Dapsone 100mg 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
Anti-infective, Anti-inflammatory
Pharmacologic Class
Sulfone, Antileprotic, Antimalarial, Anti-inflammatory
Pregnancy Category
Category C
FDA Approved
Jan 1970
DEA Schedule
Not Controlled
Overview
What is this medicine?
Dapsone is a medication used to treat certain infections, like leprosy, and some skin conditions, like dermatitis herpetiformis. It works by stopping the growth of certain bacteria and by reducing inflammation in the body.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, it's essential to use it 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 by your pharmacist or healthcare provider. Instead, check with your pharmacist for guidance on the best disposal method, or look into local drug take-back programs.
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, it's essential to use it 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 by your pharmacist or healthcare provider. Instead, check with your pharmacist for guidance on the best disposal method, or look into local drug take-back programs.
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 exactly as prescribed by your doctor. Do not stop taking it without consulting your doctor.
- Report any unusual symptoms immediately, especially fever, rash, yellowing of skin/eyes, dark urine, unusual tiredness, or shortness of breath.
- Avoid exposure to fava beans if you have G6PD deficiency, as this can worsen hemolytic anemia.
- Inform all healthcare providers that you are taking dapsone, especially before any new medications are prescribed or procedures are performed.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Standard Dose:
Highly variable depending on indication. Examples: Leprosy (multidrug therapy): 100 mg once daily; Dermatitis Herpetiformis: Initial 50 mg daily, titrate up to 100-300 mg daily; Pneumocystis Pneumonia (PCP) prophylaxis: 100 mg once daily or 50 mg twice daily, or 200 mg once weekly.
Dose Range:
50 - 300 mg
Condition-Specific Dosing:
Leprosy (MDT):
100 mg once daily (part of multi-drug therapy)
Dermatitis Herpetiformis:
Initial 50 mg daily, titrate up to 100-300 mg daily based on response and tolerance
Pneumocystis Pneumonia (PCP) Prophylaxis:
100 mg once daily or 50 mg twice daily, or 200 mg once weekly
Pediatric Dosing
Neonatal:
Not established (generally avoided due to risk of hemolysis and methemoglobinemia)
Infant:
Dosing exists for specific indications (e.g., PCP prophylaxis, leprosy) based on weight. Example for PCP prophylaxis: 2 mg/kg once daily (max 100 mg/day) or 4 mg/kg once weekly (max 200 mg/week).
Child:
Dosing exists for specific indications (e.g., PCP prophylaxis, leprosy) based on weight. Example for PCP prophylaxis: 2 mg/kg once daily (max 100 mg/day) or 4 mg/kg once weekly (max 200 mg/week).
Adolescent:
Generally adult dosing for weight-appropriate adolescents, or weight-based dosing for younger adolescents.
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment usually needed.
Moderate:
Monitor for adverse effects; consider dose reduction or extended interval if severe adverse effects occur.
Severe:
Significant dose reduction or extended interval may be necessary (e.g., 50% dose or every other day dosing) due to accumulation of parent drug and metabolites. Monitor closely.
Dialysis:
Dapsone is poorly dialyzable. Administer dose after dialysis. Monitor for adverse effects.
Hepatic Impairment:
Mild:
No specific adjustment usually needed.
Moderate:
Use with caution. Monitor for increased adverse effects (e.g., hemolytic anemia, methemoglobinemia, hepatotoxicity). Consider dose reduction.
Severe:
Contraindicated or use with extreme caution and significant dose reduction. Monitor closely for toxicity.
Pharmacology
Mechanism of Action
Dapsone is a sulfone that acts as a competitive antagonist of para-aminobenzoic acid (PABA), inhibiting bacterial folic acid synthesis (dihydropteroate synthase). This leads to bacteriostasis. Its anti-inflammatory effects are thought to involve inhibition of neutrophil myeloperoxidase, suppression of neutrophil chemotaxis, and inhibition of lysosomal enzyme release.
Pharmacokinetics
Absorption:
Bioavailability:
70-100%
Tmax:
2-8 hours (highly variable)
FoodEffect:
Minimal effect on absorption, can be taken with or without food.
Distribution:
Vd:
1.5 L/kg (large volume of distribution)
ProteinBinding:
50-90% (primarily to albumin)
CnssPenetration:
Yes, crosses the blood-brain barrier and is found in CSF.
Elimination:
HalfLife:
10-80 hours (average 20-30 hours, highly variable due to genetic polymorphism in N-acetylation)
Clearance:
Not readily available as a single rate due to complex metabolism and enterohepatic recirculation.
