Systemic absorption from prednisolone rectal foam in ulcerative colitis

Pharmacokinetics and pharmacodynamics of dexamethasone sodium-m-sulfobenzoate (DS) after intravenous and intramuscular administration: a comparison with dexamethasone phosphate (DP)

The pharmacokinetics (PK) and pharmacodynamics (effects on blood lymphocytes) of dexamethasone (D) after intravenous (i.v.) administration of dexamethasone phosphate (DP, 10 mg, equivalent to 8.3 mg of dexamethasone) and after intravenous and intramuscular (i.m.) administration of dexamethasone sulfobenzoate sodium (DS, 9.15 mg, equivalent to 6 mg of dexamethasone) were assessed. Only 25% of DS was converted into dexamethasone with a half-life for DS of 5.4 hours and 7.4 hours after i.v. and i.m. administration, respectively. Consequently, the mean residence time of D after both i.m. and i.v. administration of DS (10.4-11.6 h) was longer than that after DP administration (6.1 h). The smaller lymphocyte suppression induced by DS (50% of that after DP administration) was shown to be related to differences in the pharmacokinetics. This study revealed significant differences in the pharmacokinetics of D after administration of DS and DP and stresses the importance of the prodrug for the pharmacological response. Because of the slow and incomplete conversion of DS into dexamethasone, its use in emergency medicine situations should be critically evaluated.

Prednisolone metasulphobenzoate foam retention enemas suppress the hypothalamo-pituitary-adrenal axis

BACKGROUND

Corticosteroid enemas represent effective treatment for ulcerative proctitis, but absorption into the systemic circulation may have undesirable metabolic consequences. Prednisolone metasulphobenzoate, a lipophobic corticosteroid derivative, is designed to be absorbed poorly through the recto-sigmoid mucosa, but the effects of foam enema preparations upon the hypothalamo-pituitary-adrenal axis have not been examined.

METHODS

Nine patients suffering from active ulcerative proctitis underwent four weeks of therapy with prednisolone metasulphobenzoate foam enemas. The hypothalamo-pituitary-adrenal axis, defined using the modified single-dose metyrapone test, glucose homeostasis and lipid profiles were studied before and after treatment.

RESULTS

The hypothalamo-pituitary-adrenal axis was significantly depressed after the treatment period; mean stimulated plasma cortisol concentration fell from 384 +/- 244 (s.d.) to 288 +/- 252 nmol/L, P < 0.02; stimulated mean plasma 11-deoxycortisol concentration fell from 677 +/- 333 to 407 +/- 326 nmol/L, P < 0.01. Mean fasting plasma glucose, insulin, C-peptide, fructosamine and triglyceride concentration were unchanged, whilst the mean serum cholesterol concentrations rose from 5.6 +/- 1.1 to 6.0 +/- 1.2 mmol/L (not significant).

CONCLUSION

Prednisolone metasulphobenzoate foam enemas have significant systemic and endocrine metabolic effects, which could assume importance with long-term therapy.

Review article: topical corticosteroids in inflammatory bowel disease

It would be ideal to treat inflammatory bowel disease with topical corticosteroids that are either not absorbed through the mucosa, or have a substantial first-pass hepatic metabolism. The topical use of hydrocortisone, prednisolone-21-phosphate or betamethasone is often associated with systemic side-effects. Newer corticosteroid preparations (prednisolone metasulphobenzoate, tixocortol pivalate, fluticasone propionate, beclomethasone dipropionate and budesonide) are usually associated with minimal systemic corticosteroid activity. This article reviews the clinical activity and safety of these newer preparations.

Pharmacokinetics of rectal drug administration, Part II. Clinical applications of peripherally acting drugs, and conclusions

Part I of this article, which appeared in the previous issue of the Journal, covered general considerations, the physiology of the rectum, spreading of drugs into the colon, rectal absorption, partial avoidance of first-pass elimination, rate-controlled rectal delivery of drugs, irritation of the rectal mucosa and clinical applications of rectal administration, and discussed centrally acting drugs. In Part II, this discussion is extended to drugs which act peripherally and to methods of enhancing rectal drug absorption. The overall summary appeared in Part I.