Effects of lipid peroxidation inhibitors (BHA, BHT) on the membrane of rat liver lysosomes and mitochondria

Designing orodispersible films containing everolimus for enhanced compliance and bioavailability

INTRODUCTION

Everolimus (EVR) has been approved for the treatment of various advanced cancers and its indications are increasingly expanding. Therefore, it is crucial for patients who have difficulty in swallowing, such as pediatric and elderly patients, to obtain a convenient formulation. The oral absorption of EVR is limited due to its low solubility in water, intestinal metabolism by CYP3A4 enzyme, P-gp-mediated efflux, and metabolism in the liver. The aim of this study was to develop a novel sublingual orodispersible film loading everolimus for improving patient compliance and enhancing oral bioavailability of EVR.

RESEARCH DESIGN AND METHODS

Sublingual orodispersible films loading EVR were prepared by the solvent casting method and evaluated by in vitro and in vivo studies.

RESULTS

The properties of films were determined by scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, and Fourier-transform infrared spectrometry. The addition of acacia gum appeared to be crucial for protecting the drug from oxidation. Pharmacokinetic studies showed that loading into the sublingual orodispersible films significantly increased the oral bioavailability of EVR.

CONCLUSION

The EVR-loaded sublingual orodispersible films are a promising, economical, and convenient approach for delivering EVR efficiently in a solid dosage form.

2 Final Report on the Safety Assessment of Butylated Hydroxyanisole

Butylated hydroxyanisole (BHA) is used in cosmetic formulations as a chemical preservative and as an antioxidant. Both animal and human studies have shown that BHA is absorbed from the gastrointestinal tract and metabolized. Tissue storage may occur with BHA because of its lipid solubility. However, the amount stored is limited by rapid metabolism and excretion. Reported acute oral LD50 values for BHA in rats varied from 2.0 to > 5.0 g/kg. Formulations containing BHA elicited, at most, minimal or moderate skin and eye irritation in rabbits. An extensive number of subchronic and chronic oral studies have been conducted and are reviewed.

BHA given orally or parenterally to mice and rats was shown to inhibit the carcinogenic effects of a broad range of chemical carcinogens. BHA has been shown to inhibit mutagenesis and was not a mutagenic agent in standard in vitro tests. No evidence of carcinogenicity was observed when BHA was administered to mice by subcutaneous injection, by intraperitoneal injection, or by topical application. No carcinogenesis was demonstrated following dietary administration of BHA to either rats or dogs. An increased incidence of forestomach papillomas and squamous cell carcinomas has been observed in rats fed BHA. Studies with pregnant rabbits, mice, rats, and hamsters receiving BHA during gestation by a variety of oral dosage regimens revealed no significant embryotoxic or teratogenic effects.

Clinical data for BHA in cosmetic formulations indicated that they were generally nonsensitizing, nonphotosensitizing, and only minimally or mildly irritating. It is concluded that BHA is safe as a cosmetic ingredient in the present practices of use.

Cytotoxicity of butylated hydroxyanisole and butylated hydroxytoluene in isolated rat hepatocytes

The effects of the antioxidants butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on isolated rat hepatocytes were investigated. Both antioxidants were observed to be cytotoxic in a concentration-dependent manner at concentrations ranging from 100 to 750 microM. At equimolar concentrations BHT was more cytotoxic than BHA. Their toxicity appeared to be independent of their metabolism to reactive intermediates since inhibitors of cytochrome P-450 (metyrapone, SKF 525-A and piperonyl butoxide) had no effect on the cytotoxicity and N-acetylcysteine was also without protective effect. In addition, deuterated BHT was equitoxic with BHT. Only low temperature incubation (4 degrees), which has previously been shown to inhibit the insertion of these compounds into biomembranes, was effective in inhibiting the cytotoxic effects. Using isolated rat liver mitochondria we observed that both BHA and BHT inhibited respiratory control primarily by stimulating state 4 respiration and thus acting as membrane uncouplers. BHA and BHT also effectively dissipated membrane potential across the mitochondrial membrane and caused the release of calcium and mitochondrial swelling. These mitochondrial effects were reflected by a rapid decrease in ATP levels in intact hepatocytes which preceded cell death. These results suggest that the observed cytotoxicity of BHA and BHT to hepatocytes is related to their effects on biomembranes and mitochondrial bioenergetics.