Impact of a toxicology service on a metropolitan teaching hospital.

OBJECTIVE: To evaluate the impact of a toxicology service on a major metropolitan teaching hospital. METHOD: A descriptive comparative study of all patients presenting with poisoning or suspected poisoning 12 months before and after the commencement of a toxicology service. Data on length of stay in the emergency department, disposition, length of stay of admitted patients and substance(s) involved were examined. RESULTS: A total of 1,316 poisoned patients were studied. There was a statistically significant increase in self-poisonings from 612 to 704 (P = 0.002) and in the number of admissions from 113 to 192 (P < 0.05). There was no significant change in emergency department length of stay. The average length of stay for patients admitted under the care of the toxicology service decreased, especially for complicated patients. CONCLUSION: In the first 12 months of operation the toxicology service treated more patients than the 12-month period prior to commencement, achieving a decrease in average length of stay for those patients admitted to the service. The emergency department length of stay was not altered. We surmise that by decreasing average length of stay for the patients under the care of the toxicology service, the net increase in the general pool of unoccupied beds improves bed access for all emergency department patients.

Pharmacotherapeutics: what a difference five decades makes!

Our ability to prevent, cure or modify disease, as compared with relieving symptoms, has changed beyond recognition in the past half century. With the completion of the Human Genome Project and rapid advances in understanding of molecular biology and in technologies, our ability to target disease mechanisms and optimise an individual's responses will improve exponentially.

Bilirubin and bile acids may modulate their own metabolism via regulating uridine diphosphate-glucuronosyltransferase expression in the rat.

BACKGROUND AND AIMS: Uridine diphosphate (UDP)-glucuronosyltransferase (UGT) is a critical enzyme in the elimination of bilirubin and it also plays a role in the metabolism of bile acids. The aim of this study was to determine whether bilirubin and bile acids could modulate their own metabolism by regulating UGT levels in cultured rat hepatocytes. METHODS AND RESULTS: Incubation of hepatocytes with bilirubin (48 micromol/L) for 24 h significantly increased the mRNA expression of UGT1A1 and UGT1A5, two UGT isoforms responsible for the conjugation of bilirubin. The induction of UGT1A1 and UGT1A5 by bilirubin was concentration and time dependent. Treatment with chenodeoxycholic acid, cholic acid, deoxycholic acid, hyodeoxycholic acid and lithocholic acid at a concentration of 100 micromol/L for 48 h significantly enhanced the mRNA expression of UGT2B1, a UGT isoform responsible for the glucuronidation of bile acids. The UGT2B3 mRNA level was also increased by hyodeoxycholic acid. The regulation of UGT2B1 mRNA by chenodeoxycholic acid and hyodeoxycholic acid was dose and time dependent. CONCLUSION: Our results suggest that bilirubin and bile acids can induce UGT expression and as a result, these compounds may modulate their own metabolism. Such regulation could play a compensatory role in the pathological increased concentrations of these compounds in some hepatobiliary diseases.

Alcohol up-regulates UDP-glucuronosyltransferase mRNA expression in rat liver and in primary rat hepatocyte culture.

The interactions between alcohol and cytochrome P-450 enzymes have been well investigated. However, the data regarding the effect of alcohol on the regulation of UDP-glucuronosyltranferase (UGT) activity are less clear. The aim of the present study was to determine the role of alcohol in the regulation of UGT mRNA expression by using whole animal and primary cultured hepatocytes. Chronic ethanol feeding of rats significantly increased the expression of liver UGT1A1 mRNA to 177% of control. The mRNA levels for UGT1A5, UGT2B1 and UGT2B3 were also enhanced, but did not reach statistical significance. In cultured hepatocytes, treatment with either ethanol or isopentanol significantly increased the expression of UGT1A1, UGT1A5, UGT2B1, and UGT2B3 mRNAs, but to different degrees. The induction of UGT1A1 and UGT2B1 mRNAs by ethanol or isopentanol was time-dependent and maximal changes occurred at 48 h. The expression of UGT1A6 mRNA was not significantly modified by either ethanol or isopentanol. In conclusion, ethanol and isopentanol have direct roles in the regulation of UGT.

The effect of hormones on the expression of five isoforms of UDP-glucuronosyltransferase in primary cultures of rat hepatocytes.

