Cantharidin (Topical) (Monograph)

Brand name: Ycanth
Drug class: Antivirals

Introduction

Cantharidin is a topical antiviral agent.

Uses for Cantharidin (Topical)

Cantharidin has the following uses:

Cantharidin topical solution is indicated for the treatment of molluscum contagiosum in adult and pediatric patients 2 years of age and older.

Cantharidin (Topical) Dosage and Administration

General

Cantharidin is available in the following dosage form(s) and strength(s):

Topical solution containing 0.7% cantharidin; supplied in a glass ampule contained within a single-use applicator.

Dosage

It is essential that the manufacturer's labeling be consulted for more detailed information on dosage and administration of this drug. Dosage summary:

All healthcare professionals should receive instruction and training prior to preparation and administration of cantharidin.

Use nitrile or vinyl gloves and eye protection during preparation and administration.

For topical use only. Not for oral, mucosal, or ophthalmic use.

Pediatric Patients

Pediatric patients ≥2 years of age: Apply topically as a single application directly to each lesion every 3 weeks as needed. Do not apply near the eyes. Do not cover any treated lesions with bandages.
Do not use more than two applicators during a single treatment session.
Remove with soap and water 24 hours after treatment. If severe blistering, severe pain, or other severe adverse reactions occur, remove cantharidin with soap and water prior to 24 hours after treatment.
Do not apply other topical products on treated areas until 24 hours after cantharidin treatment or until washing.
Avoid contact with the treatment area, including oral contact, after cantharidin treatment. If contact occurs with any unintended surface, including healthy skin, immediately remove by wiping with a cotton swab or gauze.
For additional instructions on preparation and administration of cantharidin, see Full Prescribing Information.

Adults

Dosage and Administration

For topical use only. Not for oral, mucosal, or ophthalmic use.
Apply topically as a single application directly to each lesion every 3 weeks as needed. Do not apply near the eyes. Do not cover any treated lesions with bandages.
Do not use more than two applicators during a single treatment session.
Remove with soap and water 24 hours after treatment. If severe blistering, severe pain, or other severe adverse reactions occur, remove cantharidin with soap and water prior to 24 hours after treatment.
Do not apply other topical products on treated areas until 24 hours after cantharidin treatment or until washing.
Avoid contact with the treatment area, including oral contact, after cantharidin treatment. If contact occurs with any unintended surface, including healthy skin, immediately remove by wiping with a cotton swab or gauze.
For additional instructions on preparation and administration of cantharidin, see Full Prescribing Information.

Cautions for Cantharidin (Topical)

Contraindications

None

Warnings/Precautions

Toxicities Associated with Inappropriate Administration

Cantharidin is for topical use only. Cantharidin is not for oral, mucosal, or ophthalmic use.

Life threatening or fatal toxicities can occur if cantharidin is administered orally. Adverse reactions to oral ingestion of cantharidin have included renal failure, blistering and severe damage to the gastrointestinal tract, coagulopathy, seizures, and flaccid paralysis. Advise patients and/or caregivers to avoid oral contact and to avoid touching lesions after cantharidin treatment and to seek medical attention immediately if cantharidin is accidently ingested.

Ocular toxicity can occur if cantharidin comes in contact with the eyes. Adverse reactions from contact of cantharidin with the eyes can include corneal necrosis, ocular perforation, and deep ocular injuries. Do not apply cantharidin near or to the eyes. If cantharidin comes in contact with the eyes, flush eyes with water for at least 15 minutes and seek medical attention immediately.

Local Skin Reactions

Cantharidin is a vesicant. Local skin reactions at the application site were observed in 97% of subjects treated with cantharidin during clinical trials. Local skin reactions included vesiculation, pruritus, pain, discoloration, and erythema.

Avoid application near the eyes and mucosal tissues, and to adjacent healthy skin. If cantharidin contacts any unintended surface, including healthy skin, immediately remove by wiping with a cotton swab or gauze.

Avoid other topical products (e.g., creams, lotions, or sunscreen) on treated areas until 24 hours after cantharidin treatment or until washing. Application of other topical products could spread cantharidin and cause blistering or other adverse reactions to healthy skin.

