Removal of synthetic sex hormones by hydrothermal carbonization.

One of the most prominent fields of environmental chemistry is the study and the removal of micro-pollutants from aqueous matrices. Analytical techniques for their identification and quantification are becoming more sensitive and comprehensive and, as a result, an increasing number of drugs have been detected in environmental samples. However, the literature shows that conventional treatments for drinking water and wastewater are not sufficient for remove these compounds. This study aims to check whether the process of hydrothermal carbonization (CHT) is effective in removing the synthetic sex hormones: ethinyl estradiol, gestodene and cyproterone acetate from aqueous samples. The system used in CHT basically consists of a pressurized reactor made of stainless steel and solutions of compounds of interest, both individual and mixed, with a concentration of 1.0 µg.L-1 and a pH range of 2.0 to 3.0. The maximum surface temperature in the reactor was about 180 °C, the internal pressure was 20 bar with 90 minutes for the reaction. Four experiments were conducted, one for each hormone and one with the three hormones together. In individual tests removal of the compounds was found to be 99.8% for ethinyl estradiol, 99.3% for gestodene and 100% for cyproterone acetate. For a mixture of the hormones treated under the same conditions, the mean values of CHT-removal of Ethinylestradiol, Gestodene and Cyproterone Acetate were 99.60%, 96.80% and 68.90%, respectively. The impact of the matrix effect may have affected the efficiency of the hormone removal process by CHT.

Effects of oral contraceptives on metabolic profile in women with polycystic ovary syndrome: A meta-analysis comparing products containing cyproterone acetate with third generation progestins.

BACKGROUND: Although oral contraceptives (OCs) are the most common treatment in women with polycystic ovary syndrome (PCOS), their effects and safety on the metabolic profiles of these patients are relatively unknown. In this meta-analysis the effects of the different durations (from 3months to 1year) of OC treatment using cyproterone acetate (CA) or third generation progestins on metabolic profile of patients with PCOS were assessed. MATERIALS AND METHODS: PubMed, Scopus, Google Scholar and ScienceDirect databases (2001-2015) were searched to identify clinical trials investigating the effects of OC containing CA or third generation progestins on metabolic profiles of women with PCOS. Both fixed and random effect models were used. Subgroup analyses were performed based on the progestin compounds used and on duration of treatment. RESULTS: Oral contraceptive (OC) use was found to be associated with a worsening in lipid profiles but no changes were observed in other metabolic outcomes, including body mass index (BMI), fasting blood glucose (FBG), fasting insulin, homeostatic model for measuring insulin resistance (HOMA-IR) and in blood pressure (BP) values. All studied OCs showed similar effects on lipid profiles but with different timings, with products containing CA, requiring 6months to raise high density lipoprotein-cholesterol (HDL-C) levels and 12months to increase triglycerides (TG). On the contrary, products containing drospirenone (DRSP) or desogestrel (DSG) increased HDL-C after only 3months but determined elevations of TG after 6months. All OCs induced an increase in low density lipoprotein-cholesterol (LDL-C) after 12months of use. CONCLUSIONS: The study shows that, in women with PCOS, OC use is associated with significant changes in lipid profiles, including elevation not only in HDL-C but also in TG and LDL-C. All OCs studied showed similar effects but with different timings, with products containing CA generally requiring more prolonged use to increase serum lipids. Instead, OC use does not affect body weight, BP or glucose levels, with only some minor increase of fasting insulin levels.

Process development for the production of 15ß-hydroxycyproterone acetate using Bacillus megaterium expressing CYP106A2 as whole-cell biocatalyst.

