Dapsone 25mg Tablets
It is used to treat a skin problem called dermatitis herpetiformis.It is used to treat leprosy.It may be given to you for other reasons. Talk with the doctor.
Drug Class
Antileprotic; Anti-infective; Anti-inflammatory
Pharmacologic Class
Sulfone; Diaminodiphenyl sulfone
Pregnancy Category
Category C
FDA Approved
Jan 1955
DEA Schedule
Not Controlled
Overview
What is this medicine?
Dapsone is a medication used to treat certain infections, like leprosy, and skin conditions, like dermatitis herpetiformis. It works by stopping the growth of certain bacteria and by reducing inflammation in the body. It's important to take it exactly as prescribed and to have regular blood tests because it can affect your blood cells.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. Continue taking your medication as prescribed by your doctor or healthcare provider, even if you start to feel better.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep all medications in a secure location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, consult with your pharmacist for guidance on the best disposal method. You may also want to inquire about drug take-back programs in your area.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To get the most benefit from your medication, take it exactly as directed by your doctor. Carefully read all the information provided with your prescription, and follow the instructions closely. Continue taking your medication as prescribed by your doctor or healthcare provider, even if you start to feel better.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature, protected from light, and in a dry place. Avoid storing it in a bathroom. Keep all medications in a secure location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so. Instead, consult with your pharmacist for guidance on the best disposal method. You may also want to inquire about drug take-back programs in your area.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take Dapsone with food to minimize stomach upset.
- Avoid alcohol, especially if you experience liver side effects.
- Report any signs of unusual tiredness, pale skin, yellowing of skin/eyes, dark urine, bluish skin/lips, fever, sore throat, or rash immediately to your doctor.
- Do not stop taking Dapsone without consulting your doctor, even if you feel better, as your condition may worsen.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Varies significantly by indication. For Dermatitis Herpetiformis: 50 mg/day initially, adjusted based on response and tolerance. For Leprosy (multibacillary): 100 mg/day. For PCP prophylaxis: 100 mg/day or 50 mg twice daily.
Dose Range:
25 - 400 mg
Condition-Specific Dosing:
Dermatitis Herpetiformis:
Initial: 50 mg/day, titrate up by 25-50 mg every 3-7 days to achieve control, then reduce to minimum effective dose (often 50-300 mg/day).
Leprosy (Multibacillary):
100 mg/day (as part of multi-drug therapy).
Leprosy (Paucibacillary):
100 mg/day (as part of multi-drug therapy).
Pneumocystis Pneumonia (PCP) Prophylaxis:
100 mg/day or 50 mg twice daily (often with pyrimethamine or trimethoprim).
Pediatric Dosing
Neonatal:
Not established (use with extreme caution due to risk of hemolysis and methemoglobinemia).
Infant:
Not established (use with extreme caution).
Child:
Dosing varies by indication. For Leprosy: 1-2 mg/kg/day (max 100 mg/day) as part of multi-drug therapy. For PCP prophylaxis: 2 mg/kg/day (max 100 mg/day) or 4 mg/kg once weekly (max 200 mg/week).
Adolescent:
Generally adult dosing for weight-appropriate adolescents.
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment generally required, monitor for adverse effects.
Moderate:
Consider dose reduction or extended dosing interval, monitor for adverse effects. Specific recommendations vary by indication.
Severe:
Significant dose reduction or extended dosing interval recommended (e.g., 50% dose or every 2-3 days), monitor closely for toxicity.
Dialysis:
Dapsone is dialyzable. Administer dose after dialysis. Monitor for toxicity.
Hepatic Impairment:
Mild:
No specific adjustment generally required, monitor liver function.
Moderate:
Use with caution, consider dose reduction, monitor liver function and hematologic parameters closely.
Severe:
Contraindicated or use with extreme caution and significant dose reduction. Monitor closely for toxicity.
Pharmacology
Mechanism of Action
Dapsone is a sulfone antibiotic with anti-inflammatory and immunomodulatory properties. Its antibacterial action is primarily bacteriostatic, inhibiting bacterial folate synthesis by competing with para-aminobenzoic acid (PABA) for the enzyme dihydropteroate synthase. This prevents the synthesis of dihydrofolic acid, a precursor of folic acid, which is essential for bacterial growth. Its anti-inflammatory effects, particularly in dermatologic conditions like dermatitis herpetiformis, are thought to involve inhibition of neutrophil chemotaxis, lysosomal enzyme release, and possibly other mechanisms independent of its antimicrobial action.
Pharmacokinetics
Absorption:
Bioavailability:
70-100% (nearly complete)
Tmax:
2-8 hours (highly variable)
FoodEffect:
Food may slightly delay absorption but does not significantly affect the extent of absorption.
