What is Psoriasis
Psoriasis is a very common skin condition that typically affects the skin of arms and legs and nails (psoriasis of the nails). It is a recurrent inflammatory disease, characterized by a cutaneous thickening of the affected area, with silvery-white flaking.
Causes
The cause of this skin alteration is unknown, so we talk about possible triggers like:
- Dysregulation of the immune system;
- Local traumas;
- Excessive sun exposure;
- Genetic predispositions;
- Bacterial and viral infections;
- Pharmacological treatments;
- Stress.
In psoriasis patients, epidermal turnover is 10 times faster than physiological turnover; this causes an incomplete maturation of the keratinocytes, a tortuous vasculature with increased blood flow in the affected area, an infiltration of neutrophils and the consequent inflammatory trigger.
Psoriasis drugs
For more information, see also: Psoriasis Treatment Medications
The pharmacological treatment of psoriasis can be both topical and systemic.
Drug treatment for topical use may include drugs such as:
- Salicylic acid in concentration up to 10%;
- Low or high efficacy glucocorticoids depending on the severity;
- Retinoids in the form of a prodrug;
- Vitamin D derivatives as anti-proliferative;
Systemic treatment, on the other hand, may include administration:
- Of acitretin (a retinoid) orally;
- Of ciclosporin and methotrexate, immunosuppressants used to avoid post-transplant rejection, useful against psoriasis because they reduce the immune response;
- Of monoclonal antibodies (MAB), indicated for severe and refractory psoriasis.
Another category of drugs that can be used in the treatment of psoriasis is constituted by photosensitizing drugs which - depending on the case and the active ingredient used - can be administered topically, or systemically.
Salicylic acid
Salicylic acid is an active ingredient belonging to the group of beta-hydroxy acids . Its use is particularly indicated for the treatment of the forms of psoriasis that affect the scalp. The use of salicylic acid in the topical therapy of this pathology is justified by the keratolytic action it exerts.
Cortisonici
Cortisonic (or glucocorticoid) drugs are drugs with a strong anti-inflammatory activity and, for this reason, they are particularly effective in the topical treatment of psoriasis. On the other hand, they can cause unwanted effects such as irritation, burning, dry skin, hypopigmentation and their use can only be performed for short periods of time.
Examples of cortisone drugs used in the treatment of psoriasis are mometasone and hydrocortisone .
Retinoids
Retinoids are drugs derived from vitamin A (or retinol) that have proven useful in the treatment of some forms of psoriasis.
The active ingredients belonging to this group and which can be used to counter psoriatic lesions are different. In mild and moderate forms, it is usually sufficient to use topical retinoids (such as, for example, tazarotene ); while in the more severe and in the palmar forms it is possible to resort to the oral administration of acitretin .
However, retinoids are not able to produce an immediate therapeutic effect and present several contraindications and considerable side effects (for example, acitretin has a high teratogenic power).
Vitamin D derivatives
Vitamin D derivatives (such as calcipotriol and calcitriol ) are used in the topical treatment of psoriasis by virtue of their ability to inhibit the excessive proliferation of keratinocytes typical of this disorder, while favoring their differentiation.
Photosensitizing drugs
Photosensitizing drugs are active ingredients that can be administered - depending on the case - topically or systemically in order to perform what is called "phototherapy".
A classic example of photosensitizing drugs is psoralens used in PUVA therapy, in which - following the administration of the aforementioned active ingredients - the areas of the body affected by the pathology are irradiated by UVA rays.
immunosuppressant
Since one of the triggers of psoriasis is the dysregulation of the immune system, the use of immunosuppressive drugs such as cyclosporine and methotrexate can be useful in the systemic treatment of this disease.
However, given the undesirable effects that these active ingredients can cause, their use is reserved for particularly severe cases of psoriasis that do not respond to other treatments.
Biological drugs
Biological drugs are active ingredients obtained by means of living systems (such as cells or microorganisms) using biotechnological techniques.
Some of these biological drugs are very useful in the treatment of severe cases of psoriasis that do not respond to "conventional", topical or systemic treatments.
Biological drugs that can be used to treat psoriasis include etanercept and monoclonal antibodies.
Etanercept is an active ingredient of protein nature obtained by recombinant DNA techniques. The mechanism of action of this drug consists in blocking one of the numerous proteins involved in the inflammatory mechanisms (the receptor of tumor necrosis factor) that characterize psoriasis.
Monoclonal antibodies (or MABs), on the other hand, are mixed chimeric antibodies in which the variable or light chain region is of murine origin, while the heavy chain or fixed region has been humanized. MABs are also used for the treatment of tumors, as they act as immunosuppressants and anti-inflammatories.
Some examples of MAB that can be used in the treatment of psoriasis are:
- Efalizumab, a recent drug for the treatment of psoriasis; the variable region binds the T lymphocytes, blocking the adhesion, activation and migration of the latter. It is administered subcutaneously in a single weekly administration.
- Infliximab, in this case the variable region binds to tumor necrosis factor alpha (human TNF-α) - a mediator of the inflammatory process - blocking its biological function.
Did you know that ...
In March 2016, the EMA (European Medicines Agency) and the FDA (Food and Drug Administration of United States) approved a new drug for the treatment of plaque psoriasis of moderate to severe entity: it is the ixekizumab monoclonal antibody.
This active ingredient is able to selectively bind to interleukin-17A, one of the main cytokines involved in the inflammatory processes that characterize this pathology.
The added value of this monoclonal antibody lies in its ability to improve the manifestations of the disease more quickly than other "traditional" biological drugs such as etanercept.
In fact, the studies carried out showed a significant improvement in skin symptoms after only one week of treatment, but not only. Furthermore, ixekizumab has proven to be able to control the disease effectively in the long term, maintaining the "clean skin" (ie without psoriatic plaques) for a peridot longer than 60 weeks longer than the 50% of patients who underwent the clinical test.
