Studies related to the metabolism of anabolic steroids in the horse: a gas chromatographic mass spectrometric method to confirm the administration of 19-nortestosterone or its esters to horses

Simultaneous quantitation of 9 anabolic and natural steroidal hormones in equine urine by UHPLC-MS/MS triple quadrupole

A new fast and easy analytical procedure for the simultaneous detection and quantification of 9 anabolic steroids (deslorelin, dexamethasone sodium phosphate, prednisolone, methylprednisolone, stanozolol, boldenone, nandrolone, dexamethasone isonicotinate and altrenogest) in horse urine for doping control have been developed by using the ultra-high-performance liquid chromatography coupled with tandem mass spectrometry technique (UHPLC-MS/MS). A total amount of 400 μl of sample was evaporated, restored and injected in the UHPLC-MS/MS. The proposed method was fully validated showing a recovery higher than 89.12% and a coefficient of variation lower than 6.02%. The correlation coefficients range of the analyzed compound's calibration curves was 0.9955-0.9997, and the limits of detection and quantification were in the range of 0.1 and 0.25 μg/l, respectively.

Analysis of 19-nortestosterone residue in animal tissues by ion-trap gas chromatography-tandem mass spectrometry

A rapid sample treatment procedure for the gas chromatography-tandem mass spectrometry (GC-MS) determination of 19-nortestosterone (19-NT) in animal tissues has been developed. In our optimized procedures, enzymatic hydrolysis with β-glucuronidase from Escherichia coli was performed in an acetate buffer (pH 5.2, 0.2 mol/L). Next, the homogenate was mixed with methanol and heated at 60 °C for 15 min, then placed in an ice-bath at -18 °C for 2 h. After liquid-liquid extraction with n-hexane, the analytes were subjected to a normal-phase solid phase extraction (SPE) C₁₈ cartridge for clean-up. The dried organic extracts were derivatized with heptafluorobutyric anhydride (HFBA), and then the products were injected into GC-MS. Using electron impact mass spectrometry (EI-MS) with positive chemical ionization (PCI), four diagnostic ions (m/z 666, 453, 318, and 306) were determined. A standard calibration curve over the concentration range of 1-20 ng/g was reached, with Y=467084X-68354 (R²=0.9997) for 19-NT, and the detection limit was 0.3 ng. When applied to spiked samples collected from bovine and ovine, the recoveries ranged from 63% to 101% with relative standard deviation (RSD) between 2.7% and 8.9%. The procedure is a highly efficient, sensitive, and more economical method which offers considerable potential to resolve cases of suspected nandrolone doping in husbandry animals.

Metabolism of anabolic steroids and their relevance to drug detection in horseracing

The fight against doping in sport using analytical chemistry is a mature area with a history of approximately 100 years in horseracing. In common with human sport, anabolic/androgenic steroids (AASs) are an important group of potential doping agents. Particular issues with their detection are extensive metabolism including both phase I and phase II. A number of the common AASs are also endogenous to the equine. A further issue is the large number of synthetic steroids produced as pharmaceutical products or as 'designer' drugs intended to avoid detection or for the human supplement market. An understanding of the metabolism of AASs is vital to the development of effective detection methods for equine sport. The aim of this paper is to review current knowledge of the metabolism of appropriate steroids, the current approaches to their detection in equine sport and future trends that may affect equine dope testing.

