Valnemulin hydrochloride

Valnemulin, successfully developed by Sandoz in 1984, is a new generation derivative of pleuromutilin related to tiamulin. Valnemulin has low water-solubility, a short half-life period, low bioavailability, and instability. The application of valnemulin was restricted. Therefore, finding a more moderate delivery system is necessary to improve the shortcomings of valnemulin. The purpose of the study was to improve the strong stability and the irritation caused by of valnemulin hydrochloride power through pegylated-valnemulin prodrug mode. The prepared pegylated-valnemulin prodrug was characterized and evaluated by in vitro release performance under buffer solutions with pH levels of 7.4 and 3.6. The loading rate of valnemulin in PEG-succinic-valnemulin prodrug was determined by ultraviolet spectrophotometer and high performance liquid chromatography (HPLC). HPLC with evaporative light scattering detector was applied to determine the amount of PEG-succinic acid. The loading rate of valnemulin in PEG-succinic-valnemulin prodrug was 6.46%. PEG-succinic-valnemulin prodrug demonstrated a satisfactory solubility of valnemulin with 523 mg·ml;-1; and excellent stability verified by the stability experiment.

CONTEXT: ;It is necessary to develop a new salt of valnemulin to replace the veterinary antibiotic, e.g. valnemulin hydrochloride, in order to overcome its instability during storage and preparation.;OBJECTIVE: ;The objective of this study was to prepare a novel organic acid salt, valnemulin hydrogen fumarate, and to investigate its stability compared with valnemulin hydrochloride.;MATERIALS AND METHODS: ;The crystal of valnemulin hydrogen fumarate was prepared by modified crystallization method; the enhanced stabilities of valnemulin hydrogen fumarate were conducted under irradiation and humid conditions, and the experimental results were simulated at AM1 level of calculations.;RESULTS: ;Valnemulin hydrogen fumarate was more stable than valnemulin hydrochloride. After irradiation for 180 days, the content of valnemulin hydrogen fumarate decreased slightly 2.7%, whereas the content of valnemulin hydrochloride had an obvious decrease of 32.8%. Meanwhile, valnemulin hydrogen fumarate showed better anti-RH (relative humidity) ability than valnemulin hydrochloride. Under conditions of 65% and 85% RH, the absorption values of valnemulin hydrogen fumarate towards water were 0.75% and 1.20% at 48 h, whereas those of valnemulin hydrochloride were 4.