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Conversion of acitretin to etretinate in psoriatic patients is influenced by ethanol.

Acitretin has recently been introduced to replace etretinate in the treatment of severe psoriasis due to a considerable shorter terminal half-life. The previously recommended 2-month anticonceptive period after acitretin treatment has been extended to 2 years after the detection of etretinate in certain acitretin recipients. In the present study, 10 patients with severe psoriasis were treated with 30 mg acitretin daily for 3 months. Seven patients had detectable mean steady-state plasma etretinate concentrations in the range of 2.5 to 56.7 ng/ml. Four of the patients showed teratogenic levels of plasma etretinate. Consumption of alcohol appeared to be an important contributing factor for the formation of etretinate. As judged from the dose- and body-weight-normalized AUC values (AUCcor) there was a great inter-individual variation (sixfold) in the systemic availability of acitretin. After discontinuation of therapy, the rate of elimination of both acitretin (t1/2 range 1.0 to 25.4 d) and 13-cis-acitretin (t1/2 range 1.5 to 25.7 d) was found to be related to the observed mean steady-state level of etretinate as evidenced by a longer terminal t1/2 of patients with high levels of etretinate in plasma. A mean terminal elimination half-life of etretinate was found to be 45.7 d +/- 10.6 (mean +/- SD; range 27.0 to 59.3 d). The risk of metabolic formation of etretinate in acitretin recipients makes it impossible to draw any definite conclusion with regard to recommendation of length of anticonceptive period following acitretin therapy in psoriatics. Monitoring of plasma etretinate levels in acitretin-treated fertile women is advisable.

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Oral acitretin in psoriasis: drug and vitamin A concentrations in plasma, skin and adipose tissue.

The purpose of the present study was to determine the concentrations of acitretin and its main metabolite, 13-cis acitretin, in epidermis, subcutis and plasma in twelve psoriatic patients treated with 30 mg acitretin orally daily for 6 months. In addition, endogenous concentrations of vitamin A were monitored. Blood samples and biopsies from normal appearing skin were obtained prior to therapy, after 1 and 6 months of treatment and finally 1 month after cessation of therapy. Using a highly sensitive liquid chromatography method concentrations of synthetic retinoids and endogenous retinoid (retinol, 3,4-didehydroretinol) were analysed in hydrolyzed tissue samples and plasma. Steady-state concentration of acitretin in epidermis (17 +/- 9 ng/g) was reached within 1 month of therapy. There was a significant correlation between the individual plasma trough value and the epidermal concentration of acitretin after 1 month of therapy. The acitretin concentrations in subcutis varied from 15 to 1437 ng/g, but the mean values at 1 and 6 months of therapy were similar (177 and 227 ng/g, respectively). After stopping therapy the acitretin level was below the detection limit in both epidermis and serum within 1 month in 9 out of 12 patients. In contrast, only 3 of the patients were negative for acitretin in subcutis biopsies obtained 1 month after stopping therapy. The occurrence of a presumed tissue contaminator with characteristics similar to 13-cis acitretin prevented quantitation of this metabolite in many subcutis samples. The epidermal, subcutis and serum composition of retinol and 3,4-didehydroretinol remained unchanged during therapy, indicating no or only minimal interaction between acitretin and endogenous vitamin A metabolism.

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Cis-trans interconversion of acitretin in man.

The major plasma metabolite of acitretin (trans-acitretin) is its 13-cis isomer, cis-acitretin. Interconversion of cis-acitretin to trans-acitretin was demonstrated in man following administration of a single oral dose of cis-acitretin. Plasma concentrations of Ro 13-7652 (cis-acitretin) and Ro 10-1670 (trans-acitretin) were much higher after cis-acitretin administration than after trans-acitretin administration. Surprisingly, these high concentrations were not associated with a clear therapeutic effect in dermatoses (e.g. psoriasis) which are usually responsive to oral retinoids. Interactions between the cis and trans isomers formed in vivo may explain the difference in therapeutic activity of each stereoisomer when administered orally.

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Kinetics of tissue distribution and elimination of retinoid drugs in the rat. I. Acitretin.

