Cantharidin (Topical) (Monograph)

Drug class: Antivirals

Medically reviewed by Drugs.com on May 10, 2024. Written by ASHP.

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Introduction

Topical antiviral agent.

Uses for Cantharidin (Topical)

Molluscum Contagiosum

Treatment of molluscum contagiosum in adults and pediatric patients ≥2 years of age.

No consensus exists on treatment of molluscum contagiosum. The American Academy of Pediatrics Report of the Committee on Infectious Diseases supports the use of cantharidin as an option in the management of molluscum contagiosum. Cantharidin topical solution is the first FDA-approved treatment for molluscum contagiosum; no other treatments approved to date.

Cantharidin (Topical) Dosage and Administration

General

<C> Dispensing and Administration Precautions

• Cantharidin is available for administration by a healthcare professional only. All healthcare professionals should receive instruction and training prior topreparation and administration of the drug.

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

• Avoid contact (including oral contact) with the treatment area after cantharidin treatment. Avoid application near the eyes and mucosal tissue, and to healthy skin.

• If cantharidin comes into contact with any unintended surface (including healthy skin), immediatelyremove the drug.

• Avoid other topical products on treated areas until 24 hours after treatment or until washing.

• Do not cover treated lesions with bandages.

• If severe blistering, severe pain, or other severe adverse reactions occur, remove cantharidin prior to 24 hours after treatment.

• Handling and Disposal: Use nitrile or vinyl gloves and eye protection during preparation and administration of cantharidin. If any damage or leaks are observed on applicators, discard in a sharps container and handle in accordance with accepted medical practice and applicable law. Handle the cantharidin break tool as solid waste and dispose in a plastic recycling container or trash bin. Cantharidin is flammable, even after drying; avoid fire, flame, or smoking near lesions during treatment and after application until removed.

Administration

Consult the manufacturer's labeling for complete, detailed information on preparation and administration.

Topical Administration

Available as a topical solution supplied in a sealed glass ampule contained within a single-use applicator and enclosed in a protective paperboard sleeve. Each ampule contains approximately 0.45 mL of 0.7% cantharidin solution; each mL contains 7 mg (0.7%) of cantharidin. Supplied with a break tool that is co-packaged as 2 units per each carton of applicators; individual break tools available separately from the manufacturer.

For topical use only; not for oral, mucosal, or ophthalmic use. Training required for all healthcare professionals prior to preparation and administration.

Avoid contact (including oral contact) with the treatment area after treatment. Do not apply near the eyes.

If cantharidin contacts any unintended surface (including healthy skin), immediately remove by wiping with a cotton swab or gauze. Avoid use of other topical products on treated areas until 24 hours after treatment or until washing.

Avoid fire, flame, or smoking near lesions during treatment.

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

Apply topically as a single application to cover each lesion; do not use >2 applicators during a single treatment session. Remove with soap and water 24 hours after treatment. Do not cover any treated lesions with bandages. If severe blistering, severe pain, or other severe adverse reactions occur, remove with soap and water prior to the recommended 24 hours after administration.

Applicator is for a single treatment session only; do not reuse. Do not attempt to use a clogged applicator. Do not cut or modify the applicator in any manner. If any damage or leaks observed on the applicators, discard them in a sharps container.

Manufacturer outlines the following steps on preparing the applicator and administering cantharidin solution; consult labeling for more specific details:

• Put on personal protective equipment (gloves and eye protection).

• Remove applicator from the outer protective tube; do not remove applicator cap.

• Remove paperboard sleeve so that the glass ampule is visible; donot remove applicator cap prior to breaking glass ampule.

• Inspect applicator for damage (e.g., broken glass ampule, cut or cracked applicator tube).

• Break ampule using break tool; consult the labeling for specific instructions.

• Gently tap the capped end of applicator on a horizontal surface for approximately 10 seconds or until solution has collected at bottom of applicator tube.

• Test the applicator to confirm proper functioning.

• Apply solution by placing small droplet onto lesion. Use applicator tip to spread solution to cover the entire lesion. Repeat until all lesions have been treated.

• Allow solution to dry completely (up to 5 minutes) before contacting healthy skin.

• Dispose applicator in sharps container; do not reuse.

Break tool maintenance: Wipe surfaces with 70% isopropyl alcohol following each use. Inspect for damage (e.g., crack in plastic, missing or broken breaking posts) and function (e.g., hinge) prior to each use. After 12 uses or if any damage observed, manage as solid waste; dispose in general trash or plastic recycling containers.

Dosage

Pediatric Patients

Molluscum Contagiosum

<E> Topical

Pediatric patients ≥2 years of age:

Apply as a single application to cover each lesion. Do not use >2 applicators during a single treatment session.

Remove with soap and water 24 hours after treatment. Administer every 3 weeks as needed.

Adults

Molluscum Contagiosum

Topical

Apply as a single application to cover each lesion. Do not use >2 applicators during a single treatment session.

