Retinoid therapy for acne. A comparative review

Retinoids play a vital role in the treatment of acne because they act on the primary lesion, the microcomedo. They are synthetic derivatives of vitamin A (retinol), and are selected for their effectiveness. Several compounds are used for acne, either in topical or systemic form.We describe and compare the different topical retinoids, tretinoin (all-trans-retinoic acid), isotretinoin (13-cis-retinoic acid), adapalene (derived from naphthoic acid), and tazarotene (acetylenic retinoid). They act mainly as comedolytics, but anti-inflammatory actions have also been discovered recently. The retinoids have great beneficial effects, but also some adverse effects, the main one being teratogenicity. It is preferable not to use them in topical form for pregnant women, although a pregnancy test is only compulsory for tazarotene. Only isotretinoin is used in systemic form. It acts on all the factors of acne and offers long remissions, and sometimes complete cures. Precautions must be taken for women of childbearing age due to its teratogenicity. It is also important to be aware of its other adverse effects, explain them to the patient and, if possible, deal with them in advance.

Mechanism-based treatment of acne vulgaris: the value of combination therapy

Acne vulgaris has multiple pathogenic mechanisms that act in concert to produce disease. Effective therapy addresses more than one pathogenic factor to speed resolution of disease. Typically, retinoids are used to inhibit comedo formation and an antibacterial is used to suppress Propionibacterium acnes (P. acnes). Using combinations of agents can enhance efficacy, but increase side effects. Therefore, the tolerability of a topical retinoid is important. Strategies to enhance retinoid tolerability include the use of new retinoids such as adapalene, new delivery systems such as the tretinoin microsphere delivery system, or alternative dosing schedules such as short contact or every other day (QOD).

Cumulative irritation potential of adapalene 0.1% cream and gel compared with tazarotene cream 0.05% and 0.1%

Despite the many beneficial effects of dermatologic applications, most of the current treatments for acne cause local irritation. The objective of this study was to compare the ability of the epidermis to tolerate adapalene 0.1% cream and gel and tazarotene cream in concentrations of 0.05% and 0.1%. A total of 30 subjects were enrolled in the study. The test products were applied under occlusive dressings at randomized sites on the upper back for approximately 24 hours, 4 times a week, and for 72 hours, once a week, for a period of 3 weeks. Skin reactions (erythema score plus other local reactions) at the product application sites were assessed 15 to 30 minutes after dressing removal. Twenty-six subjects completed the study. A total of 16 subjects discontinued use of 1 or more of the test products because of irritation scores reaching severe or greater; all but one of these discontinuations were at sites treated with the tazarotene products. The mean 21-day cumulative irritancy indices for adapalene 0.1% cream and gel were significantly lower (P=.05) than those for tazarotene cream 0.05% and 0.1% and not notably higher than that of the negative control product.

[Skin cancer and other skin disorders in patients following solid organ transplantation]

Solid organ transplant patients have an increased risk of cutaneous squamous cell carcinomas compared to the immunocompetent population, and often develop multiple and sometimes aggressive tumours. There are few published studies or reviews, which provide guidance to the clinician in the management of these patients. In the prevention of skin cancer in organ transplant patients, patient education about the harmful effects of ultraviolet radiation, sun protection, and the early recognition of (pre)malignant skin lesions should be emphasised. Furthermore, close follow-up by a dermatologist and treatment of (pre)malignant lesions in an early stage are necessary. Chemoprevention of skin cancer can be achieved through systemic retinoids. Reduction of the dose of immunosuppressive agents can be considered. Excision is the first treatment of choice for squamous cell and basal cell carcinomas. In selected rumours curettage and electrodessication can be performed.

Prescribing patterns for topical retinoids within NAMCS data

OBJECTIVE

Fears of potentially costly use of topical retinoids for cosmetic treatment of photodamaged skin have resulted in many managed care organizations placing prior authorization requirements on this class of medications. The purpose of this investigation was to examine whether prescribing patterns of a nationally representative sample of US physicians shed light on the incidence of use of topical retinoids for indications other than acne.

METHODS

A retrospective, cross-sectional study of data from the National Ambulatory Medical Care Survey (1996--2000) was used to examine the impact of physician specialty as well as patient diagnosis of acne on the probability of retinoid prescription in weighted multivariate logistic regression models.

RESULTS

Topical retinoids were prescribed in 0.4% (14.7 million out of 3.67 billion) physician visits for any diagnosis in the 5-year period from 1996 to 2000, and in nearly 31% (12.0 million out of 38.7 million) of physician visits for a diagnosis of acne. Topical retinoids were prescribed for acne in 77.1% of the cases. This finding held when individual retinoids (tretinoin and adapalene) were examined separately. Clear age-related prescription trends are observed, with a significant decrease in prescriptions beyond the teen years. In older patients, tretinoin prescribing did not decrease as much as adapalene prescribing.

CONCLUSIONS

These data suggest that managed care organizations may want to examine their own data to determine the optimum criteria for operation of prior authorization (PA) programs for retinoids. PA requirements for these medications appear unnecessary in young patients, given the very small probability of non-acne related use. PA in older patients might be targeted to those patients on topical retinoids (such as tretinoin) for which there is evidence of efficacy in treatment of cosmetic photoaging.

The use of topical retinoids for inflammatory acne: a review of the pharmacoeconomic considerations

Few pharmacoeconomic studies exist regarding the use of topical retinoids for inflammatory acne vulgaris. Those pharmacoeconomic studies that do exist predictably involve new entrants (topical tazarotene in various formulations). The use of topical retinoids in combination with antimicrobial agents constitutes cost-effective therapy for inflammatory acne. The growing U.S. trend toward use of isotretinoin for less-severe forms of acne instead of topical retinoid-based combination therapy is problematic from clinical and cost perspectives. More pharmacoeconomic studies that consider the importance of compliance are necessary for clinicians and managed care professionals to make informed choices about the treatment of inflammatory acne.