ExcretionRoute:
Renal (primarily as metabolites), fecal (minor).
Unchanged:
Approximately 10-20% of the dose is excreted unchanged in urine.
Pharmacodynamics
OnsetOfAction:
Days to weeks for therapeutic effect in chronic conditions.
PeakEffect:
Weeks to months for full therapeutic effect in 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, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash or hives
+ Itching or red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing or tightness in the chest or throat
+ Difficulty breathing, swallowing, or talking
+ Unusual hoarseness or swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems, including:
+ Dark urine
+ Fatigue
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Signs of pancreatitis (pancreas problem), such as:
+ Severe stomach pain
+ Severe back pain
+ Severe upset stomach or vomiting
Signs of kidney problems, including:
+ Inability to urinate
+ Changes in urine output
+ Blood in the urine
+ Sudden weight gain
Signs of lupus, such as:
+ Rash on the cheeks or other body parts
+ Easy sunburn
+ Muscle or joint pain
+ Chest pain or shortness of breath
+ Swelling in the arms or legs
Pale skin
Abnormal sensations, such as burning, numbness, or tingling
Muscle weakness
Difficulty moving around
Blurred vision
Ringing in the ears
Mood changes
Rapid heartbeat
Rare but Serious Side Effects
In rare cases, this medication can cause severe blood and bone marrow problems, including aplastic anemia, which can be life-threatening. Seek medical help immediately if you experience:
Signs of infection, such as fever, chills, or sore throat
Unexplained bruising or bleeding
Purple spots on the skin
Feeling extremely tired or weak
Toxic Epidermal Necrolysis: A Rare but Serious Skin Reaction
This medication can cause a severe skin reaction called toxic epidermal necrolysis, which can lead to serious health problems and even death. Seek medical help right away if you notice:
Red, swollen, blistered, or peeling skin (with or without fever)
Red or irritated eyes
Sores in the mouth, throat, nose, or eyes
Other Side Effects
Like all medications, this drug can cause side effects. While many people experience no side effects or only mild ones, some may be more bothersome. Contact your doctor or seek medical help if you experience:
Upset stomach or vomiting
Stomach pain
Dizziness or headache
Difficulty sleeping
Reporting 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, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash or hives
+ Itching or red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing or tightness in the chest or throat
+ Difficulty breathing, swallowing, or talking
+ Unusual hoarseness or swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems, including:
+ Dark urine
+ Fatigue
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Signs of pancreatitis (pancreas problem), such as:
+ Severe stomach pain
+ Severe back pain
+ Severe upset stomach or vomiting
Signs of kidney problems, including:
+ Inability to urinate
+ Changes in urine output
+ Blood in the urine
+ Sudden weight gain
Signs of lupus, such as:
+ Rash on the cheeks or other body parts
+ Easy sunburn
+ Muscle or joint pain
+ Chest pain or shortness of breath
+ Swelling in the arms or legs
Pale skin
Abnormal sensations, such as burning, numbness, or tingling
Muscle weakness
Difficulty moving around
Blurred vision
Ringing in the ears
Mood changes
Rapid heartbeat
Rare but Serious Side Effects
In rare cases, this medication can cause severe blood and bone marrow problems, including aplastic anemia, which can be life-threatening. Seek medical help immediately if you experience:
Signs of infection, such as fever, chills, or sore throat
Unexplained bruising or bleeding
Purple spots on the skin
Feeling extremely tired or weak
Toxic Epidermal Necrolysis: A Rare but Serious Skin Reaction
This medication can cause a severe skin reaction called toxic epidermal necrolysis, which can lead to serious health problems and even death. Seek medical help right away if you notice:
Red, swollen, blistered, or peeling skin (with or without fever)
Red or irritated eyes
Sores in the mouth, throat, nose, or eyes
Other Side Effects
Like all medications, this drug can cause side effects. While many people experience no side effects or only mild ones, some may be more bothersome. Contact your doctor or seek medical help if you experience:
Upset stomach or vomiting
Stomach pain
Dizziness or headache
Difficulty sleeping
Reporting 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 skin rash, blistering, or peeling skin
- Fever, swollen glands, or flu-like symptoms (signs of Dapsone Hypersensitivity Syndrome)
- Unusual tiredness, weakness, pale skin, shortness of breath, or rapid heart rate (signs of anemia)
- Yellowing of the skin or eyes (jaundice)
- Dark or reddish-brown urine
- Bluish discoloration of lips or fingernails (cyanosis)
- Numbness, tingling, or weakness in hands or feet (peripheral neuropathy)
- Severe stomach pain, nausea, vomiting
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.
