Continuing medical education (Therapy)

Non-medication Acquired Sticky Skin: Case Report of Idiopathic Acquired Cutaneous Adherence and Review of Medication-Induced Sticky Skin

Sticky skin is a dermatologic phenomenon in which the skin may cause objects to adhere to it on contact or adhere to itself or both. The entire skin can be affected in patients with sticky skin. Alternatively, just acral sites, such as the hand, can be involved. The acquisition of sticky skin has been described in patients treated with certain medications. These drugs include retinoids, proton pump inhibitors, and antifungals; they also include combination therapy utilizing an antineoplastic agent and an antifungal drug in patients with hormone-resistant prostate cancer.

The pathogenesis of acquired cutaneous adherence in patients with androgen-independent prostate cancer was postulated to be the result of therapy-induced elevation of endogenous retinoids. Retinoids have multiple biological effects on epidermal differentiation that may contribute to the pathogenesis of acquired cutaneous adherence. These include the induction of fine, granular, mucus-like deposits within and between the keratinocytes in the upper stratum spinosum and stratum corneum, modulation of lipid composition in keratinocytes, prevention of cross-linked, cornified envelope formation in keratinocytes by the inhibition of epidermal transglutaminase, and altered and decreased content of keratin within the epidermis. We describe an older man who developed non-medication acquired sticky skin (NoMasts). His acquired cutaneous adherence was considered to be idiopathic. We postulate that aging may be associated with elevated endogenous retinoid levels in older individuals and may have resulted in his sticky skin. Further investigation into these retinoid-induced effects and to what extent they promote acquired cutaneous adherence is still needed.

50 Years of Topical Retinoids for Acne: Evolution of Treatment

Since the US Food and Drug Administration (FDA) approved tretinoin in 1971, retinoids alone or combined with other agents have become the mainstay of acne treatment. Retinoids act through binding to retinoic acid receptors, altering expression levels of hundreds of cellular proteins affecting multiple pathways involved in acne pathogenesis. Retinoids have evolved from first-generation agents, such as tretinoin, through chemical modifications resulting in a second generation (etretinate and acitretin for psoriasis), a third generation (adapalene and tazarotene) and, most recently, a fourth (trifarotene). For all topical retinoids, local irritation has been associated with poor tolerability and suboptimal adherence. Efforts to improve tolerability have utilized novel delivery systems and/or novel agents. This qualitative literature review summarizes the evolution of the four topical single-agent retinoids available for the treatment of acne in the US today and their various formulations, presenting the rationale behind their development and data from key studies.

Evaluation of retinal nerve fiber layer changes with oral isotretinoin treatment

Introduction

Central nervous system toxicity is a well-known side effect of isotretinoin treatment. The aim of this study was to establish the effects of isotretinoin on retinal nerve fiber layer (RNFL) thickness.

Materials and Methods

Study subjects received oral isotretinoin treatment for nodulocystic acne. All patients underwent a detailed ophthalmologic examination including best-corrected visual acuity, slit-lamp examination, tonometry, color vision assessment, fundoscopy, and RNFL measurement. RNFL measurements by optical coherence tomography were done at onset, and were repeated at the 1st and 6th months of therapy.

Results

A total of 22 eyes of 11 patients (seven males and four females) were included in this study. The mean age of the patients was 20.18 ± 5.13 (14–26) years. Mean RNFL thickness was 90.72 ± 9.19 (78.2–112.0) μm before treatment, 90.40 ± 9.24 (79.5–112.4) μm after 1 month of treatment, and 90.52 ± 8.92 (78.4–114.8) μm after 6 months. No statistically significant change was detected between RNFL thickness values before and after treatment.

Conclusion

No adverse effects of systemic isotretinoin treatment on RNFL thickness were observed.

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.

N-retinoyl-D-glucosamine, a new retinoic acid agonist, mediates topical retinoid efficacy with no irritation on photoaged skin

BACKGROUND

Chronic ultraviolet (UV) radiation from sunlight induces wrinkle formation. Retinoic acid (RA) can markedly improve wrinkles, although RA does have some side-effects, such as skin irritation. As the efficacy and cytotoxicity of RA has been traced to its free carboxylic acid, we synthesized a new molecule, N-retinoyl-D-glucosamine (GRA), in which a glucosamine has been attached to the polar end group of all-trans retinoic acid.