Topical antibacterial therapy for acne vulgaris

Topical antibiotics and benzoyl peroxide, are the two main topical antibacterial treatments indicated for mild-to-moderate acne vulgaris. Topical antibiotics act both as antibacterial agents suppressing Propionibacterium acnes in the sebaceous follicle and as anti-inflammatory agents. Benzoyl peroxide is a powerful antimicrobial agent that rapidly destroys both bacterial organisms and yeasts. Topical clindamycin and erythromycin have been proven to be effective against inflammatory acne vulgaris in concentrations of 1-4% with or without the addition of zinc. However, none of the antibacterials tested was more effective than benzoyl peroxide, which also has the advantage of not being associated with antimicrobial resistance. Topical antibacterial therapy should be discontinued once improvement is observed. If no improvement is observed within 6-8 weeks, the agent should be discontinued and a therapeutic switch considered. The primary limitation of benzoyl peroxide for some acne vulgaris patients is cutaneous irritation or dryness.Antibacterial therapy can be used in combination with other agents. Combining topical antibiotics and topical retinoids may enhance the efficacy, since the retinoid will improve the penetration of the antibiotic. Combining a topical antibiotic with benzoyl peroxide may increase the bactericidal effect of the antibiotic and reduce the potential for bacterial resistance. Topical and oral antibacterials should not be used in combination for the treatment of acne vulgaris, since this association may increase the risk of bacterial resistance.

Mechanisms of the comedolytic and anti-inflammatory properties of topical retinoids

Retinoids comprise a family of compounds with structures and mechanisms of action that resemble those of vitamin A (retinol), an essential nutrient which plays a role in cell growth and differentiation. The retinoids, which interact with nuclear receptors and affect gene transcription, have enormous therapeutic potential, particularly if they are receptor- and function-selective. Tretinoin was the first topical retinoid employed for the treatment of acne. In recent years, other topical retinoids for the treatment of acne have been designed from a disease-specific approach, with enhanced receptor and function selectivity, which translates to improved therapeutic effects and more favorable tolerability. The properties that differentiate the topical retinoids tretinoin, adapalene, and tazarotene have permitted clinicians to tailor acne treatment regimens for maximum therapeutic outcomes. Tretinoin (all-trans-retinoic acid), considered a first-generation retinoid, acts by altering the milieu of the microcomedo and influences desquamation of abnormal epithelium. Two receptor-selective synthetic retinoids, adapalene and tazarotene, may be classified as third-generation retinoids. Adapalene, a derivative of naphthoic acid, has comedolytic, antiproliferative, and anti-inflammatory properties. Tazarotene is a prodrug metabolized to tazarotenic acid that modulates cellular differentiation, desquamation, and inflammation.

Practical retinoid chemoprophylaxis in solid organ transplant recipients

Solid organ transplant recipients are at a significantly increased risk of developing skin cancer. Both systemic and topical retinoids are useful for chemosuppression of skin cancer in this patient population. These drugs can reduce both the present extent and the future development of premalignant and malignant skin lesions. This paper reviews the current data on the chemoprophylactic properties of topical and systemic retinoids. A practical guide for their use in organ transplant recipients is provided. Specific recommendations for implementing and maintaining therapy, as well as appropriate management and monitoring of adverse events, are presented.

Facial tolerability of topical retinoid therapy

The facial tolerability of various topical retinoids was evaluated in 253 healthy volunteers in a series of split-face, randomized, investigator-masked studies-all conducted at the same site by the same investigator. Four variables were evaluated to determine if they influenced tolerability-retinoid concentration, formulation vehicle, skin sensitivity, and individual retinoid. Lower retinoid concentrations were associated with less irritation. Vehicle influenced tolerability but whether a gel or cream formulation was better tolerated varied from retinoid to retinoid. Tolerability was superior on normal skin than "sensitive skin." On normal skin, tazarotene cream was better tolerated than tretinoin cream whereas adapalene and tretinoin microsponge gels were better tolerated than tazarotene gel. On sensitive skin, tazarotene and adapalene creams were better tolerated than tretinoin cream whereas adapalene gel was better tolerated than tazarotene gel. Retinoid concentration, vehicle, skin sensitivity, and retinoid can all affect facial tolerability. Skin vulnerability may be the most important factor.

Meta-analysis of topical tazarotene in the treatment of mild to moderate acne

Topical tazarotene has shown superior efficacy over other topical retinoids, including adapalene and tretinoin, in the treatment of mild to moderate acne. A meta-analysis of data from 6 multicenter, double-blind, randomized comparative trials was performed to determine how patient characteristics influence the efficacy and tolerability of topical tazarotene. Data on 468 patients who used tazarotene 0.1% gel or cream once daily for 12 weeks were collected. Topical tazarotene was effective and well tolerated, regardless of patients' acne severity, skin type, sex, or ethnicity. In general, 'using the cream formulation rather than the gel formulation optimized tolerability. These results indicate that topical tazarotene 0.1% gel and cream are efficacious and well-tolerated treatment options for clearing acne vulgaris across a broad range of patients.

Retinoid therapy for psoriasis

This article focuses on the treatment of psoriasis with acitretin, the only systemic retinoid approved for psoriasis, and also briefly discusses its predecessor, etretinate, which was replaced by acitretin in 1997 and is no longer available. The use of topical tazarotene is also discussed in detail. Combination therapy of retinoids, both topical and systemic,with phototherapy and other therapeutic agents is described. In addition, new retinoid analogues that are undergoing clinical investigation are mentioned. Finally, potential toxicities and adverse effects associated with retinoids are discussed.

Topical tazarotene: The BEST (balancing efficacy, speed, and tolerability) in acne trial

Results of clinical trials have shown that tazarotene cream used as monotherapy effectively reduces the number of both inflammatory and noninflammatory lesions in patients with acne vulgaris. The efficacy of tazarotene cream in clinical practice, however, has not been reported. To evaluate the benefits of tazarotene cream in everyday clinical practice, an uncontrolled observational study was conducted in a large population of patients with facial acne vulgaris; 243 investigators enrolled 1118 patients for treatment with once-daily tazarotene 0. 1% cream as monotherapy, or in combination with other agents, for up to 12 weeks. Tazarotene efficacy was well rated by both investigators and patients and had a rapid onset of action. Reduction in comedone counts was greatest when tazarotene 0.1% was used as first-line therapy. The incidence of adverse events (almost exclusively peeling, erythema, dryness, or burning) was low and typically declined with continued use of the medication. The combination of tazarotene 0.1% cream and clindamycin-benzoyl peroxide was the best tolerated of all the treatment regimens. Patients and investigators reported high levels of treatment satisfaction with topical tazarotene 0.1% cream.