If severe blistering, severe pain or other severe adverse reactions occur, remove cantharidin prior to the recommended 24 hours after administration by washing with soap and water.

Flammability

Cantharidin is a flammable liquid, even after drying. Avoid fire, flame or smoking near lesion(s) during treatment and after application until removed.

Specific Populations

Pregnancy

There are no available data with use of cantharidin in pregnant women to evaluate for a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. Animal reproduction studies were not conducted with cantharidin. Given that systemic exposure to cantharidin following topical administration is low, maternal use is not expected to result in fetal exposure to the drug.

The background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.

Lactation

Avoid application of cantharidin topical solution to areas with increased risk for potential ingestion by or ocular exposure to the breastfeeding child. There are no data on the presence of cantharidin in either human or animal milk, or the effects on the breastfed infant or on milk production. Breastfeeding is not expected to result in exposure of the child to the drug due to the low systemic absorption of cantharidin following topical administration. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for cantharidin topical solution and any potential adverse effects on the breastfeeding child from cantharidin topical solution or from the underlying maternal condition.

Pediatric Use

The safety and effectiveness of cantharidin for the treatment of molluscum contagiosum have been established in pediatric patients 2 years of age and older. The use of cantharidin in pediatric patients is supported by results from adequate and well-controlled trials in patients 2 years of age and older; although the safety and efficacy of drug use for longer than 12 weeks has not been established.

The safety and efficacy in pediatric patients below the age of 2 years have not been established.

Geriatric Use

Cantharidin has not been studied in geriatric patients.

Common Adverse Effects

Most common (incidence ≥1%) adverse reactions include the following local skin reactions at the application site: vesiculation, pain, pruritus, scabbing, erythema, discoloration, application site dryness, edema, and erosion.

Drug Interactions

Specific Drugs

It is essential that the manufacturer's labeling be consulted for more detailed information on interactions with this drug, including possible dosage adjustments. Interaction highlights:

Please see product labeling for drug interaction information.

Actions

Mechanism of Action

The mechanism of action of cantharidin in the treatment of molluscum contagiosum is unknown.

Advice to Patients

Advise the patient and/or caregivers to read the FDA-approved patient labeling (Patient Information).
Inform patients and/or caregivers that cantharidin can be fatal if ingested orally. Instruct patients and/or caregivers to avoid oral contact and to avoid touching lesions after cantharidin treatment. If cantharidin is accidentally ingested, inform patients and/or caregivers to seek medical attention immediately.
Advise patients and/or caregivers that severe eye injury can occur if cantharidin gets into the eyes. If cantharidin gets in the eyes, advise patients and/or caregivers to flush eyes with water for at least 15 minutes and seek medical attention immediately.
Inform patients and/or caregivers that treatment with cantharidin can lead to local skin reactions.
Advise patients and/or caregivers not to use other topical products (e.g. creams, lotions, or sunscreen) until 24 hours after cantharidin treatment or until washing. Advise patients and/or caregivers to remove cantharidin with soap and water prior to 24 hours after treatment and contact the healthcare provider if severe blistering, severe pain or other severe adverse reactions occur.
Inform patients and/or caregivers that cantharidin is flammable, even after drying. Instruct patients and/or caregivers to avoid fire, flame, or smoking near the lesions treated with cantharidin until cantharidin is removed.
Inform patients and/or caregivers to remove cantharidin with soap and water 24 hours after treatment. Inform patients and/or caregivers that more than one cantharidin treatment may be necessary.

Additional Information

AHFSfirstRelease^™. For additional information until a more detailed monograph is developed and published, the manufacturer's labeling should be consulted. It is essential that the manufacturer's labeling be consulted for more detailed information on usual uses, dosage and administration, cautions, precautions, contraindications, potential drug interactions, laboratory test interferences, and acute toxicity.

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

Cantharidin
Routes	Dosage Forms	Strengths	Brand Names	Manufacturer
Topical	Solution	0.7%	Ycanth	Verrica Pharmaceuticals

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