Distribution:
Vd:
1.5 L/kg (extensive tissue distribution)
ProteinBinding:
70-90%
CnssPenetration:
Yes (penetrates CSF, but concentrations are lower than plasma)
Elimination:
HalfLife:
10-80 hours (highly variable, average 20-30 hours; longer in slow acetylators)
Clearance:
Not readily available as a single value due to complex metabolism and enterohepatic recirculation.
ExcretionRoute:
Renal (primarily as metabolites), some fecal excretion.
Unchanged:
Less than 20% (primarily as metabolites)
Pharmacodynamics
OnsetOfAction:
Days to weeks for full therapeutic effect (e.g., dermatitis herpetiformis, leprosy).
PeakEffect:
Not acutely defined for chronic conditions.
DurationOfAction:
Due to long half-life, effects persist for several days after discontinuation.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction: rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, trouble breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems: dark urine, tiredness, decreased appetite, upset stomach or stomach pain, light-colored stools, vomiting, or yellow skin or eyes
Signs of pancreatitis (pancreas problem): severe stomach pain, severe back pain, or severe upset stomach or vomiting
Signs of kidney problems: inability to pass urine, changes in urine output, blood in the urine, or significant weight gain
Signs of lupus: rash on the cheeks or other body parts, easy sunburn, muscle or joint pain, chest pain or shortness of breath, or swelling in the arms or legs
Pale skin
Abnormal burning, numbness, or tingling sensations
Muscle weakness
Difficulty moving around
Blurred vision
Ringing in the ears
Mood changes
Rapid heartbeat
Rarely, this medication can cause bone marrow and blood problems, including a severe condition called aplastic anemia, which can be life-threatening. Seek medical help immediately if you experience:
Signs of infection: fever, chills, or sore throat
Unexplained bruising or bleeding
Purple spots on the skin
Feeling extremely tired or weak
In rare cases, a severe skin reaction called toxic epidermal necrolysis can occur, which can cause serious health problems and even death. Seek medical help immediately if you experience:
Red, swollen, blistered, or peeling skin (with or without fever)
Red or irritated eyes
Sores in the mouth, throat, nose, or eyes
Other Possible Side Effects
Like all medications, this drug can cause side effects. Many people may not experience any side effects or may only have mild ones. If you experience any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor or seek medical attention:
Upset stomach or vomiting
Stomach pain
Dizziness or headache
Trouble sleeping
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, this medication can cause severe and potentially life-threatening side effects. If you experience any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction: rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, trouble breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems: dark urine, tiredness, decreased appetite, upset stomach or stomach pain, light-colored stools, vomiting, or yellow skin or eyes
Signs of pancreatitis (pancreas problem): severe stomach pain, severe back pain, or severe upset stomach or vomiting
Signs of kidney problems: inability to pass urine, changes in urine output, blood in the urine, or significant weight gain
Signs of lupus: rash on the cheeks or other body parts, easy sunburn, muscle or joint pain, chest pain or shortness of breath, or swelling in the arms or legs
Pale skin
Abnormal burning, numbness, or tingling sensations
Muscle weakness
Difficulty moving around
Blurred vision
Ringing in the ears
Mood changes
Rapid heartbeat
Rarely, this medication can cause bone marrow and blood problems, including a severe condition called aplastic anemia, which can be life-threatening. Seek medical help immediately if you experience:
Signs of infection: fever, chills, or sore throat
Unexplained bruising or bleeding
Purple spots on the skin
Feeling extremely tired or weak
In rare cases, a severe skin reaction called toxic epidermal necrolysis can occur, which can cause serious health problems and even death. Seek medical help immediately if you experience:
Red, swollen, blistered, or peeling skin (with or without fever)
Red or irritated eyes
Sores in the mouth, throat, nose, or eyes
Other Possible Side Effects
Like all medications, this drug can cause side effects. Many people may not experience any side effects or may only have mild ones. If you experience any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor or seek medical attention:
Upset stomach or vomiting
Stomach pain
Dizziness or headache
Trouble sleeping
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe fatigue, weakness, dizziness, pale skin, shortness of breath (signs of anemia)
- Bluish discoloration of lips, nails, or skin (cyanosis, sign of methemoglobinemia)
- Fever, sore throat, mouth sores, easy bruising or bleeding (signs of severe blood disorders)
- New or worsening numbness, tingling, or weakness in hands or feet (signs of peripheral neuropathy)
- Severe skin rash, fever, swollen lymph nodes, facial swelling, yellowing of skin/eyes (signs of Dapsone Hypersensitivity Syndrome)
- Severe stomach pain, nausea, vomiting, dark urine, yellowing of skin/eyes (signs of liver problems)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
If you have anemia, a condition characterized by a lack of enough healthy red blood cells to carry adequate oxygen to your body's tissues.
This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health issues with your doctor and pharmacist. They will help determine if it is safe to take this medication in conjunction with your other medications and health conditions.