Retinoid-induced limb malformations

The developing limb has been studied extensively and is a useful model to study morphogenesis. During embryogenesis, limb formation is initiated as a budding off from the embryonic lateral body wall. Limb pattern is specified by a series of epithelial-mesenchymal interactions, directing proximodistal, dorsoventral and anteroposterior axes. Vitamin A metabolites, especially retinoic acid, are known to play an important role in limb development, and the effects of retinoic acid may be mediated through the retinoid receptor signaling pathways. Accumulated evidence has shown that inadequate levels (excess or deficiency) of retinoic acid cause a wide range of limb malformations. Some species have the capacity to regenerate amputated limbs, and retinoids certainly affect this process, but there is debate regarding the extent that regeneration recapitulates development. In this review, phenotypic features, pathogenesis and the molecular basis of retinoid-induced limb malformations are discussed with a description of normal limb development and endogenous retinoid pathways.

Acne: Topical treatment

Acne vulgaris is a common skin disease, affecting about 70-80% of adolescents and young adults. It is a multifactorial disease of the pilosebaceous unit.(1) The influence of androgens at the onset of adolescence leads to an enlargement of the sebaceous gland and a rise in sebum production. Additional increased proliferation and altered differentiation of the follicular epithelium eventually blocks the pilosebaceous duct, leading to development of the microcomedo as the primary acne lesion. Concomitantly and subsequently, colonization with Propionibacterium acnes increases, followed by induction of inflammatory reactions from bacteria, ductal corneocytes, and sebaceous proinflammatory agents (Fig 1).(2-5)

Hyalinosis cutis et mucosae: a 30 year follow up of a female patient

Hyalinosis cutis et mucosae is an inherited disease, characterized by deposition of a hyaline-like substance in the dermis and internal organs. In the present study, we report a 30 year follow up in a female patient with hyalinosis cutis et mucosae treated using dermabrasion and oral retinoids. In our opinion, the lesion on uncovered body areas should be corrected as soon as possible to enable a normal psychophysical development. The lesions on skin and oral mucosa may be successfully removed without remission with dermabrasion in early childhood. In addition, oral retinoids in adulthood may produce some improvement.

The pathophysiology of acne vulgaris in children and adolescents, part 2: Tailoring treatment

Various pathophysiologic factors are involved in the development of acne lesions, microcomedones, comedones, and inflammatory lesions. These factors include follicular hyperkeratosis, increased colonization of follicles by Propionibacterium acnes, increased sebum production, and inflammatory mediators. Optimal treatment of acne involves the use of agents that address these various underlying pathogenetic factors.

Keratosis punctata palmoplantaris controlled with topical retinoids: a case report and review of the literature

Keratosis punctata palmoplantaris (KPPP) is a rare genodermatosis with an autosomal-dominant pattern of inheritance. We report the case of a 61-year-old woman who presented with a long history of multiple symptomatic hyperkeratotic papules on the palms and soles. In addition, we review the literature and present the current classification of the heterogeneous group of punctate palmoplantar keratoses, the cutaneous and histologic findings, the differential diagnosis, the possible association with various anomalies including malignancies, and the various treatment options.

Modulation of cytokine production by low and high retinoid diets in ovalbumin-sensitized mice

Retinoids modulate many physiological processes such as the differentiation and growth of different cell types, including cells from the immune system. We have previously shown that retinoids modulate IgE production in vitro and in vivo. In the present study we investigated the effects of retinoids in non-sensitized and ovalbumin-sensitized mice that were fed for 11 weeks with three different vitamin A (VA) diets: a) VA-deficiency diet, b) base diet, and c) base diet supplemented with 0.5% all-trans-retinoic acid (ATRA). Phorbol-myristate-acetate (PMA)/ionomycin-stimulated SMC (splenic mononuclear cells) from mice fed with ATRA and the vitamin A-deficient diet group showed increased interleukin-4 (IL-4) responses in non-sensitized mice. After ovalbumin sensitization in the VA-deficient and the ATRA supplementation diet groups, no significant effects on IL-4 production were observed. By contrast, gamma interferon (IFN-gamma production from PMA/ionomycin-stimulated SMC was enhanced in the VA-deficient diet group in ovalbumin-sensitized mice, and also in non-sensitized mice compared to the base and the ATRA-supplemented diet group. The data indicate that VA and retinoid content in a diet influences the cytokine response in non-sensitized and also ovalbumin-sensitized mice. Therefore these molecules may serve as active modulators of cytokine production in vivo that are responsible for the induction and persistence of atopic diseases.

Acne in ethnic skin: special considerations for therapy

Acne vulgaris occurs in people of all ethnicities and races. Although the pathophysiology and treatment options are similar in all skin phototypes, darker-skinned patients have higher incidence rates of two sequelae of acne: postinflammatory hyperpigmentation and keloidal scarring. Postinflammatory hyperpigmentation may also be triggered by skin irritation. In choosing therapies for patients of color, therefore, clinicians must find a balance between aggressive early intervention to target inflammatory acne lesions, and gentle treatments to increase tolerability and avoid skin irritation. For most patients, a combination of topical retinoids, and topical or oral antibiotics with hydroquinone (as needed) to control hyperpigmentation will be successful. For patients with sensitive skin, topical agents in lower concentrations and cream vehicles are preferred. If tolerated, the retinoid strength can be titrated upward after four to six weeks. Ethnic patients also need to be counseled on use of noncomedogenic and nonirritating skin and hair-care products. Individualized care and close monitoring is required.

Systemic and topical retinoids in the management of skin cancer in organ transplant recipients

BACKGROUND

Nonmelanoma skin cancers are the most frequent malignancies in organ transplant patients. Patients who develop multiple new skin cancers may benefit from retinoid chemoprevention.

OBJECTIVE

The objective of this study was to advise on the use of retinoids in organ transplant recipients.

METHODS

A summary was performed of the existing literature regarding experience with retinoid chemoprevention for skin cancer in organ transplant patients.

RESULTS

Systemic retinoids, specifically acitretin, are effective in inhibiting tumor development in organ transplant patients. This effect is only present during therapy, however. Topical retinoids have some effect in the treatment of actinic keratoses.

CONCLUSIONS AND RECOMMENDATIONS

Systemic retinoids can be used for chemoprevention of skin cancer. For a good result, long-term treatment with acitretin is necessary. Side effects, however, limit the use of retinoid chemoprevention. It is advised that treatment be started at a low dose, and patients should be monitored regularly for triglyceride and cholesterol levels and transaminases.

