Retinoid Teratogenicity Research Articles

The Awareness of and Adherence to the Pregnancy Prevention Program for Oral Retinoids: A Questionnaire Survey in Denmark.

We aimed to investigate the awareness of oral retinoid teratogenicity and the adherence to the pregnancy prevention program (PPP) related to oral retinoid use by physicians, pharmacists, and patients in Denmark. As part of the multi-country survey, web-based questionnaires were distributed among Danish dermatologists, general practitioners, community pharmacists, and women of childbearing age, who were using or had used oral retinoids within the past 5 years. A total of 62 physicians, 96 pharmacists, and 50 oral retinoid using women responded; 95%, 100%, and 98%, respectively, were aware of the teratogenic risks of oral retinoids. For physicians, the most applied PPP measures were the usage of the patient (44%) and the healthcare professional (19%) guides, while the least applied measure was signing medication risk awareness form (3%). Among the pharmacists, the warning sign on the outer medication package was the most used measure (45%). Among the women, a majority (90%) had read the patient information leaflet included in the medication package and 72% discussed the use of contraception with their healthcare provider, while risk awareness forms and patient cards were seen by only few. In Denmark, physicians, pharmacists, and medicine users were aware about the teratogenic effects of oral retinoids. Adherence to pregnancy preventionmeasures varied, suggesting unwillingness to use the measures that require patients' signatures among physicians and a lack of awareness of pharmacy targeting measures. Accessibility of the latter measures need to be optimized to improve the safety of oral retinoid use.

Abstracts 13th PCNE Working Conference “Pharmacies' new roles in pharmaceutical care: bridging research and practice”

Abstracts 13th PCNE Working Conference “Pharmacies' new roles in pharmaceutical care: bridging research and practice”

The Origin of Teratogenic Retinoids in Cyanobacteria.

Although information about the occurrence and distribution of retinoids in the environment is scarce, cyanobacterial water blooms have been identified as a significant source of these small molecules. Despite the confirmed presence of retinoids in the freshwater blooms dominated by cyanobacteria and their described teratogenic effects, reliable identification of retinoid producers and the mechanism of their biosynthesis is missing. In this study, the cultures of several taxonomically diverse species of axenic cyanobacteria were confirmed as significant producers of retinoid-like compounds. The consequent bioinformatic analysis suggested that the enzymatic background required for the biosynthesis of all-trans retinoic acid from retinal is not present across phylum Cyanobacteria. However, we demonstrated that retinal conversion into other retinoids can be mediated non-enzymatically by free radical oxidation, which leads to the production of retinoids widely detected in cyanobacteria and environmental water blooms, such as all-trans retinoic acid or all-trans 5,6epoxy retinoic acid. Importantly, the production of these metabolites by cyanobacteria in association with the mass development of water blooms can lead to adverse impacts in aquatic ecosystems regarding the described teratogenicity of retinoids. Moreover, our finding that retinal can be non-enzymatically converted into more bioactive retinoids, also in water, and out of the cells, increases the environmental significance of this process.

Teratogenicity of retinoids detected in surface waters in zebrafish embryos and its predictability by in vitro assays.

Retinoids are newly detected compounds in aquatic ecosystems associated with cyanobacterial water blooms. Their potential health risks are only scarcely described despite numerous detections of all-trans retinoic acid (ATRA) and its derivatives in the environment. Besides the known teratogen ATRA there is only little or no information about their potency and namely their effects in vivo. We characterize ATRA and 8 other retinoids reported to occur in the environment for their bioactivity and teratogenicity using four in vitro reporter gene assays and zebrafish (Danio rerio) embryotoxicity assay. Our results document the ability of these compounds to interfere with retinoid signalling and cause teratogenicity at environmentally relevant levels with EC50 values at nM (hundreds of ng/L) levels and teratogenic indexes ranging from 2.8 (9cis retinoic acid) to 15.8 (retinal). The relative potency of individual compounds for teratogenicity ranged from 0.059 (retinal) to 0.96 (5,6-epoxy ATRA) when compared to ATRA. An environmentally relevant mixture of retinoids was tested showing good predictability of teratogenicity from the in vitro activities and additive toxicity of the mixture. The high teratogenicity of the newly described compounds associated with cyanobacteria presents a concern for developmental stages due to high conservation of the retinoid signalling across vertebrates.

