Generic Dapsone

Introduction

Dapsone (generic name: Diaminodiphenyl Sulfone) belongs to the antibacterial and anti‑inflammatory drug group. It is widely used in Hong Kong for the treatment of leprosy, dermatitis herpetiformis, certain pneumocystis infections, and as a topical agent for acne and rosacea. The medication is available in oral tablets and, for dermatological use, as a gel (brand name Aczone). Its dual antibacterial and immunomodulatory properties make it a valuable option when conventional antibiotics are insufficient.

What is Dapsone?

Dapsone is a synthetic sulfone antimicrobial that was first synthesized in the early 20th century and introduced for leprosy therapy in the 194 s. It is marketed by several manufacturers worldwide; in Hong Kong, both local distributors and international licensed pharmacies supply the drug. The oral formulation contains the active compound Diaminodiphenyl Sulfone in a 100 mg tablet, while the topical gel contains 5 % (w/w) dapsone in a creamy base.

Classification: Antibacterial, anti‑inflammatory, sulfone class.
Developed by: Originally by the Lederle Laboratories (now part of Pfizer).
Manufacturer examples: Teva Pharmaceuticals, Sun Pharmaceutical Industries, and local licensed importers.

How Dapsone Works

Dapsone interferes with bacterial folate synthesis by inhibiting the enzyme dihydropteroate synthase (DHPS). This blocks the conversion of para‑aminobenzoic acid (PABA) to dihydropteroic acid, a precursor of folic acid, which is essential for nucleic acid synthesis in susceptible organisms such as Mycobacterium leprae and Pneumocystis jirovecii.

In dermatological conditions, dapsone’s anti‑inflammatory effect is attributed to suppression of neutrophil chemotaxis and reduced generation of reactive oxygen species. The onset of antimicrobial activity typically occurs within days, while anti‑inflammatory benefits may require several weeks of continuous therapy.

Pharmacokinetics: After oral ingestion, dapsone is rapidly absorbed (bioavailability ≈ 80 %). Peak plasma concentrations are reached in 2–4 hours. The drug is extensively bound to plasma proteins, metabolised mainly by acetylation and hydroxylation in the liver, and excreted largely unchanged in the urine. The elimination half‑life ranges from 20 to 30 hours, allowing once‑daily dosing.

Conditions Treated with Dapsone

• Leprosy (Hansen’s disease) – WHO‑recommended multidrug therapy includes dapsone 100 mg daily as a cornerstone agent.
• Dermatitis herpetiformis – An autoimmune blistering disorder; dapsone 50–100 mg daily rapidly controls pruritus and lesions.
• Pneumocystis jirovecii pneumonia (PCP) prophylaxis – 100 mg daily in patients intolerant to trimethoprim‑sulfamethoxazole.
• Acne vulgaris and rosacea (topical) – 5 % dapsone gel reduces inflammatory lesions with minimal irritation.
• Other off‑label uses – Certain chronic bullous dermatoses and immunobullous diseases where neutrophil‑mediated inflammation dominates.

In Hong Kong, leprosy incidence is low (< 1 per 100 000), but imported cases and chronic dermatitis herpetiformis remain clinically relevant. Dapsone offers a cost‑effective oral option where newer biologics are not reimbursed.

Patient Groups Most Likely to Benefit

• Adults with confirmed leprosy receiving WHO multidrug therapy.
• Patients with biopsy‑proven dermatitis herpetiformis who need rapid symptom control.
• Individuals requiring PCP prophylaxis who have sulfa‑drug allergy to TMP‑SMX.
• Adults with moderate to severe inflammatory acne inadequately controlled by topical retinoids or antibiotics; the gel formulation is suitable.
• Patients with chronic neutrophilic dermatoses where conventional immunosuppressants are contraindicated.

Contra‑indications or caution: severe glucose‑6‑phosphate dehydrogenase (G6PD) deficiency, known hypersensitivity to sulfone drugs, severe hepatic or renal impairment, and pregnancy (category B in some jurisdictions, but caution advised).