The medical and surgical therapy of pseudofolliculitis barbae

Pseudofolliculitis barbae (PFB) is a common, chronic, inflammatory skin disorder seen mainly in individuals with curly hair. This condition is seen most frequently in black men who shave their beards but may also be seen in women of all races who wax or shave the axillary and pubic skin. The etiology of PFB is multifactorial, and heretofore a cure has been considered impossible for those desiring a clean-shaven face. The following article serves to discuss the current medical and surgical therapies available for this condition. Medical treatments for this condition include various combinations of topical antibiotics, corticosteroids, and retinoids. In the surgical arena, laser therapy has revolutionized the treatment of PFB and has enabled cure for the first time for those plagued by this disorder and for whom a beardless face is acceptable.

Penetration and Metabolism of Topical Retinoids in ex vivo Organ-Cultured Full-Thickness Human Skin Explants

The human epidermis contains endogenous retinoids [retinol (vitamin A) and retinyl esters] and carotenoids (mostly beta-carotene). Previous studies in the mouse have shown that the enzymes involved in retinoid metabolism are present in the epidermis. In this study, we wanted to assess the skin penetration and metabolism of topical retinoids in the human. To do this, fresh surgically excised human abdominal skin was mounted on Franz perfusion cells. Topical retinoic acid, retinal, retinol and retinyl palmitate were applied at 2.5 mg/cm(2) in oil-in-water creams containing 0.05% retinoids on the donor compartment, while the receptor compartment was filled with culture medium. The skin was incubated for 24 h at 37 degrees C, then epidermal retinoid concentrations were determined by HPLC. The same experiment was performed with mouse back skin mounted on Franz cells. Finally, topical retinoids were applied on the back of hairless mice for 24 h; then the mice were sacrificed and retinoid concentrations were assayed in the epidermis. In all three models, retinol and its esters were found to be endogenous, as was the case in previous studies in the mouse in vivo. The four applied retinoids penetrated well into the epidermis. Topical retinoic acid did not increase endogenous retinoids, whereas the latter were greatly increased following topical retinal in the mouse. Retinal was also metabolized into retinoic acid, unlike topical retinol and retinyl palmitate, which only increased endogenous retinoids. Topical retinal and retinol did undergo a higher metabolism in both mouse models than in human skin. In summary, the penetration and metabolism patterns of topical retinoids were quite similar in the two mouse models used, indicating that the Franz cells appear to be a good model to predict in vivo metabolism of topical retinoids. When applying this concept to our results obtained in Franz cells with human skin, we conclude that topical retinol and retinal load human skin with both storage and functional vitamin A.

Complications of Systemic Retinoid Therapy in Organ Transplant Recipients With Squamous Cell Carcinoma

BACKGROUND

Organ transplant recipients receiving immunosuppressive medications are at increased risk of cutaneous malignancies.

OBJECTIVE

We sought to determine the complications associated with systemic retinoid therapy in severely affected organ transplant recipients receiving treatment before or during the course of metastatic squamous cell carcinoma.

METHODS

This was a collaborative retrospective study of solid organ transplant recipients treated with systemic retinoids for severe squamous cell carcinoma, with subjective analysis of complications associated with treatment.

RESULTS

Complications and intolerance of systemic retinoid therapy were common, necessitating discontinuation of therapy in six of eight cases.

CONCLUSION

This subset of transplant patients, severely affected by skin cancer, appeared to be less able to tolerate systemic retinoid therapy than patients in formal clinical trials. Intolerance of adverse effects in this context suggests the need for novel approaches with these challenging patients.

Tazarotene 0.1% gel for refractory mycosis fungoides lesions: an open-label pilot study

BACKGROUND

Topical skin-directed therapies are used to induce remissions in early-stage mycosis fungoides (MF). They are rarely curative, and responding patients are subject to frequent relapses, emphasizing the need for alternative therapies.

OBJECTIVE

We sought to evaluate the efficacy and tolerability of topical tazarotene 0.1% gel as adjuvant therapy in the treatment of refractory MF lesions.

METHODS

A total of 20 adult patients with early patch or plaque MF limited to less than 20% body surface area (BSA) involvement whose lesions were either stable or refractory to therapy for at least 8 weeks enrolled in an open-label pilot study. Tazarotene 0.1% gel was applied to MF lesions once daily for 24 weeks. Continued concomitant use of other medications such as low- to mid-potency topical corticosteroids was permitted for the alleviation of skin irritation. Global improvement, overall disease severity, percent BSA involvement, and pruritus were evaluated every 4 weeks. Up to 6 index lesions were followed up for area, plaque elevation, scaling, and erythema scores. Skin biopsy specimens were to be taken at baseline, week 8, and week 24. Evaluable specimens were stained with hematoxylin and eosin, CD8 antibody, and CD45RO antibody.

RESULTS

In all, 20 patients enrolled, 19 received treatment, and 16 completed at least 4 weeks of topical treatment. By intent-to-treat analysis, 11 of 19 patients (58%) achieved at least a moderate (>50%) global improvement in BSA, and 35% of 99 index lesions cleared completely. Significant reductions (mean differences) were also found in the median lesional area score (-37, P =.0013), mean plaque elevation score (-.67, P =.016), mean scaling (-0.70, P =.033), and mean erythema score (-1.03, P =.002). Analysis of overall disease also disclosed statistical differences in percent of change for BSA involvement of 22% (P =.013) and of mean overall disease severity score of 34% (P =.011). Of 19 patients, 16 (84%) experienced mild or moderate local skin irritation manifested by peeling, erythema, burning, and tenderness that was managed successfully with topical steroids or reducing the frequency of treatment. Histopathology and immunohistochemistry results showed reductions in lymphocytic infiltrates and percentage of CD45RO(+) lymphocytes, and increases in the percentage of CD8(+) lymphocytes during the course of therapy.

CONCLUSION

In this small pilot study, tazarotene 0.1% gel was a well-tolerated and effective adjuvant topical for the treatment of refractory MF lesions by clinical and histologic assessments.

The efficacy of topical tazarotene monotherapy and combination therapies in psoriasis

Tazarotene (Tazorac, Allergan, Inc.) is the first topical retinoid approved for the treatment of plaque psoriasis. It has a similar onset of action compared to potent topical steroids and has the advantage of a longer remission. The common side effects associated with the drug include skin irritation (including pruritus), erythema and a burning sensation. To overcome some of these shortcomings, it has been used in combination with steroids, calcipotriene and phototherapy. Combination therapy not only results in a decrease in adverse side effects, but also enhanced efficacy. Clinical study data have shown that combination therapy is just as important as tazarotene monotherapy, if not more.