Nuclear retinoid receptors and pregnancy: placental transfer, functions, and pharmacological aspects.

Animal models of vitamin A (retinol) deficiency have highlighted its crucial role in reproduction and placentation, whereas an excess of retinoids (structurally or functionally related entities) can cause toxic and teratogenic effects in the embryo and foetus, especially in the first trimester of human pregnancy. Knock-out experimental strategies-targeting retinoid nuclear receptors RARs and RXRs have confirmed that the effects of vitamin A are mediated by retinoic acid (especially all-trans retinoic acid) and that this vitamin is essential for the developmental process. All these data show that the vitamin A pathway and metabolism are as important for the well-being of the foetus, as they are for that of the adult. Accordingly, during this last decade, extensive research on retinoid metabolism has yielded detailed knowledge on all the actors in this pathway, spurring the development of antagonists and agonists for therapeutic and research applications. Natural and synthetic retinoids are currently used in clinical practice, most often on the skin for the treatment of acne, and as anti-oncogenic agents in acute promyelocytic leukaemia. However, because of the toxicity and teratogenicity of retinoids during pregnancy, their pharmacological use needs a sound knowledge of their metabolism, molecular aspects, placental transfer, and action.

Role of the 585-nm pulsed dye laser in the treatment of acne in comparison with other topical therapeutic modalities

Background: Acne vulgaris is a disease of the pilosebaceous unit characterized by the development of inflammatory and/or non-inflammatory lesions that may progress to scars. The increase of bacterial resistance and adverse effects, the teratogenicity of retinoids and lack of response to usual therapies has led to the investigation of new therapeutic alternatives. Objective: To evaluate the role of the pulsed dye laser in the treatment of acne in comparison with other topical therapeutic modalities. Methods: We studied 45 patients with mild to moderate acne. Patients were randomly divided into three groups: group A received treatment with pulsed dye laser therapy every 2 weeks, group B received topical preparations and group C was subjected to chemical peeling using trichloroacetic acid 25%. Results: At 12 weeks of treatment, there was a significant improvement of the lesions within each group with the best results seen in group A; however, no significant difference was detected between the three treatment protocols after the treatment period. Remission in the follow-up period was significantly higher in the first group. Conclusions: Pulse dye laser therapy mainly improves the inflammatory lesions of acne with few adverse effects.

Retinoic Acid Receptor Gamma-Induced Misregulation of Chondrogenesis in the Murine Limb Bud In Vitro

Vitamin A derivatives modulate gene expression through retinoic acid and rexinoid receptor (RAR/RXR) heterodimers and are indispensable for limb development. Of particular interest, RARgamma is highly expressed in cartilage, a target affected following retinoid-induced limb insult. The goal of this study was to examine how selective activation of RARgamma affects limb development. Forelimbs from E12.5 CD-1 mice were cultured for 6 days in the presence of all-trans RA (pan-RAR agonist; 0.1 or 1.0 microM) or BMS-189961 (BMS961, RARgamma-selective agonist; 0.01 or 0.1 microM) and limb morphology assessed. Untreated limbs developed normal cartilage elements whereas pan-RAR or RARgamma agonist-treated limbs exhibited reductive effects on chondrogenesis. Retinoid activity was assessed using RAREbeta2 (retinoic acid response element beta2)-lacZ reporter limbs; after 3 h of treatment, both drugs increased retinoid activity proximally. To elucidate the expression profiles of a subset of genes important for development, limbs were cultured for 3 h and cRNA hybridized to osteogenesis-focused microarrays. Two genes, matrix GLA protein (Mgp; chondrogenesis inhibitor) and growth differentiation factor-10 (Gdf10/Bmp3b) were induced by RA and BMS-189961. Real-time PCR was done to validate our results and whole mount in situ hybridizations against Mgp and Gdf10 localized their upregulation to areas of cartilage and programmed cell death, respectively. Thus, our results illustrate the importance of RARgamma in mediating the retinoid-induced upregulation of Mgp and Gdf10; determining their roles in chondrogenesis and cell death will help further unravel mechanisms underlying retinoid teratogenicity.

