alitretinoin and 4-oxoretinoic-acid

A double-blind, placebo-controlled, randomized study using single ascending oral doses of 5 mg, 15 mg, 40 mg, 80 mg, and 150 mg of 9-cis-retinoic acid was performed to assess the single-dose pharmacokinetics, tolerability, and pharmacodynamic effects of 9-cis-retinoic acid in healthy men. Forty participants received treatment (six taking the active treatment and two taking placebo for each dose level). The pharmacokinetics of 9-cis-retinoic acid were linear over the dose range studied. Peak plasma concentrations were achieved within 3 to 4 hours on average. The half-life was in the range of 1.3 to 2.4 hours. Metabolism was the major pathway of elimination. 4-Oxo-9-cis-retinoic acid, one of four metabolites measured, which included all-trans-retinoic acid and 13-cis-retinoic acid, was the main metabolite in plasma, achieving peak plasma levels of 41% to 83% of those of 9-cis-retinoic acid. Dose-/concentration-dependent reductions of retinol in plasma, with a maximum of 30% from baseline, were observed 24 hours after administration. Baseline levels were recovered after 5 days. Concentrations of retinol binding protein remained unchanged. Overall, the drug was well tolerated at all dose levels. Adverse events observed were consistent with findings of other retinoids (all-trans-retinoic acid and 13-cis-retinoic acid) and included headache and xeroderma at high dose levels.

Topics: Adult; Alitretinoin; Antineoplastic Agents; Double-Blind Method; Humans; Isotretinoin; Male; Retinol-Binding Proteins; Retinol-Binding Proteins, Plasma; Tretinoin; Vitamin A

Retinoic acid exerts a variety of effects on gene transcription that regulate growth, differentiation, and inflammation in normal and neoplastic skin cells. Because there is a lack of information regarding the influence of metabolic transformation of retinoids on their pharmacologic effects in skin, we have analyzed the functional activity of all-trans-, 9-cis-, and 13-cis-retinoic acid and their 4-oxo-metabolites in normal human epidermal keratinocytes (NHEKs) and dermal fibroblasts using gene and protein expression profiling techniques, including cDNA microarrays, two-dimensional gel electrophoresis, and MALDI-MS. It was previously thought that the 4-oxo-metabolites of RA are inert catabolic end-products but our results indicate instead that they display strong and isomer-specific transcriptional regulatory activity in both NHEKs and dermal fibroblasts. Microarray and proteomic analyses identified a number of novel genes/gene products that are influenced by RA treatment of NHEKs or fibroblasts, including genes for enzymes catalyzing biotransformation of retinoids, corticosteroids, and antioxidants and structural and transport proteins known to be essential for homeostasis. Our results expand current knowledge regarding retinoic acid action within skin cells and the target tissue/cell regulatory systems that are important for modulating the physiological and pharmacological effects of this important class of dermatological drugs.

Topics: Alitretinoin; Electrophoresis, Gel, Two-Dimensional; Fibroblasts; Fluorescent Antibody Technique; Gene Expression Regulation; Humans; In Vitro Techniques; Isotretinoin; Keratinocytes; Male; Oligonucleotide Array Sequence Analysis; Polymerase Chain Reaction; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Tretinoin

A fully automated isocratic high-performance liquid chromatographic method for the determination of 9-cis-retinoic acid, 13-cis-retinoic acid, all-trans-retinoic acid, 4-oxo-13-cis-retinoic acid and 4-oxo-all-trans-retinoic acid, has been developed using on-line solid-phase extraction and a column switching technique allowing clean-up and pre-concentration in a single step. A 500-microliter sample of serum was diluted with 750 microliters of a solution containing 20% acetonitrile and the internal standard 9,10-dimethylanthracene. About 1000 microliters of this mixture was injected on a 20 x 4.6 mm I.D. poly ether ether ketone (PEEK) pre-column with titanium frits packed with Bondapak C18, 37-53 microns, 300 A particles. Proteins and very polar compounds were washed out to waste, from the pre-column, with 0.05% trifluoroacetic acid (TFA)-acetonitrile (8.5:1.5, v/v). More than 200 aliquots of diluted serum could be injected on this pre-column before elevated back-pressure enforces replacement. Components retained on the pre-column were backflushed to the analytical column for separation and detection at 360 nm. Baseline separation was achieved using a single 250 x 4.6 mm I.D. Suplex pKb-100 column and a mobile phase containing 69:10:2:16:3 (v/v) of acetonitrile-methanol-n-butanol-2% ammonium acetate-glacial acetic acid. A total time of analysis of less than 30 min, including sample preparation, was achieved. Recoveries were in the range of 79-86%. The limit of detection was 1-7 ng/ml serum and the precision, in the concentration range 20-1000 ng/ml, was between 1.3 and 4.5% for all five compounds. The method was applied for the analysis of human serum after oral administration of 60 mg Roaccutan. The method is well suited for pharmacological studies, while the endogenous levels of some retinoic acid isomers are below the limit of quantitation.

Topics: Acetonitriles; Alitretinoin; Autoanalysis; Chromatography, High Pressure Liquid; Drug Stability; Humans; Isotretinoin; Linear Models; Reproducibility of Results; Retinoids; Sensitivity and Specificity; Tretinoin; Trifluoroacetic Acid

Cytochrome P450 expression in liver is influenced by several factors, including sex and strain. Whereas little is known about their metabolic capabilities, Hairless rats are widely used for the studies of tropical agents. We compared Sprague-Dawley and Hairless rat metabolic behavior to validate the use of Hairless rats in pharmacokinetic and metabolic studies of topically applied drugs. Liver microsomes of male and female rats of both strains were used to investigate the in vitro metabolism of three retinoic acid (RA) isomers: all-trans-RA, 13-cis-RA, and 9-cis-RA. In all cases, a major isomerization of the tested isomer in the two others was observed. This process was independent of the presence of NADPH, but depended on the presence of microsomal proteins. In addition, we observed, to a lesser extent, the formation of 4-oxo metabolites (4-oxo-all-trans-RA, 4-oxo-13-cis-RA, and 4-oxo-9-cis-RA), with the rate of formation of each of these compounds varying with the nature of the isomer incubated. The 4-oxo metabolites formed were statistically greater in male than in female rats in the two strains studied. No significant difference in RA biotransformation was observed between Sprague-Dawley and Hairless rats. In addition, no major difference was observed between the two strains concerning the expression of the different cytochrome P450 isoforms studied. In conclusion, phase I metabolism of RAs characterized by C4-hydroxylation varied with sex, but not within the two strains studied in rats. These results strengthen the relevance of the use of Hairless rats in pharmacokinetic and metabolic studies of topical agents, including retinoids.

Topics: Alitretinoin; Animals; Cytochrome P-450 Enzyme System; Cytochromes b5; Female; In Vitro Techniques; Isoenzymes; Isotretinoin; Male; Microsomes, Liver; Rats; Rats, Sprague-Dawley; Sex Factors; Species Specificity; Stereoisomerism; Tretinoin