Retinoids: a review

Effect of oral isotretinoin on muscle strength in patients with acne vulgaris: a prospective controlled study

BACKGROUND

Musculoskeletal side effects related to isotretinoin are frequently reported. This study aimed to investigate the effect of oral isotretinoin treatment on muscle strength. Our second aim was to evaluate whether there was a correlation between the serum creatine phosphokinase (CPK) level, a specific marker of muscle breakdown, and muscle strength.

METHODS

This study included 30 patients who presented to our hospital and were started on oral isotretinoin treatment for acne vulgaris and 30 patients in the control group who were given local treatment. Age, sex, height and weight of the patients were recorded, and the body mass index (BMI) was calculated. The hamstring and quadriceps muscle strengths of the non-dominant side were evaluated in all patients using an isokinetic dynamometer, and the peak torque (PT) values ​​were recorded. In the isotretinoin group, isokinetic measurements were performed again in those that completed six-month drug treatment and compared with the initial PT values.

RESULTS

The two groups were similar in terms of age, sex, and BMI (p > 0.05). There was no significant difference between the isotretinoin and control groups in terms of muscle strength at the beginning of the treatment (p > 0.05). No significant change was observed in hamstring and quadriceps PT values in the isotretinoin group after 6 months of treatment compared to baseline (p > 0.05). No statistically significant correlation was found between the serum CPK level and hamstring and quadriceps muscle strength (p > 0.05).

CONCLUSION

Oral isotretinoin doesn't alter muscle strength. There is no relationship between the serum CPK levels and muscle strength.

Myositis Induced by Isotretinoin: A Case Report and Literature Review

Patient: Male, 45-year-old

Final Diagnosis: Myositis induced by isotretinoin

Symptoms: Muscle pain in the upper limbs with marked functional limitation associated by coluria

Medication: —

Clinical Procedure: —

Specialty: Rheumatology

Monitoring Isotretinoin Therapy in Acne: Rational Use of Laboratory Tests

Background:

Several recent long-term follow-up studies confirm the relative safety of isotretinoin in acne. Yet, conscientious dermatologists may order more laboratory tests than is strictly necessary.

Objective:

Our goals were to determine which laboratory tests used in monitoring isotretinoin therapy predict significant abnormalities, when such abnormalities are likely to occur, and to establish guidelines for practitioners in ordering these tests.

Methods:

In the Hamilton, Ontario region, 27 dermatologists were surveyed to determine the tests and their frequency requested by practicing dermatologists. We also critically reviewed the literature to establish the frequency and magnitude of laboratory tests in acne patients on isotretinoin and assessed the rationale and cost-effectiveness of the suggested tests.

Results:

Seventeen dermatologists (63%) responded. A wide range of tests were ordered at variable intervals. The literature review suggests that adverse laboratory events are uncommon and that many are clinically insignificant.

Conclusion:

Dermatologists may be requesting more laboratory tests for monitoring isotretinoin therapy than are warranted or cost-effective. We propose a rational laboratory program for monitoring patients on isotretinoin.

Presumed isotretinoin-induced extraocular myopathy

Isotretinoin a synthetic analogue of vitamin A is primarily used for cystic acne not responding to conventional treatment. Several ocular side effects including blurring of vision, decreased dark adaptation, corneal opacities and meibomian gland atrophy have been reported with prolonged use of isotretinoin. There have been reports of muscular damage caused by isotretinoin. Extra ocular myopathy as an adverse effect of long term used of isotretinoin has never been mentioned in literature. We report a case of a young male who presented to us with complaints of diplopia after using isotretinoin for a prolonged period. He was diagnosed as a case of presumed isotretinoin extraocular myopathy after imaging and other blood investigations.