Presence and metabolism of endogenous androgenic-anabolic steroid hormones in meat-producing animals: a review

The presence and metabolism of endogenous steroid hormones in meat-producing animals has been the subject of much research over the past 40 years. While significant data are available, no comprehensive review has yet been performed. Species considered in this review are bovine, porcine, ovine, equine, caprine and cervine, while steroid hormones include the androgenic-anabolic steroids testosterone, nandrolone and boldenone, as well as their precursors and metabolites. Information on endogenous steroid hormone concentrations is primarily useful in two ways: (1) in relation to pathological versus 'normal' physiology and (2) in relation to the detection of the illegal abuse of these hormones in residue surveillance programmes. Since the major focus of this review is on the detection of steroids abuse in animal production, the information gathered to date is used to guide future research. A major deficiency in much of the existing published literature is the lack of standardization and formal validation of experimental approach. Key articles are cited that highlight the huge variation in reported steroid concentrations that can result when samples are analysed by different laboratories under different conditions. These deficiencies are in most cases so fundamental that it is difficult to make reliable comparisons between data sets and hence it is currently impossible to recommend definitive detection strategies. Standardization of the experimental approach would need to involve common experimental protocols and collaboratively validated analytical methods. In particular, standardization would need to cover everything from the demographic of the animal population studied, the method of sample collection and storage (especially the need to sample live versus slaughter sampling since the two methods of surveillance have very different requirements, particularly temporally), sample preparation technique (including mode of extraction, hydrolysis and derivatization), the end-point analytical detection technique, validation protocols, and the statistical methods applied to the resulting data. Although efforts are already underway (at HFL and LABERCA) to produce more definitive data and promote communication among the scientific community on this issue, the convening of a formal European Union working party is recommended.

Some aspects of doping and medication control in equine sports

This chapter reviews drug and medication control in equestrian sports and addresses the rules of racing, the technological advances that have been made in drug detection and the importance of metabolism studies in the development of effective drug surveillance programmes. Typical approaches to screening and confirmatory analysis are discussed, as are the quality processes that underpin these procedures. The chapter also addresses four specific topics relevant to equestrian sports: substances controlled by threshold values, the approach adopted recently by European racing authorities to control some therapeutic substances, anabolic steroids in the horse and LC-MS analysis in drug testing in animal sports and metabolism studies. The purpose of discussing these specific topics is to emphasise the importance of research and development and collaboration to further global harmonisation and the development and support of international rules.

Detection of the administration of 17beta-nortestosterone in boars by gas chromatography/mass spectrometry

17beta-Nortestosterone (17betaN) is illegally used in livestock as a growth promoter and its endogenous production has been described in some animals, such as adult boars. In this paper, the metabolism of 17betaN in boars has been studied by gas chromatography/mass spectrometry (GC/MS) in order to identify markers of the exogenous administration. Administration studies of intramuscular 17betaN laurate to male pigs were performed. Free, sulphate and glucuronide fractions of the urine samples were separated and the steroids present were quantified by GC/MS. 17betaN was detected in some pre-administration samples. After administration, 17betaN, norandrosterone, noretiocholanolone (NorE), norepiandrosterone, 5beta-estrane-3alpha,17beta-diol and 5alpha-estrane-3beta,17beta-diol were detected in different fractions, being the most important metabolites, 17betaN excreted as a sulphate and free NorE. Samples collected in routine controls were also analyzed by GC/MS to identify endogenous compounds. 17betaN, norandrostenedione and estrone were detected in almost all the samples. No other 17betaN metabolites were detected. According to these results, the detection by GC/MS of some of the 17betaN metabolites described above, different from 17betaN, could be indicative of the exogenous administration of 17betaN to boars.

Studies related to the origin of C18 neutral steroids isolated from extracts of urine from the male horse: The identification of urinary 19-oic acids and their decarboxylation to produce estr-4-en-17β-ol-3-one (19-nortestosterone) and estr-4-ene-3,17-dione (19-norandrost-4-ene-3,17-dione) during sample processing