If you have anemia.
This list is not exhaustive, and it is crucial to discuss all your health conditions and medications with your doctor. Please provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Your health problems, including any medical conditions or diseases
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to ensure your safety. It is vital to verify that it is safe to take this medication with all your other medications and health conditions.
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.
If you have anemia.
This list is not exhaustive, and it is crucial to discuss all your health conditions and medications with your doctor. Please provide your doctor and pharmacist with a comprehensive list of:
All prescription and over-the-counter (OTC) medications you are taking
Any natural products or vitamins you are using
* Your health problems, including any medical conditions or diseases
Before starting, stopping, or changing the dose of any medication, including this one, consult with your doctor to ensure your safety. It is vital to verify that it is safe to take this medication with all your other medications and health conditions.
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.
As this medication may increase your sensitivity to the sun, take precautions to avoid sunburn, especially if you plan to spend time outdoors. If you experience sunburn easily while taking this drug, notify your doctor promptly.
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. Exercise caution and discuss your condition with your doctor.
Additionally, this medication may affect fertility in men, so it is crucial to discuss this potential risk with your doctor.
If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor immediately. You and your doctor will need to weigh the benefits and risks of taking this medication to ensure the best possible outcome for you and your baby.
As this medication may increase your sensitivity to the sun, take precautions to avoid sunburn, especially if you plan to spend time outdoors. If you experience sunburn easily while taking this drug, notify your doctor promptly.
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. Exercise caution and discuss your condition with your doctor.
Additionally, this medication may affect fertility in men, so it is crucial to discuss this potential risk with your doctor.
If you are pregnant, planning to become pregnant, or breastfeeding, inform your doctor immediately. You and your doctor will need to weigh the benefits and risks of taking this medication to ensure the best possible outcome for you and your baby.
Overdose Information
Overdose Symptoms:
- Cyanosis (bluish discoloration of skin/lips/nails) due to methemoglobinemia
- Severe hemolytic anemia (pallor, fatigue, shortness of breath, jaundice)
- Headache, dizziness, confusion
- Nausea, vomiting, abdominal pain
- Seizures (rare)
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment may involve methylene blue for methemoglobinemia, blood transfusions for severe anemia, and supportive care.
Drug Interactions
Contraindicated Interactions
- Not absolute contraindications, but severe interactions with: Trimethoprim (increased dapsone and trimethoprim levels, increased risk of methemoglobinemia and bone marrow suppression)
Major Interactions
- Rifampin (Potent CYP inducer, significantly decreases dapsone levels, potentially leading to therapeutic failure. Dose adjustment of dapsone may be needed.)
- Didanosine (Antacids in didanosine formulations can decrease dapsone absorption. Administer dapsone at least 2 hours before or after didanosine.)
- Antimalarials (e.g., Pyrimethamine, Proguanil): Increased risk of hematologic toxicity (e.g., megaloblastic anemia, methemoglobinemia).
Moderate Interactions
- Probenecid (Decreases renal excretion of dapsone and its metabolites, increasing dapsone levels and risk of toxicity.)
- Folic acid antagonists (e.g., Methotrexate): Increased risk of hematologic toxicity.
- CYP2E1 and CYP3A4 inhibitors (e.g., Ketoconazole, Ritonavir): May increase dapsone levels and toxicity.
- CYP2E1 and CYP3A4 inducers (e.g., Carbamazepine, Phenytoin, St. John's Wort): May decrease dapsone levels and efficacy.
Minor Interactions
- Antacids (May slightly decrease dapsone absorption if taken concurrently, separate administration.)
Monitoring
Baseline Monitoring
Complete Blood Count (CBC) with differential and reticulocyte count
Rationale: To establish baseline hematologic parameters and detect pre-existing anemia or neutropenia, and to assess for potential hemolytic anemia or methemoglobinemia.
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 with dapsone.
Timing: Prior to initiation of therapy.
Liver Function Tests (LFTs)
Rationale: To establish baseline liver function and monitor for potential hepatotoxicity.
Timing: Prior to initiation of therapy.
Routine Monitoring
Complete Blood Count (CBC) with differential and reticulocyte count
Frequency: Weekly for the first month, then monthly for 6 months, then periodically (e.g., every 3-6 months) during long-term therapy.
Target: Maintain within normal limits or acceptable therapeutic range for patient's condition.