Screening Chemicals for Receptor-Mediated Toxicological and Pharmacological Endpoints: Using Public Data to Build Screening Tools within a KNIME Workflow

Assessing compounds for their pharmacological and toxicological properties is of great importance for industry and regulatory agencies. In this study an approach using open source software and open access databases to build screening tools for receptor-mediated effects is presented. The retinoic acid receptor (RAR), as a pharmacologically and toxicologically relevant target, was chosen for this study. RAR agonists are used in the treatment of a number of dermal conditions and specific types of cancer, such as acute promyelocytic leukemia. However, when administered chronically, there is strong evidence that RAR agonists cause hepatosteatosis and liver injury. After compiling information on ligand-protein-interactions, common substructures and physico-chemical properties of ligands were identified manually and coded into SMARTS strings. Based on these SMARTS strings and calculated physico-chemical features, a rule-based screening workflow was built within the KNIME platform. The workflow was evaluated on two datasets: one with RAR agonists exclusively and another large, chemically diverse dataset containing only a few RAR agonists. Possible modifications and applications of screening workflows, dependent on their purpose, are presented.

Hepatotoxicity of isotretinoin in patients with acne and Gilbert's syndrome: a comparative study

OBJECTIVES

The objective of our follow-up study is to evaluate liver function tests (LFTs) and lipid profiles in patients with Gilbert's syndrome treated with isotretinoin because of severe acne.

SETTING

Dermatology outpatient clinics of three regional hospitals of Jaén (Spain).

PARTICIPANTS

Over 4 years, we included all patients diagnosed with severe acne. Only 37 patients were identified, of which 11 had Gilbert's syndrome.

INTERVENTIONS

All patients were treated with isotretinoin and followed-up in our outpatient clinics after 10 and 20 weeks. Patients were subjected to an interview questionnaire which included data on age, gender, complete blood count, coagulation profile, fasting blood glucose, LFTs and lipid profiles. Data and results of patients with severe acne and Gilbert's syndrome were compared with those of 26 patients with only severe acne (control group).

PRIMARY OUTCOME

Blood analyses were repeated in the follow-up visits.

RESULTS

In patients with Gilbert's syndrome, bilirubin levels showed substantial decrease over the 20-week follow-up, with more decrease after 10 weeks. None of the control group patients had significant increase in total bilirubin levels after 10 and 20 weeks of follow-up. Liver enzymes were maintained within normal levels in both groups. Both study groups did not show significant pathological increase in lipid profile levels. LDL levels were increased in the two study groups, but this increase was less substantial in patients with Gilbert's syndrome.

CONCLUSIONS

Our preliminary results suggest that oral isotretinoin could be an effective, safe treatment for patients with Gilbert's syndrome, and may lower bilirubin levels in the first 10 weeks of treatment. Limitations of the study include the small numbers of participants and the fact that it is restricted to one region of Spain.

Neuromuscular adverse effects associated with systemic retinoid dermatotherapy: monitoring and treatment algorithm for clinicians

Although neuromuscular adverse effects represent significant clinical manifestations of hypervitaminosis A syndrome, surprisingly little attention has been paid to the potential neuromuscular toxicity of vitamin A derivatives (retinoids). Since isotretinoin and acitretin are currently the two most commonly used oral retinoids in systemic dermatotherapy, this review focuses exclusively on their neuromuscular adverse effects and proposes a neuromuscular algorithm for appropriate monitoring of patients treated with these two compounds. The most frequent CNS adverse effect associated with oral isotretinoin is headache, either as an independent adverse effect or as part of benign intracranial hypertension, which is additionally characterized by nausea and visual changes. Isolated cases of stiff-person-like syndrome, epileptic seizures and generalized muscle stiffness syndrome, possibly or probably related to oral treatment with isotretinoin, have also been reported. In addition, oral isotretinoin has reportedly been associated with muscular adverse effects that most frequently manifest as myalgia and stiffness and, in rare cases, as true myopathy or rhabdomyolysis. Creatine phosphokinase, a specific marker of muscle destruction, has been found to be elevated, occasionally by up to 100 times the normal value (with or without muscular symptoms and signs), in a variable percentage of patients receiving isotretinoin treatment and particularly in those undergoing vigorous physical exercise. Oral acitretin has been found to cause peripheral nerve dysfunction, particularly of sensory fibres, which in rare cases leads to clinically evident sensory disturbances. Less clear is the causal relationship between acitretin and benign intracranial hypertension or myopathy, whereas an isolated case of cranial nerve IV (oculomotor) palsy and a further case of thrombotic stroke during treatment with oral acitretin have been reported. Systemic diseases with involvement of nervous and/or muscle tissue and neuromuscular disorders should be regarded as exclusion criteria for initiation of oral retinoid therapy. Additionally, intense physical exercise and concurrent treatment with neurotoxic or myotoxic drugs should be avoided during treatment with oral retinoids. In order to minimize the potential risk of neuromuscular adverse effects, a neuromuscular algorithm is suggested that may be useful for monitoring patients taking oral retinoids.