For almost two decades we have known that enzymatic hydrolysis of "normal" urine samples from the entire male horse using Escherichia coli (E. coli) followed by solvolysis (ethyl acetate:methanol:sulphuric acid) results in the detection of significant amounts of estr-4-ene-3,17-dione (19-norandrost-4-ene-3,17-dione) along with estr-4-en-17beta-ol-3-one (19-nortestosterone, nandrolone) in extracts of the hydrolysed urine and that both steroids are isolated from the solvolysis fraction. This solvolysis process is targeted at the steroid sulphates. Also we have shown that 19-norandrost-4-ene-3,17-dione and 19-nortestosterone are isolated from testicular tissue extracts. Subsequently, evidence was obtained that 19-nortestosterone detected in extracts of "normal" urine from male horses may not be derived from the 17beta-sulphate conjugate. However, following administration of 19-nortestosterone based proprietary anabolic steroids to all horses (males, females and castrates), the urinary 19-nortestosterone arising from the administration is excreted primarily as the 17beta-sulphate conjugate. Thus, if the 19-nortestosterone-17beta-sulphate conjugate arises only following administration this has interesting implications for drug surveillance programmes to control administration of 19-nortestosterone based anabolic preparations to male horses. These results have led us to consider that the precursors to 19-nortestosterone and 19-norandrost-4-ene-3,17-dione, present in the urine prior to the hydrolysis steps, have the same basic structure except for the functionality at the 17-position. We have used preparative high pressure liquid chromatography (LC) and LC fractionation to separate these precursors from the high amounts of oestrogenic sulphates present in "normal" urine from the entire male horse. Purified fractions have then been studied by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) to identify the precursors.

Quantitation of 17β-nandrolone metabolites in boar and horse urine by gas chromatography–mass spectrometry

A method to quantify metabolites of 17beta-nandrolone (17betaN) in boar and horse urine has been optimized and validated. Metabolites excreted in free form were extracted at pH 9.5 with tert-butylmethylether. The aqueous phases were applied to Sep Pak C18 cartridges and conjugated steroids were eluted with methanol. After evaporation to dryness, either enzymatic hydrolysis with beta-glucuronidase from Escherichia coli or solvolysis with a mixture of ethylacetate:methanol:concentrated sulphuric acid were applied to the extract. Deconjugated steroids were then extracted at alkaline pH with tert-butylmethylether. The dried organic extracts were derivatized with MSTFA:NH4I:2-mercaptoethanol to obtain the TMS derivatives, and were subjected to analysis by gas chromatography mass spectrometry (GC/MS). The procedure was validated in boar and horse urine for the following metabolites: norandrosterone, noretiocholanolone, norepiandrosterone, 5beta-estran-3alpha, 17beta-diol, 5alpha-estran-3beta, 17beta-diol, 5alpha-estran-3beta, 17alpha-diol, 17alpha-nandrolone, 17betaN, 5(10)-estrene-3alpha, 17alpha-diol, 17alpha-estradiol and 17beta-estradiol in the different metabolic fractions. Extraction recoveries were higher than 90% for all analytes in the free fraction, and better than 80% in the glucuronide and sulphate fractions, except for 17alpha-estradiol in the glucuronide fraction (74%), and 5alpha-estran-3beta, 17alpha-diol and 17betaN in the sulphate fraction (close to 70%). Limits of quantitation ranged from 0.05 to 2.1 ng mL(-1) in the free fraction, from 0.3 to 1.7 ng mL(-1) in the glucuronide fraction, and from 0.2 to 2.6 ng mL(-1) in the sulphate fraction. Intra- and inter-assay values for precision, measured as relative standard deviation, and accuracy, measured as relative standard error, were below 15% for most of the analytes and below 25%, for the rest of analytes. The method was applied to the analysis of urine samples collected after administration of 17betaN laureate to boars and horses, and its suitability for the quantitation of the metabolites in the three fractions has been demonstrated.

