RESUMO
Bexarotene is a synthetic analogue of retinoic acid and exerts protective effects on the nervous system. However, low bioavailability and poor solubility of the crystal type I form severely limits the application of bexarotene in the clinic. A co-amorphous sample of bexarotene-PVP-K30 was prepared and the structure was characterized by X-ray diffraction and infrared spectroscopy. To determine the pharmacokinetics and tissue distribution of bexarotene, an LC-MS method was established to profile and quantify bexarotene in plasma and tissues of SD rats. In vitro dissolution indicated that the co-amorphous form improved the dissolution of bexarotene in pure water 4.17-fold. After rats were orally administered bexarotene or bexarotene-PVP-K30 co-amorphous (equivalent to 30 mg·kg-1 bexarotene) the AUC of bexarotene was 7 034.89 and 10 174.03 μg·L-1·h respectively, the peak time was advanced from 7.33 h to 0.9 h with the amorphous form, and Cmax was enhanced from 627.76 to 3 011.88 μg·L-1. The co-amorphous form yielded higher concentrations of bexarotene in various tissues, especially brain, liver and kidney. Animal welfare and experimental procedures complied with the rules of the Animal Ethics Committee of the Institute of Materia Medica, Chinese Academy of Medical Sciences. The results indicate that bexarotene-PVP-K30 co-amorphous improves the pharmacokinetic characteristics of bexarotene and provides preclinical data in support of bexarotene-PVP-K30 for the treatment of brain diseases.
RESUMO
[ABSTRACT]AIM:ToexploretheeffectofretinoidXreceptor(RXR)agonistbexarotene(Bex)andvitaminD receptor (VDR) agonist calcitriol (Cal) on the expression of nuclear factor-kappa B (NF-κB) and the development of atherosclerosis in streptozotocin-induced diabetic apolipoprotein E knockout ( STZ-ApoE-/-) mice.METHODS: Male mice were treated for 12 weeks as follows:(1) C57+vehicle;(2) ApoE-/-+vehicle;(3) STZ-ApoE-/-+vehicle;(4) STZ-ApoE-/-+Bex (10 mg· kg-1· d-1);(5) STZ-ApoE-/-+Cal (10 μg/kg, twice a week);(6) STZ-ApoE-/-+Bex (10 mg· kg-1· d-1) +Cal (10 μg/kg, twice a week).Intraperitoneal injection of STZ was performed to establish the diabetic animal model .Western blotting and immunohistochemical method was used to detect NF-κB level in the thorac-ic aorta.Plaque area in the thoracic aorta was measured using HE staining .RESULTS:Compared with the C57 mice, the fasting blood glucose in the ApoE-/-mice was not remarkably changed .The levels of total cholesterol ( TC) and low-densi-ty lipoprotein ( LDL) were greatly increased .The fasting blood glucose and lipid levels in STZ-ApoE-/-group were much higher than those in ApoE-/-group.Compared with STZ-ApoE-/-group, the fasting blood glucose and lipid levels in Bex group and Cal group were not significantly changed .Compared with the C57 mice, the protein expression of NF-κB in the ApoE-/-mice and the STZ-ApoE-/-mice was remarkably increased .Compared with STZ-ApoE-/-group, the levels of NF-κB in Bex group, Cal group and combination group were greatly decreased .Compared with STZ-ApoE-/-group, the thoracic artery plaque areas in Bex group and Cal group were inhibited (both P<0.05).Compared with Bex group, the plaque area of the thoracic artery in combination group was significantly decreased (P<0.05).CONCLUSION:Bexaro-tene or calcitriol decreases the development of atherosclerosis in streptozotocin -induced diabetic ApoE-/-mice.Bexarotene combined with calcitriol affords greater protection than monotherapy .The mechanism may be involved in down-regulating the expression of NF-κB.