Rats were injected with single intravenous doses of acitretin (6 mg/kg), and concentrations of the drug and its metabolite, 13-cis-acitretin, were determined in plasma and nine tissues up to 6 hr postdose. A newly developed sensitive method for the determination by HPLC of acitretin, 13-cis-acitretin, and etretinate was used. Acitretin rapidly appeared in liver and muscle, where it underwent redistribution into skin and adipose tissue. Tissue/plasma concentration ratios of acitretin ranged from 2.8 to 0.3 in the order adipose tissue > brain, liver > lung, heart, kidney, spleen > skin, muscle. Adipose tissue storage was moderate and short-lived. The metabolite, 13-cis-acitretin, was detected in all tissues but not in plasma; it accounted for < 10% of the administered dose at any time. No etretinate could be detected as a metabolite in plasma or tissues. After 6 hr, < 1% of the dose remained in the body as acitretin and 13-cis-acitretin. Disappearance was monophasic, with an elimination half-life of 70 min in plasma and 68 +/- 9 min in the nine tissues. The volume of distribution was 0.6 liters/kg and clearance 6 ml.min-1.kg-1. Acitretin was characterized by rapid first-order elimination and the absence of storage in a deep compartment.

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Quantification of acitretin in human plasma by microbore liquid chromatography-negative chemical ionization mass spectrometry.

A highly sensitive liquid chromatographic-mass spectrometric procedure has been developed to quantitate plasma concentrations of acitretin, a dermatologic agent used to treat severe psoriasis. The assay utilizes the combination of normal-phase microbore high-performance liquid chromatography, negative chemical ionization mass spectrometry, selective ion monitoring and stable isotope dilution. The method has been used to measure acitretin and its metabolite, 13-cis-acitretin, over a range of 1-20 ng/ml in human plasma. The inter-assay precision was 5.3% for acitretin and 3.9% for 13-cis-acitretin, while the intra-assay precisions for acitretin and 13-cis-acitretin were 10.8 and 12.7%, respectively. Reproducibility of the assay for acitretin and 13-cis-acitretin, which was determined by the relative standard deviation of multiple analyses of the same quality assurance sample, was 5.9 and 8.1%, respectively.

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Acitretin improves psoriasis in a dose-dependent fashion.

Acitretin, a metabolite of etretinate, was given to 38 patients for the treatment of psoriasis. During the first 8 weeks patients received either placebo, 10 mg, 25 mg, 50 mg, or 75 mg of acitretin daily in a double-blind manner. The dosages of 10 mg and 25 mg daily did not achieve any statistically significant improvement in psoriasis over placebo; however, both the 50 and 75 mg dosages were statistically significantly better than placebo. Side effects were primarily mucocutaneous and occurred in most patients receiving 25 mg or more of acitretin daily. After the double-blind period, patients continued treatment in an open fashion until they had received a total of 24 weeks of acitretin therapy. Most patients received 50 mg of acitretin daily, which adequately cleared their psoriasis. After approximately 3 months without acitretin, most patients required retreatment. Subsequent 24-week courses of therapy were generally effective and well tolerated. The most common laboratory abnormalities were elevations of triglyceride, cholesterol, and liver transaminase levels. The efficacy and side effects of acitretin appear to be similar to those of etretinate; the principal advantage of acitretin is its shorter half-life. Although acitretin is a potent teratogen, its rapid elimination makes it a viable treatment for psoriasis among women of childbearing potential.

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The effect of addition of calcipotriol ointment (50 micrograms/g) to acitretin therapy in psoriasis.