BACKGROUND: CYP106A2 from Bacillus megaterium ATCC 13368 was first identified as a regio- and stereoselective 15ß-hydroxylase of 3-oxo-∆4-steroids. Recently, it was shown that besides 3-oxo-∆4-steroids, 3-hydroxy-∆5-steroids as well as di- and triterpenes can also serve as substrates for this biocatalyst. It is highly selective towards the 15ß position, but the 6ß, 7α/ß, 9α, 11α and 15α positions have also been described as targets for hydroxylation. Based on the broad substrate spectrum and hydroxylating capacity, it is an excellent candidate for the production of human drug metabolites and drug precursors. RESULTS: In this work, we demonstrate the conversion of a synthetic testosterone derivative, cyproterone acetate, by CYP106A2 under in vitro and in vivo conditions. Using a Bacillus megaterium whole-cell system overexpressing CYP106A2, sufficient amounts of product for structure elucidation by nuclear magnetic resonance spectroscopy were obtained. The product was characterized as 15ß-hydroxycyproterone acetate, the main human metabolite. Since the product is of pharmaceutical interest, our aim was to intensify the process by increasing the substrate concentration and to scale-up the reaction from shake flasks to bioreactors to demonstrate an efficient, yet green and cost-effective production. Using a bench-top bioreactor and the recombinant Bacillus megaterium system, both a fermentation and a transformation process were successfully implemented. To improve the yield and product titers for future industrial application, the main bottlenecks of the reaction were addressed. Using 2-hydroxypropyl-ß-cyclodextrin, an effective bioconversion of 98% was achieved using 1 mM substrate concentration, corresponding to a product formation of 0.43 g/L, at a 400 mL scale. CONCLUSIONS: Here we describe the successful scale-up of cyproterone acetate conversion from shake flasks to bioreactors, using the CYP106A2 enzyme in a whole-cell system. The substrate was converted to its main human metabolite, 15ß-hydroxycyproterone acetate, a highly interesting drug candidate, due to its retained antiandrogen activity but significantly lower progestogen properties than the mother compound. Optimization of the process led to an improvement from 55% to 98% overall conversion, with a product formation of 0.43 g/L, approaching industrial process requirements and a future large-scale application.

Antiandrogens act as selective androgen receptor modulators at the proteome level in prostate cancer cells.

Current therapies for prostate cancer include antiandrogens, inhibitory ligands of the androgen receptor, which repress androgen-stimulated growth. These include the selective androgen receptor modulators cyproterone acetate and hydroxyflutamide and the complete antagonist bicalutamide. Their activity is partly dictated by the presence of androgen receptor mutations, which are commonly detected in patients who relapse while receiving antiandrogens, i.e. in castrate-resistant prostate cancer. To characterize the early proteomic response to these antiandrogens we used the LNCaP prostate cancer cell line, which harbors the androgen receptor mutation most commonly detected in castrate-resistant tumors (T877A), analyzing alterations in the proteome, and comparing these to the effect of these therapeutics upon androgen receptor activity and cell proliferation. The majority are regulated post-transcriptionally, possibly via nongenomic androgen receptor signaling. Differences detected between the exposure groups demonstrate subtle changes in the biological response to each specific ligand, suggesting a spectrum of agonistic and antagonistic effects dependent on the ligand used. Analysis of the crystal structures of the AR in the presence of cyproterone acetate, hydroxyflutamide, and DHT identified important differences in the orientation of key residues located in the AF-2 and BF-3 protein interaction surfaces. This further implies that although there is commonality in the growth responses between androgens and those antiandrogens that stimulate growth in the presence of a mutation, there may also be influential differences in the growth pathways stimulated by the different ligands. This therefore has implications for prostate cancer treatment because tumors may respond differently dependent upon which mutation is present and which ligand is activating growth, also for the design of selective androgen receptor modulators, which aim to elicit differential proteomic responses dependent upon cellular context.

Cyproterone acetate loading to lipid nanoparticles for topical acne treatment: particle characterisation and skin uptake.

PURPOSE: Topical cyproterone acetate (CPA) treatment of skin diseases should reduce side effects currently excluding the use in males and demanding contraceptive measures in females. To improve skin penetration of the poorly absorbed drug, we intended to identify the active moiety and to load it to particulate carrier systems. MATERIALS AND METHODS: CPA metabolism in human fibroblasts, keratinocytes and a sebocyte cell line as well as androgen receptor affinity of native CPA and the hydrolysis product cyproterone were determined. CPA 0.05% loaded solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), a nanoemulsion and micropheres were characterized for drug-particle interaction and CPA absorption using human skin ex-vivo. RESULTS: Native CPA proved to be the active agent. Application of CPA attached to SLN increased skin penetration at least four-fold over the uptake from cream and nanoemulsion. Incorporation into the lipid matrix of NLC and microspheres resulted in a 2-3-fold increase in CPA absorption. Drug amounts within the dermis were low with all preparations. No difference was seen in the penetration into intact and stripped skin. CONCLUSION: With particulate systems topical CPA treatment may be an additional therapeutic option for acne and other diseases of the pilosebaceous unit.

Effects of steroidal and non-steroidal antiandrogens on wild-type and mutant androgen receptors.