Láser de colorante pulsado en el tratamiento del acné. Estudio de la eficacia clínica y mecanismo de acción

Introduction Acne vulgaris is a multifactorial disease of the pilosebaceous unit characterized by the development of inflammatory (papules, pustules, cysts) and/or non inflammatory lesions (open and closed comedones) that may progress to scars. The increase of bacterial resistances, adverse effects and teratogenicity of retinoids and lack of response to usual therapies have led to investigate new therapeutic alternatives for acne. Material and method We studied 36 patients with mild to moderate acne vulgaris. We performed treatment every 4 weeks using pulsed dye laser therapy with a wavelength of 585 nm and pulse duration of 350 microseconds. Results At twelve weeks of treatment a decrease of 27 % of non inflammatory lesions and of 57 % of active lesions was observed. Treatment was well tolerated and considered positive, in terms of healing, in 25 patients. Conclusions Pulse dye laser therapy mainly improves inflammatory lesions of acne with few adverse effects.

Pulsed Dye Laser Treatment of Acne. Study of Clinical Efficacy and Mechanism of Action

Introduction Acne vulgaris is a multifactorial disease of the pilosebaceous unit characterized by the development of inflammatory (papules, pustules, cysts) and/or non inflammatory lesions (open and closed comedones) that may progress to scars. The increase of bacterial resistances, adverse effects and teratogenicity of retinoids and lack of response to usual therapies have led to investigate new therapeutic alternatives for acne. Material and method We studied 36 patients with mild to moderate acne vulgaris. We performed treatment every 4 weeks using pulsed dye laser therapy with a wavelength of 585 nm and pulse duration of 350 microseconds. Results At twelve weeks of treatment a decrease of 27% of non inflammatory lesions and of 57% of active lesions was observed. Treatment was well tolerated and considered positive, in terms of healing, in 25 patients. Conclusions Pulse dye laser therapy mainly improves inflammatory lesions of acne with few adverse effects.

Casting a Broad Network: Fishing for Mechanisms of Retinoid Teratogenicity

Casting a Broad Network: Fishing for Mechanisms of Retinoid Teratogenicity

Retinoid teratogenicity in the macaque: verification of dosing regimen.

To further define teratogenicity associated with 13-cis-retinoic acid (13-cis-RA) in the cynomolgus monkey, the drug was orally administered on three different treatment regimens. Experiment (Exp.) 1 (2.5 mg/kg/day, gestational day [GD] 12-27, n = 11) investigated the teratogenicity of a single daily dose of 13-cis-RA administered shortly after embryo implantation. Pharmacokinetic sampling was done to determine retinoid profiles on the first (GD12) and last (GD27) days of treatment. Exposure to 13-cis-RA during early organogenesis in Exp. 2 (2.5 mg/kg/day, GD20-27, and 2 x 2.5 mg/kg/day, GD28-30, n = 5) investigated the potential adverse effects of 13-cis-RA on the developing limb. The use of multiple doses of 13-cis-RA in Exp. 3 (2 x 2.5 mg/kg/day, GD26-27, n = 5) investigated the necessity of double dosing on the induction of retinoid embryopathy in the macaque. Malformations of retinoid target organs as well as embryolethality were most prevalent when single daily doses of 13-cis-RA were administered during pre- and early organogenesis in Exp. 1. Moreover, multiple doses on GD26-27 failed to induce any manifestation of abnormal development in Exp. 3. These results confirm that the lowest observed adverse effect level (LOAEL) in macaques is 2.5 rather than 5.0 times greater than that observed in human pregnancies. Exposure during forelimb development (GD20-30) in Exp. 2 was unsuccessful in inducing defects of this skeletal region, although defects in several retinoid target organs (i.e., cerebellum and internal ear) were present, indicating that a teratogenic threshold was achieved. Pharmacokinetic analysis of 13-cis-RA and its metabolites on GD12 and 27 in Exp. 1 showed considerable exposure to the administered drug and its 4-oxo-metabolite. In contrast, the exposure to all-trans-RA was negligible. The results support the use of a specific treatment schedule in early gestation in the macaque as the most appropriate model for characterizing the teratogenic potential of retinoids in humans.