PURPOSE: To investigate the direct effects of sex hormones, growth hormone, thyroid hormones and dexamethasone on the regulation of UDP-glucuronosyltransferase (UGT). METHODS: Rat hepatocytes were cultured on matrigel and treated with various hormones. Northern blot analysis was carried out using cDNA probes to family 1 and family 2 isoforms. RESULTS: Treatment with 10(-5) M testosterone increased the mRNA levels of UGT 2B1 by 29% and UGT2B3 by 32%. Incubation of growth hormone (10 mU) with hepatocytes suppressed the expression of UGT2B1 and UGT2B3 by 17% and 38%, respectively. T3 administration resulted in a time and dose-dependent effect on the expression of UGT 1 isoforms, with increased UGT1A6 by 70%, and decreased UGT1A1 by 38% and UGT1A5 by 35%. All UGT isoforms except UGT 1A6 studied in this assay were up-regulated by dexamethasone, but to different degrees. The regulation of UGT1A1 and UGT2B1 by dexamethasone was dose and time dependent, and the induction of dexamethasone in the expression of UGT1A1 and UGT2B1 was blocked by cycloheximide but not dichloro-1-D-ribofuranosylbenzimidazole. CONCLUSIONS: This study demonstrates that multiple hormones take part in the regulation of UGT mRNA expression in the rat and individual genes can be differentially modulated.

Regulation of uridine diphosphate glucuronosyltransferase during the acute-phase response.

The acute-phase response is associated with profound effects on oxidative drug metabolism. However, the effects on glucuronidation are poorly characterized. The aim of the present study was to determine the role of mediators of the acute-phase response in the regulation of hepatic uridine diphosphate glucuronosyltransferase (UGT) expression. Family 1 and family 2 UGT isoforms were studied in turpentine-injected rats and in primary hepatocyte cultures exposed to cytokines and/or dexamethasone. In the in vivo model, glucuronidation of p-nitrophenol was unaffected, while testosterone glucuronidation was reduced to 65% of control (P<0.01). In contrast, the mRNA level of UGT1*1 (which metabolizes bilirubin, not phenols) was depressed to 16% of control (P<0.002), while the mRNA level of UGT2B3 (which metabolizes testosterone) was reduced to 53% (P<0.05). In primary hepatocyte culture, dexamethasone treatment resulted in a 3.4-fold induction of UGT1*1 mRNA levels (P<0.001) but only a 1.5-fold induction of UGT2B3 (P=0.1). Interleukin-6 in the presence of dexamethasone resulted in a marked dose-dependent suppression of both UGT1*1 and UGT2B3, although to different degrees. Interleukin-1 had no effect on UGT mRNA levels. Thus, inflammatory mediators, such as cytokines and glucocorticoids, may be important determinants of both oxidative and conjugative drug metabolism by the liver.

Sex hormones differentially regulate isoforms of UDP-glucuronosyltransferase.

PURPOSE: To investigate the role of sex hormones in the regulation of UDP-glucuronosyltransferase (UGT). METHODS: We examined liver from adult, prepubertal, gonadectomised and gonadectomised plus hormone replaced rats of both sexes. Immunohistochemistry and immunoblots were performed using a polyclonal UGT antibody to a number of family 1 and family 2 UGT isoforms. Northern blot analysis was performed utilising cDNA probes to family 1 and family 2 isoforms. RESULTS: Immunohistochemistry demonstrated variations in intensity and distribution of staining in the hormonally manipulated rats. Immunoblots showed variations in individual band intensity between rat groups. Immunoblots using a more specific antibody (anti-17 beta-hydroxysteroid UGT, which recognises UGT2B3 and UGT2B2) demonstrated marked differences between male and female rats and significant alterations after gonadectomy and testosterone replacement in the male rats. In northern analysis, UGT2B3 and 2B1 mRNA were significantly higher in adult males than females, and in prepubertal males compared to prepubertal females. In male rats, gonadectomy resulted in a 45-53% reduction in UGT2B3 and 2B1 levels respectively, which increased significantly with testosterone treatment to greater than normal adult levels. No change in UGT2B3 or 2B1 occurred after gonadectomy in females. In contrast, UGT1*1 mRNA tended to be higher in adult female and prepubertal female rats than in their male counterparts. In females, gonadectomy resulted in significant up-regulation of UGT1*1, while gonadectomy plus oestradiol treatment resulted in markedly reduced levels. UGT1*1 mRNA was not significantly altered by gonadectomy in males. CONCLUSIONS: This study demonstrates the differential effects of sex hormones on the expression of isoforms from the two phylogenetically distinct UGT families.

