Dexamethasone Concentrations in Plasma and Milk of Cows Following the Injection of Long- and Short-Acting Dexamethasone Esters

Abstract

A radioimmunoassay has been developed for the measurement of dexamethasone in plasma and milk of cows injected with long-and short-acting dexamethasone esters. Dexamethasone antiserum was produced by injecting cows with a dexamethasone-21-hemisuccinate-human serum albumin complex. The antisera was highly specific for dexamethasone, cross-reacting less than 0·7 % for all endogenous steroids tested.Plasma concentrations of dexamethasone in cows injected intramuscularly with either 20 mg dexamethasone-21 trimethyl acetate (n = 2) or the tributyl derivative (n = 2) reached a peak level of 0·6-1 . 1 ng/ml in 2-6 days then declined to undetectable levels ( < O· 15 ng/ml) by 14 days after injection. In general, dexamethasone concentrations in milk were 0·3--0·5 times the plasma concentrations but showed the same pattern of values.Plasma dexamethasone concentrations were also determined in three lactating dairy cows injected intramuscularly with tritiated dexamethasone-21 trimethyl acetate. In these cows plasma dexamethasone concentrations, as determined by isotopic dilution, reached maximal levels of 1· 1-1 ·6 ng/ml in 1-3 days then declined to levels of around 0·05 ng/ml within 30 days. The concentrations of dexamethasone in milk of two of these cows were, in general, similar to those found in plasma.In three cows injected intramuscularly with 20 mg dexamethasone sodium phosphate the concentrations of dexamethasone in plasma rose sharply to maximum levels of 24-70 ng/ml within 2-20 min after injection and fell to undetectable levels ( < O· 15 ng/ml) after 72 h.

Effect of reducing milk production using a prolactin-release inhibitor or a glucocorticoid on metabolism and immune functions in cows subjected to acute nutritional stress

“…The dexamethasone half-life in bovine plasma is between 5 and 6 h (Toutain et al, 1982;Gaignage et al, 1991). Fairclough et al (1981) showed in dairy cows that the peak plasma concentration of dexamethasone occurred 2 to 20 min after the i.m. injection of 20 mg of dexamethasone sodium phosphate.…”

Residual Potential of Dexamethasone and its Effect on Goat Milk

“…DXM is 50 times more powerful than the steroid cortisol (Becker 2011). It has been stated that Fairclough et al (1981) I.M administration of DXM most probably due to the formation of phosphate and acetate esters which can lead to the sustained release of DXM into the systemic circulation. Coelho et al (1995) also reported that with the administration of phosphate and acetate esters plasma levels of DEX is also elevated.…”

Review Hormones in Milk

“…These authors have shown that concentration of free estrogen is higher in whole milk than in skim milk, and that this hormone is present in various commercial milk products such as reconstituted nonfat dry milk, whey, and dry curd cottage cheese, with the highest concentration found in butter. dexamethasone in milk after its administration to cows (123), but another laboratory demonstrated its presence (124). In human and bovine milk, the appearance of prednisone (125) and prednisolone (126) was demonstrated after administration during lactation.…”