Pitfalls in trimethylsilylation of anabolic steroids

Mixtures such as N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA), ammonium iodide and dithioerythreitol (DTE) or MSTFA, trimethyliodosilane and DTE were used for derivatisation of anabolic steroids extracted from 2 g kidney fat and present at ng kg(-1) level. They are leading to unexpected products. Their identity and mechanism of formation have been discussed. A new silylation mixture was developed to overcome these pitfalls: N,O-bis-trimethylsilyl-acetamide was used in combination of 2.5% of MSTFA/I(2) (1000:10 (v/w)). A single product consisting in ether-TMS and/or enol-TMS derivative was observed for all tested steroids with a stability demonstrated for at least 48 h. Quantitative application was proved even at the low ng kg(-1) level in a complex biological matrices, i.e. kidney fat.

The metabolism of norethandrolone in the horse: characterization of 16-, 20- and 21-oxygenated metabolites by gas chromatography/mass spectrometry

After oral administration to a thoroughbred gelding, the anabolic steroid norethandrolone was converted into a complex mixture of oxygenated metabolites. These metabolites were extracted from the urine, deconjugated by methanolysis and converted to their O-methyloxime trimethylsilyl derivatives. Gas chromatographic/mass spectrometric analysis indicated the major metabolites to be 19-norpregnane-3,16,17-triols, 19-norpregnane-3,17,20-triols and 3,17-dihydroxy-19-norpregnan-21-oic acids. Some minor metabolites were also detected.

Preliminary study of the metabolism of 17 alpha-methyltestosterone in horses utilizing gas chromatography-mass spectrometric techniques

Little is known about the metabolism of 17 alpha-alkyl anabolic steroids in horses. In this study, the metabolism of 17 alpha-methyltestosterone is investigated by oral administration of a (1 + 1) mixture of the steroid and its deuteriated analogue. Both compounds were synthesized from dehydroisoandrosterone (DHA), using a Grignard reaction followed by an Oppenauer oxidation. Post-administration urine extracts were analysed by gas chromatography--mass spectrometry (GC-MS) using both electron impact (IE) and chemical ionization (CI). Interpretation of the data was facilitated by observation of the fragment ions present in the mass spectra. Notably, the D-ring fragment ions were indicative of 15- or 16-hydroxylation, where 16-hydroxy metabolites showed ion pairs at m/z 218/221 and at m/z 231/234 while 15-hydroxy compounds gave the 231/234 ion pair alone. Unaltered D-rings showed fragment ions at m/z 143/146. The data showed that the main phase 1 metabolic processes were partial and complete reduction of the 3-oxo-4-ene group, 15-hydroxylation, 16-hydroxylation, 17-epimerization and hydroxylation at at least two other undetermined sites, postulated as the 6 and 11 positions. Phase 2 metabolism, in the form of glucuronide and sulfate formation, was also common. The information provided by this investigation will result in improved effectiveness of confirmatory analytical procedures for 17 alpha-alkyl anabolic steroids.

Detection of 19-nortestosterone and its urinary metabolites in miniature pigs by gas chromatography-mass spectrometry

The metabolism of 19-nortestosterone was investigated in a miniature non-castrated male pig (boar), in a castrated pig (barrow) and in a female pig (sow). Urine samples were taken before and at regular intervals after the injection of 100 mg of Laurabolin (nortestosterone laurate). The sample clean-up consists in preliminary solid-phase extraction, followed by high-performance liquid chromatographic purification and fractionation. Finally, gas chromatography-mass spectrometry is used to identify the 19-nortestosterone metabolites.

Derivatization and gas chromatographic-mass spectrometric detection of anabolic steroid residues isolated from edible muscle tissues

A method was developed for the detection of anabolic steroid residues in edible muscle tissues. After enzymic digestion of the tissue and purification on disposable C18 solid-phase extraction columns, the extract was injected onto a C18 reversed-phase high-performance liquid chromatographic column. Three fractions or windows were collected, each containing specific analytes. After evaporation to dryness, the residues were subjected to a derivatization procedure which yielded suitable derivatives. After gas chromatographic-mass spectrometric analysis, both gas chromatographic retention data and mass spectral data were used for the detection and identification of nortestosterone, testosterone, estradiol, ethinylestradiol, trenbolone, methyltestosterone, chlormadinone acetate, medroxyprogesterone acetate and megestrol acetate.