Risks, Side Effects, and Interactions

Common

• Hemolysis (especially in mild G6PD deficiency) – mild anemia, jaundice.
• Methemoglobinemia – cyanosis, shortness of breath; usually dose‑related.
• Pruritus or rash – may signal hypersensitivity.
• Gastrointestinal upset – nausea, abdominal discomfort.
• Mottled skin (drug‑induced hyperpigmentation) – especially on the face and hands after prolonged use.

Rare

• Dapsone hypersensitivity syndrome (DHS) – fever, lymphadenopathy, rash, hepatitis; can be life‑threatening.
• Peripheral neuropathy – numbness or tingling in extremities.
• Aplastic anemia – pancytopenia, extremely uncommon.
• Severe oxidative hemolysis in profound G6PD deficiency – may require transfusion.

Serious

• Severe hemolytic anemia leading to renal failure.
• Acute liver failure from DHS.
• Life‑threatening Stevens‑Johnson syndrome or toxic epidermal necrolysis.
• Severe methemoglobinemia (> 20 %) requiring methylene blue therapy.

Drug–Drug Interactions

• Trimethoprim‑sulfamethoxazole – additive sulfonamide toxicity, increased risk of blood dyscrasias.
• Isoniazid, rifampicin – hepatic enzyme induction may lower dapsone levels.
• Warfarin – potentiates anticoagulant effect; monitor INR.
• Antiretrovirals (e.g., zidovudine) – overlapping marrow suppression.
• Alcohol – may exacerbate hepatic toxicity.

Patients should disclose all concomitant medications, including over‑the‑counter supplements.

Practical Use: Dosing, Missed Dose, Overdose

• Leprosy – 100 mg oral tablet once daily; continue for the duration of WHO‑recommended multidrug therapy (usually 6‑12 months).
• Dermatitis herpetiformis – 50–100 mg once daily; adjust based on clinical response and laboratory monitoring.
• PCP prophylaxis – 100 mg once daily; assess renal function regularly.
• Topical acne/rosacea – Apply a thin layer of 5 % dapsone gel to affected areas once daily, preferably in the evening; wash hands after application.

Missed dose: Take the missed tablet as soon as remembered unless the next scheduled dose is within 4 hours; in that case, skip the missed dose and resume the regular schedule. Do not double‑dose.

Overdose: Symptoms may include severe nausea, vomiting, metabolic acidosis, and profound hemolysis. Seek emergency medical care immediately. Treatment is supportive; methylene blue may be administered for methemoglobinemia.

Precautions: Take with food to improve gastrointestinal tolerance. Avoid excessive alcohol. Monitor complete blood count, liver enzymes, and methemoglobin levels at baseline and periodically (every 2–4 weeks initially).

Buying Dapsone from Our Online Pharmacy

Patients in Hong Kong can obtain Dapsone through our online pharmacy. We provide a discreet, cost‑effective service that connects you with licensed overseas suppliers while complying with Hong Kong regulations.

• Affordable pricing – Prices are close to manufacturer cost, significantly lower than retail pharmacy rates.
• Verified quality – All stock comes from GMP‑certified manufacturers; each batch is accompanied by a certificate of analysis.
• Guaranteed delivery – Express shipping (typically 7 days) and regular airmail (≈ 3 weeks) are available, with discreet packaging to protect privacy.
• Online‑only access – We specialize in international medicines that may not be stocked locally, ensuring you receive the exact formulation prescribed.

Our platform operates as a pharmacy broker service, collaborating with overseas licensed pharmacies. This model allows us to maintain strict privacy standards and provide a seamless, reliable supply chain for patients who have limited access to traditional pharmacies or insurance coverage.