Topical retinoid and antibiotic combination therapy for acne management

The agents most commonly used in combination for the management of acne include topical retinoids and antibiotics. Topical retinoids normalize desquamation of the follicular epithelium, whereas antibiotics inhibit the growth of P. acnes and the production of free fatty acids. This therapeutic combination decreases comedogenesis, bacterial growth, and inflammation, thus targeting three of the four pathogenic factors associated with acne. Efficacy and tolerance are maximized with combination therapy, and the degree of skin irritation is minimized. Furthermore, adjunctive therapy with topical retinoids and antibiotics tends to produce results more quickly than single-agent therapy. This article will examine the individual agents used in combination for acne management, and discuss the mechanisms by which they achieve efficacy. The rationale of utilizing topical retinoids with antibiotics will be highlighted, particularly in relation to improved tolerance and reduced irritation.

[Prescription of retinoids in psoriasis]

Systemic retinoids inhibit keratinisation and have anti-inflammatory properties. In 30 years, they have revolutionised numerous aspects of dermatological practice, particularly in the management of psoriasis. In the management strategy of severe psoriasis, acitretin has first place of the medications currently available. It is the on-going treatment par excellence. It is even more effective and better tolerated when doses are progressively increased in steps to reach the optimal effective dose that corresponds to the maximum tolerated dose. The dose is adjusted according to this tolerance and not to standardise doses. With this precondition, the secondary effects are benign, sometimes bothersome with an increasing fragility of the mucous membranes of the epithelia and the phaneres, bearing witness to the medication impregnation of tissues and the interference with the natural retinoids. Due to their teratogenic risk, the only restriction concerns women of childbearing age in whom all prescription of retinoids is subject to some legal considerations that are indispensable to respect.

A Synthetic Retinoid Am80 (Tamibarotene) Rescues the Memory Deficit Caused by Scopolamine in a Passive Avoidance Paradigm

Memory deficit in rats treated with scopolamine was rescued by several synthetic retinoids, RAR-ligands (Am80, Am555S, Tp80) and an RXR-ligand (HX630). These results may have implications for the treatment of Alzheimer's disease, age-related dementia, Parkinson's disease, and other neurological disorders.

Current concepts of the pathogenesis of acne: implications for drug treatment

The pathogenesis of acne is complex, with strong evidence supporting the involvement of sebaceous hyperplasia, follicular hyperkeratinisation, bacterial hypercolonisation, as well as immune reactions and inflammation. High sebum concentrations and follicular hyperkeratinisation lead to a change of the follicular milieu with consecutive proliferation of bacteria, chiefly Propionibacterium acnes. This leads to further increased production of the pro-inflammatory cytokines interleukin-1alpha and tumour necrosis factor alpha by T cells and keratinocytes, leading to proliferation of both cell types. Follicular keratinocytes fail to differentiate by apoptosis and produce hypergranulosis similar to the impermeable skin outer layer, resulting in the formation of microcomedones. Further inflammatory responses lead to the development of increasing degrees of severity in inflammatory forms of acne. Retinoids aid the differentiation and reduce the hyperproliferation of keratinocytes, and can inhibit the migration of leucocytes. Combination therapy using retinoids plus benzoyl peroxide or antibacterials can treat existing acne lesions faster than the individual agents alone and can also prevent the development of new lesions. The new retinoids (e.g. adapalene) have not only the typical potent comedolytic activity but also anti-inflammatory effects. When added to antibacterial therapy, topical retinoids demonstrate faster and significantly greater reduction of inflammatory acne lesions and comedones than antibacterials alone.

Retinoids: therapeutic applications and mechanisms of action in cutaneous T-cell lymphoma

Retinoids, natural and synthetic derivatives of vitamin A, are biological regulators of differentiation, proliferation, apoptosis, and immune response. Retinoic-acid-receptor-selective retinoids (all-trans retinoic acid, 13-cis-retinoic acid, and the synthetic analogs isotretinoin, etretinate and acitretin) have been used for years as monotherapy and/or in combination for treatment of cutaneous T-cell lymphoma (CTCL). Orally administered bexarotene, the first synthetic highly selective retinoid-X-receptor retinoid to be approved by the FDA for CTCL, was shown to be active against the cutaneous manifestations of all stages of CTCL. The topical gel formulation was also effective for early cutaneous manifestations of CTCL or as an adjunct to systemic or phototherapy. Bexarotene treatment induces apoptosis of CTCL cells with down-regulation of its receptors and of survivin, an inhibitor of apoptosis. Identification of new receptor subtype-selective retinoids, combination of various receptor-selective retinoids or other agents, and a new drug delivery system may improve the clinical efficacy of retinoids in the future.

Topical and systemic retinoid therapy for cutaneous T-cell lymphoma

Because curative therapies for CTCL are not yet available, short of TSEB in patients who have early-stage disease and allogeneic bone marrow transplantation in patients who have more advanced disease, the goal of current therapies is to prevent progression of MF and to preserve quality of life. The overall conclusion drawn from the studies reported in the literature, is that retinoids as monotherapy, or in combination with other nonaggressive treatment modalities, represent a low-risk treatment alternative that is especially suitable for controlling early stages of MF and other CTCL. A combination of therapies may be more effective in controlling CTCL as shown with IFN-alpha plus retinoids, and, recently, IFN-alpha with bexarotene and other modalities. For example, isotretinoin, followed by TSEB (for stage I to II disease) or preceded by chemotherapy (for stage II and IV disease) and bexarotene plus PUVA or photopheresis plus IFN, gave overall response rates of 82% and 69% in patients who had MF and SS, respectively. Retinoids as monotherapy may induce complete remissions, but usually these responses are of short duration and relapses are common. Clinical response is not identical to histologic clearance. Even in cases with clinically complete clearance of skin lesions, lymphoid infiltrates persisted, which are most likely the source of recurrences. The new generation of retinoids, the RXR selective agonists like bexarotene, represent a promising approach for refractory or persistent MF that is unresponsive to first-line therapies. Individual differences in response to retinoids may be due to different expression of retinoid receptors, functional polymorphisms in metabolizing retinoids, or resistance to some retinoids. In the future, pharmacogenomic studies are needed to clarify the mechanisms that underlie the differing response rates of patients who have CTCL to retinoids. In addition, new agonists of RAR and RXR, either selective or pan agonists, will become available and will enlarge the spectrum of vitamin A analogs that have antitumoral properties.