UDP-glucuronosyltransferase in the regenerating rat liver.

In both acute and chronic liver disease in man, elimination of drugs metabolized by the cytochrome P450 (CYP) enzymes is impaired. In contrast, those drugs metabolized by UDP-glucuronosyltransferase (UGT) have a relatively normal elimination. Studies in rats with experimentally induced liver injury also show this relative preservation of glucuronidation. In liver disease, a number of factors, including inflammation, fibrosis and regeneration, may be associated with this differential effect on drug metabolism. Partial hepatectomy provides a model in which to isolate the effects of liver regeneration on drug metabolism. Partial hepatectomy or sham operation was performed in 24 male Sprague-Dawley rats and three rats from each group were studied at days 1, 2, 4 and 6. Comparison between CYP and UGT was made at the protein level using immunohistochemistry and immunoblotting probed with a polyclonal antibody to UGT, identifying both family 1 and family 2 isoforms, and an antibody to the CYP isoform CYP2C11. Steady state messenger RNA levels of four isoforms of UGT were assessed by northern blot analysis. By both immunohistochemistry and immunoblotting, the level of CYP protein decreased from day 2 to 6 after hepatectomy. In contrast, the UGT protein level was not altered by partial hepatectomy. Northern blot analysis of UGT isoforms demonstrated differential regulation of isoforms from the two major families. The UGT family 1 isoforms were initially markedly depressed following partial hepatectomy and then steadily rose over 6 days to greater than the level in controls. In contrast, there was an apparent increase in UGT2B1 mRNA (not significant) on day 2, while UGT2B3 mRNA was maintained over the six days. These results demonstrate that during hepatic regeneration the protein content of total UGT is normal, while CYP2C11 protein is markedly reduced. Northern blot analysis suggests that individual isoforms of UGT are differentially regulated during the regeneration process.

UDP glucuronosyltransferase in the cirrhotic rat liver.

In patients with cirrhosis, the elimination of drugs metabolized by glucuronidation is relatively preserved, in comparison with the metabolism of drugs by oxidation. This study explores this phenomenon at a molecular level. In cirrhotic rat livers the content of UDP-glucuronosyltransferase (UGT) was examined by immunohistochemistry and immunoblotting using three antibodies: (i) a polyclonal antibody directed against a broad number of UGT isoforms from both family 1 and family 2; (ii) a family 2-specific antibody; and a (iii) family 1-specific antibody. The steady state mRNA level of UGT of a family 2 isoform was also detected by northern blot analysis. The results demonstrate normal or increased UGT protein by immunohistochemistry and immunoblot in cirrhotic livers compared with controls. This was accompanied by increased steady state mRNA encoding the UGT isoform UGT2B1. In contrast, an isoform of cytochrome P450 (CYP2C11) was reduced markedly in both immunohistochemical staining and immunoblot analysis. These results suggest that in cirrhosis there is a comparative increase or at least a maintenance of UGT enzyme content and that this most likely occurs at a pretranslational level.

Assessment of general practitioners' management of hyperlipidaemia. A study using personal visits and a scenario-based questionnaire.

In summary our study has looked at the current management practices of hyperlipidaemia by general practitioners in an innovative way. Our results suggest that most GPs are managing this condition appropriately. Where their management differs from current guidelines is mainly in introducing medication early. We obtained significantly lower participation rates in the metropolitan as compared with the regional and rural areas, but we found no significant differences in the overall assessment of appropriate management between the different geographical regions of Victoria.

Release of latent glucuronosyltransferase activity contributes to the sparing of glucuronidation in experimental liver injuries.