OBJECTIVES

To analyse the effect of topical GRA in wrinkle repair and anti-irritation in photoaged mice compared with topical RA, as well as to determine retinoic acid receptor (RAR) and retinoid X receptor (RXR) transactivation activity in vitro.

METHODS

Hairless mice were irradiated with 60 mJ cm-2 of UVB for 10 weeks, and then topically treated with 0.05% GRA or 0.05% RA for 8 weeks. An in vitro transcriptional assay was performed and the activity of GRA in 293 cells transfected with RAR-alpha or RXR-alpha expression plasmid and luciferase reporter plasmid then determined.

RESULTS

Topical GRA and RA brought about almost complete disappearance of the wrinkles caused by UVB irradiation. The two ligands promoted both a wide repair zone histologically, and the expression of type 1 collagen in the skin. In contrast, topical GRA treatment did not produce irritation such as erythema or roughness, or alteration of transepidermal water loss values, compared with RA. In the in vitro luciferase assay, GRA resulted in significant dose-dependent RAR transactivation activity in a 100 times higher concentration range than RA. GRA did not mediate RXR transactivation activity at all.

CONCLUSIONS

Topical GRA appears to be able to repair photoaged skin damage without any of the irritation caused by topical RA, probably via RAR transactivation activity.

Improvement in psoriasis with rosiglitazone in a diabetic and a nondiabetic patient

The authors conducted a prospective, open-label, pilot trial of the effects of the antidiabetic thiazolidinedione (TZD) rosiglitazone in two patients with moderate to severe plaque psoriasis. Case 1: A lean, euglycemic 43-year-old nondiabetic man with a 2-year history of plaque psoriasis presented with lesions involving 10% of his body surface (Figures 1A, 1B, 1C). He had no other chronic or acute medical problems. He had previously been managed sporadically with topical triamcinolone acetonide, an intermediate-strength glucocorticoid, and was off antipsoriatic medication for 5 months. He was started on rosiglitazone p.o., 8 mg q.d. After 10 weeks on rosiglitazone, the lesions developed increased erythema, spreading, and shedding of scale (Figures 2A, 2B, 2C). After an additional 26 weeks, the lesions had largely disappeared (Figures 3A, 3B, 3C). The patient remained euglycemic throughout the study. His liver function enzymes (alanine transferase [ALT] and aspartate transferase [AST]) remained normal throughout the study: ALT, 23 IU/L; AST, 47 IU/L before treatment; ALT, 25 IU/L; AST, 33 IU/L after treatment. There were no adverse events. Case 2: An overweight 68-year-old woman (body mass index, 29 kg/m2; with a 12-year history of type 2 diabetes and 5-year history of psoriasis presented with generalized plaque psoriasis over 20% of her body, including two large, thick, silvery plaques with the texture of leather over the lower part of the back (Figure 4A). She was given rosiglitazone p.o., 4 mg b.i.d. for 24 weeks, which resulted in significant improvement in psoriasis (Figure 4B). After an additional 26 weeks on rosiglitazone, the plaques had cleared on her back (Figure 4C) and over her entire body, including scalp, ears, and posterior forearms (not shown). Her glycemic control improved (hemoglobin A1c decreased from 7.7% to 7.2%) and liver function remained normal throughout the study (ALT, 24 IU/L; AST, 14 IU/L before treatment; and ALT, 26 IU/L; AST, 15 IU/L after treatment). There were no adverse events.

Classical juvenile pityriasis rubra pilaris in a patient with Down syndrome

We report a case of classical juvenile pityriasis rubra pilaris (CJPRP) in a 15-year-old boy with Down syndrome. The rash was extensive, severe, accompanied by intense itching and responded to low-dose etretinate. Xerosis and cheilitis were also present, suggesting that keratinization defects associated with Down syndrome may be involved in the pathogenesis of CJPRP. PRP is a rare dermatological disorder and to the best of our knowledge, this is the first reported case of CJPRP in a patient with Down syndrome.