Our purpose was to find out whether the addition of calcipotriol ointment (50 micrograms/g) to systemic treatment with acitretin produces additional therapeutic effects and thereby an acitretin-sparing effect, and further to investigate the safety and tolerability of this combination. A multicentre, randomized, double-blind placebo-controlled study was designed. Patients were randomized to receive calcipotriol or placebo. All patients were treated with a starting dose of 20 mg acitretin per day and doses were adjusted at 2-weekly intervals with increments of 10 mg per day up to a maximum of 70 mg per day. The dose requirement for acitretin, clinical signs and adverse events were recorded. Seventy-six patients were randomized to treatment with calcipotriol 50 micrograms/g ointment twice daily and 59 patients to treatment with the vehicle only twice daily. Clearance or marked improvement was achieved by 67% of the patients in the calcipotriol group and by 41% of the patients in the placebo group (P = 0.006). Calcipotriol treatment proved to have a statistically significant additional effect to acitretin on the Psoriasis Area and Severity Index, redness, thickness and scaliness as compared with placebo. Clearance or marked improvement was achieved with a statistically significantly lower cumulative dose of acitretin by the patients in the calcipotriol group as compared with the placebo group. The number of patients reporting adverse events was pronounced and largely related to acitretin. No significant differences were observed between the two treatment groups with respect to adverse events. Laboratory assessments were essentially normal. The addition of calcipotriol ointment to acitretin treatment contributes to the efficacy, reduces the cumulative dose of acitretin to reach marked improvement or clearance, and is well-tolerated and safe.

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In-vitro skin pharmacokinetics of acitretin: percutaneous absorption studies in intact and modified skin from three different species using different receptor solutions.

The aromatic synthetic retinoid acid derivative, acitretin, is efficacious in several cutaneous diseases. Its toxicological profile makes a topical form with no or reduced systemic adverse effects desirable. Direct application of a topical acitretin formulation might result in therapeutic skin concentrations at the site of the disease while minimizing systemic exposure. The present studies define the percutaneous absorption characteristics of acitretin from an isopropylmyristate formulation. We investigated, in-vitro, (1) the role of receptor solution variations, (2) the role of skin modifications, (3) the influence of skin from three different species on the absorption of topically applied acitretin and (4) the drug distribution within the skin. Addition of solubilizers (Polyethylenglycol-20 and albumin) to the receptor solutions improved the flux of acitretin through monkey skin, whereas the acitretin concentration in the skin was not affected by the various receptor solutions used. Acitretin flux through tape-stripped monkey skin and dermis was only slightly higher than through intact skin. Acitretin concentration in human skin was significantly higher than in rhesus monkey or guinea-pig skin. Topical application of acitretin can produce dermal concentrations in excess of those achieved by therapeutic oral doses.

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[Acitretine].

Acitretin (Soriatane(R)) is an aromatic retinoïd (carboxylic acid metabolite of etretinate). Acitretin has a terminal elimination half-life of about 55 to 60 hours. However, concomitant intake of alcohol induces transformation to etretinate (lipophilic ester) which has a longer terminal elimination half life (84 to 168 days). Due to the teratogenic effect of acitretin, contraception should be used during therapy and 2 years afterwards. Acitretin monotherapy is effective in pustular psoriasis and psoriatic palmo-plantar keratoderma. In the other forms of psoriasis, combination with phototherapy (PUVA, UVB) or topical therapy is necessary (calcipotriol, corticosteroids). Acitretin is effective in cutaneous disorders of keratinization (ichtyosis, palmo-plantar keratoderma, Darier's disease). Severe cutaneous forms of lichen planus were recently recognized as indications of acitretin treatment; 35 to 40 mg daily is the mean effective dosage in adults (0.5 mg/kg/j in children). Acitretin was shown effective in preventing the development of new skin carcinomas in predisposed patients (Xeroderma pigmentosum, immunosupression). Acitretin is a potent teratogen. Mucocutaneous side effects are varied (cheilitis, dry mucosae, xerosis, palmo-plantar peeling, hair loss.), dose-dependent and reversible. Biological side-effects consist principally in elevations of transaminases (5 to 8% of patients). Acute hepatotoxic reactions are rare. Hyperlipidemia is another side-effect commonly observed. Bony changes (ligament calcifications, osteoporosis) have been reported with various incidence. In children, growth and development have to be monitored. Combination of acitretin with potentially hepatotoxic molecules (methotrexate) is contraindicated, as is combination with cyclines (risk of intracranial hypertension).

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Food increases the bioavailability of acitretin.

