Rectal absorption of [Bis (acetato) ammine dichloro (cyclohexylamine) platinum(IV)] (BMS-182751), a new anti-tumor agent, in rats.

The rectal absorption of a platinum anti-tumor agent, [bis (acetato) ammine dichloro (cyclohexylamine) platinum(IV)] (BMS-182751), was investigated in rats. BMS-182751 was co-ground with various carriers to improve its poor aqueous solubility. The highest drug dissolution was observed for the co-ground mixture of BMS-182751 and low molecular (LM) gelatin (1:9, w/w), followed by beta-cyclodextrin and polyvinylpyrrolidone. The influence of a suppository base or additive on the rectal absorption of BMS-182751 in the drug state of crystalline powder or co-ground mixture was examined in vitro using excised rat rectum. A macrogol base gave much higher BMS-182751 permeation across the rat rectum than that from a Pharmasol base. The addition of sodium caprylate or caprylic acid to the macrogol base markedly enhanced the drug permeation, and a 3% addition of sodium caprylate to the base afforded maximum drug permeation. Two rectal formulations, the co-ground mixture with LM-gelatin plus 3% sodium caprylate in macrogol and the crystalline drug alone plus 3% sodium caprylate in macrogol, as well as an oral aqueous drug suspension, were administered to rats. The Cmax and AUC0-24h values for platinum from the former suppository were 5.1- and 4.1-fold greater than those from the oral suspension, respectively. The values from the latter suppository were almost comparable to those from the suspension. These results suggest that the suppository may provide a promising therapeutic means for cancer treatment using this platinum agent.

Enhanced rectal absorption of amphotericin B lyophilized with glycyrrhizinate in rabbits.

The influence of bases and additives in the formulation for rectal absorption of amphotericin B (AMB) lyophilized with dipotassium glycyrrhizinate (GLYK) was investigated using rabbits in relation to an in vitro release test. The release of AMB from the fatty base of Witepsol or a medium chain triglyceride (MCT) was markedly faster than that from the hydrophilic base of macrogol. The addition of polyoxyethylene (2) lauryl ether (POE(2)LE) into the fatty bases led to a marked increase in the release rate, whereas POE(9)LE or sodium lauryl sulfate resulted in a significantly lower release rate. Animals received rectally each of seven AMB formulations of Witepsol H-15, macrogol, MCT with surfactants and aqueous solution. The absorption of the AMB lyophilized mixture with GLYK at a 1:9 molar ratio from a MCT base was significantly superior to that from macrogol. The addition of POE(2)LE into the MCT base resulted in a marked increase in bioavailability, showing the highest bioavailability of 4.9%. High serum levels of over 100 ng/ml of serum were maintained for 24 h following administration. The lowest bioavailability was 0.32% for the macrogol suppository. There was a good correlation between the release rate of AMB from the formulations and bioavailability. These results suggest that an AMB rectal formulation may provide a promising therapeutic alternative to infusion, taking into account the serum level of AMB exceeding the minimal inhibitory concentration of the infecting organism.

Effect of glycyrrhizinate on dissolution behavior and rectal absorption of amphotericin B in rabbits.

The effects of dipotassium glycyrrhizinate (GLYK) on the dissolution behavior and bioavailability of amphotericin B (AMB) were investigated. The mixtures of AMB and GLYK were prepared at different molar ratios by lyophilization. Lyophilization resulted in amorphous AMB either alone or in the mixture. Dissolution rates of AMB of the mixtures were markedly faster than that of lyophilized AMB alone, which was followed by a decrease of dissolution. The initially-enhanced dissolution rate was likely to be due to the improvement of surface wettability of drug particles with GLYK rather than the amorphous state of AMB. A phase solubility study of AMB with GLYK indicated that the increasing solubility was caused by micellar solubilization. The in vitro release rate of AMB from suppositories containing the lyophilized mixtures was significantly accelerated by increasing the amount of GLYK. The rectal absorption of AMB from suppositories containing either the drug alone, a physical mixture or a lyophilized mixture was studied using rabbits. The absorption of the mixture (AMB/GLYK = 1/9) was about 35 times greater in the area under the serum concentration-time curve (0-24 h) than that of lyophilized AMB alone. These results suggest that GLYK is useful for improving the dissolution property of AMB and the bioavailability of the drug incorporated in suppositories.

In ovo interference of embryo non-lethal avian infectious bronchitis viruses (IBV) with velogenic Newcastle disease virus and embryo adapted IBV.

Avian infectious bronchitis virus (IBV) interfered with the lethal effects of velogenic Newcastle disease virus (NDV) and embryo adapted IBV in eggs previously inoculated with non-lethal IBV. Greater interference was noted in eggs superinfected with embryo adapted IBV than velogenic NDV. The interference could be eliminated by treating the initial IBV with homologous anti-IBV serum.

Effect of different passage histories of infectious bronchitis virus on the sensitivity to inhibitors in chick serum and their removal by trypsin.

Sensitivity of the Beaudette strain of infectious bronchitis virus (IBV) to non-antibody inhibitors in neutralization tests depended on the passage history of the virus. The chick embryo kidney cell-adapted (E71 CEK11) virus was the most sensitive, but after one chick embryo (CE) passage (E71 CEK11 E1), this virus showed reversion to the sensitivity of the parent virus (E71). IBV inhibitors in chicken serum could be removed by treatment with trypsin but not with phospholipase C.