BACKGROUND: Molecular basis for secondary antiandrogen therapy in prostate cancer with mutant androgen receptors (ARs) is not fully elucidated. MATERIALS AND METHODS: Effects of steroidal and non-steroidal antiandrogens on transcriptional activities of wild-type and mutant (W741C, T877A, and W741C+T877A) ARs were measured. Crystal structure analysis and docking studies were performed using Molecular Operating Environment (MOE) package. RESULTS: DHT-induced transcriptional activity of the T877A mutant and the W741C mutant was suppressed by bicalutamide and hydroxyflutamide, respectively. Nilutamide suppressed the W741C mutant and the double mutant. Cyproterone acetate modestly inhibited the W741C mutant and the double mutant. The structural studies suggested that nilutamide and cyproterone acetate retain their antiandrogenic properties against both the W741C mutant and the double mutant due to fact that mutation W741C does not permit formation of key hydrophobic interaction between ligand and AR ligand binding domain, which is necessary for their conversion into agonists. CONCLUSIONS: Switching antiandrogens may be reasonable in prostate cancer with mutant ARs.

Crystal structure of the T877A human androgen receptor ligand-binding domain complexed to cyproterone acetate provides insight for ligand-induced conformational changes and structure-based drug design.

Cyproterone acetate (CPA) is a steroidal antiandrogen used clinically in the treatment of prostate cancer. Compared with steroidal agonists for the androgen receptor (AR) (e.g. dihydrotestosterone, R1881), CPA is bulkier in structure and therefore seemingly incompatible with the binding pockets observed in currently available x-ray crystal structures of the AR ligand-binding domain (LBD). We solved the x-ray crystal structure of the human AR LBD bound to CPA at 1.8A in the T877A variant, a mutation known to increase the agonist activity of CPA and therefore facilitate purification and crystal formation of the receptor.drug complex. The structure demonstrates that bulk from the 17alpha-acetate group of CPA induces movement of the Leu-701 side chain, which results in partial unfolding of the C-terminal end of helix 11 and displacement of the loop between helices 11 and 12 in comparison to all other AR LBD crystal structures published to date. This structural alteration leads to an expansion of the AR binding cavity to include an additional pocket bordered by Leu-701, Leu-704, Ser-778, Met-780, Phe-876, and Leu-880. Further, we found that CPA invokes transcriptional activation in the L701A AR at low nanomolar concentrations similar to the T877A mutant. Analogous mutations in the glucocorticoid receptor (GR) and progesterone receptor were constructed, and we found that CPA was also converted into a potent agonist in the M560A GR. Altogether, these data offer information for structure-based drug design, elucidate flexible regions of the AR LBD, and provide insight as to how CPA antagonizes the AR and GR.

Evaluation of an eucalyptus oil containing topical drug delivery system for selected steroid hormones.

In the present study the permeation and the chemical stability of 17-beta-estradiol, progesterone, cyproterone acetate and finasteride incorporated in an eucalyptus oil containing microemulsion system have been investigated. The formulations contained 1% (w/w) of the steroid hormones. Self diffusion coefficients determined by pulsed-field-gradient spin echo NMR spectroscopy were used to characterise the microemulsion. From these results a bicontinuous structure is proposed for the multicomponent system. However a correlation between the self diffusion of the hormones in the vehicle and the transdermal flux was not indicated. Explanations for this were self assembling, formation of aggregates between the components of the microemulsion and drugs and different effects because of different solubility of the drugs. By addition of certain polymers the skin permeation rates could be improved with exception of cyproterone acetate. Beside standard diffusion experiments, the residual drug content in the skin was investigated. Drug stability was monitored by analysing the steroid hormone content in the different formulations over an observation period of 6 weeks and could be improved by polymers. In addition, viscosity measurements were performed. They indicated an influence of the polymers and drugs on the viscosity in all formulations.

Rheology and NMR self-diffusion experiments as well as skin permeation of diclofenac-sodium and cyproterone acetate of new gel preparations.

