Diphencyprone/Diphenylcyclopropenone (DCP)

The purpose of this brochure is to provide basic information on commonly asked questions about Diphencyprone (DCP). It does not contain all the available information on this condition and certainly cannot be used in replacement of a consultation with your doctor or pharmacist.

What is DCP used for?
DCP is a contact immunotherapy and can be used in the treatment of alopecia areata or viral warts. Use of DCP involves multiple visits to the hospital over several months. Contact immunotherapy is used in the treatment of severe alopecia areata which does not respond to topical treatments or intralesional steroid injection. DCP works by inducing allergic contact dermatitis where the mild inflammatory reaction is associated with hair regrowth. Evidence of hair regrowth may be seen as early as within three months but the time taken to achieve significant hair growth varies for individuals. Around 50% to 60% of patients achieve worthwhile hair regrowth.

DCP can also be used in the treatment of recalcitrant viral warts (warts that do not respond to usual therapy). It works by inducing a hypersensitivity reaction to trigger the immune system to fight the virus.

How is DCP being used?

1. The first visit involves a sensitisation procedure, whereby a high concentration of DCP is applied to a small patch of hair loss on the scalp and left on for 24 hours. Thereafter, DCP should be removed with tissue and you should wash the affected area. You may experience an itch or notice a blister at the spot where DCP was applied. Do not be alarmed, these symptoms will disappear in two to three weeks.
2. You will be assessed one to two weeks later to decide if DCP works for you. If an eczematous reaction (i.e. the area becomes red and itchy) is present, you can be started on DCP. 
3. DCP is usually applied once a week and this continues until hair has regrown. It comes in different concentrations and may be gradually increased over time.
4. It is recommended to leave DCP on the affected area for 24 hours. However, if reaction is intolerable (severe itching, burning or blistering), the DCP may be washed off after a minimum of four hours. The aim is to achieve tolerable itch for 24 to 48 hours.
5. It is advisable to shield your head with a cap or cloth for protection from sunlight after application. This is to prevent DCP from getting degraded by sunlight. Care should be taken to avoid accidentally smudging the DCP on other areas.

Treatment is recommended to be continued for at least six months. If no response is observed after six to 12 months, it may be recommended to stop the treatment.

What side effects can this medicine cause? What can I do about them?
Treatment is usually safe. Any side effects are usually due to hypersensitivity to DCP and no long-term side effects have been reported. Possible side effects of DCP include:

• Severe dermatitis or blistering:
  This is the most common side effect, but risk can be minimised through careful titration of DCP concentration. Also, it may be possible to develop rashes on other parts of the body that is not exposed to DCP. If this happens and is severe and extensive, please consult the doctor immediately.
• Swelling of lymph nodes behind ears or neck:
  This is usually temporary but may persist throughout the treatment period.