Vitamin A and infancy. Biochemical, functional, and clinical aspects

Vitamin A is a very intriguing natural compound. The molecule not only has a complex array of physiological functions, but also represents the precursor of promising and powerful new pharmacological agents. Although several aspects of human retinol metabolism, including absorption and tissue delivery, have been clarified, the type and amounts of vitamin A derivatives that are intracellularly produced remain quite elusive. In addition, their precise function and targets still need to be identified. Retinoic acids, undoubtedly, play a major role in explaining activities of retinol, but, recently, a large number of physiological functions have been attributed to different retinoids and to vitamin A itself. One of the primary roles this vitamin plays is in embryogenesis. Almost all steps in organogenesis are controlled by retinoic acids, thus suggesting that retinol is necessary for proper development of embryonic tissues. These considerations point to the dramatic importance of a sufficient intake of vitamin A and explain the consequences if intake of retinol is deficient. However, hypervitaminosis A also has a number of remarkable negative consequences, which, in same cases, could be fatal. Thus, the use of large doses of retinol in the treatment of some human diseases and the use of megavitamin therapy for certain chronic disorders as well as the growing tendency toward vitamin faddism should alert physicians to the possibility of vitamin overdose.

Computerized reminders to monitor liver function to improve the use of etretinate

OBJECTIVE

to determine whether computerized reminders during the process of prescribing can improve the use of drugs requiring prior laboratory testing according to the indications listed in the Drug Package Insert.

MEASURES

Change in proportion of appropriate prescribing and frequency of severe hepatotoxicity between pre- and post-intervention.

METHODS

etretinate, a medication indicated for psoriasis, was selected as a monitored drug because it was the most prescribed of all the identified drugs that require specific prior laboratory tests. Computerized reminders are designed to alert a physician who is about to prescribe etretinate either without the alanine aminotransferase (ALT) test or the aspartate aminotransferase (AST) test within 3 months or despite abnormality in ALT or AST. Data on alerts were gathered by using electronic mail whenever alerts occurred.

RESULTS

prescriptions of etretinate with normal ALT or AST results within the previous three months increased suddenly from 25.9% (127/491) in the pre-intervention period to 66.2% (353/533) in the post-intervention period (P < 0.0001). Moreover, three patients who used etretinate had markedly abnormal tests in the pre-intervention period, but none of the patients were classified in this way in the post-intervention period.

CONCLUSIONS

the computerized reminders appear to improve physicians' use of a drug requiring specific prior laboratory tests.

Effect of topical tazarotene in the treatment of congenital ichthyoses

The clinical efficacy and tolerability of the topical receptor-selective retinoid tazarotene in the treatment of congenital ichthyoses was investigated. Twelve consecutive patients with different forms of congenital ichthyosis were enrolled in an open, non-randomized, intraindividually controlled, half-side pilot study. Diagnoses were X-linked recessive ichthyosis, non-erythrodermic autosomal recessive lamellar ichthyosis, autosomal dominant ichthyosis vulgaris and ichthyosis bullosa of Siemens (IBS). Tazarotene 0.05% gel was applied unilaterally daily on a defined body area measuring 10% of the body surface area. The contralateral side was treated with an ointment containing 10% urea. After 14 days, application frequency was reduced to three times a week, and stopped after another 2 weeks. The follow-up period was 3 months. Reduction in scaling and roughness was used to assess the clinical response in the tazarotene-treated area compared with the control area. Clinical and laboratory assessments were performed every 14 days during the trial. Unilateral improvement in favour of the tazarotene-treated side was observed in nine of 12 patients (75%). Four patients (33%) achieved an excellent response and four (33%) achieved a good response. No therapeutic effect was seen in patients with IBS. The remission persisted during the reduction phase and after discontinuation for up to 2 months. Local irritation in three patients was the only side-effect detectable. Short-term topical application of tazarotene 0.05% gel is a very effective and well-tolerated treatment modality in different forms of congenital ichthyoses and may be an alternative to systemic retinoid therapy.

