Tazarotenic Acid Research Articles

Formulation development of tazarotene-loaded PLGA nanoparticles for follicular delivery in the treatment of inflammatory skin diseases

Tazarotene is a widely prescribed topical retinoid for acne vulgaris and plaque psoriasis and is associated with skin irritation, dryness, flaking, and photosensitivity. In vitro permeation of tazarotene was studied across the dermatomed human and full-thickness porcine skin. The conversion of tazarotene to the active form tazarotenic acid was studied in various skin models. Tazarotene-loaded PLGA nanoparticles were prepared using the nanoprecipitation technique to target skin and hair follicles effectively. The effect of formulation and processing variables on nanoparticle properties, such as particle size and drug loading, was investigated. The optimized nanoparticle batches with particle size <500 µm were characterized further for FT-IR analysis, which indicated no interactions between tazarotene and PLGA. Scanning electron microscopy analysis showed uniform, spherical, and non-agglomerated nanoparticles. In vitro release study using a dialysis membrane indicated a sustained release of 40–70 % for different batches over 36 h, following a diffusion-based release mechanism based on the Higuchi model. In vitro permeation testing (IVPT) in full-thickness porcine skin showed significantly enhanced follicular and skin delivery from nanoparticles compared to solution. The presence of tazarotenic acid in the skin from tazarotene nanoparticles indicated the effectiveness of nanoparticle formulations in retaining bioconversion ability and targeting follicular delivery.

Transdermal Drug Delivery of Tazarotene: Determining Tazarotene's Potential in Local Transdermal Therapy.

Retinoid-based drugs, while effective, are associated with systemic toxicity. Topical alternatives offer a safer option, and tazarotene, a third-generation synthetic retinoid, holds promise. This study investigates tazarotene's transdermal delivery potential, focusing on its application for joint-related conditions. The aim of this study was to investigate the suitability of tazarotene as a candidate for transdermal delivery into joints. In vitro permeation studies, using porcine skin, assessed tazarotene's transdermal drug delivery from solution and gel formulations. A tape-stripping analysis determined stratum corneum retention and a pilot study using porcine joints assessed tazarotene's ability to reach articular cartilage. Ultra Performance Liquid Chromatography coupled with a mass detector method was used to quantify tazarotene and tazarotenic acid permeation. The results validate that tazarotene can permeate porcine skin and accumulate in articular cartilage in detectable amounts. The detection of tazarotene and tazarotenic acid in both the in vitro permeation studies and the pilot study on porcine joints validate the drug's potential therapeutic use for hand osteoarthritis. This study lays the groundwork for future research, contributing insights into tazarotene's potential for transdermal drug delivery and guiding further exploration in topical retinoid applications.

Simultaneous determination of tazarotene, clindamycin phosphate and their active metabolites in Bama mini-pig skin by LC-MS/MS: Application to the development of a tazarotene/clindamycin phosphate cream

Topical tazarotene combined with clindamycin phosphate can significantly improve the adherence and outcomes for the treatment of acne vulgaris than monotherapy, a novel tazarotene (0.05%)/clindamycin phosphate (1.2%) cream is thus developed. However, the pharmacokinetics and potential interaction of tazarotene and clindamycin phosphate in skin when formulated together remain unknown, which should be investigated to assess this novel cream. In the present work, a sensitive and rapid LC-MS/MS method for simultaneous determination of tazarotene, clindamycin phosphate and their active metabolites tazarotenic acid, clindamycin in Bama mini-pig skin was developed and reported for the first time. After pretreatment of the skin samples, the analytes were well separated on a Hypersil BDS C8 column (4.6 × 100 mm, 2.4 μm) using 0.2% (v/v) formic acid-0.1% (w/v) ammonium acetate water solution and acetonitrile as mobile phase in linear gradient elution. Quantification of tazarotene, clindamycin phosphate and their active metabolites tazarotenic acid, clindamycin was conducted under positive electrospray ionization mode using multiple reactions monitoring detection. The LC-MS/MS method was fully validated and then applied to the dermal pharmacokinetic study of the tazarotene/clindamycin phosphate cream. According to the obtained results, tazarotene and clindamycin phosphate did not have any drug-drug interaction when they were formulated together in the cream for topical application. Their absorption and metabolism features in the skin were also characterized, which can support the clinical medication regimen of tazarotene/clindamycin phosphate cream.

