A few weeks ago, the Spanish journal “Actualidad en Farmacología y Terapéutica” published a work carried out by the research team led by Dr. Antonio Ferrer and Dr. Asia Fernández at IDIBE – UMH on their latest advances in itching treatment. Today we are talking about this work and its applications.
Itching, or pruritus, is an annoying tingling sensation experienced in the skin as a result of various causes that leads us to scratch in order to feel relief. Everyone throughout his or her life suffers from several itching episodes that, in most cases, usually last for a few days. However, there is the so-called “chronic itching” suffered by people with itching sensation for a period longer than 6 weeks. In such cases, some professionals don’t talk about it as a symptom, but as a disease in itself instead.
The study of pruritus has led to its classification into 4 subgroups depending on the trigger agent. Thus, one can distinguish between the itching we feel when an external agent, such as a mosquito or rubbing with an irritant, directly activates the dermal nerve endings, and the itching resulting from the activation of this system by some internal condition, may be viral (herpes, chickenpox), metabolic or mental. Whatever the causing element, imbalance in nerve endings and dermal nociceptors cause this unpleasant sensation that significantly decreases the quality of life of people with it.
Treatment of itching, especially chronic itching, supposes a challenge for the pharmacological and cosmetic industry, as there are no remedies that completely satisfy patients with pruritus.
One of the molecules involved in triggering the sensation of itching and pain is the TRPV1 receptor. This receptor is found in both nerve endings and skin cells (keratinocytes and sebocytes) and its main function is to self-activate by detecting superficial changes that can be harmful to the body. For example, TRPV1 is activated when the temperature rises above 42ºC or in the presence of acidic pH. TRPV1 is also activated by capsaicin interaction, the main ingredient of jalapenos and peppers. Hence, the intake of these products awakens a feeling of itching in the body.
Interestingly, the application of capsaicin at the dermal level (in cream or patch) is a known and widely used pharmacological treatment for the relief of itching and chronic pain, as it produces the desensitization of the TRPV1 receptor. However, its application is very annoying for patients due to the burning sensation it causes on the skin. In addition, recent studies suggest that the buildup of capsaicin in the skin could be carcinogenic when it comes into contact with ultraviolet radiation from the sun.
The research team led by Dr Antonio Ferrer and Dr. Asia Fernandez in collaboration with other European research institutes have developed a series of capsaicin-based molecules capable of interacting with the TRPV1 receptor causing neither burning sensation, nor accumulating on the skin. Numerous studies, both in vitro and in vivo, have shown that these molecules are effective in itching relief. Prospera Biotech uses some of these neurocosmetic ingredients for the development of its formulations for sensitive skin.
Fernández Carvajal A et al. Moduladores del termorreceptor TRPV1 desactivables metabólicamente en la farmacología del prurito. Rev. Soc. Esp. Farmacol. Vol 18 (2020) 3: 162-172