Acitretin and Etretinate

Acitretin

Acitretin, a synthetic retinoid, is the pharmacologically active metabolite of etretinate. It is currently approved by the US Food and Drug Administration for the treatment of severe psoriasis in adults and has been established as a second-line therapy for the treatment of psoriasis resistant to the use of topical therapy. It is also an option for generalized pustular psoriasis, palmoplantar pustulosis, exfoliative erythrodermic psoriasis, and severe psoriasis in the setting of acitretin. It also has been shown to have chemo-preventative characteristics. Acitretin is limited by its teratogenicity and therefore considered inappropriate in most female patients of childbearing age. Common side effects include mucocutaneous dryness and elevated triglycerides.

A review of acitretin for the treatment of psoriasis

BACKGROUND

Acitretin is an oral retinoid that is approved for the treatment of psoriasis. It is unique compared to other systemic therapies for psoriasis such as methotrexate and cyclosporine in that it is not immunosuppressive. It is, therefore, safe for use in psoriasis patients with a history of chronic infection such as HIV, hepatitis B, hepatitis C or malignancy who have a contraindication to systemic immunosuppressive therapy and require systemic therapy because topical therapy is inadequate and they are unable to commit to phototherapy. Acitretin is one of the treatments of choice for pustular psoriasis. Even though acitretin is less effective as a monotherapy for chronic plaque psoriasis, combination therapy with other agents, especially UVB or psoralen plus UVA phototherapy, can enhance efficacy.

OBJECTIVE

To provide an updated review of the safety and efficacy of acitretin in the treatment for psoriasis.

METHODS

Literature review of journal articles from 2008 to 2009 since the last review of acitretin evaluated medical literature from 2005 to 2008.

RESULTS/CONCLUSION

Acitretin is an effective systemic therapy for psoriasis and is generally well tolerated at low doses for long-term use. If monotherapy with acitretin is inadequate, it can be used in combination with other treatments, particularly UVB phototherapy, to increase efficacy.

Management of psoriasis: the position of retinoid drugs

Oral synthetic retinoids have been established as effective systemic therapy for psoriasis since their introduction for clinical use in the 1970s; a compound for topical use, tazarotene has been recently marketed. Despite the demonstrated clinical success of retinoid therapy in psoriasis, its mechanism of action has not been fully elucidated, and investigators are confronted with two paradoxes. One is that the binding of retinoids to nuclear retinoic acid receptors (RARs) does not match their therapeutic efficacy: acitretin activates the three receptor subtypes, RAR-alpha, -beta and -gamma, without measurable receptor binding, whereas tazarotene preferentially binds to and activates RAR-beta and -gamma in preference to RAR-alpha. The other is that there is already increased formation of retinoic acid in the psoriatic lesion. Answering these questions should result in better use of these drugs in the treatment of psoriasis. Oral administration of acitretin remains one of the first therapeutic choices for severe psoriasis, particularly in association with ultraviolet light therapy, of which it may decrease the carcinogenic risk. Topical tazarotene is suitable for moderate plaque psoriasis. Its efficacy and tolerability can be enhanced by the addition of topical corticosteroids; its irritative potential is counterbalanced by a sustained therapeutic effect after the treatment is stopped.

Retinoids: fascinating up-and-coming scenario

Retinoids have been in sharp focus ever since their introduction 30 years ago. They include any drug (s) that bind to retinoid receptors and elicit a biological response. Enormous information on the subject seems to embroil the recent literature. Practically it is impossible to clearly comprehend the undercurrents. The meticulously dispensing text envisages surmounting the perspective reader's predicaments. Accordingly, retinoids and their related facets namely retinoid receptors, classification, mode of action, and the pharmacological diversity have been precisely defined. Commonly used systemic retinoids too have been given a substantial fresh look along with their monitoring. Overall, adverse effects and relative and absolute contraindications have been scrupulously incorporated. Human immuno deficiency virus (HIV) and isoretinoid for acne, in particular, have been highlighted. Micronized isotretinoin formulations have also been taken care so also commonly used topical retinoids. Tretinoin and their newer formulation have also been accounted for along with tretinoin polymer cream. Adapalene, a new chemical entity possessing a unique physico-chemical activity similar to that of tretinoin has also been dealt with. Newer retinoids are likely to be a subject of intrigue. A focus on future potentials of retinoids is its special ingredient. The inclusion of details of rexinoid the most recent introduction in their purview is likely to invoke interest to further consolidate its reckoning in future. All in all the text of the paper should provide an insight into the current rumbling around retinoids.