In patients with parenchymal liver disease, glucuronidation of drugs is generally preserved but oxidation is impaired. This study explores the effects of liver injuries induced in rats by the administration of acute carbon tetrachloride, chronic bile duct ligation and chronic choline deficiency for 30 weeks on the glucuronidation of p-nitrophenol and 1-naphthol, both before and after solubilization of the microsomes and compares this to three measures of oxidation. Cytochrome P450 content was reduced to 17% of control values after acute carbon tetrachloride and to 35% of control values after bile duct ligation. Cytochrome C reductase fell to 58 and 32% of control and aniline hydroxylase to 46 and 13%, respectively, after acute carbon tetrachloride and bile duct ligation. P-nitrophenol glucuronidation by native microsomes was 206 and 73% of controls in the respective models, while 1-naphthol glucuronidation was 167 and 66% of control. Latent uridine diphosphate-glucuronosyltransferase (UDP-GT) activity, that is, differences between solubilized and native activity, was decreased by each liver injury. Chronic choline deficiency had little effect on the oxidation and native glucuronidation activity, although latent glucuronidation activity was lower. These studies suggest a preservation of glucuronidation compared to oxidation at the microsomal level in these experimental liver injuries. The data also support the hypothesis that a release of latent UDP-GT activity may contribute to this phenomenon.

Factors affecting the hepatic elimination of oxidized and of glucoronidated high clearance drugs following acute administration of carbon tetrachloride.

The factors affecting drug elimination following acute administration of carbon tetrachloride (CCl4) were investigated using a perfused rat liver system. Morphine and pethidine were used as markers of hepatic glucuronidation and oxidation, respectively. Hepatoxicity of CCl4 was indicated by widespread cellular necrosis and raised serum asparatate aminotransferase levels. At a perfusion rate of 10 ml/min, the extraction ratio of morphine in the normal liver was 0.67 +/- 0.18 and fell to 0.48 +/- 0.03 (p < 0.001) in the acutely damaged livers. The hepatic clearance of morphine fell from 6.7 +/- 0.2 ml/min in controls to 4.7 +/- 0.3 (p < 0.005) in the treated livers. Similar changes were seen at perfusion rates of 7 and 12 ml/min. Intrinsic clearances calculated according to both the venous equilibrium and the undistributed sinusoidal models were independent of perfusion rate and were also lower in the damaged livers. Perfusion rate was a dominant factor in determining morphine elimination in control livers. However, in the damaged livers, the fall in intrinsic clearance resulted in the elimination of morphine being mixed, i.e. both capacity and flow limited. At a perfusion rate of 10 ml/min, the extraction ratio of pethidine was 0.97 +/- 0.01 in control livers and was reduced to 0.91 +/- 0.02 (p < 0.005) in damaged livers. The hepatic clearance also fell at each perfusion rate in the damaged livers. As for morphine, the intrinsic clearances of pethidine calculated by both venous equilibrium and undistributed sinusoidal models gave qualitatively similar results and were lower in the damaged livers than controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Improving the quality of antibiotic prescription patterns in general practice. The role of educational intervention.

OBJECTIVE: To assess the quality of antibiotic prescribing by Victorian general practitioners, and the effectiveness of educational intervention techniques in improving prescribing. DESIGN: A randomised, controlled, parallel group trial. SETTING AND PARTICIPANTS: In rural and metropolitan Victoria, 182 general practitioners (78 control, 104 intervention) began and 103 (41 control, 62 intervention) completed the study. INTERVENTION: Participants recorded their antibiotic prescribing for tonsillitis. The intervention group received an educational mailing campaign. A project pharmacist visited each doctor to discuss campaign messages. MAIN OUTCOME MEASURE: The percentages of prescriptions of antibiotics for tonsillitis complying with those recommended in Antibiotic guidelines. RESULTS: In the intervention group, prescriptions consistent with recommendations in the guidelines increased from 60.5% before the campaign to 87.7% afterwards. Improvement also occurred in the control group, from 52.9% to 71.7% of prescriptions. The improvement within the intervention group was significantly greater than that within the control group. CONCLUSIONS: The educational campaign significantly improved the prescribing of appropriate antibiotics for tonsillitis by general practitioners.

The effect of a nutritional model of chronic liver injury on the hepatic glucuronidation of morphine in rats.

The effect of a choline-deficient diet on the hepatic glucuronidation of morphine was investigated using a rat perfused liver system. Rats fed a choline-deficient diet developed a fatty liver with minimal necrosis. Despite the morphological changes, neither hepatic extraction ratio (0.51 +/- 0.02 in control; 0.45 +/- 0.04 in the choline-deficient rats) nor intrinsic clearance (0.85 +/- 0.05 in control; 0.77 +/- 0.09 in choline-deficient rats) were affected by this injury model. This finding suggests that glucuronidation is relatively resistant to this chronic liver injury.