The viscoelastic properties of two transparent semisolid preparations, one consisting of surfactant, paraffin oil, and water (BAS), and the other consisting of surfactant, cetylstearyl-2-ethylhexanoate, and water (CUBO), were characterized by oscillatory measurements. In (1)H-NMR diffusion experiments it was confirmed that the formulations are O/W systems, and the three-dimensional packing of the closed globular aggregates form a cubic structure. Moreover, standard diffusion experiments with porcine skin using Franz cells were performed with incorporated diclofenac-sodium and cyproterone acetate, respectively. The cumulative amount released after 48 h of diclofenac-sodium were excellent with 665.28 microg/cm(2) and with 36.7 microg/cm(2) for cyproterone acetate. The new drug-containing formulations were also prepared as transdermal patches by using carrageenan as a matrix. In diffusion studies zero-order kinetics was found for both drugs, but with a higher lag time for cyproterone acetate. The total work of adhesion was analyzed by tensile studies on porcine skin and found to be very good. The presented cubic gels as well as mixtures with carrageenan are promising alternative drug carrier systems for topical pharmaceutical as well as cosmetics.

Permeation of cyproterone acetate through pig skin from different vehicles with phospholipids.

The permeation of cyproterone acetate (CPA) from Derma Membrane Structure (DMS) creams and liposomal formulations was investigated. Standard diffusion experiments with dermatomed porcine skin were performed. The cumulative CPA amount permeated of the DMS creams was between 2.9 and 6.8 microg/cm(2) within 48 h. By addition of a phospholipid concentrate, the CPA permeation could be 2.6-fold further increased compared to the control DMS. A working temperature of 60 degrees C resulted in a change of the preparation and a higher permeation which could be confirmed by additional differential scanning calorimetry studies. In case of the liposomal formulations, the CPA permeation was strongly dependent on the lipid content. The higher the lipid content, the higher was the CPA permeation. Extruding procedures for decreasing the particle size of the liposomes resulted in a two-fold increase in CPA permeation compared to the unextruded liposomes. It is possible to control the CPA permeation by combining various formulations containing different phospholipids with saturated and unsaturated fatty acids.

Evidence that chlormadinone acetate exhibits antiandrogenic activity in androgen-dependent cell line.

Chlormadinone acetate (CMA), like other 17-hydroxyprogesterone derivatives, is thought to be a potential antiandrogen on the basis of its effect on spontaneous benign prostatic hyperplasia (BPH) in dogs. This work was undertaken to find out whether CMA presents antiandrogen activity in human androgen-dependent cell line. For this purpose, we used PALM cells, the PC-3 cell line stably transfected with human androgen receptor and a luciferase gene under transcriptional control of MMTV. Potential antiandrogenic activity was compared with that of cyproterone acetate (CPA), a standard steroidal antiandrogen. Both compounds were tested in competitive binding assays at 37 degrees C in the presence of 1 nM of [3H] R1881, a synthetic and non-metabolizable androgen. Their impact on AR transcriptional activity was evaluated by the measure of luciferase activity in the presence of R1881 with increasing concentrations of CMA or CPA (10(-8)-10(-6) M). In whole cell binding assays, competitive studies revealed that the Ki for CMA was 3.3 +/- 1.5 x 10(-8) M (versus 7.2 +/- 1.3 x 10(-8) M for CPA). Inhibition of AR transcriptional activity was 40 +/- 5% for CMA (3 x 10(-7) M) versus 59 +/- 6% for CPA at the same concentration. Moreover, CMA caused a slower import of green fluorescent protein (GFP)-AR to the nuclei of COS-7 cells than R1881. These data show that CMA exerted a competitive binding for AR and significantly decreased the AR transcriptional activity. In conclusion, this synthetic progestin presents simultaneous antiandrogenic activity that could be helpful as a new therapeutic option in women with luteal defect along with clinical signs of hyperandrogenism.

Cyproterone acetate: a genotoxic carcinogen?

Cyproterone acetate, a widely used synthetic progestagen with antiandrogenic activity, is known for years to produce liver tumours in rats, with a higher incidence in females. This effect was attributed to a rodent-specific tumour promoting mode of action based on the detection of a strong hepato-mitogenic activity of cyproterone acetate. However, more recent studies have demonstrated that cyproterone acetate is sex-specifically activated to (a) DNA-damaging intermediate(s) in the liver of female rats which result in the formation of DNA adducts, induction of DNA repair, and increased levels of micronuclei and gene mutations. Consistent with a sex-specific genotoxicity, cyproterone acetate showed a tumour-initiating potential in a liver foci assay with female rats but not with male rats. Most important, cyproterone acetate was found to induce formation of DNA adducts in primary cultures of human hepatocytes indicating that human liver cells have the capacity to activate cyproterone acetate to genotoxic intermediates. However, the overall assessment of the preclinical data presented in this review suggests that induction of liver tumours in female rats most probably depends on both, genotoxic and mitogenic effects which would suggest a non-linear mode of action with regard to tumour formation. With the exception of DNA adduct formation all other adverse effects induced by cyproterone acetate in rat liver, including gene mutations and liver tumours, can be detected at very high dose levels only. Hence, a cancer risk estimate based on a simple linear extrapolation from high dose to low exposure conditions of recommended clinical use would be questionable. Human data from pharmacoepidemiological studies that specifically addressed the question of possible liver cancer risk in patients treated with cyproterone acetate do in principle support this interpretation. In agreement with these considerations the regulatory authorities of the European Union came to the common conclusion that a possible cancer risk associated with the clinical use of cyproterone acetate, if any, appears to be low and the risk-benefit ratios for the currently authorised indications remain favourable.

