine before you have any medical tests. The results of the bentiromide (e.g., Chymex) test for pancreas function are affected by this medicine.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

• More common
  • Fever;  headache (continuing);  itching;  skin rash 
  
  

• Less common
  • Aching of joints and muscles;  difficulty in swallowing;  pale skin;  redness, blistering, peeling, or loosening of skin;  sore throat;  unusual bleeding or bruising;  unusual tiredness or weakness;  yellow eyes or skin 
  
  

• Rare
  • Blood in urine;  lower back pain;  pain or burning while urinating;  swelling of front part of neck 
  
  

Also, check with your doctor as soon as possible if the following side effect occurs:

• More common
  • Increased sensitivity of skin to sunlight 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Diarrhea;  loss of appetite;  nausea or vomiting 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, sulfapyridine is used in certain patients with the following medical conditions:

• Pemphigoid
• Pyoderma gangrenosum
• Subcorneal pustular dermatitis

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for these uses.