Remember, do not initiate, discontinue, or modify the dosage of any medication without first consulting your doctor to ensure your safety.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
If you have anemia, a condition characterized by a lack of enough healthy red blood cells to carry adequate oxygen to your body's tissues.
This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health issues with your doctor and pharmacist. They will help determine if it is safe to take this medication in conjunction with your other medications and health conditions.
Remember, do not initiate, discontinue, or modify the dosage of any medication without first consulting your doctor to ensure your safety.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Regular blood tests will be necessary, as directed by your doctor, to monitor your condition. Be sure to discuss any concerns or questions with your doctor.
This medication may increase your sensitivity to the sun, making it easier to get sunburned. Take precautions when spending time outdoors, such as using protective measures, and notify your doctor if you experience excessive sunburn.
If you have a deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), you may be at a higher risk of developing anemia. Individuals of African, South Asian, Middle Eastern, and Mediterranean descent are more likely to have low G6PD levels.
Additionally, this medication may affect fertility in men, and it is crucial to discuss this potential risk with your doctor.
If you are pregnant, planning to become pregnant, or breastfeeding, it is essential to consult with your doctor to weigh the benefits and risks of this medication to both you and your baby.
This medication may increase your sensitivity to the sun, making it easier to get sunburned. Take precautions when spending time outdoors, such as using protective measures, and notify your doctor if you experience excessive sunburn.
If you have a deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), you may be at a higher risk of developing anemia. Individuals of African, South Asian, Middle Eastern, and Mediterranean descent are more likely to have low G6PD levels.
Additionally, this medication may affect fertility in men, and it is crucial to discuss this potential risk with your doctor.
If you are pregnant, planning to become pregnant, or breastfeeding, it is essential to consult with your doctor to weigh the benefits and risks of this medication to both you and your baby.
Overdose Information
Overdose Symptoms:
- Nausea, vomiting, abdominal pain
- Cyanosis (bluish discoloration) due to methemoglobinemia
- Headache, dizziness, confusion
- Seizures
- Hemolytic anemia (delayed onset, 24-48 hours post-ingestion)
What to Do:
Seek immediate medical attention. Call 911 or your local emergency number. For poison control, call 1-800-222-1222. Treatment may involve gastric lavage, activated charcoal, and specific antidotes like methylene blue for methemoglobinemia, and supportive care for hemolytic anemia.
Drug Interactions
Contraindicated Interactions
- Not typically contraindicated with specific drugs, but caution with drugs that significantly increase methemoglobinemia risk or severe myelosuppression.
Major Interactions
- Trimethoprim (increased dapsone and MADDS levels, increased risk of methemoglobinemia and myelosuppression)
- Rifampin (decreased dapsone levels, potential loss of efficacy)
- Didanosine (decreased dapsone absorption)
- Clozapine (increased risk of agranulocytosis)
- Zidovudine (increased risk of hematologic toxicity, especially anemia)
- Drugs causing methemoglobinemia (e.g., nitrates, local anesthetics like prilocaine, sulfonamides, phenazopyridine) - additive risk.
Moderate Interactions
- Probenecid (inhibits renal excretion of dapsone, increasing levels)
- CYP3A4 inhibitors (e.g., azole antifungals, macrolides, protease inhibitors) - may increase dapsone levels.
- CYP3A4 inducers (e.g., carbamazepine, phenytoin, phenobarbital) - may decrease dapsone levels.
- Folic acid antagonists (e.g., pyrimethamine, methotrexate) - additive myelosuppression.
- Antacids (containing magnesium/aluminum) - may decrease dapsone absorption.
Minor Interactions
- Not specifically documented for minor interactions, but general caution with drugs affecting liver enzymes or hematopoiesis.
Monitoring
Baseline Monitoring
Complete Blood Count (CBC) with differential
Rationale: To establish baseline hematologic parameters and detect pre-existing anemia or neutropenia, and to monitor for hemolysis, methemoglobinemia, and agranulocytosis.
Timing: Prior to initiation of therapy.
Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency screen
Rationale: Patients with G6PD deficiency are at significantly increased risk of severe hemolytic anemia. Dapsone is contraindicated in severe G6PD deficiency.
Timing: Prior to initiation of therapy.
Liver Function Tests (LFTs)
Rationale: To establish baseline liver function and monitor for drug-induced hepatotoxicity.
Timing: Prior to initiation of therapy.
Renal Function Tests (Creatinine, BUN)
Rationale: To assess baseline renal function, as dose adjustments may be needed in impairment.
Timing: Prior to initiation of therapy.
Routine Monitoring
Complete Blood Count (CBC) with differential
Frequency: Weekly for the first month, then monthly for 6 months, then every 3-6 months or as clinically indicated.
Target: Hemoglobin, WBC, platelet counts within normal limits for patient. Monitor for significant drops.