Dose dependent induction of DNA adducts, gene mutations, and cell proliferation by the antiandrogenic drug cyproterone acetate in rat liver.

1. CPA does not only induce the formation of DNA adducts but also of mutations in female rat liver. 2. The mutation frequency exhibited a characteristic time course. Within a period of 3 days post administration, a tremendous increase was noted, which remained at a high level until 2 weeks post exposure. Thereafter, most mutation-carrying cells were eliminated within a period of 2 weeks leaving a cell population remaining at a constant level for another 4 weeks. Thus, the length of the observation period post exposure, i. e. the manifestation time, seems to be a critical factor for the strength of the mutagenic response. The highest as observed between 1 and 2 weeks post exposure. Correspondingly, the dose response curve recorded 2 weeks post exposure showed a higher mutagenic response than the curve after 6 weeks of exposure recorded previously. 3. When CPA-induced mutations were recorded as a function of the dose, mutation frequencies at the lower dose range were found that did not differ from those of controls. The non-effective dose recorded 2 weeks post exposure was much lower than that recorded after 6 weeks of exposure indicating that it is a function of the manifestation time. Since DNA adducts were formed in high amounts at the non-effective doses, we assume that the mitogenic activity required for the conversion of DNA adducts into mutations was not sufficiently strong. The liver of adult animals exhibits a very low endogeneous proliferation rate, which is not likely to contribute significantly to the expression of mutations. We conclude that it is the mitogenic activity of CPA itself, which stimulates the expression of mutations.

Experience with cyproterone acetate in the treatment of precocious puberty.

The authors review their experience (1967-present) in the use of cyproterone acetate (CPA) in precocious puberty. CPA was found effective in persistently suppressing pituitary gonadotropic secretion when administered orally at a dose of 50 mg b.i.d. (70-100 mg/d). After the introduction of gonadotropic analogues (GnRHa) for treatment of central precocious puberty, short term use of CPA was found useful to counteract the initial stimulatory effect of the GnRHa as well as an adjunct drug in case of very active adrenarche causing advanced bone age during GnRHa treatment. The final heights of girls treated with CPA and girls treated with D-Trp6-LHRH were found comparable: 157.8+/-5.1 cm vs 159.6+/-6.3 cm, respectively. The main adverse effects were occasional fatigue due to partial adrenal insufficiency with CPA and gynecomastia in a few boys. Liver function tests were normal in all patients with the exception of one boy with severe hypothalamic disease, including precocious puberty, who developed liver cirrhosis 3 years after stopping CPA following 5 years treatment. Other indications for CPA treatment during childhood and adolescence, such as fast puberty, congenital adrenal hyperplasia and acne, are also mentioned.

A stability-indicating HPLC method to determine cyproterone acetate in tablet formulations.

A simple and accurate liquid chromatographic method was developed to estimate cyproterone acetate (CA) in pharmaceuticals. The drug was chromatographed on a reversed-phase C18 column. Eluents were monitored at a wavelength of 254 nm utilizing a mixture (60:40) of acetonitrile and water. Solution concentrations were measured on a weight basis to avoid the use of an internal standard. The method was statistically validated for linearity, accuracy, precision, and selectivity. Due to its simplicity and accuracy, we believe that the method can be used for routine quality control analysis. No specific sample preparation is required except for the use of a column guard and a suitable prefilter attached to the syringe.

The role of antiandrogens in hormone replacement therapy.