Hepatic enzyme activity is the major factor determining elimination rate of high-clearance drugs in cirrhosis.

The relative importance of alterations in hepatic enzyme activity, blood flow and drug binding to drug elimination in patients with liver disease remains controversial. In addition, liver disease appears to selectively impair drug oxidation pathways while leaving glucuronidation preserved. These studies using isolated perfused rat livers were designed to examine the effects of liver disease on the hepatic extraction and clearance and intrinsic clearance of morphine, a glucuronidated drug, and meperidine, an oxidized drug, under controlled blood flow and drug-binding conditions. We chose chronic carbon tetrachloride-induced cirrhosis as the liver disease. At a flow rate of 12 ml/min, the extraction of meperidine was reduced from 0.91 +/- 0.02 ml/min in controls to 0.76 +/- 0.04 ml/min (p < 0.05) in cirrhosis, hepatic clearance was reduced from 10.9 +/- 0.3 ml/min in controls to 9.15 +/- 0.48 ml/min (p < 0.05) in cirrhosis and intrinsic hepatic clearance was reduced from 179 +/- 35 ml/min in controls to 69 +/- 14 ml/min (p < 0.05) in cirrhosis. In contrast, for morphine we saw no significant changes: extraction ratio, 0.59 +/- 0.02 in controls and 0.49 +/- 0.04 in cirrhosis; hepatic clearance, 7.02 +/- 0.26 ml/min in controls and 6.04 +/- 0.42 ml/min in cirrhosis; and hepatic intrinsic clearance, 15.4 +/- 1.2 ml/min in controls and 13.9 +/- 2.3 ml/min in cirrhosis. Regression analysis of hepatic clearance vs. hepatic blood flow and hepatic clearance vs. hepatic intrinsic clearance demonstrate that in normal livers the elimination of both morphine and meperidine is mainly dependent on blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Double-blind, placebo controlled, crossover study of lamotrigine in treatment resistant partial seizures.

The results of a multicentre, randomised, double-blind, placebo controlled, crossover trial of lamotrigine as add-on therapy in patients with partial seizures poorly controlled by established antiepileptic drugs (AEDs) are presented. The study consisted of two 12 week treatment periods each followed by a four week washout period. During the lamotrigine treatment phase, patients received 150 mg or 300 mg daily dose depending on their concomitant AEDs to achieve concentrations in the range 1-3 mg/L. Forty one patients were entered at four centres and all patients entered completed the study. There was a highly significant (p < 0.001) decrease in total seizure counts on lamotrigine compared with placebo. Overall, 22% of patients experienced at least a 50% reduction in the total numbers of all seizures types on lamotrigine, compared with none on placebo. When the total numbers of partial seizures (simple and complex partial) were analysed there was also a significant (p < 0.05) reduction in seizure counts on lamotrigine compared with placebo. When total numbers of secondarily generalised seizures were compared the trend for a reduction in this seizure type did not achieve significance (0.05 < p < 0.1). Concomitant AED plasma concentrations were virtually unchanged. It is concluded that lamotrigine is an effective AED in the treatment of therapy-resistant partial seizures.

Arterial lignocaine concentrations following cervical plexus blockade for carotid endarterectomy.

Arterial lignocaine concentrations were measured in twenty-six patients who had carotid endarterectomy performed under deep and superficial cervical plexus blockade. A dose of 6 mg/kg of 1.5% lignocaine with 1:200,000 adrenaline was used, as well as additional supplementation by the surgeons when required. Concentrations obtained produced a mean peak of 5 micrograms/ml and were similar to those previously reported from multiple bilateral intercostal blockade, which is the regional technique widely considered to produce the highest systemic levels of local anaesthetic. Apart from one peak concentration of 16.9 micrograms/ml, levels were well below the convulsion threshold. We find the technique acceptable and safe for carotid surgery and lignocaine toxicity is not identified as a problem.

Covert self poisoning with brodifacoum, a 'superwarfarin'.

The clinical course of a patient poisoned with the 'superwarfarin' brodifacoum and a method for estimation of plasma levels is described. It was characterised by prolonged depression of Vitamin K-dependent clotting factors poorly responsive to Vitamin K administration.