Issue 12, 1998

Residues of nortestosterone esters at injection sites.Part 1. Oral bioavailability†

Abstract

Injectable esters of 17β-19-nortestosterone (β-NT) have been used illegally for growth promotion in European Union (EU) cattle production. There are no data on oral bioavailability of free β-NT from β-NT esters. Adult non-pregnant female Landrace pigs (n = 4) were fitted with jugular vein cannulae and were treated as follows with an appropriate ‘flushing out’ period between each treatment: an intravenous bolus of β-NT at 0.1 mg kg1 body weight (NTiv), 300 mg nortestosterone phenylpropionate (NTPP) in oil of arachis administered per os (NTPPoil) and 300 mg NTPP in aqueous suspension administered per os (NTPPaq). Blood samples were taken for up to 24 h and analysed for free β-NT by enzyme immunoassay. Calculation of the area under the plasma time concentration curve (AUC), allowed absolute bioavailability estimations for both oral treatments. Mean bioavailability of β-NT following NTPPaq was 0.35% (range 0.25–0.41%) compared to 2.25% (range 0.86–2.85%) for NTPPoil. Mean ± standard error of mean time of maximum plasma concentration (Tmas) of free β-NT occurred earlier (2.3 ± 0.6 h) with NTPPoil compared to NTPPaq (10.3 ± 1.03 h) and the maximum plasma concentration (Cmax) was also greater for NTPPoil compared to NTPPaq (36.1 ± 6.49 vs. 3.2 ± 0.31 µg l1). It is concluded that the presence of arachis oil enhances the absorption of NTPP. Notwithstanding the possible effects that cooking and other food processing may have on such injection site residues, extrapolation of these results to man suggests that consumption of NTPP-containing injection sites may result in peak plasma concentrations of free β-NT which are significantly greater than those observed following injection of NT esters.

Article information

Article type
Paper

Analyst, 1998,123, 2475-2478

Residues of nortestosterone esters at injection sites.Part 1. Oral bioavailability†

J. D. G. McEvoy, C. E. McVeigh and W. John McCaughey, Analyst, 1998, 123, 2475 DOI: 10.1039/A804919J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements