Pathobiodynamics: changes in ascorbate metabolism in rats with peripheral inflammation

Effect of adjuvant-induced systemic inflammation in rats on hepatic disposition kinetics of taurocholate

It has been reported that the adjuvant-induced inflammation could affect drug metabolism in liver. Here we further investigated the effect of inflammation on drug transport in liver using taurocholate as a model drug. The hepatic disposition kinetics of [(3)H]taurocholate in perfused normal and adjuvant-treated rat livers were investigated by the multiple indicator dilution technique and data were analyzed by a previously reported hepatobiliary taurocholate transport model. Real-time RT-PCR was also performed to determine the mRNA expression of liver bile salt transporters in normal and diseased livers. The uptake and biliary excretion of taurocholate were impaired in the adjuvant-treated rats as shown by decreased influx rate constant k(in) (0.65 ± 0.09 vs. 2.12 ± 0.30) and elimination rate constant k(be) (0.09 ± 0.02 vs. 0.17 ± 0.04) compared with control rat group, whereas the efflux rate constant k(out) was greatly increased (0.07 ± 0.02 vs. 0.02 ± 0.01). The changes of mRNA expression of liver bile salt transporters were found in adjuvant-treated rats. Hepatic taurocholate extraction ratio in adjuvant-treated rats (0.86 ± 0.05, n = 6) was significantly reduced compared with 0.93 ± 0.05 (n = 6) in normal rats. Hepatic extraction was well correlated with altered hepatic ATP content (r(2) = 0.90). In conclusion, systemic inflammation greatly affects hepatic ATP content/production and associated transporter activities and causes an impairment of transporter-mediated solute trafficking and pharmacokinetics.

Hepatic pharmacokinetics of propranolol in rats with adjuvant-induced systemic inflammation

Systemic inflammation is known to affect drug disposition in the liver. This study sought to relate and quantitate changes in hepatic pharmacokinetics of propranolol with changes in hepatic architecture and physiology in adjuvant-treated rats. Transmission electron microscopy was used to assess morphological changes in mitochondria and lysosomes of adjuvant-treated rat livers. The disposition of propranolol was assessed in the perfused rat liver using the multiple indicator dilution technique. Hepatic extraction and mean transit time were determined from outflow-concentration profiles using a nonparametric method. Kinetic parameters were derived from a two-phase physiologically based organ pharmacokinetic model. Possible relationships were then explored between the changes in hepatic drug disposition and cytochrome P-450 activity and iron concentration. Adjuvant treatment induced the appearance of mitochondrial inclusions/tubularization and irregularly shaped lysosomes in rat livers. Livers from adjuvant-treated rats had (relative to normal) significantly higher alpha(1)-acid glycoprotein (orosomucoid) and iron tissue concentrations but lower cytochrome P-450 content. The hepatic extraction, metabolism, and ion trapping of propranolol were significantly impaired in adjuvant-treated rats and could be correlated with altered iron store and cytochrome P-450 activity. It is concluded that adjuvant-induced systemic inflammation alters hepatocellular morphology and biochemistry and consequently influences hepatic disposition of propranolol.

Influence of extra-intestinal inflammation on the in vitro absorption of 14C-glucose and the effects of anti-inflammatory drugs in the jejunum of rats

Inflammation was induced in the hind legs of rats by formalin injection and the in vitro jejunal absorption of 14C-glucose was studied. Treatment of rats with formalin caused a reduction in the in vitro absorption of glucose from the jejunum. Oral administration of oxyphenbutazone or a herbal anti-inflammatory drug (Withania somnifera) prior to formalin injection, resulted in no alteration in the jejunal absorption of glucose.

An analysis of the gastro-intestinal side-effects of non-steroidal anti-inflammatory drugs, with particular reference to comparative studies in man and laboratory species

A critical analysis has been performed of reports published on the incidence of gastro-intestinal (GI) side-effects found in arthritic patients being treated with non-steroid anti-inflammatory (NSAI) drugs. The results show the following: 1. The incidence of GI ulceration (as revealed by gastroscopy) and haemorrhage in arthritic patients taking NSAI drugs may be higher than suspected from clinical trial data. 2. Incidence of all GI side-effects (including ulceration and haemorrhage) may be lower with some of the new NSAI drugs than with traditional drugs (e.g. aspirin, indomethacin and phenylbutazone). 3. Arthritic patients may be more susceptible to the ulcerogenic actions of NSAI drugs. Experiments with animals, together with evidence from clinical studies, indicate that stress factors and the presence of decreased mucosal resistance in the diseased state may contribute to the enhanced susceptibility of the GI tract towards the ulcerogenicity of NSAI drugs. 4. Comparison of data on gastroscopic observations in man with the author's data on the effects of NSAI drugs in stress-sensitized rats shows the latter technique appears to be a useful means of predicting the ulcerogenic potential of NSAI drugs in man. The comparison has also been used to predict the ulcerogenicity of drug - alcohol combinations; alcohol being a common ulcerogen consumed by many patients. Some NSAI drugs with low ulcerogenic activity (i.e. azapropazone, benoxaprofen and fenclofenac) in the stressed-rat assay show little or no interaction with alcohol. These studies using laboratory animals show the importance of employing conditions to mimic environmental factors (e.g. stress and alcohol consumption) which might predispose individuals to ulcerogenic or other side-effects of NSAI drugs. From these studies it appears possible to construct 'predictive profiles' of the relative ulcerogenicity of NSAI drugs which may be applicable to the clinical situation in man.