Optimizing therapy: tazarotene in combination with phototherapy

Phototherapy is often used in combination with other antipsoriatic treatments in an attempt to improve efficacy and reduce patients' cumulative exposure to radiation. Although this aim has been achieved with some combinations, the additional therapies often introduce a potential risk of other tolerability and safety problems. The efficacy of tazarotene reported in clinical trials to date suggest that this drug may help to improve the efficacy of phototherapy, and perhaps reduce the ultraviolet light exposure required without introducing additional, clinically significant problems. Preliminary results from the first 10 patients in a clinical trial investigating such combination therapy are reported here. They demonstrate that the addition of tazarotene to UVB phototherapy increases the percentage of patients achieving treatment success (> or = 50% global improvement in psoriasis) from 60% to 100% at Day 81. The UVB plus tazarotene combination achieved consistently greater reductions in the elevation and scaling of difficult-to-treat psoriatic plaques than UVB phototherapy alone or UVB phototherapy plus vehicle gel. The tazarotene combination therapy also achieved initial treatment success in less than half the time needed with phototherapy alone (median of 32 vs. 67 days). Combining UVB phototherapy with tazarotene treatment appears to offer a valuable therapeutic option that is more efficacious and faster than UVB phototherapy alone.

Occurrence of gouty tophi following acitretin therapy

Acitretin (Ro 10-1670 or Neotigason), a free acid and the main metabolite of etretinate (Ro 10-9359 or Tigason), is the most recent of the retinoids used orally in the treatment of psoriasis and numerous other dermatoses exhibiting disorders of keratinization. In the majority of cases, its side-effects are similar to those of hypervitaminosis A.

Pharmacokinetics and safety review of tazarotene

The safety profile of tazarotene is superior to that of orally administered retinoids. The limited percutaneous penetration of tazarotene limits its systemic absorption and this, combined with its rapid metabolism in the skin and the plasma to the more water-soluble active metabolite, tazarotenic acid, helps prevent accumulation of the drug in fat containing tissues. Urinary and fecal elimination are virtually complete within 2 to 3 days and 7 days after dosing, respectively. Tazarotene also exhibits no indication of mutagenicity, carcinogenicity, phototoxic potential, photoallergic potential, or contact sensitization.

Tazarotene in combination with phototherapy

Despite the vast array of available therapies for treating psoriasis, there remains a need for safer, more effective treatments. Topical tazarotene has been shown to be effective in treating mild-to-moderate psoriasis without causing the adverse effects, such as mucocutaneous toxicity, hyperostosis, and elevation in serum lipids, often associated with orally administered retinoids. A 2-week pretreatment with tazarotene 0.1% gel once daily, followed by tazarotene plus UVB therapy (tazarotene-UVB) 3 times per week for 10 weeks, was more effective than UVB therapy alone or in combination with vehicle gel in reducing plaque elevation, scaling, and erythema. The tazarotene-UVB treatment was well tolerated, and no phototoxicity was observed. Treatment success, defined as a moderate response or better in psoriatic lesions (ie, > or = 50% improvement in psoriatic lesions compared with baseline), was achieved within 32 days with the tazarotene-UVB treatment, compared with 67 days with UVB alone or UVB plus vehicle gel.

All-trans retinoic acid compromises desmosome expression in human epidermis

An undesirable side-effect of retinoid treatment is skin fragility. As desmosomes are important in maintaining the cohesion of epidermal keratinocytes, we investigated whether all-trans-retinoic acid (RA) compromises desmosome expression in human epidermis, thereby predisposing skin to fragility. Solutions containing 0.025% RA, 5% sodium dodecyl sulphate (SDS) as an irritant control, or vehicle alone were applied to three sites on the buttocks of normal volunteers (n = 9). Treated sites were occluded for 4 days, and biopsies taken under local anaesthesia. Cryostat sections were stained with a panel of antibodies to desmosomal proteins and visualized by immunofluorescence microscopy. Stained sections were randomized and assessed for intensity of staining. The epidermal thickness of each treated site was quantified by image analysis. Western blots of epidermal desmocollins were quantified by densitometry. RA and SDS treatments significantly, but equivalently, increased epidermal thickness compared with vehicle. Immunohistochemically, both RA and SDS were shown to reduce epidermal staining for desmoplakin, desmoglein 1, plakophilin 1 and desmocollin 3 equally compared with vehicle-treated skin (P < 0.001). RA produced a greater reduction in desmocollin 1 staining compared with SDS (P < 0.001). Similar reductions in desmocollins were found by Western blot analysis. Reduced desmocollin expression may indicate compromised desmosomal adhesion, leading to the skin fragility that results from retinoid treatment.

