チキソコルトール

R - Respiratory system

A - Alimentary tract and metabolism

QR - Respiratory system

QA - Alimentary tract and metabolism

Tixocortol presents the characteristic of local action which reduces significantly the side effects of systemic glucocorticoids. Reports have demonstrated that gastrointestinal administration of tixocortol generates a decrease in abdominal pain, bleeding, and frequency of stools which resulted in an amelioration in the malabsorption laboratory tests. All the effects were independent of suppression of the pituitary-adrenal axis, which was shown by the absence of significant depression of cortisol. Administration of tixocortol as a nasal spray has been shown to respect nasal drainage by the ciliary beats of the pituitary mucosa. The actions of tixocortol have no effect on leukocyte count, blood glucose level, sodium urinary excretion, and immunosupressive activity on lymphocytes.

The mechanism of action of tixocortol is similar to other corticosteroids regarding the binding sites and prostaglandin synthesis but the local properties of tixocortol are given by the immediate liver metabolism and transformation withing red blood cells. All the immediate transformations of tixocortol classified it as part of the nonsystemic steroids.

Tixocortol is rapidly modified within red blood cells and it is immediately metabolized by a first-pass liver metabolism. The metabolites of tixocortol are mainly represented by the formation of sulfo- and glucurono-conjugates which are later hydrolyzed from the conjugate forming neutral steroids. The metabolic transformations are the reduction of the 3-keto and delta 4 system, reduction of the C-20 carbonyl group, oxidation of the C-11 alcohol and cleavage of the side chain at C-17. The specific metabolic pathways of the C-21 thiol ester function were its transformation into methylthio, methylsulfonyl and methylsulfonyl derivatives and reductive cleavage of the C-21-S bond leading to 21-methyl structures. None of the metabolites have affinity for glucocorticoid receptors. This and the extensive metabolism explains the exclusive local activities of tixocortol.

The absorption of tixocortol is the same as in other steroids including hydrocortisone. Oral administration of tixocortol presents a 10-20% bioavailability with a significantly lower plasma Cmax than cortisol. The fast metabolism, larger volume of distribution and low bioavailability donates tixocortol with the absence of systemic activity.

Tixocortol has a rapid elimination after continuous metabolism. Urine analysis of oral administration of tixocortol demonstrate a complete lack of unchanged drug.

Studies have shown that oral or intravenous administration of tixocortol presents a significantly larger volume of distribution compared to cortisol of 21.7 L/kg.

Studies have shown that oral or intravenous administration of tixocortol presents a significantly larger clearance rate compared to cortisol of 33.3 L h/kg.