Use of oral isotretinoin in photoaging therapy

BACKGROUND

Many drugs are being used for prevention and treatment of photoaging, especially topical retinoids. The use of systemic retinoids, more specifically, isotretinoin, for this purpose has not been properly addressed to date. Our study was designed to assess the systemic use of isotretinoin used alone for the therapy of cutaneous photoaging.

OBJECTIVE

To demonstrate that isotretinoin is converted into retinoid and improves the appearance of the photoaged skin.

METHODS

Fifty women aged 40 to 60 years, phototype I, II, or III according Fitzpatrick, were selected to receive 20 mg of isotretinoin orally 3 times a week for a 3-month period. Patients underwent clinical and laboratory evaluation. Two biopsies and photographic control were performed. Patients were requested to use only topical photoprotecting agents during the treatment. Improvement in photoaging clinical parameters were evaluated through pictures taken and also through an evaluation form. Anatomopathologic parameters were obtained by comparing collagen degeneration and skin trophism. Results. Thirty patients fully complied with study requirements and were adequately analyzed. From the anatomopathologic data, an improvement of photoaging in 20 patients was observed.

CONCLUSIONS

Isotretinoin improves photoaging with few adverse events because of the low dose used and to the short treatment duration.

Medication-induced intracranial hypertension in dermatology

Pseudotumor cerebri (PTC) is a syndrome of intracranial hypertension that is idiopathic or from an identified secondary cause. It is characterized by headaches and visual manifestations. The hallmark of PTC is papilledema and the feared consequence is visual loss that may be severe and permanent. The idiopathic form generally occurs in obese women of childbearing age. Various medications may produce PTC in patients at any age, including children. Several medications used in dermatology, particularly those used in the treatment of acne vulgaris, are associated with PTC. There is a strong association with tetracycline usage. Minocycline and doxycycline have also been linked to PTC, although there are relatively few reported cases. PTC has also been described with retinoids, including vitamin A (retinol) and isotretinoin. Although corticosteroids are often used to lower intracranial pressure acutely, corticosteroid withdrawal after long-term administration may induce increased intracranial pressure. A high index of suspicion, early diagnosis and treatment generally yield a good prognosis.

Simultaneous occurrence of folliculitis decalvans capillitii in identical twins

Folliculitis decalvans is a chronic purulent folliculitis resulting in permanent hair loss and follicular atrophy. We report 32-year-old identical female twins presenting with relapsing pruritic outbreaks on the scalp resulting in areas of permanent baldness. Staphylococcus aureus was detected in the lesions of both women. Histopathology confirmed the diagnosis of folliculitis decalvans. Immunological testing showed no alteration of the immune system. To our knowledge, this is the first report on folliculitis decalvans occurring in identical twins, suggesting a possible genetic component in this disease.

Isotretinoin use in acne: prospective evaluation of adverse events

BACKGROUND

Isotretinoin is an effective treatment for severe acne. Although the spectrum of side effects has been well documented, the changing incidence of such side effects over the course of treatment has not been studied in detail.

OBJECTIVES

The purpose of our study was to examine a group of patients monthly over their course of treatment and prospectively document the side effects experienced.

METHODS

Over the period between January 1991 and July 1996, 124 courses of treatment with isotretinoin for severe acne were followed. The patients were treated for 4 months at a dose of 1 mg per kg body weight. A questionnaire was administered monthly, inquiring specifically about side effects known to be associated with isotretinoin. Any additional side effects were also noted.

RESULTS

The majority of patients experienced persistent dryness of lips. Dry eyes affected 40% of patients; this continued throughout treatment in 25%. Contact lens wearers were more likely to develop conjunctivitis. Lower back pain was reported early in about 30% of patients and fewer than 10% of patients would develop it later in the course of treatment. Arthralgia was noted in 16.5% of patients at the first visit and there was little change with ongoing treatment. Hair loss was experienced in a small percentage but was rarely noted on more than one occasion. Headaches occurred in less than 10% and were occasionally severe, but most often intermittent and recorded at a single visit. Depression occurred in 4% of patients and tended to persist throughout the treatment. All these patients completed the full course of treatment.

