Tolerance of Cyto-selective Difluoroethane-based Cryotherapy

Cryotherapy is more and more used to improve skin appearance. Devices using difluoroethane, manufactured by CRYONOVE PHARMA, are already available on the local and international markets, e.g. CRYOBEAUTY MAINS and CRYOBEAUTY CORPS.

However, the cryogenic gas (conventional cryotherapy - liquid nitrogen) creates a dermabrasion of the skin surface and person receiving this kind of treatment presents an impaired skin during a few days following the treatment as temporary damage of stratum corneum, erythema, scars, burns.

Following the side effects occurring after conventional cryotherapy application, it seems interesting for the sponsor to select other sequences of a cryogenic spray (4 prototypes of devices) which could be used for lentigo treatment with a same benefit for the consumers without any safety outcomes.

This study will assess the use of different prototypes with a sequence of application of cryogenic gas which reaches a higher temperature than those which used with the reference device, in order to increase the acceptability of the device.

(CS4_3) proof of concept, interventional, monocentric, aims to evaluate the tolerance of cryotherapy treatments applied on healthy skin on the back of the hands.

The main objective of the study is to evaluate on phototype V and VI, the tolerance of 4 different conditions of cryotherapy treatments (4 prototypes) applied on healthy skin on the back of the hands.

Prototypes (812A-v1), (812C-v1), (812D-v1) and (812F-v1) will be applied on hands areas by the same order for all volunteers using a reposition mask. On each hand 2 devices will be attributed starting from the middle point of the hand toward to the lateral internal and lateral external edges of the hand. The distance between 2 treatment areas will be 2 cm.

Each area will be treated 1 time during the study at D0. The treatment will starts from right hand with prototypes (812A-v1) and (812C-v1), then left hands with the prototypes (812D-v1) and (812F-v1) .

Prior to any study device application, the dermatologist will assess the adverse events.

The dermatologist will verify that the skin has not been treated by cosmetic products (no presence of cream that could interfere with the treatment) and is dry.

The procedure will take place at the investigation site. An operator previously trained by the dermatologist will apply the study device to the patient's hand.

Subjects will lie down and the device will be administered upside down.

The prototypes will be applied 10 minutes apart so that pain can be measured without interference from application to application.

Eligibility Criteria:
Inclusion Criteria:

* Female or male.
* Ages \> 18.
* Phototype V et VI (according with Fitzpatrick scale)
* Agreeing not to be exposed to the sun (or artificial UV) during the study.
* Informed, having undergone a general clinical examination attesting to his/her ability to participate in the study.
* Having given written consent for participation in the study.
* No suspicion of carcinoma after investigation by a dermatologist.

Exclusion Criteria:

* Having performed cosmetic treatments (exfoliants, scrubs or self-tanners, facials, UV ...) in the month before the start of the study, at the level of the hand.
* Having applied a depraving product in the month prior to the start of the study, at the hands (except cleansing products).
* Having performed cosmetic treatments in a dermatologist (laser, IPL (Intensed pulsed light), peeling, creams, cryotherapy ...), on the hands in the last 6 months.
* With dermatosis, autoimmune disease, systemic, chronic or acute disease, or any other pathology that may interfere with treatment or influence the results of the study (people with diabetes or circulatory problems,allergic to cold, Raynaud's syndrome...).
* Receiving treatment by general or local (dermo corticoids, corticosteroids, diuretics ...) likely to interfere with the evaluation of the parameter studied.
* Participating in another study or being excluded from a previous study.
* Unable to follow the requirements of the protocol.
* Vulnerable: whose ability or freedom to give or refuse consent is limited.
* Major protected by law (tutorship, curatorship, safeguarding justice...).
* People unable to understand, read and write English/French/Ukrainian language. However, the impartial witness will be introduced to current study to make translations if necessary, during all course of the study for each volunteer and respective section for signature and date will be implemented to the "Information Sheet and Informed Consent Form".
* Unable to be contacted urgently over the phone.

For female subjects:

* Pregnant woman (or wishing to be pregnant during study) or while breastfeeding.
* A woman, who does not use effective methods of contraception.