The use of retinoids in the pediatric patient

Oral retinoids are molecules derived from vitamin A that represent one of the most important steps forward in dermatologic therapeutics in the present century. The treatment of acne, severe psoriasis, and severe disorders of keratinization, prevalent diseases in children and adolescents, have radically changed since the advent of oral retinoids. Like most highly-effective medications, oral retinoids also have important untoward effects. Specialists, and in particular, dermatologists and pediatricians should be prepared to maneuver the delicate balance between therapeutic efficacy and side effects in order to give the pediatric patient the maximum benefit with the lowest possible risk.

Once-daily tazarotene gel versus twice-daily fluocinonide cream in the treatment of plaque psoriasis

BACKGROUND

A new class of topical receptor-selective acetylenic retinoids, the first of which is tazarotene, has been developed.

OBJECTIVE

Our purpose was to compare the safety, efficacy, and duration of therapeutic effect of 12 weeks of once-daily tazarotene 0.1% and 0.05% gel with that of twice-daily fluocinonide 0.05% cream in the treatment of patients with plaque psoriasis.

METHODS

Three hundred forty-eight patients with plaque psoriasis were enrolled and 275 patients completed a multicenter, investigator-masked, randomized, parallel-group clinical trial.

RESULTS

Both tazarotene gels were as effective as fluocinonide in reducing plaque elevation after 1 week of treatment, and tazarotene 0.1% gel was similar to fluocinonide in reducing scaling of trunk/limb lesions at all study weeks except week 4. Tazarotene 0. 1% gel was similar to fluocinonide in reducing scaling of knee/elbow lesions at weeks 8 and 12. Fluocinonide had a significantly greater effect on erythema than tazarotene at weeks 2 through 8. However, treatments were not significantly different at week 12, and tazarotene demonstrated significantly better maintenance of therapeutic effect after cessation of therapy.

CONCLUSION

Tazarotene 0.1% and 0.05% gels were safe and effective in the treatment of mild-to-moderate plaque psoriasis.

Regulation of retinoidal actions by diazepinylbenzoic acids. Retinoid synergists which activate the RXR-RAR heterodimers

In human HL-60 promyelocytic leukemia cells, diazepinylbenzoic acid derivatives can exhibit either antagonistic or synergistic effects on the differentiation-inducing activities of natural or synthetic retinoids, the activity depending largely on the nature of the substituents on the diazepine ring. Thus, a benzolog of the retinoid antagonist LE135 (6), 4-(13H-10,11,12,13-tetrahydro-10, 10,13,13,15-pentamethyldinaphtho[2,3-b][1,2-e]diazepin-7-yl) benzoic acid (LE540, 17), exhibits a 1 order of magnitude higher antagonistic potential than the parental LE135 (6). In contrast, 4-[5H-2,3-(2,5-dimethyl-2,5-hexano)-5-methyldibenzo[b,e] [1,4]diazepin-11-yl]-benzoic acid (HX600, 7), a structural isomer of the antagonistic LE135 (6), enhanced HL-60 cell differentiation induced by RAR agonists, such as Am80 (2). This synergistic effect was further increased for a thiazepine, HX630 (29), and an azepine derivative, HX640 (30); both synergized with Am80 (2) more potently than HX600 (7). Notably, the negative and positive effects of the azepine derivatives on retinoidal actions can be related to their RAR-antagonistic and RXR-agonistic properties, respectively, in the context of the RAR-RXR heterodimer.

All-trans retinoic acid suppresses liver injury induced by Propionibacterium acnes and lipopolysaccharide in rats

All-trans retinoic acid (ATRA) has been reported to exert major effects on the immune system, including monocytes/macrophages. The present study was designed to determine whether ATRA would modulate macrophage-associated liver injury induced by Propionibacterium acnes and lipopolysaccharide (LPS) in rats. All-trans retinoic acid administration alleviated the liver injury and reduced the incidence of death following hepatic failure. Serum alanine aminotransferase (ALT) levels 5 h after, and survival rates within 12 h after the administration of LPS were significantly lower in the ATRA-treated group (134+/-119 IU/L and 72.7%) compared with the control group (713+/-411 IU/L and 18.2%; P< 0.05). Histological findings supported these results. These effects may be due to suppression of tumour necrosis factor-alpha (TNF-alpha) and superoxide anions produced by activated macrophages. Serum levels of TNF-alpha 1 h after LPS administration were significantly lower in the ATRA-treated group (60.5+/-7.0 ng/mL) as compared with the control group (105.2+/-39.3 ng/mL; P< 0.05). Formazan deposition that was generated by the perfusion of the liver with nitroblue tetrazolium, also suggested suppression of the release of superoxide anions from hepatic macrophages. These results suggest that ATRA acts as an immunomodulator in liver injury by suppressing the activation of liver macrophages.

