An efficient procedure for extraction and determination of steroids in the tissue of laboratory animals

Determination of corticosteroids in tissue samples by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determination of corticosterone and 11-dehydrocorticosterone (11-DHC) levels in KKA(y) mouse liver and adipose tissue, and hydrocortisone and cortisone levels in human adipose tissue has been developed. The corticosteroids were extracted from liver tissue with methanol/water and ethyl acetate for adipose tissue samples. Corticosterone and 11-DHC were separated with a methanol gradient and hydrocortisone and cortisone with an acetonitrile gradient containing trifluoroacetic acid on a reversed-phase column within 15 min. The corticosteroids were detected after electrospray ionization in positive mode with multiple reaction monitoring (MRM). The limits of quantification (LOQ) were estimated to be 15 nmol/kg liver and 1.6 nmol/kg adipose tissue for corticosterone and 5.4 nmol/kg liver and 0.92 nmol/kg adipose tissue for 11-DHC. The LOQ was estimated to be 0.2 nmol/kg adipose tissue for hydrocortisone and 0.4 nmol/kg adipose tissue for cortisone. The limits of detection (LOD) at 3 times S/N were estimated to be 0.07 nmol/kg adipose tissue for hydrocortisone 0.1 nmol/kg adipose tissue for cortisone. The variation of endogenous levels in KKA(y) mouse from different animals (CV%) was high with mean liver tissue levels of 117+/-25 (S.D.)nmol/kg for corticosterone and 62+/-19 (S.D.)nmol/kg for 11-DHC (n=5) and adipose tissue levels of 39+/-20 (S.D.)nmol/kg for corticosterone and 2.4+/-0.9 (S.D.)nmol/kg for 11-DHC (n=9). Endogenous levels in human biopsy samples from adipose tissue were 12+/-7.0 (S.D.)nmol/kg for hydrocortisone and 3.0+/-1.6 (S.D.)nmol/kg for cortisone (n=16). The new LC-MS/MS methods showed sufficient sensitivity and selectivity for determination of endogenous levels of corticosteroids in both KKA(y) mouse liver and adipose tissue samples and human adipose tissue samples. The selectivity of the methods was verified by analysis of two different productions from each analyte.

Emulsion formulations of testosterone for nasal administration

The nasal route has received a great deal of attention due to the many advantages of nasal delivery over parenteral administration. The male sex hormone testosterone is ineffective when administered orally due to its gut wall and first-pass metabolism. Therefore, an alternative method for delivery would be the intranasal route, if the lack of aqueous solubility can be overcome. In this study a new approach to emulsion formulations of the drug has been proposed based on the hypothesis that increased absorption is possible upon solubilization of the drug and/or prolongation of the formulation residence time in the nose. Three differently charged testosterone submicron size emulsion formulations with various zeta potentials (+24.8, -23.0 and 0.06 mV) were prepared as nasal spray formulations. A dose of approximately 3.8 mg testosterone per rabbit was administered to four rabbits and the bioavailability of the emulsion formulations was assessed and compared with an i.v. formulation via solid-phase extraction, followed by an HPLC analysis method. Statistical analysis of the normalized data indicated a bioavailability of 55, 51 and 37% for positively, negatively and neutrally charged emulsions respectively. The results of this study strongly suggest that emulsion formulations have some potential to be considered for nasal delivery. Further, both the positively and negatively charged emulsion formulations provided a better bioavailability than the neutral charged emulsion, probably indicating that the charged particle interactions between emulsion globules and the mucus layer prolong the contact of drug with nasal membrane thus enhancing drug absorption.

Steroid metabolism by embryonic tissues of Arctic charr, Salvelinus alpinus

High-performance liquid chromatography analysis of extracts of Arctic charr (salvelinus alpinus) eggs revealed the presence of several steroids, predominantly progestogens together with testosterone. Yolk sac embryos were incubated with tritiated progesterone ([3H]P4) or 17-hydroxyprogesterone ([3H]17OHP) to examine the ability of the embryos to metabolize progestogens in vitro; both progestogen precursors were converted to various free and conjugated steroids metabolites (sulfates and glucuronides). [3H]P4 was completely metabolized to form steroids that coeluted with standard 11-oxygenated androgens, corticosteroids, progestogens, and some other unidentified metabolites. This report also describes the biosynthesis of 17,20 beta-dihydroxy-4-pregnen-3-one and 17,20 beta-dihydroxy-4-pregnen-3-one 20-sulfate by embryos of Arctic charr that were incubated with 17OHP.