Co-oxidation of all-trans retinol acetate by human term placental lipoxygenase and soybean lipoxygenase

The oxidation of all-trans retinol acetate (t-RAc) mediated by soybean lipoxygenase (SLO) and affinity purified human term placental lipoxygenase (HTPLO) was investigated. Under optimum assay conditions, SLO, which is used as a model enzyme, exhibited a specific activity of 850 nmol of t-RAc depleted/min/nmol of enzyme. For HTPLO, incubation of 100 μM t-RAc, 2 mM linoleic acid, and 50 μg of enzyme protein in Tris buffer at pH 9.0 was essential to observe the optimum rate of t-RAc cooxidation (370 nmol of t-RAc depleted/ min/mg protein). The linoleate dependent cooxidation of t-RAc by both SLO and HTPLO was significantly inhibited by micromolar concentrations of nordihydroguaiaretic acid, butylated hydroxytoluene, butylated hydroxyanisole, gossypol, and 5,8,11-eicosatriynoic acid. These results suggest that t-RAc is metabolized via the lipoxygenase pathway. Significant rate of t-RAc oxidation by HTPLO observed in this study suggests that it may constitute an important part of the puzzle worthy of consideration in the understanding of retinoid teratogenicity in humans.

Major adverse effects from systemic drugs: Defining the risks

This review covers the most important adverse effects from systemic drugs prescribed by dermatologists. The emphasis is on major adverse effects from these drugs that are either life-threatening or more commonly may lead to significant, irreversible morbidity. In descending order of relative risk for a fatal outcome or persistent morbidity, the major adverse effects discussed are dapsone agranulocytosis, methotrexate pancytopenia, retinoid teratogenicity, corticosteroid osteonecrosis, immunosuppression carcinogenesis, methotrexate hepatotoxicity, cyclosporine nephrotoxicity, azathioprine agranulocytosis and pancytopenia, corticosteroid osteoporosis, retinoid bone toxicity, corticosteroid hypothalamic—pituitary—adrenal axis suppression, and corticosteroid growth suppression. The great majority of these adverse effects are preventable, are diagnosable at an early, reversible stage, or can be readily managed should the complication occur. Furthermore, after carefully reviewing reports on the occasional fatal outcomes from the adverse effects discussed in this review, I believe virtually all deaths could have been prevented with careful attention to definable risk factors and with proper monitoring measures. Overall, the goal of this review is to bring clinicians to a proper level of concern regarding the risks from these drugs, while allowing safe use of potentially risky systemic drugs to the benefit of patients with serious and important skin conditions.