Determination of clobetasol propionate, tazarotene and tazarotenic acid in Bama mini-pig skin by UPLC-MS/MS: Application to pharmacokinetic and drug-drug interaction studies

Tazarotene and clobetasol propionate are efficacious for the treatment of psoriasis. The plasma pharmacokinetic assessments of tazarotene or clobetasol propionate have been reported. However, the pharmacokinetic characteristics of tazarotene and clobetasol propionate in skin when used together have not been studied. In the present study, sensitive and rapid methods were developed for the determination of clobetasol propionate, tazarotene and its active metabolite tazarotenic acid in Bama mini-pig skin by UPLC-MS/MS. After homogenization and pretreatment of skin samples, the separation was performed on a WondaSiL C18 column (4.6 × 150 mm, 5 μm) for tazarotene and clobetasol propionate. The separation of tazarotenic acid was achieved on a BDS HYPERSIL C18 column (4.6 × 100 mm, 2.4 μm). All the analytes were quantified with positive electrospray ionization and multiple reactions monitoring mode. The assay was validated in the range of 22-1111 ng/g for tazarotene and clobetasol propionate, 2-111 ng/g for tazarotenic acid in skin samples. The methods were fully validated to meet the requirements for bioassay in accuracy, precision, recovery, reproducibility, stabilities and matrix effects, and successfully applied to evaluate the novel combination ointment of tazarotene and clobetasol propionate. The obtained intradermal content-time curves characterized the dermal absorption and metabolism features of the combination ointment. It was also found that there was no significant drug-drug interaction trend between tazarotene and clobetasol propionate. The obtained results would be essential for the development and clinical applications of this novel combination ointment.

Insights into the degradation chemistry of tazarotene, a third generation acetylenic retinoid: LC-HRMS (Orbitrap), LC-MSn and NMR characterization of its degradation products, and prediction of their physicochemical and ADMET properties

Tazarotene is a prodrug that belongs to the acetylenic class of retinoids. The drug was subjected to hydrolytic, oxidative and photolytic stress testing to establish its comprehensive degradation chemistry. The drug proved to be unstable under acidic and basic hydrolytic conditions, yielding tazarotenic acid, which is a known major degradation product (DP) and an active metabolite. Additionally, two DPs each were generated upon interaction of drug and tazarotenic acid with HCl, used as an acid stressor. These were experimentally proven as pseudo DPs, as they did not originate when H2SO4 was employed as the stressor. The drug was also unstable under oxidative and photolytic conditions, yielding six DPs. All the products were separated on reversed phase (C18) column, using mobile phase composed of 10 mM ammonium formate (pH 3.5) and acetonitrile, which was run in a gradient mode. The separated DPs were subjected to LC-HRMS and LC-MSn studies for their initial characterization. Seven hydrolytic and oxidative DPs that could be isolated using semi-preparative column were subjected to extensive 1D (1H, 13C and DEPT-135) and 2D (COSY, HSQC and HMBC) NMR studies to confirm their structures. In total, five novel DPs were characterized, apart from two previously reported DPs, viz., tazarotenic acid and tazarotene sulfoxide, and four additional pseudo DPs. The complete degradation pathway of the drug was established. In silico ADMET properties of the drug and its DPs were evaluated using ADMET Predictor™.

Application of an In Vitro Psoriatic Skin Model to Study Cutaneous Metabolization of Tazarotene

Psoriasis is an inflammatory skin disease characterized by the presence of whitish and scaly plaques, which can cover up to 90% of the body surface. These plaques result from the hyperproliferation and abnormal differentiation of keratinocytes. Dermopharmaceutical testing of new therapies is limited by healthy and pathological skin models, which are not closely enough mimicking their in vivo counterparts. In this study, we exploited percutaneous absorption and Ultra Performance Liquid Chromatography (UPLC) analyses in order to determine the metabolic capacity of our psoriatic skin model. Skin substitutes were reconstructed according to the self-assembly method and tested regarding their percutaneous absorption of a topical formulation of tazarotene, followed by UPLC analyses. Histological and immunofluorescence analyses confirmed both the healthy and psoriatic phenotypes. Results from percutaneous absorption showed a significant level of tazarotene metabolite (tazarotenic acid) when the formulation was applied over 24 h on the skin substitutes. The presence of tazarotenic acid in the dermis and the epidermis of healthy and psoriatic skin substitutes confirms the metabolic capacity of both skin models, and thereby their ability to screen new molecules with antipsoriatic potential. In conclusion, the present data suggest that our psoriatic skin model could possibly be used in clinic to screen in vitro responses of patient to a panel of drugs without having them experiencing the drawback of each drug.