Comparative tolerability of systemic treatments for plaque-type psoriasis

Psoriasis is a chronic, debilitating skin condition that affects millions of people and is attributed to both genetic and environmental factors. Topical therapy is generally considered to be the first-line treatment of psoriasis. However, many patients do not respond to topical therapy or have disease so extensive that topical therapy is not practical. For these patients, systemic therapy is indicated. Presently, there are four available systemic treatments, psoralen with ultraviolet A (PUVA), methotrexate, oral retinoids (acitretin), and cyclosporin. Unfortunately, all of these treatments have significant potential adverse effects. PUVA may acutely cause nausea, pruritus and sunburn. More chronic and concerning is the development of PUVA lentigines, ocular complications and skin cancer. Non-melanoma skin cancer has been directly linked to PUVA; however, the association with melonoma is more elusive. Methotrexate use most notably carries the risk of hepatic fibrosis and cirrhosis, which is not always evident on liver function tests. Other more rare, but potentially life-threatening adverse effects include pancytopenia, lymphoproliferative disorders and acute pneumonitis. The addition of folic acid may help to reduce the risk of increasing liver enzymes and haematological toxicity seen in those taking methotrexate. Both methotrexate and oral retinoids are teratogenic and should never be used in pregnancy. Oral retinoids are probably the least effective available systemic medication for the treatment of plaque psoriasis. The effects are improved with the addition of other systemic therapies. Acitretin has replaced the formerly used etretinate primarily because of the significantly shorter half-life. The adverse effects are generally mild and reversible, making the drug fairly safe for long-term use. The most commonly seen adverse effects include elevated serum lipids, generalised xerosis and alopecia. Bony abnormalities, while somewhat controversial, have also been described and include diffuse idiopathic skeletal hyperostosis, skeletal calcifications and osteoporosis. Cyclosporin is the most recently approved systemic medication for plaque psoriasis. The nephrotoxicity associated with the use of cyclosporin can be minimised when used in lower doses and for a limited duration. Hypertension is usually mild and can be seen in up to about one-third of patients receiving long-term therapy. Cutaneous and internal malignancies have also been reported with cyclosporin and tend to be correlated with duration of treatment. In this review, we will examine the potential adverse effects with these US Food and Drug Administration-approved treatments in adults, with specific emphasis on the controversies that surround long-term therapy with these agents and their cumulative adverse effects.

Acitretin combination therapy

Systemic therapies used in psoriasis such as methotrexate, PUVA, cyclosporine, and acitretin often have side effects that limit their usefulness. Combination therapy, an effective strategy for treating psoriasis, allows use of lower doses of medications to achieve superior therapeutic results with fewer side effects. Acitretin is one of the most popular drugs used in combination with other systemic therapies for psoriasis. Details of the regimens used and results obtained from combining acitretin with PUVA, cyclosporine, and methotrexate are discussed.

Acitretin in psoriasis: an overview of adverse effects

Oral retinoids are among the drugs of choice for pustular and erythrodermic psoriasis. In addition, retinoids are effective in combination with other topical and systemic agents for the treatment of plaque-type psoriasis. Acitretin, the active retinoid metabolite, has replaced etretinate in retinoid therapy of psoriasis because of its more favorable pharmacokinetic profile, including a significantly shorter half-life. Retinoids, including acitretin, are potent teratogens, leading to strict requirements for pregnancy prevention during and after their use. Other retinoid side effects are generally preventable or manageable through proper patient selection, dose adjustments, and routine monitoring. Mucocutaneous side effects such as cheilitis and hair loss are the most common dose-dependent side effects, requiring dose reduction in some patients. Less common effects such as hepatotoxicity, serum lipid alterations, pancreatitis, and possible skeletal effects are also discussed.