Action Threshold: Significant drop in hemoglobin (>2 g/dL), severe anemia, neutropenia (<1500/mm³), or significant reticulocytosis (indicating hemolysis) warrants dose reduction or discontinuation.
Liver Function Tests (LFTs)
Frequency: Monthly for the first 6 months, then periodically (e.g., every 3-6 months) during long-term therapy.
Target: Within normal limits.
Action Threshold: Significant elevation of transaminases (>3x ULN) or signs of liver injury warrants investigation and potential discontinuation.
Clinical assessment for peripheral neuropathy
Frequency: Periodically, especially with long-term therapy.
Target: Not applicable.
Action Threshold: Development of new or worsening numbness, tingling, or weakness warrants investigation and potential discontinuation.
Symptom Monitoring
- Signs of hemolytic anemia (e.g., pallor, fatigue, shortness of breath, dark urine, jaundice)
- Signs of methemoglobinemia (e.g., cyanosis, headache, dizziness, shortness of breath, fatigue, confusion)
- Signs of Dapsone Hypersensitivity Syndrome (DHS) (e.g., fever, rash, lymphadenopathy, hepatitis, eosinophilia, atypical lymphocytes)
- Signs of peripheral neuropathy (e.g., numbness, tingling, weakness in extremities)
- Signs of liver dysfunction (e.g., nausea, vomiting, abdominal pain, dark urine, jaundice)
- Severe skin reactions (e.g., Stevens-Johnson Syndrome, Toxic Epidermal Necrolysis)
Special Patient Groups
Pregnancy
Category C. Dapsone should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. It crosses the placenta. Cases of methemoglobinemia and hemolytic anemia in newborns have been reported.
Trimester-Specific Risks:
First Trimester:
Potential for teratogenicity, though human data are limited and largely reassuring for structural defects. Risk of hematologic effects.
Second Trimester:
Risk of hematologic effects (hemolytic anemia, methemoglobinemia) in the fetus.
Third Trimester:
Increased risk of hemolytic anemia and methemoglobinemia in the newborn, especially if the infant is G6PD deficient.
Lactation
L3 (Moderate risk). Dapsone is excreted into breast milk. There is a risk of hemolytic anemia and methemoglobinemia in breastfed infants, particularly those with G6PD deficiency. Weigh benefits of breastfeeding against potential risks. Monitor infant for signs of hemolysis or cyanosis.
Infant Risk:
Risk of hemolytic anemia and methemoglobinemia, especially in G6PD deficient infants. Monitor for jaundice, pallor, or cyanosis.
Pediatric Use
Used in children for specific indications (e.g., leprosy, PCP prophylaxis, dermatitis herpetiformis). Dosing is weight-based. Children, especially neonates and infants, are more susceptible to methemoglobinemia and hemolytic anemia. G6PD testing is crucial before initiation.
Geriatric Use
Use with caution in elderly patients due to potential for decreased renal and hepatic function, which may lead to increased drug levels and higher risk of adverse effects. Monitor hematologic parameters and liver function closely.
Clinical Information
Clinical Pearls
- Always test for G6PD deficiency before initiating dapsone therapy due to the risk of severe hemolytic anemia.
- Dapsone Hypersensitivity Syndrome (DHS) is a serious, potentially fatal reaction that can occur 3-8 weeks after initiation. Educate patients on symptoms (fever, rash, lymphadenopathy, hepatitis, eosinophilia) and to seek immediate medical attention.
- Methemoglobinemia is a common dose-related side effect, often asymptomatic at lower levels but can cause cyanosis and hypoxia at higher levels. Methylene blue is the antidote.
- Peripheral neuropathy is a rare but serious side effect, typically occurring with high doses or prolonged therapy. It is usually reversible upon discontinuation.
- Dapsone is a cornerstone of multi-drug therapy for leprosy, significantly reducing the risk of drug resistance.
Alternative Therapies
- For Leprosy: Rifampin, Clofazimine (used in combination with dapsone)
- For Dermatitis Herpetiformis: Sulfapyridine, Sulfamethoxypyridazine (less common now)
- For Pneumocystis Pneumonia (PCP) Prophylaxis: Trimethoprim/Sulfamethoxazole (TMP/SMX), Atovaquone, Pentamidine
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (generic 100mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (preferred generic) on most commercial and Medicare Part D plans.
General Drug Facts
If your symptoms or health issues persist or worsen, it is essential to contact your doctor promptly. 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. If you have any questions or concerns about this medication, don't hesitate to discuss them with 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 detailed information about the overdose, including the medication taken, the amount, and the time it occurred.