CONCLUSION

This prospective analysis has shown that patients treated with isotretinoin experienced a predictable series of side effects. Some occurred fleetingly, but several persisted for the duration of treatment.

The influence of retinoic acid and retinoic acid derivatives on beta2 integrins and L-selectin expression in HL-60 cells in vitro

A decreased expression of the beta2-integrin CD11b molecules on peripheral neutrophils from patients with pustular psoriasis occurred during treatment with retinoid compounds. Since this effect could not be mimicked in vitro with isolated peripheral neutrophils, the effect of retinoid compounds on cell differentiation was investigated. The promyelocytic cell line, HL60, was used to study what effect different retinoid compounds had on the cell surface expression of CD11b and L-selectin (CD62L) molecules, complement-mediated phagocytosis, adhesion and the oxidative burst. Retinoid-differentiated cells showed a significantly lower expression of CD11b and CD62L, and a decreased phagocytosis and oxidative burst compared to DMSO-differentiated HL60 cells or peripheral blood neutrophils. The diminished expression of beta2-integrins or L-selectin did not affect their adhesion to non-activated or lipopolysaccharide-activated endothelial cells in vitro but may however affect adhesion to vascular endothelium under shear forces during blood flow. These results suggest that retinoid treatment could affect several early steps in the inflammatory process.

Tocoretinate inhibited the contraction of collagen gel matrices by human dermal fibroblasts with tenascin-C expression

Retinoids are strong tissue modifiers and have been used to treat severe acne, keloids and photo-aged skin. Tocoretinate (TR), ester bound retinoic acid and tocopherol, has been topically applied for skin ulcers and, more recently, for sclerotic skin diseases. To clarify the mechanism of tissue softening by retinoids and TR, we investigated their effects on the contraction of hydrated type-1 collagen gel matrices by human dermal fibroblasts and on tenascin-C expression. TR, 13-cis-retinoic acid/isotretinoin and all trans-retinoic acid significantly inhibited collagen gel matrices contraction at concentrations from 10(-4) to 10(-8) M without significant changes of the fibroblast growth. TR and the other two retinoids dose-dependently induced tenascin-C expression in the fibroblasts. Since tenascin-C is involved in cellular detachment and tissue remodeling, these results suggest that TR and other retinoids down-regulated the tensile tension of fibroblasts in collagen gel matrices by the induction of tenascin-C.

Topical tocoretinate improved hypertrophic scar, skin sclerosis in systemic sclerosis and morphea

Four patients with systemic scleroderma (SSc), 4 patients with morphea, and 4 patients with hypertrophic scar were treated with topical tocoretinate for 6 months to 3 years and studied clinically and histopathologically. Clinically, all of the lesions responded to this therapy. The stiffness of the skin lesions, glossy appearance of the lesions, and telangiectasia improved. Histopathologically, the proliferated collagen fibers decreased in thickness, and the inter-fiber spaces increased. Immunoreactive tenascin-C expressed in the proliferated deep dermal fibers of the SSc and hypertrophic scar lesions was markedly decreased compared with the level before the topical tocoretinate therapy. Topical tocoretinate has been used for the treatment of ulcers; it is also a potent treatment for sclerotic skin diseases.

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.

Rheumatologic complications of vitamin A and retinoids

Retinoids are synthetic derivatives of vitamin A. They are administered primarily for dermatological conditions, such as psoriasis, acne, and disorders of keratinization. Toxicity has proven a significant problem with long-term administration of the retinoids. Bone abnormalities mimicking seronegative spondyloarthropathy or diffuse idiopathic skeletal hyperostosis have been described in many cases, as well as other rheumatologic manifestations such as arthritis, myopathy, and vasculitis. These retinoid-related adverse effects are reviewed.