Acitretin: optimal dosing strategies

Acitretin is an oral synthetic retinoid effective in the treatment of psoriasis. As monotherapy, acitretin has been shown to be most effective in treating pustular and erythrodermic types of the disease. Monotherapy with acitretin for plaque-type psoriasis is often less successful; however, its use in combination with other therapies is highly effective in treating this form of the disease. Dose-response studies have established the effective dose range of acitretin as well as the dose-dependence of its side effects. Because both efficacy and side effects can vary substantially among individual patients, proper dosing of acitretin requires a balance between optimizing response and minimizing toxicity for each patient. Optimal dosing for individual patients may be achieved through a dose-escalation strategy involving initiation of therapy at low doses (10 to 25 mg/day) and, if necessary, gradually increasing the dose as tolerated until optimal response is achieved.

Etretinate Therapy for Refractory Sclerodermatous Chronic Graft-Versus-Host Disease

Chronic graft-versus-host disease (GVHD) is the most common late complication of allogeneic bone marrow transplantation (BMT). The sclerodermatous form of the disease is often refractory to standard treatment modalities. Based on reports of response to etretinate, a synthetic retinoid, among patients with scleroderma, we have added etretinate to the treatment regimen of 32 patients with refractory sclerodermatous chronic GVHD. This case series is comprised mainly of patients who had chronic GVHD of long duration (median of 30 months before the initiation of etretinate). Most had failed to respond to three or more agents before etretinate treatment was started. Clinical response was assessed after 3 months of therapy. Five patients did not complete a 3-month trial. Among the 27 patients evaluable for response, 20 showed improvement including softening of the skin, flattening of cutaneous lesions, increased range of motion, and improved performance status. Four showed no response after 3 months of therapy and 3 had progression of their sclerosis. Overall, etretinate has been fairly well tolerated in our patients, with skin breakdown and/or ulceration leading to its discontinuation in 6 patients. We believe the results in our patients are encouraging and suggest that further evaluation of etretinate in the treatment of sclerodermatous chronic GVHD is warranted.

Etretinate Therapy for Refractory Sclerodermatous Chronic Graft-Versus-Host Disease

Chronic graft-versus-host disease (GVHD) is the most common late complication of allogeneic bone marrow transplantation (BMT). The sclerodermatous form of the disease is often refractory to standard treatment modalities. Based on reports of response to etretinate, a synthetic retinoid, among patients with scleroderma, we have added etretinate to the treatment regimen of 32 patients with refractory sclerodermatous chronic GVHD. This case series is comprised mainly of patients who had chronic GVHD of long duration (median of 30 months before the initiation of etretinate). Most had failed to respond to three or more agents before etretinate treatment was started. Clinical response was assessed after 3 months of therapy. Five patients did not complete a 3-month trial. Among the 27 patients evaluable for response, 20 showed improvement including softening of the skin, flattening of cutaneous lesions, increased range of motion, and improved performance status. Four showed no response after 3 months of therapy and 3 had progression of their sclerosis. Overall, etretinate has been fairly well tolerated in our patients, with skin breakdown and/or ulceration leading to its discontinuation in 6 patients. We believe the results in our patients are encouraging and suggest that further evaluation of etretinate in the treatment of sclerodermatous chronic GVHD is warranted.

Uses of vitamins A, C, and E and related compounds in dermatology: a review

Vitamins have been increasingly used as prophylactic and therapeutic agents in the management of skin disorders. The current literature is replete with studies that promote the potential benefits of these compounds and attempt to elucidate their mechanisms of action. We review the literature and discuss the roles, safety, and efficacy of vitamins A, C, and E and related compounds in cutaneous health and disease.

Reactions and interactions of some commonly used systemic drugs in dermatology

This article deals with the main interactions and adverse effects of some drugs that are used daily by dermatologists. It includes tetracyclines and Minocycline in the treatment of acne; antimalarials and discoid lupus; dapsone; thalidomine; oral retinoids; methotrexate and cyclosporine. Several of these drugs are discussed.

Systemic retinoids. What's new?

Despite major advances in the molecular biology and pharmacology of retinoids, no new compound has been developed for systemic use. This article addresses some questions related to the indications of oral retinoids already on the market, e.g. isotretinoin, acitretin, as well as tretinoin, reviews some recently reported undesirable effects, and discusses the recent concepts generated by basic research that may lead to new drugs to be used in pharmacology.