Action Threshold: Significant drop in hemoglobin (>2 g/dL), neutropenia (<1500/mm³), or thrombocytopenia (<100,000/mm³) warrants dose reduction or discontinuation.
Methemoglobin levels
Frequency: Periodically, especially if signs of cyanosis or dyspnea are present, or if high doses are used.
Target: <2% (normal), <10% (generally well-tolerated)
Action Threshold: >10-15% methemoglobin or symptomatic methemoglobinemia warrants dose reduction or discontinuation and potential treatment with methylene blue.
Liver Function Tests (LFTs)
Frequency: Monthly for the first 3-6 months, then periodically or as clinically indicated.
Target: AST, ALT, bilirubin within normal limits.
Action Threshold: Significant elevation (e.g., >3x ULN) warrants investigation and potential discontinuation.
Symptom Monitoring
- Fatigue, pallor, shortness of breath, dark urine (signs of hemolysis/anemia)
- Bluish discoloration of skin/lips/nails (cyanosis, sign of methemoglobinemia)
- Headache, dizziness, nausea, weakness (signs of methemoglobinemia)
- Rash, fever, lymphadenopathy, eosinophilia (signs of Dapsone Hypersensitivity Syndrome)
- Numbness, tingling, weakness in extremities (signs of peripheral neuropathy)
- Sore throat, fever, signs of infection (signs of agranulocytosis)
- Yellowing of skin/eyes, abdominal pain, dark urine (signs of hepatotoxicity)
Special Patient Groups
Pregnancy
Dapsone is classified as Pregnancy Category C. Studies in animals have shown adverse effects on the fetus, and there are no adequate and well-controlled studies in pregnant women. However, dapsone has been used in pregnant women for conditions like leprosy and PCP prophylaxis when the benefits outweigh the potential risks. It crosses the placenta. Neonatal methemoglobinemia and hemolysis have been reported.
Trimester-Specific Risks:
First Trimester:
Potential for teratogenicity, though human data are limited and largely reassuring for leprosy treatment.
Second Trimester:
Risk of hemolytic anemia and methemoglobinemia in the fetus/neonate.
Third Trimester:
Increased risk of hemolytic anemia and methemoglobinemia in the neonate, especially if G6PD deficient.
Lactation
Dapsone is excreted into breast milk. The American Academy of Pediatrics considers dapsone to be compatible with breastfeeding, but caution is advised. Infants, especially those with G6PD deficiency, are at risk of hemolytic anemia and methemoglobinemia. Monitor breastfed infants for signs of hemolysis (pallor, jaundice, lethargy) and cyanosis.
Infant Risk:
L3 (Moderate risk) - Potential for hemolytic anemia and methemoglobinemia, especially in G6PD deficient infants. Monitor infant for adverse effects.
Pediatric Use
Use with caution, especially in neonates and young infants due to increased susceptibility to hemolytic anemia and methemoglobinemia. G6PD deficiency testing is crucial. Dosing is weight-based for specific indications.
Geriatric Use
Use with caution. Elderly patients may have reduced renal or hepatic function, increasing the risk of adverse effects. Monitor hematologic parameters and organ function closely. Start with lower doses and titrate slowly.
Clinical Information
Clinical Pearls
- Always test for G6PD deficiency before initiating dapsone therapy due to the risk of severe hemolytic anemia.
- Patients should be educated on the signs and symptoms of methemoglobinemia (cyanosis, dyspnea, headache) and hemolytic anemia (fatigue, pallor, dark urine) and instructed to seek immediate medical attention if these occur.
- Dapsone Hypersensitivity Syndrome (DHS) is a rare but potentially fatal reaction, typically occurring 3-6 weeks after initiation, characterized by fever, rash, lymphadenopathy, hepatitis, and eosinophilia. Prompt recognition and discontinuation are critical.
- The half-life of dapsone is highly variable (10-80 hours) and is longer in 'slow acetylators,' which can influence dosing and monitoring.
- Vitamin E and C (ascorbic acid) have been used to reduce methemoglobinemia associated with dapsone, but their routine use is not universally recommended and should be discussed with a physician.
- Dapsone can cause peripheral neuropathy, especially with long-term use or higher doses. Monitor for new onset numbness, tingling, or weakness.
Alternative Therapies
- For Leprosy: Rifampin, Clofazimine, Ofloxacin, Minocycline, Clarithromycin.
- For Dermatitis Herpetiformis: Gluten-free diet (primary treatment), Sulfapyridine (alternative to dapsone).
- For Pneumocystis Pneumonia (PCP) Prophylaxis: Trimethoprim-sulfamethoxazole (TMP-SMX), Atovaquone, Pentamidine (aerosolized).
Cost & Coverage
Average Cost:
Varies, typically $20-$100 per 30 tablets (25mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (preferred generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.