Practicality in using diphenyl cyclo propenone for alopecia areata.

Diphenyl cyclo propenone (DPCP) is used as a topical immunomodulator in alopecia areata. It is a potent allergen. The process of procuring, dilution and application limits its wider use. This short communication aims to make the DPCP application easy to use.

INTRODUCTION

Diphenyl cyclo propenone (DPCP) is used as a topical immunomodulator in alopecia areata. DPCP was first used by Happle et al. for alopecia areata.[1] It is a potent contact allergen in humans and animals; 98-99% of the cases of alopecia areata can be sensitized on the scalp skin.[2] Although its use has been increasing of late, the process of procuring, dilution and storage at a particular concentration is cumbersome and limits its wide use. This short communication aims to make the DPCP preparation and application easy for the readers.

Sigma Aldrich™ supplies DPCP (www.sigmaaldrich.com). DPCP is available as 1 and 5 g powder in amber-colored glass bottles. DPCP dissolves better in acetone. Ultraviolet radiation and heat causes its degradation to diphenylacetylene and carbon monoxide.[2] The standard solvent, acetone, is a strong UV light absorber and inhibits this process.[2] For dilution, first, the DPCP is weighed in a weighing scale and then diluted with the required quantity of acetone. Initial sensitization is carried out with a 2% solution, which is made by dissolving 20 mg in 1 ml of acetone. Further dilution can be prepared by making a stock solution of 2% and diluting with acetone taken in a pipette as per the concentration [Tables 1 and 2].

Table 1

Dilution for diphenyl cyclo propenone

Table 2

Dilution from the stock solution 2%

Percentage=weight/volume×dilution×100 (%=w/v×dilution×100)

To prepare a 0.001% solution, 0.1 ml of stock solution is mixed with 200 ml of acetone, and 5 ml of the resulting solution can be used for application over the scalp. The rest of the solution should be stored in air tight, screw-capped amber-colored containers for further use. Storage of the diluted solution is difficult as acetone often evaporates, leading to a change in the concentration. Fresh solution can be made every time to avoid this. For concentrations of 0.01% and above, DPCP can be weighed prior and stored in glass containers to which acetone can be added in the required amount at the time of application as this saves time and prevents wastage (e.g., 0.01% can be made by adding 10 ml acetone in 1 mg preweighed DPCP containers).

The diluted solutions are placed in a wide-mouthed glass beaker and applied on the scalp with cotton swab. Application needs to be done fast to cover the entire scalp before acetone starts evaporating in the beaker. Health care professionals should take proper precautions of wearing a glove, face mask and apron during the DPCP application as the spill of solution may cause an irritant/urticarial reaction. Patients are advised to wait for 5-10 min in the out patient department before covering their head with a cap or cloth to protect from sunlight. Patients are advised not to wash their scalp for 48 h after DPCP application. After 48 h, patients should be advised to shampoo the scalp to remove the residual DPCP. During these 48 h, patients should be advised not to touch the scalp accidentally either by themselves or others. If accidental contact has occurred, then they should wash their hands immediately. DPCP application is repeated weekly.

The common adverse effects after DPCP applications are local eczema with blistering, regional lymphadenopathy and contact urticaria.[34] Rare adverse effects include an erythema multiforme-like reaction, hyperpigmentation, hypopigmentation and vitiligo.[34]