Pharmacokinetics of 19-nortestosterone esters in normal men

A reliable method for the isolation of 19-nortestosterone (NT), testosterone (T) and dihydrotestosterone (DHT) by high-performance liquid chromatography (HPLC) and quantitation of the individual steroids by radioimmunoassays is described. The method was used to measure serum concentrations of NT, T and DHT in a pharmacokinetic study and in a clinical trial for male fertility control. Following intramuscular injection of either 50 mg 19-nortestosterone-3-(p-hexoxyphenyl)-propionate (NP) or 50 mg 19-nortestosterone-decanoate (ND) serum NT increased rapidly to maximal concentrations of 4.6 +/- 3.2 and 2.0 +/- 1.3 nmol/l (+/-SD), respectively, in the 6 volunteers. The half-life time was 8 days for ND and 21 days for NP. Based on these findings a clinical trial with NP was performed. NP was given to 5 healthy men in doses of 100 mg/week for the first 3 weeks followed by 200 mg/week for 10 further weeks. Serum NT levels increased gradually and maximal concentrations were reached in the 13th treatment week (20.2 +/- 3.4 nmol/l). Measurable amounts of NT were detectable for 19 weeks after the last injection. The study shows that NT accumulates under this treatment regime and wider spacing of the injection intervals may be possible in future trials.

Gas chromatographic/mass spectrometric analysis of 19-nortestosterone urinary metabolites in man

A sensitive and highly specific method based on capillary column gas chromatography/mass spectrometry has been developed for the detection of 19-nortestosterone (17 beta-hydroxy-4-estren-3-one) metabolites in urine. After intramuscular administration of 19-nortestosterone decanoate to man, urine samples were collected during several days and treated with Helix pomatia digestive juice. The free steroids were extracted and converted into O-methyl-oxime-trimethylsilyl or the trimethylsilyl ether derivatives and analysed by capillary column gas chromatography/mass spectrometry (GC/MS). Three isomeric metabolites were detected and identified as 3 alpha-hydroxy-5 alpha-extran-17-one (19-norandrosterone), 3 alpha-hydroxy-5 beta-estran-17-one (19-noretiocholanolone) and 3 beta-hydroxy-5 alpha-estran-17-one (19-norepiandrosterone). Packed column GC/MS was also employed in the selected ion monitoring mode for the specific detection of 19-norandrosterone, the most abundant urinary metabolite of 19-nortestosterone. These gas chromatographic/mass spectrometric methods are highly specific tests which can be used on a routine basis for the confirmation of 19-nortestosterone administration to athletes as well as for therapeutic monitoring following administration of the drug.

The identification of C-18 neutral steroids in normal stallion urine

As part of a continuing research program associated with the detection of anabolic steroid residues in horse urine, normal samples from entire male horses have now been investigated. Isomers of three C-18 neutral steroids; 4-estren-17-ol-3-one (1), estrane-3,17-diol (2) and an unsaturated estranediol having a possible structure (3), have been identified in urine samples from two male horses aged 8 and 14 years. Of these three steroids, compound (2) was not detected in the urine of a 2.5 yr old entire male nor in the majority of post-race urine samples from entire male horses average age 3.8 yrs (n = 34). Ten of these samples showed tentative indications of this compound. Although the isolation of isomers of estrane-3,17-diol from human non-pregnancy urine has been reported previously, analysis of non-pregnancy urine samples in the present study did not reveal the presence of these compounds.