The use of gemfibrozil in a patient with chronic myelogenous leukemia to successfully manage retinoid-induced hypertriglyceridemia

Systemic retinoids are used in the management of chronic cutaneous conditions and life-threatening dermatoses. Unfortunately, drug-induced hypertriglyceridemia may necessitate either dose reduction or discontinuation of therapy. The purpose of this article is to describe the successful management of isotretinoin-induced hypertriglyceridemia with gemfibrozil in a leukemia patient. Sequential serum chemistries were performed prior to, during, and following treatment with a systemic retinoid and a lipid-regulating agent. A prompt and sustained normalization of fasting triglycerides occurred following the initiation of gemfibrozil in a patient with isotretinoin-induced hypertriglyceridemia. When retinoids are being used in the management of serious conditions, the initiation of therapy with gemfibrozil to reduce the elevated triglycerides may be appropriate in those patients with retinoid-induced hypertriglyceridemia.

Retinoids for the future: investigational approaches for the identification of new compounds

One desired goal for future retinoid development is the dissociation of therapeutic benefit from teratogenic risk. It is not known if this result can be achieved, but increasing our understanding of the molecular mechanisms of retinoid action offers rational approaches to the attainment of this goal. The basis for these new approaches is the recent discovery of nuclear receptors for all-trans-retinoic acid and for the 9-cis form of retinoic acid. These receptors, like the steroid hormone receptors, are ligand-dependent transcription factors. Retinoids act by binding to these receptors and modulating specific gene pathways that ultimately control cell differentiation and development. Retinoic acid is required for normal embryonic development, and retinoic acid concentrations are regulated in the developing embryo. The malformations associated with in utero exposure to retinoids might be the result of inappropriate activation of specific receptors and inappropriate modulation of specific gene pathways. At least three nuclear receptors for all-trans-retinoic acid and three nuclear receptors for the 9-cis form of retinoic acid are known to exist, with the two receptor subfamilies interacting to form heterodimers. This multiplicity of receptors and receptor interactions suggests that differences may exist among receptors in the biologic effects they mediate. Although some retinoid ligands are not specific, others are highly selective for one particular receptor. Contrasting the effects of ligands with different specificities should increase understanding of the biologic responses associated with specific receptors and efforts to dissociate therapeutic activity from undesired effects.

Pyoderma faciale in a patient with Crohn's disease

We wish to report the progress of a patient with pyoderma faciale and Crohn's disease. The patient is interesting in that on two occasions the relapse in her skin condition coincided with the introduction of non-steroidal anti-inflammatory drugs. Therapy with isotretinoin was effective and well tolerated.

Clinical evaluation of etretinate for the treatment of canine solar-induced squamous cell carcinoma and preneoplastic lesions

BACKGROUND

Tumors of the skin and subcutaneous tissue account for 30% of all canine neoplasms. Canine solar-induced squamous cell carcinoma (SCC) is the most frequently reported canine cutaneous neoplasm.

OBJECTIVE

The purpose of this study was to provide preliminary observations on the safety and efficacy of etretinate for the treatment of solar-induced SCC and associated preneoplastic lesions in dogs.

METHODS

Etretinate was administered to 10 dogs at 1 mg/kg twice daily for a minimum of 90 days.

RESULTS

Clinically, two dogs showed complete resolution of their preneoplastic lesions, three dogs had partial responses, two dogs maintained stable disease, and three dogs showed progression of lesions after 90 days of etretinate administration. Three dogs showed histologic improvement, four dogs showed no changes, and three dogs showed evidence of progressing SCC. Treatment-related biochemical abnormalities included reversible hypertriglyceridemia and transient serum liver enzyme elevations in three dogs.

CONCLUSION

These preliminary findings suggest that etretinate, at the dosage administered, may provide therapeutic efficacy for solar-induced preneoplastic lesions in the dog, particularly for those multifocal lesions not easily managed by local methods of therapy.