Development of a simple method for simultaneous determination of tazarotene and betamethasone dipropionate and their metabolites using LC-MS method and its application to dermatopharmacokinetic study.

In our study, a method for the determination for tazarotene and betamethasone dipropionate in human tissue-engineered skin was established. Tazarotene gel, betamethasone dipropionate cream or a combination cream was administered to the skin. Then the skin was taken off at 0.25, 0.75, 1.75, 3, 5, 8, 12, 24, 36, 48 h time points after the residual drug was removed. The concentrations of tazarotene, betamethasone dipropionate and their major metabolites in skin were determined by LC-MS. Tazarotene and tazarotenic acid were detected in the concentration range of 2-200 μg/mL with an LLOQ of 2 μg/mL. Betamethasone dipropionate was detected in the concentration range 0.5-300 μg/mL with an LLOQ of 0.5 μg/mL, and betamethasone was detected at 2-200 μg/mL with an LLOQ of 2 μg/mL. The intra- and inter-day precisions of the four analytes in the skin homogenate were all <15% (RSD, %). The results showed that tazarotene could be metabolized to tazarotenic acid and betamethasone dipropionate could be metabolized to betamethasone in tissue-engineered skin. The results also revealed that this method was suitable for the simultaneous determination of tazarotene, betamethasone dipropionate and their metabolites in tissue-engineered skin.

Biochemical Effects of Retinoid Derivatives on Mesenchymal Stem Cells In Vitro

The studies we performed targeted the effects of all-trans retinol (vitamin A) and some retinoid derivatives (including tretinoin or all-trans retinoic acid, retinyl propionate, 9-cis retinoic acid, 13-cis retinoic acid), as well as of tazarotenic acid on apoptosis of rat mesenchymal stem cells, cultured after isolation. Tazarotenic acid is considered to be relatively selective and a potent agonist for RARb and RARg and less for RARa. The same time, tazarotenic acid is not binding to RXRs (retinoid X receptors). The relevant analysis of our experimental results demonstrated that 13-cis retinoic acid was the most potent inducer of apoptosis of cultured mesenchymal stem cells of rat origin when compared to other retinoid derivatives, as follows: 13-cis retinoic acid ] 9-cis retinoic acid ] tazarotenic acid ] all-trans retinoic acid ] retinyl propionate ] retinol (or vitamin A). Very interesting and unexpected were the apoptotic effects of 1 �M tazarotenic acid for 24 hours in our experiments, very close to those induced by all-trans retinoic acid (tretinoin). The apoptosis induced by 13-cis retinoic acid, a principal activator of RARb and RARg, and that induced by 9-cis retinoic acid, a major activator of RXRs, suggests different pathways activated by these retinoid derivatives.

Comparison of the ligand binding site of CYP2C8 with CYP26A1 and CYP26B1: a structural basis for the identification of new inhibitors of the retinoic acid hydroxylases

The CYP26s are responsible for metabolizing retinoic acid and play an important role in maintaining homeostatic levels of retinoic acid. Given the ability of CYP2C8 to metabolize retinoic acid, we evaluated the potential for CYP2C8 inhibitors to also inhibit CYP26. In vitro assays were used to evaluate the inhibition potencies of CYP2C8 inhibitors against CYP26A1 and CYP26B1. Using tazarotenic acid as a substrate for CYP26, IC50 values for 17 inhibitors of CYP2C8 were determined for CYP26A1 and CYP26B1, ranging from ∼20 nM to 100 μM, with a positive correlation observed between IC50s for CYP2C8 and CYP26A1. An evaluation of IC50’s versus in vivo Cmax values suggests that inhibitors such as clotrimazole or fluconazole may interact with CYP26 at clinically relevant concentrations and may alter levels of retinoic acid. These findings provide insight into drug interactions resulting in elevated retinoic acid concentrations and expand upon the pharmacophore of CYP26 inhibition.

Identification of Tazarotenic Acid as the First Xenobiotic Substrate of Human Retinoic Acid Hydroxylase CYP26A1 and CYP26B1.