Eighteen healthy male volunteers received 50 mg oral doses of acitretin on two occasions, according to a random crossover design. Acitretin was administered during a complete fast or following a moderate breakfast. Plasma samples were obtained at various times and the concentration of acitretin and its 13-cis isomeric metabolite (Ro 13-7652) were quantified by a specific HPLC assay. The AUC0-15 for acitretin was increased when administered with food for all subjects (except one) with a mean increase of 90% (from 1175 to 2249 ng/ml.hr). The maximum plasma concentration of acitretin (Cmax) was increased by 70% when administered with food (from 245 to 416 ng/ml), while the time to reach Cmax was unaffected. The ratio of AUC of Ro 13-7652 to acitretin was the same for both the fasted and fed conditions; therefore, the formation of metabolite was not influenced by concomitant ingestion of food. The presence of food increases the apparent bioavailability of acitretin. A likely mechanism behind this observation is an increase in acitretin solubility in addition to an increase in the lymphatic absorption and a prolonged residence time of the drug in the gastrointestinal tract.

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Biopharmaceutics of beta-cyclodextrin derivative-based formulations of acitretin in Sprague-Dawley rats.

Acitretin, an active metabolite of etretinate, is as effective as etretinate in the treatment of psoriasis. Recently, we developed some water-soluble formulations of acitretin with 2-hydroxypropyl-beta-cyclodextrin (HPBCD)/randomly substituted methyl-beta-cyclodextrin (RMBCD). In this study, the biopharmaceutic properties of these formulations were tested in Sprague-Dawley rats. After single intravenous dosing (2.5, 5, or 10 mg/kg) with the HPBCD-based formulation, the area under the plasma concentration-time curve of acitretin increased proportionally with the dose and its clearance remained unchanged within the tested dose range. We also found that the RMBCD-based formulation of acitretin improved its bioavailability and decreased the variations in various pharmacokinetic parameters. The improved biopharmaceutic properties of RMBCD-based acitretin might be attributed to its enhanced aqueous solubility. The elimination of acitretin through bile excretion was also studied. Our results indicated that the major fraction of acitretin (approximately 40%) was excreted in the bile as beta-glucuronide conjugate and only trace amounts were excreted as unconjugated acitretin (approximately 0.5%). This finding further confirmed the importance of conjugated metabolism and biliary excretion in the elimination of this drug.

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In vitro metabolism of acitretin by human liver microsomes: evidence of an acitretinoyl-coenzyme A thioester conjugate in the transesterification to etretinate.

The aromatic retinoid acitretin is the primary active metabolite of etretinate, and in this study we investigated the ethyl esterification of acitretin to etretinate using [(14)C]acitretin and human liver microsomes. Samples were analysed by TLC, HPLC, and LC-MS. Essential requirements for the transesterification reaction were identified and included viable microsomal protein, ATP, CoASH, and ethanol. Human liver microsomes catalysed formation of acitretinoyl-CoA at the rate of 0.08 +/- 0.02 nmol/min/mg (mean +/- SD, N = 10). Acitretinoyl-CoA was pivotal for the transesterification to etretinate and in the presence of methanol, ethanol, n-propanol, n-butanol, and hexanol, the corresponding esters, namely methyl-, ethyl (etretinate)-, propyl-, butyl-, and hexyl-acitretinate, were formed. On average, 1.7% of the acitretin present in the incubation was converted to etretinate in the presence of ethanol. In the absence of ethanol, transesterification did not proceed. Inhibition of the ester hydrolysis of etretinate by bis-p-nitrophenylphosphate (BNPP, 1 mM) prevented futile cycling of etretinate via acitretinoyl-CoA. An additional finding was that acitretin (15-30 microM) activated significantly human liver microsomal long-chain fatty acid-CoA ligase (E.C.6.2.1.3, LCL), resulting in enhanced formation of palmitoyl-CoA. This study demonstrated that in the presence of ethanol the ethyl esterification of acitretin to etretinate proceeds via formation of acitretinoyl-CoA. Predicting clearance of acitretin in vivo via this unique metabolic pathway will be a challenge, as the intracellular concentration of ethanol could never be predicted with any degree of accuracy in humans.

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[Acitretin induces apoptosis and changes of relative signaling pathway in epidermoid carcinoma cell line A431].