[Standard and experimental therapy of cutaneous T-cell lymphoma]

Cutaneous T-cell lymphoma represent a heterogeneous group of diseases characterized by skin invasion of monoclonal T-lymphocytes. These cutaneous T-cell lymphomas are divided into 3 groups based on clinical, histological and immunohistological characteristics: Indolent with a survival time of over 10 years, aggressive with a survival time less than 10 years and provisional (EORTC classification). Standard treatments such as PUVA, total skin electron beam, methotrexate, polychemotherapy regimens, retinoids and photopheresis have been used for years. Bexarotene is a newly registered drug. To achieve better response rates, several new drugs are being evaluated in clinical trails, including imiquimod, denileukon-diftitox, liposomal doxorubicin, adeno-interferon-gamma and various combination approaches.

Topical acne drugs: review of clinical properties, systemic exposure, and safety

This review examines the commonly available topical acne agents and factors that determine their percutaneous absorption. Reported and theoretical adverse effects from systemic exposure are detailed. The topical retinoid class, which includes tretinoin, adapalene and tazarotene, and the topical antibacterials, clindamycin and erythromycin, are regulated by prescription in most countries. Used appropriately, the above-mentioned drugs deliver, at most, miniscule amounts of active ingredient into the circulation. Clear-cut links to systemic toxicity in humans are practically nonexistent, except in the case of topical clindamycin, which has been associated with diarrhea rarely, and there have been 2 cases of pseudomembranous colitis reported. Birth defects have occurred in two patients treated with tretinoin and one patient treated with adapalene, but causation was not proven. Another prescription drug, 20% azelaic acid, is associated with relatively high systemic exposure, which is presumed innocuous because it is a normal dietary constituent whose endogenous levels are not altered by topical use. Benzoyl peroxide, salicylic acid, sulfur, and sodium sulfacetamide are available in concentrations of 2% or more in over-the-counter acne treatments and some prescription products. All of these agents are known to exhibit some degree of percutaneous absorption. They remain largely unregulated because, other than skin irritation, only local allergic contact dermatitis from benzoyl peroxide in about 2.5% of patients and rare local and systemic hypersensitivity reactions from sodium sulfacetamide have been reported. Salicylism has occurred using methyl salicylate ointments and high concentrations of salicylic acid on widespread areas of hyperkeratotic skin, but there are no known cases resulting from salicylic acid acne products. Caution is advised in special circumstances, such as during childhood, pregnancy, lactation and concomitant therapy with other drugs, because relevant studies are lacking. Animal data support avoidance of many topical agents, particularly known teratogens such as retinoids and salicylic acid, in pregnant women. Salicylate avoidance is advised during lactation, because aspirin use carries the risk of bleeding disorders in nursing infants.

Oral retinoid use reduces cutaneous squamous cell carcinoma risk in patients with psoriasis treated with psoralen-UVA: a nested cohort study

BACKGROUND

Small open studies of patients at high risk for squamous cell carcinoma (SCC) of the skin suggest that oral retinoid use reduces the risk of these tumors. Among patients at lower risk, randomized trials of low doses of retinoids did not demonstrate significant chemopreventive effects. Patients with psoriasis treated with oral psoralen-UVA have a high risk of SCC development. Oral retinoids are used to treat psoriasis. We performed a nested cohort study to assess whether oral retinoids reduce skin cancer risk among patients with psoriasis exposed to psoralen-UVA.

METHODS

From 1985 to 2000, 135 patients (11.3% of surviving patients in our cohort) used retinoids for at least 26 weeks in 1 year or more. For these 135 patients, we compared each person's SCC and basal cell carcinoma incidence during years of substantial oral retinoid use and other years. We used Poisson regression models to adjust for potential confounders.

RESULTS

In a paired analysis, which compared each patient's own tumor experience while using and not using retinoids, retinoid use was associated with a 30% reduction in SCC incidence (196 SCCs/1000 and 302 SCCs/1000 years of use and no use, respectively; P =.002). After adjusting for other factors associated with SCC risk, the incidence of SCC was significantly decreased during years of substantial retinoid use (incidence rate ratio = 0.79; 95% confidence interval = 0.65, 0.95). Oral retinoid use and basal cell carcinoma incidence were not significantly associated.

CONCLUSION

In patients with psoriasis treated with psoralen-UVA, systemic retinoid use reduced SCC risk but did not significantly alter basal cell carcinoma incidence.

Systemische Therapie des kutanen Lupus erythematodes. Systemic treatment of cutaneous lupus erythematosus

The treatment of cutaneous lupus erythematosus (CLE) remains a therapeutic challenge. In many cases, systemic treatment of the disease is necessary, especially in cases resistant to topical treatment or with internal organ involvement. Even though many different agents can be employed in this situation, most are not approved in Germany for the treatment of CLE. We give an overview of the agents used in the systemic treatment of CLE and review their mechanisms of action, indications and their practical use in cutaneous LE based on literature results and our own experience. We discuss corticosteroids, antimalarials, dapsone, azathioprine, cyclophosphamide, methotrexate, retinoids, cyclosporine A, mycophenolate mofetil, sulfasalazine, thalidomide, clofazimine, tacrolimus, immunoglobulins, monoclonal antibodies, plasmapheresis, etanercept, infliximab, feflunomid, gold and interferon-alpha.

Cumulative irritancy comparison of adapalene gel 0.1% versus other retinoid products when applied in combination with topical antimicrobial agents

This randomized, investigator-blinded study evaluated the level of skin tolerance to adapalene gel 0.1%, tretinoin cream 0.025%, or tretinoin microsphere gel 0.1% when applied in combination with clindamycin phosphate lotion 1%, erythromycin gel 2%, benzoyl peroxide gel 5%, or erythromycin-benzoyl peroxide gel. A total of 37 subjects underwent daily application of the topical antimicrobial and retinoid products to sites on their upper back under protective patches for approximately 16 hours each day; Friday patches were left in place over the weekend. Testing continued daily for 3 weeks or until discontinuation caused by a severe adverse reaction to any of the test products or to the patch. Adapalene gel 0.1% demonstrated statistically significantly (P <.001) less irritation after repeated application under occlusive conditions than tretinoin cream 0.025% or tretinoin microsphere gel 0.1%. Moreover, the application of adapalene gel 0.1% under these conditions, concomitantly with various antimicrobial agents, was safe and well tolerated in this subject population. In view of its low irritation potential and its efficacy, adapalene gel 0.1%, in combination with antimicrobial agents should be considered for the treatment of acne vulgaris.