FAQ

• Is Dapsone available in both brand‑name and generic forms in Hong Kong?
  Yes. The original brand‑name product for oral tablets is often listed as Dapsone®, while numerous generic manufacturers supply the same 100 mg tablet containing Diaminodiphenyl Sulfone. The topical gel is marketed under the brand Aczone; generic gels with identical concentration are also available.

• How should Dapsone be stored at home?
  Store tablets at room temperature (15‑30 °C) in a dry place, away from direct sunlight and moisture. The gel should be kept in its original container, tightly closed, and protected from excessive heat.

• Can I import Dapsone for personal use without a prescription in Hong Kong?
  Importation of prescription‑only medicines without a valid prescription is prohibited under Hong Kong law. Our online pharmacy requires a professional evaluation to ensure compliance with local regulations.

• What are the differences between Dapsone formulations sold in the US, EU, and Asia?
  The oral 100 mg tablet is largely identical worldwide, containing the same active ingredient and excipients. However, some Asian manufacturers may use different tablet binders, which can affect dissolution time. Topical formulations (5 % gel) share the same active concentration but may differ in the vehicle (cream vs. gel) based on regional regulatory approvals.

• Are there any special warnings for Asian patients taking Dapsone?
  No ethnicity‑specific contraindications have been reported. Nonetheless, clinicians often screen for G6PD deficiency, which has a higher prevalence in certain Asian subpopulations, before initiating therapy.

• Can Dapsone be used safely in combination with COVID‑19 antiviral treatments?
  Current evidence does not indicate a direct interaction with most oral antivirals (e.g., Paxlovid). However, overlapping hematologic toxicities (e.g., with remdesivir) may require closer monitoring of blood counts.

• Is it possible to obtain a telemedicine prescription for Dapsone through your service?
  Yes. After completing an online health questionnaire, a licensed healthcare professional reviews your information and, if appropriate, issues a prescription that can be fulfilled by our pharmacy.

• What packaging does Dapsone come in when ordered online?
  Oral tablets are packaged in sealed, tamper‑evident blisters or bottles containing the exact quantity ordered. The gel is supplied in a 30 g or 100 g tube, wrapped in a discreet outer box.

• How long does it take to receive Dapsone after ordering from our online pharmacy?
  Express shipping typically delivers within 7 days, while standard airmail takes about 3 weeks. Tracking information is provided for all shipments.

• Is a prescription required to purchase Dapsone in Hong Kong?

• Can Dapsone be taken with food or should it be taken on an empty stomach?
  Dapsone is best absorbed with food, which also reduces gastrointestinal irritation. Taking the tablet with a meal or a small snack is recommended.

• What laboratory tests are needed before and during Dapsone therapy?
  Baseline complete blood count, liver function tests, and G6PD screening are advised. During treatment, CBC and liver enzymes should be monitored every 2–4 weeks for the first three months, then every 2–3 months thereafter.

Glossary

G6PD deficiency

A hereditary enzyme deficiency that reduces red blood cells’ ability to handle oxidative stress, increasing the risk of hemolysis with certain drugs, including dapsone.

Methemoglobinemia

A condition where hemoglobin is oxidized to methemoglobin, impairing its oxygen‑carrying capacity and causing cyanosis.

Dapsone hypersensitivity syndrome (DHS)

A rare, severe drug reaction characterized by fever, rash, lymphadenopathy, and hepatitis; it requires immediate discontinuation of the drug.

Half‑life

The time required for the plasma concentration of a drug to reduce by 50 %; for dapsone it ranges from 20 to 30 hours, supporting once‑daily dosing.

⚠️ Disclaimer

The information provided about Dapsone is for general knowledge only. It does not replace professional medical consultation. All treatment decisions should be made under the supervision of a qualified healthcare provider. We assume all readers are responsible adults capable of making informed decisions about their health. Our online pharmacy offers access to Dapsone for individuals who may have limited availability through traditional pharmacies, prescription‑based insurance schemes, or who are seeking affordable generic alternatives. Always consult your doctor before starting, changing, or discontinuing any medication.