Remove with soap and water 24 hours after treatment. Administer every 3 weeks as needed.

Special Populations

Hepatic Impairment

No specific dosage recommendations at this time.

Renal Impairment

No specific dosage recommendations at this time.

Geriatric Patients

No specific dosage recommendations at this time.

Cautions for Cantharidin (Topical)

Contraindications

• None.

Warnings/Precautions

Toxicities Associated with Inappropriate Administration

For topical use only; notfor oral, mucosal, or ophthalmic use.

Life-threatening or fatal toxicities can occur if administered orally; reactions such as renal failure, blistering and severe damage to the GI tract, coagulopathy, seizures, and flaccid paralysis reported. Advise patients and/or caregivers to avoid oral contact and to avoid touching lesions after treatment, and to seek immediate medical attention if accidental ingestion occurs.

Ocular toxicity (e.g., corneal necrosis, ocular perforation,deep ocular injuries) can occur if cantharidin contacts the eyes. Do not apply near or to the eyes. If cantharidin contacts the eyes, flush eyes with water for ≥15 minutes and seek immediate medicalattention.

Local Skin Reactions

Vesicant. Local skin reactions at the application site (e.g., vesiculation, pruritus, pain, discoloration, erythema) reported.

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 cotton swab or gauze.

Avoid topical products (e.g., creams, lotions, sunscreen) on treated areas until 24 hours after treatment or until washing.

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

Flammability

Flammable, even after drying.

Avoid fire, flame, or smoking near lesions during treatment and after application until removed.

Specific Populations

Pregnancy

No data available to assess drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes.

Low systemic exposure following topical administration; maternal use not expected to result in fetal exposure to drug.

Lactation

Not known whether distributed in human milk; effects on breast-fed infants or on milk production also unknown.

Low systemic exposure following topical administration; breast-feeding not expected to result in exposure of child to drug.

Consider developmental and health benefits of breast-feeding, mother's clinical need for cantharidin, and any potential adverse effects on the breast-fed infant from the drug or underlying maternal condition.

Avoid application to areas with increased risk for potential ingestion or ocular exposure to breast-feeding child.

Pediatric Use

Safety and effectiveness established in pediatric patients ≥2 years of age; safety and efficacy of use for >12 weeks not established in this population.

Safety and efficacy not established in pediatric patients <2 years of age.

Geriatric Use

Safety and efficacy not established; not studied in geriatric patients to date.

Hepatic Impairment

Effects of hepatic impairment on cantharidin pharmacokinetics unknown.

Renal Impairment

Effects of renal impairment on cantharidin pharmacokinetics unknown.

Common Adverse Effects

Most common adverse effects (≥1%): Local skin reactions at application site: vesiculation, pain, pruritus, scabbing, erythema, discoloration, application site dryness, edema, erosion.

Drug Interactions

No drug interaction studies performed to date.

Cantharidin (Topical) Pharmacokinetics

Absorption

Bioavailability

Minimal systemic exposure following topical application.

Not detectable in 15 out of 16 treated subjects; detectable plasma level observed in 1 subject at the 2-hour post-dose assessment.

Distribution

Extent

Not known if distributed into human milk.

Stability

Storage

Topical

Solution

20–25ºC; excursions permitted between 15–30ºC. Protect from light.

Actions

• Vesicant.

• Exact mechanism of action in treatment of molluscum contagiosum unknown.

• Causes degradation of desmosomes in the epidermis and blistering, which promotes shedding of infected keratinocytes.

Advice to Patients

• Advise patients 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. Inform patients and/or caregivers to seek immediate medical attention if cantharidin is accidentally ingested.

• Advise patients and/or caregivers that severe eye injury can occur if cantharidin enters the eyes. If cantharidin enters the eyes, advise patients and/or caregivers to flush eyes with water for ≥15 minutes and to seek immediate medical attention.

• Inform patients and/or caregivers that cantharidin can cause local skin reactions.

• Advise patients and/or caregivers not to use other topical products (e.g., creams, lotions, sunscreen) until 24 hours after cantharidin treatment or until washing.

• Advise patients and/or caregivers to remove cantharidin with soap and water 24 hours after treatment. If severe blistering, severe pain, or other severe adverse reactions occur, inform patients and/or caregivers to remove cantharidin with soap and water prior to 24 hours after treatment, and to contact their clinician.

• 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 the drug is removed.

• Inform patients and/or caregivers that more than one cantharidin treatment may be necessary.

• Advise patients to inform their clinician of existing or contemplated concomitant therapy, including prescription and OTC drugs and dietary or herbal supplements, as well as any concomitant illnesses.

• Advise women to inform their clinician if they are or plan to become pregnant or plan to breast-feed.

• Inform patients of other important precautionary information.

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.

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 is obtained through an exclusive distributor and a designated specialty pharmacy. Contact the manufacturer or consult the Ycanth website ([Web]) for specific availability information.

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