Topical and light-based treatments for actinic keratoses

Actinic keratosis is currently believed to be an early stage in the evolution of squamous cell carcinoma. Active and intensive treatment of actinic keratosis may prevent the formation of invasive squamous cell carcinoma and potential metastases. While destructive methods of treatment of actinic keratosis remain the gold standard for the eradication of visible and palpable actinic keratoses, new medical therapies may accomplish this goal more comfortably and reliably for the patient. Newer topical medications, light therapy and photodynamic therapy are generating promising results that presage more widespread use in the future. These novel therapies for the early treatment of actinic keratosis may be administered in combination or serially, with the locus of treatment at any given time possibly restricted to a region of affected skin. Treatment of incipient or subclinical lesions may mitigate the risk of future squamous cell carcinomas lesions. Widespread actinic keratosis constitutes a persistent medical problem that requires long-term management. The role of traditional and novel treatments in the routine treatment of actinic keratosis will be determined by the efficacy, limitations and the practicality of each of these methods in individual patients. As the first stage of squamous cell carcinoma, actinic keratosis is worthy of prompt evaluation and active treatment.

Guidelines for the management of acne vulgaris in adolescents

This article reviews the treatment of acne in adolescents. The choice of therapy should be principally based on the type of lesion and the severity of the acne, but psychosocial disability relating to the disease and the presence of scarring may also influence the approach to treatment.Mild acne generally requires topical treatment only. Benzoyl peroxide, azelaic acid, and antibacterials are generally used for inflammatory lesions. Topical retinoids are particularly effective for noninflamed lesions, and combination therapies are useful for mixed lesions. Moderately severe acne generally requires oral antibacterials. Tetracyclines/oxytetracycline and erythromycin are usually the first-line antibacterials. Second-generation tetracyclines, such as lymecycline, doxycycline, and minocycline, show improved absorption. Minocycline has the advantage of being rarely associated with Propionibacterium acnes antibacterial resistance, but can occasionally lead to potentially serious adverse effects. Trimethoprim is a useful third-line antibacterial therapy for patients resistant to other antibacterial therapies. Benzoyl peroxide should generally be used in combination with oral antibacterials as this has been shown to reduce the development of antibacterial resistance. For severe nodular acne, isotretinoin is the treatment of choice. In addition, over recent years dermatologists have increasingly used this drug to treat patients with moderate acne which has not responded to other systemic therapies, particularly when associated with scarring or significant psychological disability. However, this use is outside the current license of the drug. Isotretinoin is associated with a number of serious adverse effects and careful monitoring of patients during therapy is required.Physical therapies for the treatment of acne nodules and macrocomedones are also important adjuncts to drug therapies.

Topical treatment in acne: current status and future aspects

During the last 20 years, the number of topical and systemic drugs for the treatment of acne vulgaris has been enriched. Topical drugs on the one hand have been newly discovered or further developments of already available agents such as in the group of retinoids or galenic formulation have improved efficacy or local tolerance. Topical retinoids are a mainstay in acne treatment since 1962. All-trans retinoic acid was the first and is still in use. Its irritative potential has led to the new galenics, i.e. incorporation in microsponges and in propolyomers, which increased the tolerability significantly. The isomer of tretinoin, isotretinoin, has the same clinical efficacy, but also a lower irritancy. A real breakthrough was adapalene, a retinoid-like agent, with a different retinoid receptor-binding profile, but in addition to the same clinical efficacy on inflammatory and non-inflammatory acne lesions compared to tretinoin, a better tolerability and, therefore, compliance. Unfortunately, over the past years topical retinoids have been less used in inflammatory acne than they should be, taking the the mechanisms of action into account. Topical antimicrobials, in particular topical antibiotics, should be used less often than in the past and only for short periods to avoid the development of resistances. It seems better to combine those agents with topical retinoids, with BPO or with azelaic acid to enhance the efficacy and slow down the development of resistance. BPO is still the gold standard for papular-pustular acne of mild-to-moderate type in concentrations of 2-5%. Azelaic acid is an alternative with efficacy on the comedo and is antibacterial without development of resistances. Finally, the physical removal by electrocautery or CO(2) laser of multiple densely packed closed comedones, macrocomedones and microcysts is necessary to enhance the efficacy of topical comedolytic agents and to speed up the therapeutic results. Photodynamic therapy has not yet been proven efficacious in controlled studies. Blue and red light can probably be used in association with local agents but enhancement of the irritative potential of topical and systemic agents has to be considered.

Systemic and topical drugs for aging skin

The rejuvenation of aging skin is a common desire for our patients, and several options are available. Although there are some systemic methods, the most commonly used treatments for rejuvenation of the skin are applied topically. The most frequently used topical drugs include retinoids, alpha hydroxy acids (AHAs), vitamin C, beta hydroxy acids, anti-oxidants, and tocopherol. Combination therapy is frequently used; particularly common is the combination of retinoids and AHAs. Systemic therapies available include oral retinoids and vitamin C. Other available therapies such as chemical peels, face-lifts, collagen, and botulinum toxin injections are not discussed in this article.

Acne vulgaris: one treatment does not fit all

With many treatments now available for acne vulgaris, the treatment must be tailored to the type and severity of the lesions. Most mild-to-moderate cases can be treated with a benzoyl peroxide product, a topical or oral antibiotic, a topical retinoid, or a combination of these medications. Antibiotic resistance is becoming a challenge for many once-reliable topical and oral antibiotics.

Current concepts in the treatment of acne: report from a clinical roundtable

Acne vulgaris is the most common skin disorder in the United States, affecting approximately 17 million people. This figure includes 80% of all persons between the ages of 11 and 30 years, regardless of race, ethnicity, or gender (Kraning and Odland, 1979). Acne has a significant economic and social impact on doctor visits, medications, and absenteeism, as well as in the negative effect it can have on self-image and outlook, especially during the emotionally critical period of adolescence. Persons with acne may think of themselves as unworthy and socially unacceptable. Severe acne may lead to scarring and disfigurement, aggravating the already present psychosocial aspects of this condition. Because of the multifactorial nature of acne, current treatment options aim to modify one or more of its pathogenic factors. Clinical experience has shown that combination therapies, which affect multiple aspects of pathophysiology, are most likely to achieve this goal and help in its long-term management and resolution.