Retinoid augmentation of bioactive interleukin-1 production by murine keratinocytes

The effect of retinoids on the production of interleukin-1 (IL-1) by murine epidermal keratinocytes was investigated. Freshly isolated keratinocytes were cultured in the presence of etretinate, acitretin, all-trans retinoic acid or 13-cis retinoic acid at concentrations of 8 x 10(-9)-8 x 10(-6) mol/l. Exposure of keratinocytes to retinoids increased IL-1 bioactivity in culture supernatants and cell extracts at concentrations as low as 8 x 10(-9) mol/l, as assessed by T-cell proliferation. Prolongation of the culture period enhanced the augmentative effect of retinoids. All-trans retinoic acid and 13-cis retinoic acid had a greater ability to induce IL-1 production than the two aromatic retinoids, etretinate and acitretin. Treatment with 8-methoxypsoralen plus ultraviolet A radiation and treatment with triamcinolone acetonide both reduced the effect of retinoids on the production of bioactive IL-1.

Keratoderma hereditaria mutilans. Etretinate treatment and electron microscope studies

Keratoderma hereditaria mutilans is a rare inherited cornification disorder characterized by hyperkeratosis of palms and soles with a characteristic "honey-comb" appearance, keratotic constriction furrows of one or more digits (pseudo-ainhum) and threatening spontaneous amputation. Approximately 30 cases have been reported, but the ultrastructural features have not been well characterized. In this article, we describe the clinical, histologic, and ultrastructural findings in our patient. A biopsy specimen taken before treatment with etretinate showed hyperkeratosis with a well-preserved granular layer and acanthosis. Ultrastructural examination disclosed that the spinous cells and granular cells contained marked swollen mitochondria, many desmosomes, and that corneocytes contained many membrane coating granules (MCG) and lipid like vacuoles. After initiation of treatment, considerable clinical improvement was observed, but without significant histologic modification. The principal post-treatment ultrastructural changes were the reduction of mitochondrial swelling in spinous and granular cells and the reduction in the number of MCG in corneocytes. The intercellular spaces showed increased amounts of fine and coarse granular substances. Stimulation of Langerhans cells was observed. Marginal band formation occurred normally after treatment.

Acitretin in the treatment of severe disorders of keratinization. Results of an open study

The purpose of this open, noncomparative study with acitretin (Ro 10-1670) was to evaluate the clinical response of patients with various nonpsoriatic disorders of keratinization and to establish for these patients the optimal dosage for both efficacy and tolerance. Thirty-three patients (21 adults and 12 children or adolescents) with ichthyoses, palmoplantar hyperkeratosis, or Darier's disease were treated for a period of 4 months. Most patients showed marked improvement or remission. The results obtained in congenital ichthyosiform erythroderma, lamellar ichthyosis, and Papillon-Lefèvre syndrome were judged as better than those usually reported with etretinate. The side effects observed in our patients were similar to those reported with etretinate, with the exception of scaling of palms and soles, which had an incidence and severity greater than expected with etretinate. The optimal acitretin dosage providing the best efficacy with minimal undesirable effects varied from patient to patient. The mean daily dose (+/- SD) was 27 +/- 11 mg in adults and 0.7 +/- 0.2 mg/kg in children or adolescents.

Rheumatological symptoms due to retinoids

Isotretinoin and etretinate are synthetic derivatives of vitamin A widely used in the treatment of dermatological diseases, mainly those affecting keratinization. They have numerous side-effects, among which the rheumatic symptoms are not the most common or the most severe. The main skeletal adverse reaction of retinoids is hyperostosis. It mainly occurs with protracted treatments and high dosages, and its incidence may exceed 80% after a few years of administration. Hyperostosis is axial, located in the cervical and thoracic spine, and may be responsible for limitation of movement; in the appendicular bone, enthesopathies occur at the foot, pelvis, hip, and less commonly the shoulder and elbow. They are usually mild and asymptomatic. The radiological appearance is very similar to diffuse idiopathic skeletal hyperostosis. Isotretinoin tends to be responsible for axial involvement, etretinate for peripheral locations. The other skeletal side-effects are uncommon and include periosteal proliferation, calcification of the interosseous membrane of the forearm and diffuse radiological bone hyperlucency. In children, premature epiphyseal closure is very rare. About 20% of patients complain of musculoskeletal pain and arthralgias. A few cases of true arthritis have been reported. Retinoids may be responsible for muscular damage and an abnormality of muscular tone resembling the stiff-man syndrome. Some cases of necrotizing vasculitis and three cases of Wegener's granulomatosis have been observed in patients treated with retinoids. Except for these latter arguable cases, rheumatoid syndromes due to retinoids are rather benign, and should not be an obstacle to the future development of their therapeutic utilization.

