From the Guidelines
Cantharidin should be prescribed as a 0.7% solution, applied every 3 weeks up to four times, for the treatment of cutaneous warts, as recommended by the British Association of Dermatologists' guidelines 1.
Prescription Guidelines
When prescribing cantharidin, it is essential to follow the guidelines to minimize adverse effects and ensure effective treatment. The medication should be applied directly to the lesion, avoiding surrounding healthy skin, and then covered with a bandage for 4-6 hours before washing off.
Treatment Sessions
Treatment sessions are usually repeated every 1-4 weeks until resolution, with a maximum of four treatments 1.
Patient Instructions
Patients should be instructed that blistering is expected and part of the treatment mechanism, but excessive pain or severe reactions warrant immediate medical attention.
Contraindications
Cantharidin is contraindicated in pregnant women, immunocompromised patients, and for lesions on the face, genitals, or mucous membranes.
Mechanism of Action
The medication works by creating controlled tissue damage through acantholysis, causing the lesion to blister and eventually slough off.
Side Effects
Side effects include pain, blistering, temporary hyperpigmentation, and rarely scarring.
Post-Treatment Care
Patients should keep the treated area clean and dry, avoid scratching, and understand that multiple treatments may be necessary for complete resolution.
Recommended Treatment Summary
The British Association of Dermatologists' guidelines recommend cantharidin as a treatment option for cutaneous warts, with a strength of recommendation D 1. Other treatment options include salicylic acid, cryotherapy, and imiquimod, among others 1.
From the FDA Drug Label
All healthcare professionals should receive instruction and training prior to preparation and administration of YCANTH. For topical use only. Not for oral, mucosal, or ophthalmic use. Apply a single application directly to each lesion every 3 weeks as needed. Do not use more than two applicators during a single treatment session. Remove with soap and water 24 hours after treatment.
The prescription guidelines and instructions for cantharidin (cantharidine) are as follows:
- Topical use only: Cantharidin is for topical use only and should not be used orally, mucosally, or ophthalmically.
- Application: Apply a single application directly to each lesion every 3 weeks as needed.
- Dosage: Do not use more than two applicators during a single treatment session.
- Removal: Remove the treatment with soap and water 24 hours after application.
- Precautions: Avoid contact with healthy skin and eyes, and avoid fire, flame, or smoking near the treated area until the treatment is removed.
- Administration: All healthcare professionals should receive instruction and training prior to preparation and administration of cantharidin 2.
From the Research
Prescription Guidelines and Instructions for Cantharidin
- Cantharidin is available in two liquid preparations for dermatologic use: Canthacur (0.7% cantharidin) and Canthacur PS (1% cantharidin 30%/salicylic acid/2% podophylotoxin) 3.
- Canthacur is indicated for the treatment of common warts, periungual warts, and molluscum contagiosum, while Canthacur PS is indicated only for plantar warts 3.
- A proprietary drug-device combination product, YCANTH™, containing cantharidin 0.7% topical solution, has been approved for the topical treatment of molluscum contagiosum in adult and pediatric patients 2 years of age and older in the USA 4.
- Cantharidin can be used to treat molluscum contagiosum, with a solution of 0.9% or 0.7% being safe and effective, and its application should be done by a physician 5.
- The use of cantharidin for treating molluscum contagiosum is generally well tolerated and has high rates of parental satisfaction, with detailed instructions for its use available in the literature 6.
Application Techniques and Precautions
- Cantharidin preparations provide painless applications with outcomes similar to other treatment modalities for warts and molluscum contagiosum 3.
- The application of cantharidin should be done with caution, as it can cause toxic effects following oral ingestion, including ulceration of the gastrointestinal and genitourinary tracts, along with electrolyte and renal function disturbance in humans and animals 3.
- Cantharidin is a strong inhibitor of protein phosphatases types 1 and 2A, and its use should be carefully considered in patients with certain medical conditions 7.