Immunobiological Treatment in Psoriasis

Psoriasis is an inflammatory condition the cause of which is unknown at this time. There is certainly a genetic component to this condition and work over the last decade or so has shown that it is an immunological disease. It has long been known there is inflammation within the plaques of psoriasis. A chance observation that an immunosuppressive drug called cyclosporine used to prevent rejection in individuals with organ transplants cleared psoriasis. This showed that white blood cells called lymphocytes were important in the production of psoriasis, More recently a huge amount of work has defined many of the immunological events involved in psoriasis. Interestingly, the immune response may have strong similarities to that which occurs in patients with rheumatoid arthritis, Crohn’s disease and possibly multiple sclerosis.

There is an immune activation of white cells called lymphocytes. The type of lymphocytes called T-cell lymphocytes are activated and in turn produce chemical mediators known as cytokines. These cause the cells within the epidermis to grow quickly. Lymphocytes are part of the defense system and are in a sense the paratroopers of the immune system which attack a variety of antigens such as viruses. The skin is very active in the immunological organ which explains why we develop rashes as a result of allergic reactions to multiple substances including medications. Part of the life history of a T-lymphocyte is that it is produced in the bone marrow and travels through lymph nodes and makes a journey through the skin - particularly the epidermis. An antigen is something such as a protein that we have an immune response to. Before this can happen there are specific cells whose function are to present antigens to lymphocytes and some of them live within the epidermis.

Once a lymphocyte has been introduced to an antigen it becomes activated and it becomes a specialist against a specific target. The antigen or the target for the immunologic attack in psoriasis is not known but it is clear that activated lymphocytes that are an important part of the process of making psoriasis. The interaction between the lymphocytes and the cells that introduce the antigen and the cytokines that are produced is very complicated. Cytokines are chemicals such as interferon, interleukin or tumor necrosis factors. Luckily for us these activated lymphocytes will stay on the job of attacking something within the epidermis and do not go off to other parts of the body to cause inflammation. They do not prevent other lymphocytes from being available to fight colds and other infections.

The discovery of the interactions between these cells and the specific receptors on the cell urfaces as well as the chemicals that they release has given scientists an opportunity to develop drugs that block this cascade of activity at different points.

Dovobet®

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INTRODUCTION
Dovobet (50 micrograms/gram calcipotriol and 0.5 milligrams/gram betamethasone dipropionate) is a topical ointment approved for use in Canada to treat plaque psoriasis. Dovobet has become the topical therapy of choice for many patients with plaque type psoriasis not involving the face or skin folds... | Read more ...

CLININCAL EXPERIENCE
More than six international studies involving over 6,000 patients have shown reductions in the PASI (Psoriasis Area and Severity Index) of approximately 40% after one week of treatment and 70% after four weeks... | Read more ...

INDICATIONS
Used to treat chronic plaque psoriasis that covers less than 30% of the body surface (see following slides for clarification). Dovobet is not often used to treat the scalp because the sticky base does not allow for easy application or removal... | Read more ...

PATIENT PROFILE
Patients with chronic plaque psoriasis that covers less than 30% of the body surface. In some cases, a patient could use it on a greater BSA if he/she wanted to as long as the use/week is 100 g per week or less... | Read more ...

DOSING
Dovobet should be applied to the affected area once daily for four weeks. Several studies have shown that there are no statistically significant differences between applying the ointment once daily or twice daily... | Read more ...

EFFICACY
Six international studies involving more than 6,000 patients using Dovobet to treat psoriasis have shown PASI reductions of approximately 40% after one week of treatment and 70% after four weeks. Additional studies have shown that Dovobet has superior... | Read more ...

COMPLIANCE
Compliance is aided by the convenience of the once daily dosing of Dovobet. Compliance is also less of a problem than with most products due to the rapid onset of action. Significant improvement is usually seen within the first week... | Read more ...

SIDE EFFECTS, SAFETY AND RISKS
Because Dovobet is a combination drug, the frequency of side effects reported is less than would be expected if using each compound on its own: for example, the anti-inflammatory action of the corticosteroid (betamethasone dipropionate) minimizes the irritation often reported when using calcipotriol alone... | Read more ...

COST OF TREATMENT
It is probably the single most effective topical therapy available for psoriasis, so patients are generally prepared to pay for this. It is somewhat more expensive than the equivalent potent topical steroid, but the rapid and significant improvement in quality of life... | Read more ...

View the entire Dovobet^® presentation.

Immunobiological Treatment in Psoriasis - An Overview