Transplacental pharmacokinetics of a synthetic retinoid which is not bound by mouse embryonic cellular retinoic acid-binding protein

Teratogenicity is a major side effect ofretinoids, a class of compounds used in dermatology and oncology. The binding of retinoids to cellular retinoic acid-binding protein (CRABP) has been suggested to be important for the mechanism of retinoid embryopathy. Here data are presented on the transplacental pharmacokinetics of CD394 (4-(3-(1-adamantyl)-4-methoxybenzamido] benzoic acid) which does not bind to murine embryonic CRABP, although it is active in rat whole embryo culture and teratogenic in the rabbit in vivo. A single intragastric dose of CD394 (10 mg/kg) was administered to mice on day 11 of gestation. The extent of placental transfer of CD394, determined by HPLC, resembled more that of 13-cis-retinoic acid which also does not bind to CRABP, than that of the CRABPbinding all-trans-retinoic acid. C Max values of CD394 obtained after 1–2 h were: 1368 ± 652 ng/ml for plasma, 203 ± 132 ng/g for embryo and 856 ± 563 ng/g for placenta. AUC (area-under-the-concentration-time-curve) values (0–12 h) were: 4319 ng × h/ml for plasma, 751 ng × h/g for embryo and 3163 ng × h/g for placenta. Thus, CD394 reached the embryo, although embryonic AUC values were less than one fifth of the maternal plasma AUC values. CD394 did not alter endogenous retinol concentrations in plasma, embryo, yolk sac or placenta. Our results indicate that CD394 reaches the embryo in vivo without binding to CRABP, although embryonic concentrations stayed well below plasma levels. This supports the opinion that binding to embryonic CRABP is not a prerequisite for reaching effective embryo concentrations and for the teratogenicity of retinoids.

Localization of CRABP‐I and CRABP‐II mRNA in the early mouse embryo by whole‐mount in situ hybridization: Implications for teratogenesis and neural development

Retinoic acid (RA) has been implicated in vertebrate neural pattern formation. In this paper we analysed the expression patterns of the cellular retinoic acid binding proteins (CRABP-I and II) during early morphogenesis in normal and RA-treated mouse embryos by whole-mount in situ hybridization. This technique allowed a detailed analysis of the spatial and temporal changes in mRNA expression pattern. Both CRABPs were expressed in a rhombomere specific pattern; putative neural crest cells in the branchial arches expressed the CRABPs at levels corresponding to the rhombomere from which they were derived. CRABP-II, but not CRABP-I, was expressed in the neural epithelium caudal to the hindbrain. CRABP-I is strongly expressed in a fine net-like pattern which extends from the caudal diencephalon to the rostral hindbrain and remains predominantly dorsal to the lateral midline of the neural tube. This network corresponds to the pattern formed by the putative first axons of the embryonic mouse brain which are produced by the developing neurons of the mesencephalic nucleus of the trigeminal nerve. Although the expression of CRABP-I was unaffected by a teratogenic dose of RA, CRABP-II expression was increased slightly with no alteration in the normal spatial or temporal boundaries. These results support the suggestion that the CRABPs may play an important role in modulating endogenous RA levels, particularly in the developing nervous system and its neural crest derivatives. Furthermore, the limited ability of CRABP mRNA levels to respond to exogenous retinoids may be a factor in retinoid teratogenicity.

A retinoic acid receptor α antagonist counteracts retinoid teratogenicity in vitro and reduced incidence and/or severity of malformations in vivo

The role of retinoic acid receptors (RAR) in retinoid-induced teratogenesis is mainly unknown. The aim of the present studies was to demonstrate the effect of a RARα antagonist on retinoid-induced teratogenic effects in vitro and in vivo. In micromass cultures of rat limb bud cells a RARα antagonist was able to counteract differentiation inhibiting effects of a RARα agonist. In mouse studies, the selective RARα antagonist reduced frequency and/or severity of major malformations. Our observations indicate the potentiality of selective RAR agonists and antagonists in dissecting the function of nuclear receptors and in particular cases of retinoid teratogenesis, to assign to the different receptors a primary role in determining one or another of the multiple malformations.