Tazarotene gel, a new retinoid, for topical therapy of psoriasis: vehicle-controlled study of safety, efficacy, and duration of therapeutic effect

BACKGROUND

Topical therapy providing initial improvement and maintenance of effect after treatment of the large majority of patients with limited, mild to moderate psoriasis is not presently available. Previous topical retinoids have generally been either ineffective or too irritating for therapy of psoriasis.

OBJECTIVE

Our purpose was to evaluate a new topical retinoid, tazarotene, in the treatment of stable plaque psoriasis during treatment and posttreatment periods.

METHODS

In a double-blind manner, 324 patients were randomly selected to receive tazarotene 0.1% or 0.05% gel, or vehicle control, once daily for 12 weeks and were then followed up for 12 weeks after treatment.

RESULTS

Of the total, 318 patients could be evaluated. Tazarotene gels were superior (p < 0.05) to vehicle, often as early as treatment week 1, in all efficacy measures: plaque elevation, scaling, and erythema; treatment response; percentage treatment success (patients with > or = 50% improvement); and time to initial success. Efficacy was equivalent on target lesion sites (trunk or limbs and knees or elbows) and overall. A sustained therapeutic effect was observed for 12 weeks after treatment. Tazarotene gel was cosmetically acceptable. There was low systemic absorption, limiting toxicity to local irritation.

CONCLUSION

Once-daily tazarotene was effective and safe as a topical monotherapy for plaque psoriasis, providing rapid reduction of signs and symptoms.

Effects of retinoids on the production of tumour necrosis factor-alpha and nitric oxide by lipopolysaccharide-stimulated rat Kupffer cells in vitro: evidence for participation of retinoid X receptor signalling pathway

Kupffer cells play important roles in the development of liver injury by producing cytokines and free radicals. In consequence inhibition of these inflammatory mediators will be one of the targets for treating liver diseases. Retinoids modulate a wide variety of functions of monocytes/macrophages. Cellular effects of retinoids are mediated by two families of nuclear receptors, retinoic acid receptors (RARs) and retinoid X receptors (RXRs). We examined the effects of several kinds of natural and synthetic retinoids on the production of tumour necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) by LPS-stimulated rat Kupffer cells in vitro. Of the various retinoids tested, 9-cis-retinoic acid (9-cis-RA) and Ro 13-6307 which are agonists of both RARs and RXRs, suppressed the production of TNF-alpha and NO in a concentration-dependent fashion, whereas three types of RAR-selective agonists, Ro 13-7410, Ro 40-6055 and Ro 19-0645 did not show any effect. Furthermore, the RAR alpha antagonist, Ro 41-5253, did not prevent the effects induced by 9-cis-RA. The results suggest that these effects of 9-cis RA and Ro 13-6307 were induced by the RXRs-dependent signalling pathway.

Vitamin A and its congeners

Vitamin A (retinol) is a fat-soluble vitamin that is necessary for cell growth and differentiation. Excess vitamin A has been associated with teratogenic effects in animals and humans. Because vitamin A deficiency is very uncommon in the industrialized world, the current recommendation is that routine vitamin A supplementation is not necessary. If vitamin A supplements are used, they should be limited to less than 5,000 IU per day. Systemic administration of the naturally occurring retinoid tretinoin has been associated with birth defects, fetal resorption, and stillbirths in animals; however, topical use is not associated with increased birth defects and is classified as a category B drug during pregnancy. The synthetic retinoids isotretinoin, etretinate, and etretin are strictly contraindicated during pregnancy (category X) as they have been associated with teratogenic syndromes in humans. In addition, owing to the prolonged elimination half-life of aromatic retinoids, effective contraception should be used for at least 2 years following discontinuation of treatment with these drugs.