OBJECTIVE: To study the effects of Acitretin on growth inhibition and apoptosis of epidermoid carcinoma cell line A431 and its molecular mechanisms. METHODS: A431 cells were treated with Acitretin at the concentration of 10(-5)mol/L in different time intervals. The inhibition of cell growth was determined by MTT method, morphological changes were observed by electron microscopy, apoptosis was assessed by flow cytometry and Annexin-V staining. The mRNA expression levels of STAT3, cyclinD1 and p42/44MAPK were detected by reverse transcriptase polymerase chain reaction (RT-PCR). The protein expression levels of P-STAT3 and CyclinD1 were observed by Western blot in A431 cells. RESULT: (1)Acitretin inhibited the growth of A431 cells in vitro in a dose-and time-dependent manner. Morphological changes revealed characteristics of cell apoptosis. Flow cytometry showed more sub-G(1) phase in A431 cells and more cells positively stained with Annexin-V. (2)Acitretin significantly inhibited the expression of STAT3 and CyclinD1 mRNA in A431 cells in vitro in a time-dependent manner(P<0.05). The p-STAT3 and CyclinD1 protein levels were down regulated. The Acitretin could also down regulate the p42/4MAPK mRNA in A431 cells. (3) After incubation with Acitretin, the mRNA level of CyclinD1 in A431 cells was positively correlated with that of STAT3(p<0.05). The protein level of CyclinD1 was also positively correlated with that of p-STAT3(p<0.05). However, there was no correlation between Mrna levels of CyclinD1 and p42/44MAPK. CONCLUSION: (1)Acitretin plays an inhibitory role in the tumor cell growth and induces the cell apoptosis in A431 cells. (2)The regulation of the Jak/STAT3 signaling pathway may play an important role in inducing growth inhibition and apoptosis by Acitretin in A431 cells.

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[Acitretin therapy in keratinization disorders].

The introduction of the oral retinoid etretinate in the past decade has proved to be a major advance in the treatment of disorders of keratinization. During the past few years a new retinoid acitretin has been investigated in clinical trials. Acitretin has a half-life time of 2 days, versus 100 days for etretinate. Acitretin has therefore a great advantage with respect to the teratogenic potential of retinoids. The period of contraception after cessation of acitretin therapy is only two months, compared with two years for etretinate. From December 1989, etretinate has been replaced by acitretin in The Netherlands. In the Department of Dermatology of the University Hospital of Nijmegen, 36 patients with various disorders of keratinization were treated with acitretin. In this communication therapeutic results of acitretin therapy are reported. Clinical efficacy and side effects of acitretin are similar to those observed with etretinate.

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Acitretin versus etretinate in severe psoriasis. A double-blind randomized Nordic multicenter study in 168 patients.

The efficacy and tolerability of acitretin (etretin) in severe psoriasis was compared with that of etretinate in a double-blind randomized study for 12 weeks. A total of 127 patients received acitretin and 41 received etretinate. The initial daily dose was 40 mg/day over 4 weeks and was subsequently adjusted according to individual response. From week 5-12 the mean daily dose was 42.9 mg of acitretin (0.58 mg/kg) versus 49.2 mg of etretinate (0.65 mg/kg). Acitretin gave a PASI score reduction from baseline of 70.5% and etretinate a reduction of 68.4% (mean values). Acitretin tended to give more discomfort than etretinate, particularly with regard to hair loss and peeling of palms and soles. The differences found between acitretin and etretinate may be related to higher maximum plasma concentrations of acitretin. The considerably shorter half-life of acitretin, gives it a great advantage over etretinate with regard to risk of teratogenicity after cessation of treatment.

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A double-blind comparison of acitretin and etretinate in the treatment of severe psoriasis. Results of a Nordic multicentre study.