The negligible systemic availability of retinoids with multiple and excessive topical application of isotretinoin 0.05% gel (Isotrex) in patients with acne vulgaris

The potential systemic availability of retinoids from topically applied isotretinoin was assessed in 12 men with acne vulgaris. Isotretinoin 0.05% gel was applied to patients at a daily dose of 20 gm (equivalent to 10 mg of isotretinoin) over a 1900 cm2 surface area of skin on the face, back, and chest for 30 days. Blood samples were collected throughout the study and up to 48 hours after the last topical application; they were assayed for isotretinoin, tretinoin, and 4-oxo-isotretinoin by specific high-performance liquid chromatography. Plasma concentrations of isotretinoin, tretinoin, and 4-oxo-isotretinoin were not measurable (less than 20 ng/ml) at any time. Most adverse experiences were cutaneous; a few systemic adverse experiences were judged to be remotely related to topical drug administration. The lack of measurable plasma concentrations of isotretinoin, tretinoin, or 4-oxo-isotretinoin and systemic adverse experiences indicates negligible systemic availability of retinoids even after multiple application of isotretinoin 0.05% gel at doses approximately 12 times greater than normal daily use.

Multiple keratoacanthomas treated with oral retinoids

Multiple eruptive keratoacanthoma of Witten and Zak is a rare disorder characterized by numerous small, eruptive tumors and larger, more typical keratoacanthomas. Affected patients have features of Grzybowski-type keratoacanthomas and Ferguson Smith type. Two patients with multiple keratoacanthomas were treated with oral retinoids. Both patients had hundreds of follicular papules on the trunk and extremities. Less common lesions included nodules with central horn-filled craters more characteristic of classic keratoacanthomas. Retinoid therapy resulted in regression of the larger, more typical keratoacanthomas in both patients. The small follicular keratoacanthomas remained unaffected. Thus oral retinoids are only partially beneficial for the treatment of the Grzybowski type or the Witten and Zak type of multiple eruptive keratoacanthomas.

Effects of retinoids on DNA synthesis of pig epidermis: its relation to epidermal beta-adrenergic adenylate cyclase response and to epidermal superoxide dismutase activity

It has been suggested that the epidermal beta-adrenergic adenylate cyclase response and the epidermal superoxide dismutase (SOD) activity is inversely associated with keratinocyte cell proliferation. Effects of various retinoids on the thymidine incorporation of pig epidermis were compared with their effects on the beta-adrenergic response and the SOD activity. Following 24 h incubation with synthetic retinoids (etretin and E-5166 (3,7,11,15-tetramethyl-2,4,6,10,14-hexadecapentaenoic acid)), thymidine incorporation of epidermis was significantly decreased. The effect of etretin was more potent than that of E-5166; the former revealed the inhibitory effect at lower concentrations than the latter. The effect of etretinate was not statistically significant. Following the 24 h incubation with the synthetic retinoids, the epidermal beta-adrenergic adenylate cyclase responses were increased. Etretin was again more potent than E-5166, while etretinate showed also little effect on the beta-adrenergic response of epidermis. Thus the inhibitory effect on the thymidine incorporation was inversely correlated with the beta-adrenergic augmentation effect among these synthetic retinoids. On the other hand, physiologic retinoids (retinol and retinoic acid) revealed no correlation between these two parameters; whereas both compounds decreased the thymidine incorporation to a similar extent, only retinoic acid revealed a marked beta-adrenergic augmentation effect. Decreased SOD activity has been observed in various hyperproliferative epidermis. The SOD activity, however, was totally unaffected by the retinoid-treatments.

Hepatic toxicity of vitamin A and synthetic retinoids

Vitamin A and synthetic retinoids have recently been used increasingly in a variety of health related concerns. Hepatic toxicity is an uncommon but serious side-effect of several Vitamin A derivatives which may lead to cirrhosis. This review will focus on the clinical and pathologic findings of hepatic involvement in chronic hypervitaminosis A and on the evidence concerning the potential hepatotoxicity of currently available synthetic retinoids.