Cytochrome P450 (CYP) 26A1 and 26B1 are heme-containing enzymes responsible for metabolizing all-trans retinoic acid (at-RA). No crystal structures have been solved, and therefore homology models that provide structural information are extremely valuable for the development of inhibitors of cytochrome P450 family 26 (CYP26). The objectives of this study were to use homology models of CYP26A1 and CYP26B1 to characterize substrate binding characteristics, to compare structural aspects of their active sites, and to support the role of CYP26 in the metabolism of xenobiotics. Each model was verified by dockingat-RA in the active site and comparing the results to known metabolic profiles ofat-RA. The models were then used to predict the metabolic sites of tazarotenic acid with results verified by in vitro metabolite identification experiments. The CYP26A1 and CYP26B1 homology models predicted that the benzothiopyranyl moiety of tazarotenic acid would be oriented toward the heme of each enzyme and suggested that tazarotenic acid would be a substrate of CYP26A1 and CYP26B1. Metabolite identification experiments indicated that CYP26A1 and CYP26B1 oxidatively metabolized tazarotenic acid on the predicted moiety, with in vitro rates of metabolite formation by CYP26A1 and CYP26B1 being the highest across a panel of enzymes. Molecular analysis of the active sites estimated the active-site volumes of CYP26A1 and CYP26B1 to be 918 Å(3)and 977 Å(3), respectively. Overall, the homology models presented herein describe the enzyme characteristics leading to the metabolism of tazarotenic acid by CYP26A1 and CYP26B1 and support a potential role for the CYP26 enzymes in the metabolism of xenobiotics.

Simultaneous determination of tazarotene and its active metabolite tazarotenic acid in minipig plasma by LC-MS/MS and its application in pharmacokinetic study after topical administration of tazarotene gel.

To study the systemic exposure of tazarotene formulation after topical administration, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous determination of tazarotene and tazarotenic acid in minipig plasma. Similar extraction recoveries for both analytes were obtained after the plasma samples were acidified by glacial acetic acid (5%) and extracted by ethyl ether-cyclohexane (4:1, v/v). Separation of the analytes was achieved within a short time by the addition of 0.1% formic acid to the mobile phase. Gradient elution was used to avoid the matrix effect. The method was linear over the concentration range of 10-600 pg/mL for both analytes. The data of intra- and inter-run precision and accuracy were lower than 5.2%, 7.3% and 7.3% for both analytes. The developed method can be applied to investigate the transdermal pharmacokinetics and the systemic exposure of tazarotene formulation after topical administration.

Evaluation of change in the skin concentration of tazarotene and betamethasone dipropionate based on drug–drug interaction for transdermal drug delivery in miniature pig

1. The present study was designed to investigate drug–drug interaction in a new combination cream which contains both tazarotene (TZRT) and betamethasone dipropionate (BTMSDP) by comparing the pharmacokinetic (PK) behaviors of TZRT, BTMSDP, and their major metabolites, tazarotenic acid (TZRTAC) and betamethasone (BTMS) with those in the commonly prescribed TZRT gel and BTMSDP cream.2. The trial was performed on six Bama mini-pigs. The different regions on the back side of each pig were randomly assigned to one of three treatment groups: TZRT 0.05% gel, BTMSDP 0.05% cream, and combination cream. The stratum corneum and epidermis–dermis samples were collected at various times after drug administration and analyzed for TZRT, TZRTAC, BTMSDP, and BTMS by LC-MS/MS. Compared with TZRT gel alone, TZRT + BTMSDP did not significantly change the PK profiles of TZRT; neither did BTMSDP + TZRT significantly change the PK profiles of BTMSDP, compared with the BTMSDP cream alone. In addition, the concentrations of TZRTAC and BTMS in most samples were below the lower limit of quantitation (LLOQ).3. The results suggest that there was no significant drug–drug interaction trend between TZRT and BTMSDP in the process of transdermal permeation of combination cream into the stratum corneum and epidermis–dermis of mini-pigs.

Tazarotene Foam versus Tazarotene Gel: A Randomized Relative Bioavailability Study in Acne Vulgaris

Tazarotene, a retinoid pro-drug, is available in gel, cream and foam for the topical treatment of acne vulgaris. This single-centre, randomized, open-label study assessed relative bioavailability of its active metabolite tazarotenic acid after dosing of tazarotene foam or gel. Subjects with moderate-to-severe acne received a mean, once-daily dose of 3.7 g tazarotene foam or gel applied to face, chest, upper back and shoulders. Blood samples were collected pre-dose on multiple days and multiple time points over a 72-h period to measure plasma tazarotenic acid and tazarotene. Mean tazarotenic acid area under the plasma concentration-time curve (AUC) and maximum measured plasma concentration (Cmax) values were significantly higher for gel versus foam. Cmax occurred within 5-6 h after dosing, with an apparent terminal elimination half-life (t½) of 18-22 h. Accumulation was observed upon repeated dosing with steady-state conditions achieved at day 20. Mean tazarotene concentrations were also higher following gel application versus foam. Both foam and gel demonstrated an acceptable safety profile. Tazarotene foam, 0.1 % is an alternative to gel with less systemic exposure.