Infant mortality: The role of the macaque as a model for human disease

Factors which have been identified as the leading causes of infant mortality include birth defects, hemoglobinopathies, prematurity, and Sudden Infant Death Syndrome (SIDS). In order to further our understanding of the specific causes of infant mortality and the mechanisms by which they occur, suitable animal models will be required. Studies with nonhuman primates (specifically the macaque) have addressed malformation/functional deficit syndromes such as those associated with Fetal Alcohol Syndrome (FAS), nutritional deficiencies, and retinoid teratogenicity. These studies have provided critical information for further basic and preventive research. In addition, efforts to evaluate the safety of diagnostic ultrasound continue to aid in identifying safe methods for exposure. From a prenatal perspective, cellular transplantation has been shown to be a feasible method for treating individuals with inherited defects in utero, thereby avoiding postnatal transplantation and the associated risks. Longterm complications of prematurity have also been pursued with growth factors (i.e., epidermal growth factor) noted to play an important role in both pre- and postnatal development of the gastrointestinal tract and lung. As one of the most distressing causes of death in infancy, SIDS will require a concentrated effort to understand the basic mechanism(s) responsible for the characteristic respiratory complications. The nonhuman primate will continue to provide critical information as the model of choice for the human in determining the causes, mechanisms, and treatments for these significant causes of infant death. © 1994 Wiley-Liss, Inc.

Induction of RAR-β2 Gene Expression in Embryos and RAR-β2 Transactivation by the Synthetic Retinoid Ro 13-6307 Correlates with Its High Teratogenic Potency

Vitamin A (retinol), its metabolite all-trans retinoic acid (RA), and many synthetic analogs (retinoids) express variable potencies as teratogens. Although biological activities of retinoids are mediated by nuclear RA receptors (RARs) and retinoid X receptors (RXRs), it is not known if any of these receptors mediate teratogenicity, and if the potency also depends on the nature of the ligand-receptor interactions. Previous evidence has implicated that one specific isoform, RAR-β2, does play a role in mediating retinoid teratogenicity. Here, we employed an aromatic retinoid with a triene side chain, Ro 13-6307, to study its interactions with RAR-β2 since its teratogenicity is much higher and its accessibility to the embryo is much lower than RA. A fully teratogenic dose of Ro 13-6307 (10 mg−kg) given to pregnant mice preferentially elevated the level of RAR-β2 mRNA in susceptible embryonic regions (maximal induction, 10- to 12-fold above control in limb buds) in a manner comparable to a fully teratogenic dose of all-trans RA (100 mg−kg). Using the RAR-β2 promoter linked to a reporter gene in cotransfection experiments, the efficacy of Ro 13-6307 and RAR-β2 in transcription transactivation was found to be 30-40 times greater than all-trans RA. Since the teratogenic potency of Ro 13-6307 is estimated from a previous study to be 44-fold greater than all-trans RA, we suggest that the teratogenicity of this synthetic retinoid is generally proportional to its ability to enhance receptor function.

Whole embryo culture and teratogenesis

Whole embryo culture (WEC) is under evaluation in numerous laboratories to determine the role it should play in teratogen testing. There is general agreement that its role is to complement the Segment II Teratology studies required by regulatory authorities. Currently it is used as a 'screen' in order to minimize the number of compounds used in animal tests and also to determine the mechanism(s) of teratogenesis. This brief review focuses on the study of retinoid teratogenicity in WEC in order to illustrate these points.

Computer Automated Structure Evaluation (CASE) of the teratogenicity of retinoids with the aid of a novel geometry index

The CASE (Computer Automated Structure Evaluation) program, with the aid of a geometry index for discriminating cis and trans isomers, has been used to study a set of retinoids tested for teratogenicity in hamsters. CASE identified 8 fragments, the most important representing the non-polar terminus of a retinoid with an additional ring system which introduces some rigidity in the side chain. The geometry index helped to identify relevant fragments with an all-trans configuration and to distinguish them from irrelevant fragments with other configurations.