Effect of beta-carotene supplementation on plasma and yolk IgY levels induced by NDV vaccination in Japanese quail

Newly hatched Japanese quail (Coturnix coturnix japonica) chicks were fed diets containing different levels of retinoids (vitamin A) or beta-carotene. Group A received a commercial diet containing 10,000 IU vitamin A per kilogram. The diets of Groups B, C, and D contained no vitamin A but were supplemented with 1-, 2.5-, and 5-fold retinol equivalents of beta-carotene. Each group contained 16 quails in a 1:1 sex ratio. At 8 weeks of age the quails were immunized orally with Newcastle disease virus (NDV) vaccine according to the manufacturer's recommendations. Boosters were given three times at two-week intervals. Blood samples were taken at two-week intervals until 14 weeks of age. The anti-NDV IgY titre was determined by a locally developed direct enzyme-linked immunosorbent assay (ELISA). Groups A and B showed nearly the same antibody response. This indicates that the preformed vitamin A and the equivalent beta-carotene have the same immunomodulatory effect. Groups receiving higher doses of beta-carotene (Groups C and D) exhibited significantly higher plasma IgY levels compared to Groups A and B. The results indicate that elevated doses of beta-carotene have a slight effect on the adaptive immune response in Japanese quail.

The rationale for using a topical retinoid for inflammatory acne

Both comedogenesis and the development of inflammatory lesions in acne vulgaris appear to be related to genetic as well as immune processes. The key regulatory cytokine, interleukin-1alpha, has recently been documented as playing a major role in both the hypercornification and the orchestration of immune factors, ultimately resulting in noninflammatory and inflammatory lesions. Topical retinoids, such as tretinoin, and topical retinoid analogs, such as adapalene and tazarotene, help normalize the abnormal follicular keratinocyte desquamation - a key pathophysiologic factor in comedogenesis. This normalization also helps mitigate against the development of a propitious microenvironment for Propionibacterium acnes. Preclinical data suggest that topical retinoids and retinoid analogs may also have direct anti-inflammatory effects. A wealth of clinical data confirms that topical retinoids and retinoid analogs significantly reduce inflammatory lesions. Comparative clinical trials also demonstrate that adapalene has the best cutaneous tolerability profile of all these agents. Optimal therapy for inflammatory acne would involve the use of topical retinoids or retinoid analogs combined with oral or topical antibacterials.

Nukleäre Hormonrezeptoren: Interventionsmöglichkeiten jenseits von Glukokortikoiden, Retinoiden und Vitamin D

Nuclear hormone receptors are ligand-dependent transcription factors. The class of nuclear hormone receptors that form heterodimers with retinoid X receptor includes members that are well established targets of current dermatological therapeutics such as the retinoic acid receptor (RAR) and the vitamin D receptor (VDR) as well as more recently discovered receptors including the peroxisome proliferator-activated receptors (PPAR) and the liver X receptor (LXR). After ligand activation (often lipid metabolites), these intracellular receptors exert their functions by binding to specific response elements in regulatory sequences of target genes, preferentially those involved in differentiation, energy expenditure and lipid metabolism. A number of selective activators has been developed by combinational chemistry, initially for their anti-diabetic and lipid lowering properties as well as their ability to regulate bile acid and drug metabolism. However, these activators also have marked effects on cutaneous homeostasis. Therefore, these compounds have important implications for dermatological therapy. In this review, the clinical implications of the more recently discovered members of the nuclear hormone receptor family are discussed.

Retinoids as a potential treatment for experimental puromycin-induced nephrosis

1 Puromycin aminonucleoside (PAN)-induced nephrosis is a model of human minimal change disease. In rats, PAN induces nephrotic-range proteinuria, renal epithelial cell (podocyte) damage, infiltration of mononuclear leukocytes, and apoptosis of several renal cell types. 2 Retinoic acid (RA) modulates a wide range of biological processes, such as inflammation and apoptosis. Since renal damage by PAN is characterized by inflammatory infiltration and epithelial cell death, the effect of treatment with all-trans RA (tRA) was examined in the PAN nephrosis model and in the cultured differentiated podocyte. 3 Treatment with tRA 4 days after PAN injection did not inhibit the proteinuria peak but reversed it significantly. However, treatment with tRA both before and 2 days after the injection of PAN protected the glomerular epithelial cells, diminishing the cellular edema and diffuseness of the foot process effacement. Preservation of the podocyte architecture correlated with the inhibition of proteinuria. The anti-inflammatory effect of tRA was evidenced by the inhibition of PAN-induced interstitial mononuclear cell infiltration and the decreased renal expression of two molecules involved in monocyte infiltration: fibronectin and monocyte chemoattractant protein-1. TUNEL assays showed that tRA inhibited the PAN-induced apoptosis of cultured differentiated mouse podocytes. 4 We conclude that tRA treatment may prevent proteinuria by protecting the podocytes from injury and diminishing the interstitial mononuclear infiltrate in the model of PAN nephrosis. Retinoids are a potential new treatment for kidney diseases characterized by proteinuria and mononuclear cell infiltration.

[Chemoprevention of oral cancer]

BACKGROUND

Morbidity and mortality from oral cancer is still considerable, and has not improved significantly over the last four or five decades. Early preventive intervention in persons at high risk may improve treatment results.

MATERIAL AND METHODS

This review is based on our previously published data and by searches in the Medline and PubMed databases, using the following terms as key words: "oral premalignancies", "oral leukoplakia", "tumour progression", "genomic instability", "aneuploidy", "prognosis", "head and neck cancer", and "chemoprevention".

RESULTS

Chemoprevention requires the early and reliable identification of persons at high risk of cancer. Retinoids have a clinically documented effect towards head-and-neck cancer, but are associated with unacceptable side-effects. Coxibs and inhibitors of epidermal growth factor receptors are candidate agents for chemoprevention of oral cancer.

INTERPRETATION

It is now possible to identify persons at high risk of developing oral cancer who may benefit from chemopreventive use of coxibs or inhibitors of epidermal growth factor receptors.