The most widely used antiandrogens in clinical practice are cyproterone acetate, a derivative of 17-hydroxyprogesterone, and dienogest, a 19-norprogestin. An established sequential preparation for hormone replacement therapy (HRT) consists of 11 days of 2 mg estradiol valerate, 10 days of 2 mg estradiol valerate with 1 mg cyproterone acetate, followed by a 7-day drug-free interval (Climen, Schering AG, Berlin, Germany). Cyproterone acetate is highly progestogenic, has no androgenic properties, and is antiandrogenic above a certain dose. Cyproterone acetate does not counteract the estrogenic effects of estradiol valerate in Climen. This therapy, therefore, has optimal effects on lipid metabolism and coronary heart disease risk, protects the endometrium and reduces menopausal symptoms, preserves bone and reduces osteoporotic fracture risk, and has antiandrogenic effects on the skin and other androgen-sensitive epidermal structures. Dienogest, on the other hand, will soon be introduced in a continuous combined HRT. Dienogest has a 17 alpha-cyanomethyl group instead of the 17 alpha-ethinyl group typical of the common 19-nortestosterone derivatives. It is also referred to as a hybrid progestogen because it has pharmacodynamic properties (e.g. antiandrogenicity) in common with progesterone derivatives. A fixed formulation containing 2 mg estradiol valerate and 2 mg dienogest (Climodien) for continuous combined HRT has been developed. This formulation had excellent effects on vasomotor and neurovegetative symptoms. The bleeding pattern was generally highly satisfactory and similar to that with Kliogest, as were the results of endometrial biopsies after 12 cycles of treatment. Lipid metabolic changes may be interpreted as beneficial. Dienogest had no adverse effects on the vasorelaxant effect of estradiol valerate in postmenopausal women, as shown by markers of vascular function. Neuropsychological studies utilizing evoked potentials showed shortening effects on sleep latency and an improvement in cognitive information processing. Continuous combined HRT with dienogest, therefore, may come to be regarded as the HRT of choice in postmenopausal patients with mood defects. In summary, HRT with antiandrogenic progestogens has its specific indications with respect to preserving metabolic estrogenicity, specific antiandrogenic effects and specific effects on vigilance and mood disorders.

Induction of micronuclei and of enzyme-altered foci in the liver of female rats exposed to progesterone and three synthetic progestins.

Progesterone (PG) and three structurally similar synthetic progestins-norethisterone (NE), allylestrenol (AE), and dydrogesterone (DG)-have been compared for their ability to induce the formation of micronuclei and of enzyme-altered foci in the liver of female rats. In the micronucleus assay, carried out in rats given a single p.o. dose of 100 mg kg-1 3 days before partial hepatectomy and sacrificed for cell sampling 2 days later, the frequency of micronucleated hepatocytes was 3.5-fold higher than in controls with PG, 2.8-fold with DG, 2.2-fold with NE and 2.1-fold with AE, but the increase was statistically significant only for PG. In the liver foci assay, performed to evaluate the tumor initiating activity of p. o. dosing with 100 mg kg-1 once a week for 6 successive weeks, the values of the number and area of gamma-glutamyltranspeptidase-positive foci were, as compared to controls, 15.9- and 100-fold higher with NE, and 13.9- and 52-fold higher with AE, but only the increase of area produced by NE was statistically significant; PG and DG did not display in this test any activities. Considered together with previous findings, these results suggest that NE might be biotransformed in the liver into reactive species and thus behave as a weak genotoxic agent.

Local inhibition of sebaceous gland growth by topically applied RU 58841.

The biological activity of a series of nonsteroidal, pure androgen receptor inhibitors was compared using the Syrian hamster ear skin sebaceous gland model. RU 58841, RU 56187, RU 38882 and cyproterone acetate were applied topically for 4 weeks on the ventral ear pinna of sexually mature male Syrian hamsters. Their order of efficacy was as follows: RU 58841 > RU 56187 > RU 38882 > cyproterone acetate. Maximal reduction of 60% in the size of the sebaceous glands was observed in hamsters treated with RU 58841 at a dose of 10 micrograms per day. This degree of inhibition occurred without any systemic side effects as shown by the absence of inhibition on the contralateral untreated ear pinna. Longer treatment did not produce greater inhibition since extending the treatment period from 4 weeks to 12 weeks showed similar data. The effect of RU 58841 was reversible since the inhibited sebaceous glands returned to normal size within 4 weeks after the cessation of the topical applications. The potent localized inhibition of sebaceous glands by RU 58841 demonstrates the excellent potential of this compound as a topical drug for the treatment of acne and other androgen-mediated disorders.