Detection and quantitation of 19-norandrosterone in urine by isotope dilution-mass spectrometry

A highly accurate method has been developed for detection and quantitation of 19-norandrosterone, the major urinary metabolite of 19-nortestosterone in man. A suitable 14C labelled standard was obtained by i.m. injection of [4-14C]-19-nortestosterone into a human volunteer. A fixed amount of this internal standard was added to a fixed amount of urine and the mixture was treated with Helix pomatia for 24 h. After extraction and purification by t.l.c., the mixture was converted into methoxime-trimethylsilyl derivative and analyzed by combined GC-MS. Unlabelled 19-norandrosterone could be quantitated from the ratio between the tracings of the ions at m/z 256 and m/z 258, corresponding to M-90-31 ions. In alternative procedures the ions at m/z 346 and 348 (corresponding to the M-31 ions) could be used. Under the conditions employed, urinary 19-norandrosterone could be identified and quantitated in concentrations exceeding 20 ng/ml. The steroid could be traced in urine up to 6 weeks after i.m. administration of 25 mg of the decanoate of 19-nortestosterone (Deca-Durabol). When using radioimmunoassay with antibodies towards unmetabolized 19-nortestosterone, it was possible to trace urinary 19-nortestosterone only for 1-2 weeks after the administration. The present method has been successfully used for analysis of 19-norandrosterone in urine samples obtained from athletes involved in competition.

Plasma concentrations and urinary excretion of nandrolone and/or its metabolites after intramuscular injection of nandrolone phenylpropionate to horses

A radioimmunological method was used as a screening procedure to determine the period of detection or "clearance time", for the horse, of therapeutic doses of the synthetic anabolic steroid nandrolone phenylpropionate. Seven horses, either at rest or being exercised, were given a course of weekly intramuscular injections of the steroid. On the separate occasion, some of the horses were given a single intramuscular injection of the same compound. The weekly injections maintained a high plasma concentration of nandrolone and/or metabolites. The mean (+/- sd) period of detection in plasma of these compounds was 23 (+/- 2) days (range 21 to 25) in resting horses and 20 (+/- 6) days (range 14 to 27) in exercised animals. The mean period of detection in urine was 25 (+/- 7) days (range 16 to 32) and 25 (+/- 12) days (range 9 to 38) for resting and exercised horses, respectively. After a single intramuscular injection to resting horses, the mean periods of detection were 12(+/- 2) days (range 9 to 15) and 13 (+/- 2) days (range 11 to 16) in plasma and urine, respectively. In all experiments there was considerable individual variation in the time taken for the plasma and urine concentrations to return to pre-dose values. This variation was particularly marked in the urine of exercised horses given a course of injections. With horses in training, this period may be over 5 weeks, a period approaching the minimum of 42 days advocated by the Royal College of Veterinary Surgeons that the therapeutic use of anabolic steroids should be discontinued before racing.

Capillary column gas chromatographic mass spectrometric analysis of anabolic steroid residues using splitless injections made at elevated temperatures

The use of capillary column gas chromatography mass spectrometry has been investigated for the detection of the presence of estrane-3,17 alpha-diol in horse urine extracts; the detection of this diol confirms the administration of anabolic steroids based upon 19-nortestosterone. To reduce analysis time, but yet maintain a solvent effect in the splitless injection mode, injections have been made at elevated temperatures (190-220 degree C) using high boiling solvents (dodecane b.p. 214 degree C and tetradecane b.p. 252 degree C).

Studies related to the metabolism of anabolic steroids in the horse: testosterone

1. After intramuscular administration of [4-14C]testosterone to two cross-bred gelded horses, 45% of the radioactivity was excreted in urine in 96 h. Small amounts of urinary activity could still be detected at 200 h. 2. Neutral metabolites obtained after both enzyme and acid hydrolysis of urine samples have been investigated by g.l.c.-mass spectrometry. 3. 5 alpha-Androstane-3 beta, 17 alpha-diol was found only in the enzyme-hydrolysable extract and testosterone only in the acid-hydrolysable extract. 5 alpha-Androstane-3 beta, 17 beta-diol and 3 beta-hydroxy-5 alpha-androstan-17-one were found predominantly in the acid-hydrolysable extract.