Inhibition of IL-1-induced IL-6 production by synthetic retinoids

The effects of retinoids and retinoid antagonists on IL-6 production in MC3T3-E1 cells were investigated. None of the synthetic retinoids examined stimulated IL-6 production, but all of them strongly inhibited IL-6 production induced by mouse IL-1 alpha. Their inhibitory activities correlated well with their differentiation-inducing activities in HL-60 assay or their binding affinities to nuclear retinoic acid receptors (RARs). Among three retinoid antagonists, two weak antagonists exhibited similar inhibition of mouse IL-1 alpha-induced IL-6 production, whereas a potent retinoid antagonist, 4-(13H-10,11,12,13-tetrahydro-10,10,13,13,15-pentamethyl-dinaph tho[2,3-b] [1,2-e]diazepin-7-yl)benzoic acid (LE540, 14), enhanced IL-6 production under the same conditions.

Oral retinoids--efficacy and toxicity in psoriasis

Psoriasis is a disease of unknown aetiology, affecting approximately 1-3% of the population. In most cases involving relatively localized disease, patients are best managed with either topical therapy alone or topical therapy in combination with UV-phototherapy. However, approximately 35% of patients do not respond well to these conventional treatments or have moderate-to-severe disease requiring more aggressive forms of therapy. The second-generation retinoids, etretinate and its metabolite acitretin, are important additions to the armamentarium of agents used to treat these recalcitrant or severe forms of the disease. Generalized pustular psoriasis generally responds well to high-dose (0.7-1 mg/kg/day) oral retinoid monotherapy. In contrast, increasing small doses of the retinoid are recommended initially in erythrodermic psoriasis in order not to provoke the disease. Long-term clinical experience favours a combination treatment of the retinoid with either topical and/or UV irradiation in chronic plaque-like psoriasis. Both oral retinoids have comparable efficacy and tolerability profiles, and the relapse rates for both drugs are similar. The toxicities associated with both short- and long-term treatment with oral retinoids are significant and include mucocutaneous effects, adverse modulation of serum lipid chemistries, elevation of liver enzymes, and after long-term chronic dosing, skeletal and ligamentous calcification, and hyperostosis. Both etretinate and acitretin, like all retinoids, are known teratogens in animal models, and documented evidence exists for teratogenic activity in humans as well. Consequently, women of childbearing age are strongly advised to avoid pregnancy during treatment and up to 5 years following cessation of therapy with both etretinate and the carboxylic acid metabolite acitretin.

Early clinical development of tazarotene

Initial clinical investigations on tazarotene, a new acetylenic retinoid, have suggested potential usefulness in the treatment of mild-to-moderate plaque psoriasis. Tazarotene promotes healing of psoriatic lesions by modulating the key pathogenetic factors in this disease. It is not sensitizing, phototoxic, or photoallergenic, but causes moderate dose-related skin irritation. Systemic absorption is minimal and elimination is rapid, providing a low potential for systemic adverse effects. Tazarotene effectively treats mild-to-moderate plaque-type psoriasis, the benefits seem to be sustained after the cessation of therapy, and once-daily treatment is equally effective as more frequent application.

Clearing of psoriasis by a novel immunosuppressive macrolide

Accumulating evidence suggests that psoriasis may be a genetically determined immunogenic, inflammatory disorder based on an ongoing autoreactive Th-1 response. Systemic immunosuppressive therapy is highly effective but fraught with longterm side effects. Our research therefore focuses on therapeutic strategies that induce local immunosuppression in the skin by topical, transepidermal delivery of immunosuppressive drugs. SDZ 281-240 is a newly developed macrolide of the ascomycin type. It is immunosuppressive by mechanism of action similar to that of FK506 but has no antiproliferative activity against keratinocytes in vitro. To evaluate whether SDZ 281-240 exhibits antipsoriatic activity when applied topically, we tested 15 patients with severe, recalcitrant psoriasis, using a microplaque assay in randomized, double-blind, placebo-controlled study, comparing the therapeutic efficacy of the macrolide with a potent halogenated corticosteroid and vehicle. All patients showed a significant improvement of psoriatic lesions treated with two concentrations of the macrolide and, as expected, with the corticosteroid but not with placebo. Both concentrations of the macrolide led to clearing of psoriasis after 10 days of treatment and biopsies confirmed a reversal of the histopathological and immunopathological phenotype of psoriasis to that of normal skin. Thus, an immunosuppressive agent that interferes with early T cell activation can be designed to penetrate into psoriatic lesions when applied topically and to be functionally active within the skin to suppress the ongoing psoriatic process.