Two-Photon Fluorescence Excitation Microscopy to Assess Transscleral Diffusional Pathways in an Isolated Perfused Bovine Eye Model

To assess the feasibility of using two-photon microscopy to study the pattern of diffusion through the sclera of a tracer (tazarotenic acid [TA]). Polyvinyl alcohol films containing 1% tazarotenic acid (PVA-TA) were applied to the equatorial sclera of isolated perfused bovine eyes. Two-photon microscopy (TPM) was used to determine the lateral spread and depth of penetration of TA in the sclera over time. Protein and collagen binding were determined, and calibration standards were prepared by TPM imaging at 10 μm depth in scleral samples that had been immersed for 24 hours in solutions of TA of 0.7, 7.0, or 70 μg/mL. TA was weakly bound to collagen and sclera (<55%) but strongly bound to plasma protein (95%). In perfused eyes, 50 minutes after PVA-TA application, peak fluorescence in the sclera was detected at a 210-μm depth. By 85 minutes after application of the PVA-TA film, fluorescence had disappeared from surface layers of the sclera and was at maximum at 250 to 290 μm. Penetration of the tracer followed the track of scleral collagen bundles rather than that of the proteoglycan ground substance between collagen bundles. TPM can image in real time the progressive diffusion of TA from its source in a PVA-TA film applied to the equatorial sclera of the isolated perfused bovine eye and follow its subsequent penetration deeper into the sclera. The data suggest that lateral spread and deeper penetration of the test compound occurred along the course of scleral collagen bundles. Imaging was possible to a depth of 340 μm, the average thickness of the human equatorial sclera.

Disposition and Biotransformation of the Acetylenic Retinoid Tazarotene in Humans

Oral tazarotene, an acetylenic retinoid, is in clinical development for the treatment of psoriasis. The disposition and biotransformation of tazarotene were investigated in six healthy male volunteers, following a single oral administration of a 6 mg (100 microCi) dose of [14C]tazarotene, in a gelatin capsule. Blood levels of radioactivity peaked 2 h postdose and then rapidly declined. Total recovery of radioactivity was 89.2+/-8.0% of the administered dose, with 26.1+/-4.2% in urine and 63.0+/-7.0% in feces, within 7 days of dosing. Only tazarotenic acid, the principle active metabolite formed via esterase hydrolysis of tazarotene, was detected in blood. One major urinary oxidative metabolite, tazarotenic acid sulfoxide, accounted for 19.2+/-3.0% of the dose. The majority of radioactivity recovered in the feces was attributed to tazarotenic acid representing 46.9+/-9.9% of the dose and only 5.82+/-3.84% of dose was excreted as unchanged tazarotene. Thus following oral administration, tazarotene was rapidly absorbed and underwent extensive hydrolysis to tazarotenic acid, the major circulating species in the blood that was then excreted unchanged in feces. A smaller fraction of tazarotenic acid was further metabolized to an inactive sulfoxide that was excreted in the urine.

A pilot study on the use of topical tazarotene to treat squamous cell carcinoma in situ

To the Editor: Tazarotene is the first of a new generation of acetylenic retinoids developed for the topical treatment of mild-to-moderate plaque psoriasis. It is a prodrug metabolized in the skin and plasma to tazarotenic acid, the active form.

Effects of tazarotene 0.1 % cream in the treatment of facial acnevulgaris: Pooled results from two multicenter, double-blind, randomized, vehicle-controlled, parallel-group trials