Acitretin, the free acid of etretinate, is less lipophilic and has a much shorter terminal half-life than the parent compound. The present double-blind, randomized study compared the therapeutic effectiveness and the tolerability of acitretin (n = 127) and etretinate (n = 41) in psoriasis. Patients were treated with 40 mg daily for the first 4 weeks and with an individually adjusted dose for the subsequent 8 weeks. The average daily doses of acitretin (0.54 mg/kg/day) and etretinate (0.65 mg/kg/day) were similar. The PASI (Psoriasis Area and Severity Index) scores improved in parallel in the 2 treatment groups. At the completion of the study, the PASI score improvement was 75.8% for acitretin and 70.8% for etretinate. Both acitretin and etretinate resulted in mucocutaneous side effects. Assessments of tolerability by investigators and patients showed a statistically significant difference in favour of etretinate. These results demonstrate that acitretin and etretinate have similar therapeutic effectiveness in psoriasis. Although the tolerance to acitretin was lower than to etretinate, acitretin offers the important advantage of a much shorter period of potential teratogenicity and is, therefore, to be preferred in women of childbearing potential.

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Influence of pregnancy on the pharmacokinetic disposition of two aromatic retinoids (etretinate and acitretin) in the rat. II. Single and multiple oral dosing studies.

During a multiple dose regimen of etretinate, steady state trough plasma concentrations of etretinate in nonpregnant female rats reached their peak levels (15 ng/ml) by day 10 and remained between 10 and 15 ng/ml through day 19. Steady state trough concentrations of acitretin in nonpregnant animals following etretinate multiple dosing reached their peak levels (53 ng/ml) at day 7 and declined to 16 ng/ml at day 19. A similar decline was observed following multiple oral dosing of acitretin itself, suggesting autoinduction of acitretin clearance. In single dose studies, the apparent oral bioavailability of etretinate was similar (4-5%) for both pregnant and nonpregnant rats (p greater than 0.05). The ratio of the AUC of acitretin to etretinate following etretinate administration was 10-fold greater than that reported for iv studies. Acitretin bioavailability was 10-fold greater than that for etretinate (57%); again, there was no difference between the pregnant and nonpregnant groups (p greater than 0.05). The apparent mean residence time and t1/2 of both etretinate and acitretin were similar for both groups (pregnant and nonpregnant). However, the time course of both etretinate and acitretin was greatly prolonged compared to iv studies. These studies suggest that the marked differences in the bioavailability (etretinate vs. acitretin) and in the time course of these retinoids (iv vs. oral) could have a substantial impact on their apparent toxicity.

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Acitretin elimination in Sprague-Dawley rats pretreated with phenobarbital or beta-naphthoflavone.

Male Sprague-Dawley rats were pretreated with either phenobarbital (PB) or beta-naphthoflavone (BNF), after which acitretin (0.84-0.86 mg/kg) was administered intravenously and plasma was sampled with time. Animals were killed 24 hr after dosing, and livers were removed. Hepatic microsomal protein was isolated, frozen, and later used for quantitation of hepatic microsomal protein concentration, total cytochrome P450 concentration, and microsomal activities of methoxy-, ethoxy-, pentoxy-, and benzyloxyresorufin O-dealkylation (MROD, EROD, PROD, and BROD, respectively). Plasma concentrations of acitretin and its primary metabolite isoacitretin were quantified by reversed-phase HPLC. PB pretreatment increased the systemic clearance (CLs) of acitretin 33%, but did not statistically significantly affect the volume of distribution (Vss) or mean residence time (MRT). PB pretreatment increased hepatic microsomal protein and total P450 concentrations, and increased the activity of MROD 7-fold, EROD 8-fold, PROD 121-fold, and BROD 106-fold. BNF pretreatment increased acitretin CLs 152% and reduced MRT by two-thirds; Vss was unchanged. Hepatic microsomal protein and total P450 concentrations were increased after BNF pretreatment, as were the activities of MROD 20-fold, EROD 32-fold, PROD 1-fold, and BROD 6-fold. These results indicate that PB moderately induces acitretin CLs in Sprague-Dawley rats, but the magnitude of induction suggests that the predominant PB-inducible enzymes do not play a major role in acitretin elimination. BNF pretreatment substantially increased acitretin CLs in male Sprague-Dawley rats, which strongly implicates involvement of P4501A1 and/or 1A2, and suggests the potential for clinically relevant interactions between acitretin disposition and drugs and activities that induce these pathways.

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