Accumulation of the β-agonist clenbuterol by pigmented tissues in rat eye and hair of veal calves

Dürsch, I.; Meyer, Heinrich; Karg, H.

doi:10.2527/1995.7372050x

Cited by 33 publications

(11 citation statements)

References 3 publications

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“…The lower concentrations observed in the eyes may have been due to insufficient time for Cb to accumulate and/or to the lack of pigment in the eyes of albino rats. 45,46 Enantiomers. In the present study, no in vivo enantiomeric Cb inversion was observed.…”

Section: Drug Distribution: Rac-clenbuterol 24-h Tissue Levelsmentioning

confidence: 99%

?-Agonist-induced alterations in organ weights and protein content: Comparison of racemic clenbuterol and its enantiomers

et al. 2000

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Clenbuterol is a relatively selective beta2-adrenergic partial agonist that has bronchodilator activity. This drug has been investigated as a potential countermeasure to microgravity- or disuse-induced skeletal muscle atrophy because of presumed anabolic effects. The purpose of this study was to: 1) analyze the anabolic effect of clenbuterol's (-)-R and (+)-S enantiomers (0.2 mg/kg) on muscles (cardiac and skeletal) and other organs; and 2) compare responses of enantiomers to the racemate (0.4 mg/kg and 1.0 mg/kg). Male Sprague Dawley rats were treated with: a) racemic clenbuterol (rac-clenbuterol, 0.4 or 1.0 mg/kg); b) enantiomers [clenbuterol (-)-R or (+)-S]; or c) vehicle (1.0 mL/kg buffered saline). Anabolic activity was determined by measuring tissue mass and protein content. HPLC teicoplanin chiral stationary phase was used to directly resolve racemic clenbuterol to its individual enantiomers. In skeletal muscle, both enantiomers had equal anabolic activity, and the effects were muscle- and anatomic region-specific in magnitude. Although the enantiomers did not affect the ventricular mass to body weight ratio, clenbuterol (+)-S induced a small but significant increase in ventricular mass. Both clenbuterol enantiomers produced significant increases in skeletal muscle mass, while being less active in producing cardiac ventricular muscle hypertrophy than the racemic mixture.

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Section: Drug Distribution: Rac-clenbuterol 24-h Tissue Levelsmentioning

confidence: 99%

?-Agonist-induced alterations in organ weights and protein content: Comparison of racemic clenbuterol and its enantiomers

et al. 2000

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“…Melanin-containing eye material in cattle is known to accumulate clenbuterol very well and permit a prolonged detection period [7,9,10]. Even spiked eye matrix preferentially accumulated clenbuterol in the retina at the betareceptors site.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, these matrices have limited value for the detection of illegal use of clenbuterol. However, melanin-containing tissues, such as retina and hair, are known to accumulate clenbuterol very well and permit a prolonged detection period following drug withdrawal [9,10]. Following treatment of several species with clenbuterol, the highest residue levels were found in the retina of cattle [7] and chicken eyes [11].…”

Section: Introductionmentioning

confidence: 99%

Development of clenbuterol reference materials: lyophilized bovine eye samples free of clenbuterol (CRM 673) and containing clenbuterol (CRM 674). Part 1. Preparation, homogeneity and stability

Pfaffl

Ginkel

McEvoy

et al. 2001

Fresenius J Anal Chem

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Within the EU Standards, Measurement and Testing Program (SMT) two clenbuterol reference materials (RMs) were developed. Since clenbuterol readily accumulates and is slowly depleted from pigmented tissues such as the retina, homogenized eye liquid content is the most sensitive tissue for the detection of clenbuterol misuse. Therefore, both of the RMs were produced from bovine eye matrix: a negative control--RM 673 eye reference material, clenbuterol free (<0.50 microg/kg eye matrix) and a positive--RM 674 eye reference material containing clenbuterol (approximately 10 microg/kg eye matrix). Eyes were sampled from 103 German Simmental cattle and the inner liquid content was homogenized to a wet homogenized liquid content (HLC). This clenbuterol negative pool was divided into two sub-pools, one of which was spiked with clenbuterol to a final concentration of 10 microg clenbuterol/kg HLC. Of each pool exactly 2.0 +/- 0.01 g (+/- 0.5%) portions were weighed into 790 containers. Lyophilization of the 1,580 containers was performed in one batch. Parameters for the filling of containers, dry matter content, and residual moisture were in accordance with EU requirements. A three-year stability study and two homogeneity studies at various storage temperatures (-60 degrees C, -20 degrees C, +4 degrees C, +20 degrees C, and +37 degrees C) were performed. Low variation was observed within all of the homogeneity studies, proving that each of the RMs were homogeneous and that this was independent of storage temperature and storage time. In the stability studies, measured clenbuterol concentrations remained constant for RM 673 under the detection limit at 0.15 +/- 0.01 microg clenbuterol equivalent/kg HLC (n = 110) and were also constant for RM 674 at 11.21 +/- 0.15 microg clenbuterol/kg HLC (n=150; measured as duplicates). These studies demonstrate that clenbuterol-containing and clenbuterol-free RMs in bovine eye matrix can be successfully produced. Based on the results described above, it is concluded that both RMs may be suitable as candidates for certification.

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“…Various recent studies [6][7][8][9] have shown the potential for pigmented tissues in control programmes for unauthorised substances in animal husbandry, particularly clenbuterol, due to the selective fixation which occurs between melanin and these substances and remains stable. The retina is, therefore, a widely used matrix in most clenbuterol determination techniques, such as immunological tests, radioimmunoassay [6] or enzyme immunoassay [7][8][9][10][11], and in chromatographic techniques such as: HPLC with UV [12] or electrochemical [13] detection and GC -MS [14], after various extraction or purification procedures, such as liquid-liquid extraction [13][14] and solid-phase extraction [ 12].…”

Section: 5-dichloro-a-[(tert-butylamino) Methyl] Benzyl Alco-mentioning

confidence: 99%

Diphasic dialysis extraction technique for clenbuterol determination in bovine retina by gas chromatography-mass spectrometry

et al. 1999

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Accumulation of the β-agonist clenbuterol by pigmented tissues in rat eye and hair of veal calves

Cited by 33 publications

References 3 publications

?-Agonist-induced alterations in organ weights and protein content: Comparison of racemic clenbuterol and its enantiomers

?-Agonist-induced alterations in organ weights and protein content: Comparison of racemic clenbuterol and its enantiomers

Development of clenbuterol reference materials: lyophilized bovine eye samples free of clenbuterol (CRM 673) and containing clenbuterol (CRM 674). Part 1. Preparation, homogeneity and stability

Diphasic dialysis extraction technique for clenbuterol determination in bovine retina by gas chromatography-mass spectrometry

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