Background: Topical retinoids are one of the most effective classes of topical drugs used to treat acne vulgaris.The effects of the gel formulation of the topical retinoid tazarotene have been widely reported, but few data on the cream formulation are available. Objective: The primary aim of the 2 studies reported in this article was to determine the effects of tazarotene0.1 % cream in patients with facial acne vulgaris. Methods: Two randomized, double-blind, parallel-group studies were performed. The first was conducted at 14 investigational sites across the United States, and the second took place at 15 sites, with 5 of these providing blood samples for analysis of tazarotenic acid. In both studies, patients aged ≥12 years with facial acne vulgaris were randomized to receive tazarotene or vehicle cream QD for 12 weeks. Lesion counts (noninflammatory, inflammatory, and total) and overall clinical and global assessments were made at weeks 0 (baseline), 4, 8, and 12. Adverse events (AEs) were monitored throughout the study In one of the studies, therapeutic drug monitoring was performed at weeks 4 and 8 in members of the study population who gave consent for blood withdrawal. Results: Eight hundred forty-seven patients were enrolled in the 2 studies (430 males, 417 females; mean age,19 years; age range, 11–52 years [1 patient was entered into the study at age 11 years, in violation of the protocol]). At 12 weeks, the median percentage changes from baseline in all 3 lesion counts were significantly lower with tazarotene than with vehicle (all, P < 0.001), as were the overall clinical and global responses (both, P < 0.001). Treatment-related AEs whose incidence was higher with tazarotene than with vehicle included desquamation, dry skin, erythema, a burning sensation on the skin, and skin irritation (all, P < .001) and pruritus ( P < 0.01); most (83%–98%) were mild or moderate. Systemic exposure to tazarotenic acid was limited (mean, <0.1 ng/mL) and did not increase with time. Conclusions: In these 2 studies in adolescent and adult patients with facial acne vulgaris, tazarotene 0.1%cream QD for 12 weeks was effective and well tolerated. Systemic exposure to tazarotenic acid was limited.

Simple and convenient dosing is possible with oral tazarotene

Background: An oral formulation of tazarotene is currently in development for the treatment of moderate to very severe plaque psoriasis and severe nodulocystic acne. Objectives: To assess the effects of food and body weight on the pharmacokinetics (PK) of oral tazarotene and its primary active metabolite, tazarotenic acid. Methods: A clinical study in healthy volunteers investigated the effects of food and body weight on the PK profile of oral tazarotene (single dose or seven consecutive daily doses ranging from 3 mg to 12 mg). Results: Taking 6 mg oral tazarotene with a high-fat meal did not affect the absorption of tazarotene—plasma tazarotenic acid AUC ratios in subjects who had taken tazarotene with a high-fat meal were completely within the 80–125% boundary (90% confidence interval) of those in fasted subjects. Cmax ratios were partially outside the 80–125% boundary but this divergence was most likely due to data variability and a small sample size. Comparisons of plasma tazarotenic acid Cmax and AUC values among subjects of differing body weights showed virtually no effect of body weight on systemic tazarotenic acid exposure (p > 0.05). Specifically, while there was a significant correlation of AUC with body weight on Day 0, there was no such correlation with Cmax and there was no correlation between Cmax or AUC and body weight on Day 9. Conclusion: The lack of influence of food and body weight on the PK profile of oral tazarotene should help facilitate simple and convenient dosing.

A phase 1 study of tazarotene in adults with advanced cancer

Tazarotene is an acetylenic retinoid which is metabolised to tazarotenic acid and which binds selectively to the retinoid receptors RARβ and RARγ. The safety, toxicity and pharmacokinetics of oral tazarotene were determined over 12 weeks of treatment in 34 patients with advanced cancer. Commonly seen toxicities were mucocutaneous symptoms, musculoskeletal pain and headache. Dose-limiting toxicities were hypercalcaemia, hypertriglyceridaemia and musculoskeletal pain. The maximum tolerated dose of tazarotene in this schedule is 25.2 mg day−1. Plasma concentrations of tazarotenic acid were found to peak rapidly within 1–3 h of dosing and thereafter declined quickly. The Cmax and AUC values on day 0, and weeks 2 and 4 were similar indicating no drug accumulation. The dose-normalised Cmax and AUC values at different dose levels and different study days appeared to be similar indicating linear pharmacokinetics. No objective responses were seen, although stable disease was seen in six out of eight evaluable patients receiving the three highest dose levels of tazarotene (16.8, 25.2 or 33.4 mg day−1). We conclude that oral tazarotene is well tolerated when administered daily for 12 weeks, has a favourable toxicity profile compared with other retinoids and merits further investigation as an anticancer therapy.

Treatment of warty dyskeratoma with tazarotenic acid

<h2>Abstract</h2> A patient with warty dyskeratoma was successfully treated with tazarotenic acid gel. We present evidence to support that this did not occur by chance and suggest that tazarotenic acid be investigated further for the treatment of similar dyskeratatic disorders. (J Am Acad Dermatol 2002;46:S4.)