Place in therapy
Cantharidin is efficacious in the treatment of warts; however studies evaluating its efficacy are limited, small, and poorly designed. The efficacy of cantharidin has been demonstrated as monotherapy and in combination with podophyllin and salicylic acid.
Cantharidin is a schedule II drug and appropriate for self-care; however it must be applied by a physician or chiropodist. The solution is applied directly to the wart and to a 1 mm rim of normal skin. After application the lesion must be occluded for a minimum of 24 hours; some sources report occluding the lesion for upwards of 7 days. Cantharidin may be repeated every 1 to 3 weeks until the wart resolves. Based on the available evidence and the inconvenience of application, cantharidin should be reserved as a second-line treatment.
Cantharidin is appropriate for use in children. Studies have yet to evaluate its safety in pregnancy; it is therefore pregnancy category risk C. Its use is contraindicated in anyone with known hypersensitivity to cantharidin or components of the formulation.
Cantharidin preparations are generally well tolerated. Application is painless. Twenty-four to 72 hours after application a blister forms which may result in mild to moderate pain. The pain is generally less than what is experienced with cryotherapy. The blister may take up to 2 weeks to heal. Blistering is intensified by the duration of occlusion with adhesive tape and contact time. Blistering is greater in fair-skinned individuals; therefore contact time should be adjusted accordingly. Severe blistering can result from improper. Cantharidin should only be applied by a physician.
When used appropriately adverse effects are rare. Mild to moderate pain from the blister, temporary erythema, and transient dermal pruritus and irritation are the most common adverse effects. Ring warts and post-inflammatory hypo/hyperpigmentation rarely occur with application. Scaring of the wart lesion is unlikely to occur if cantharidin is applied correctly. Lymphangitis, cellulitis and lymphedema are very rare complications and have been reported with the use of cantharidin for plantar warts.
References
1. Kacar N, Tasli L, Ergin S, Erdogan BS. Cantharidin-podophylotoxin-salicylic acid versus cryotherapy in the treatment of plantar warts: a randomized prospective study. J Eur Acad Dermatol Venereol.2012;26(7):889-93.
2. Lexi-Comp. [Internet] Professional Monograph. [Updated May 17, 2012; cited on June 8, 2012. Cantharidin. Available at http://online.lexi.com/lco/action/doc/retrieve/docid/patch_f/6518.
3. Lichon V, Khachemoune, A. Plantar warts: a focus on treatment modalities. Dermatol Nurs. 2007;19(4):372-5.
4. Mallin A. Chapter 40—Plantar Warts. In: Patient Self Care. 1st ed. Canadian Pharmacists Association;2002. p. 468–71.
5. Moed L, Shwayder TA, Wu Chang M. Cantharidin Revisited a blistering defense of an ancient medicine. Arch Dermatol. 2001; 137: 1357-60.
6. NAPRA [Internet]. Search National Drug Schedule. [Updated Feb 23, 2012; cited on June 8, 2012]. Available at http://napra.ca/pages/Schedules/Search.aspx.
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Cantharidin is efficacious in the treatment of warts; however studies evaluating its efficacy are limited, small, and poorly designed. The efficacy of cantharidin has been demonstrated as monotherapy and in combination with podophyllin and salicylic acid.
Cantharidin is a schedule II drug and appropriate for self-care; however it must be applied by a physician or chiropodist. The solution is applied directly to the wart and to a 1 mm rim of normal skin. After application the lesion must be occluded for a minimum of 24 hours; some sources report occluding the lesion for upwards of 7 days. Cantharidin may be repeated every 1 to 3 weeks until the wart resolves. Based on the available evidence and the inconvenience of application, cantharidin should be reserved as a second-line treatment.
Cantharidin is appropriate for use in children. Studies have yet to evaluate its safety in pregnancy; it is therefore pregnancy category risk C. Its use is contraindicated in anyone with known hypersensitivity to cantharidin or components of the formulation.
Cantharidin preparations are generally well tolerated. Application is painless. Twenty-four to 72 hours after application a blister forms which may result in mild to moderate pain. The pain is generally less than what is experienced with cryotherapy. The blister may take up to 2 weeks to heal. Blistering is intensified by the duration of occlusion with adhesive tape and contact time. Blistering is greater in fair-skinned individuals; therefore contact time should be adjusted accordingly. Severe blistering can result from improper. Cantharidin should only be applied by a physician.
When used appropriately adverse effects are rare. Mild to moderate pain from the blister, temporary erythema, and transient dermal pruritus and irritation are the most common adverse effects. Ring warts and post-inflammatory hypo/hyperpigmentation rarely occur with application. Scaring of the wart lesion is unlikely to occur if cantharidin is applied correctly. Lymphangitis, cellulitis and lymphedema are very rare complications and have been reported with the use of cantharidin for plantar warts.
References
1. Kacar N, Tasli L, Ergin S, Erdogan BS. Cantharidin-podophylotoxin-salicylic acid versus cryotherapy in the treatment of plantar warts: a randomized prospective study. J Eur Acad Dermatol Venereol.2012;26(7):889-93.
2. Lexi-Comp. [Internet] Professional Monograph. [Updated May 17, 2012; cited on June 8, 2012. Cantharidin. Available at http://online.lexi.com/lco/action/doc/retrieve/docid/patch_f/6518.
3. Lichon V, Khachemoune, A. Plantar warts: a focus on treatment modalities. Dermatol Nurs. 2007;19(4):372-5.
4. Mallin A. Chapter 40—Plantar Warts. In: Patient Self Care. 1st ed. Canadian Pharmacists Association;2002. p. 468–71.
5. Moed L, Shwayder TA, Wu Chang M. Cantharidin Revisited a blistering defense of an ancient medicine. Arch Dermatol. 2001; 137: 1357-60.
6. NAPRA [Internet]. Search National Drug Schedule. [Updated Feb 23, 2012; cited on June 8, 2012]. Available at http://napra.ca/pages/Schedules/Search.aspx.
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