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Rosuvastatin: a highly effective new HMG-CoA reductase inhibitor.

Rosuvastatin, a new statin, has been shown to possess a number of advantageous pharmacological properties, including enhanced HMG-CoA reductase binding characteristics, relative hydrophilicity, and selective uptake into/activity in hepatic cells. Cytochrome p450 (CYP) metabolism of rosuvastatin appears to be minimal and is principally mediated by the 2C9 enzyme, with little involvement of 3A4; this finding is consistent with the absence of clinically significant pharmacokinetic drug-drug interactions between rosuvastatin and other drugs known to inhibit CYP enzymes. Dose-ranging studies in hypercholesterolemic patients demonstrated dose-dependent effects in reducing low-density lipoprotein cholesterol (LDL-C) (up to 63%), total cholesterol, and apolipoprotein (apo) B across a 1- to 40-mg dose range and a significant 8.4% additional reduction in LDL-C, compared with atorvastatin, across the dose ranges of the two agents. Rosuvastatin has also been shown to be highly effective in reducing LDL-C, increasing high-density lipoprotein cholesterol (HDL-C), and producing favorable modifications of other elements of the atherogenic lipid profile in a wide range of dyslipidemic patients. In patients with mild to moderate hypercholesterolemia, rosuvastatin has been shown to produce large decreases in LDL-C at starting doses, thus reducing the need for subsequent dose titration, and to allow greater percentages of patients to attain lipid goals, compared with available statins. The substantial LDL-C reductions and improvements in other lipid measures with rosuvastatin treatment should facilitate achievement of lipid goals and reduce the requirement for combination therapy in patients with severe hypercholesterolemia. In addition, rosuvastatin's effects in reducing triglycerides, triglyceride-containing lipoproteins, non-HDL-C, and LDL-C and increasing HDL-C in patients with mixed dyslipidemia or elevated triglycerides should be of considerable value in enabling achievement of LDL-C and non-HDL-C goals in the numerous patients with combined dyslipidemias or metabolic syndrome who require lipid-lowering therapy. Rosuvastatin is well tolerated alone, and in combination with fenofibrate, extended-release niacin, and cholestyramine, and has a safety profile similar to that of currently marketed statins. A large, long-term clinical trials program is under way to investigate the effects of rosuvastatin on atherosclerosis and cardiovascular morbidity and mortality.

Animals↗

The use of simvastatin, an HMG CoA reductase inhibitor, in older patients with hypercholesterolemia and atherosclerosis.

Epidemiological evidence suggests that elevated serum cholesterol, especially the low density lipoprotein (LDL) fraction, the total/high density lipoprotein (HDL)-cholesterol ratio, and the LDL/HDL-cholesterol ratio, remains a risk factor for atheromatous disease up to the age of 79 years. We studied the efficacy and tolerability of simvastatin, an HMG CoA reductase inhibitor, in 20 patients aged 65 to 75 years with clinical evidence of atheromatous disease. After four weeks of treatment, there was a 29% fall in LDL-cholesterol levels (P less than .01 vs placebo) with low dose simvastatin and a 38% fall with high dose simvastatin (P less than .001 vs placebo). Similar falls were seen in total cholesterol levels and the LDL/HDL-cholesterol and total/HDL-cholesterol ratios. Apoprotein B levels decreased by approximately 20% with both doses (P less than .05 vs placebo). In an open extension of the study, the decreases in lipid parameters were sustained for a further 48 weeks of treatment with doses of simvastatin ranging from 10 to 40 mg. Two patients required the addition of cholestyramine. Although a small study like this cannot establish safety and tolerance, side effects were minor and did not require stopping therapy in any patient. Simvastatin is an effective cholesterol lowering agent in older patients.

Aged↗

Preliminary observation with dronabinol in patients with intractable pruritus secondary to cholestatic liver disease.

Pruritus due to cholestatic liver disease can be particularly difficult to manage and frequently is intractable to a variety of medical therapies. The aim of our study is to evaluate the efficacy of delta-9-tetrahydrocannabinol (delta-9-THC) for intractable cholestatic related pruritus (ICRP) that has failed conventional (and unconventional) remedies. Three patients were evaluated for plasmapheresis because of ICRP. All 3 patients had previously been extensively treated with standard therapies for ICRP including: diphenhydramine, chlorpheniramine, cholestyramine, rifampicin, phenobarbital, doxepin, naltrexone, UV therapy, and topical lotions. Even multiple courses of plasmapheresis were performed without any benefit for the intractable pruritus. All patients reported significant decreases in their quality of life, including lack of sleep, depression, inability to work, and suicidal ideations. All patients were started on 5 mg of delta-9-THC (Marinol) at bedtime. All 3 patients reported a decrease in pruritus, marked improvement in sleep, and eventually were able to return to work. Resolution of depression occurred in two of three. Side effects related to the drug include one patient experiencing a disturbance in coordination. Marinol dosage was decreased to 2.5 mg in this patient with resolution of symptoms. The duration of antipruritic effect is approximately 4-6 hrs in all three patients suggesting the need for more frequent dosing. Delta-9-tetrahydrocannabinol may be an effective alternative in patients with intractable cholestatic pruritus.

Adult↗

Postoperative chylous ascites.

The case of an infant, aged 2 months and 23 days, with chylous ascites after nephrectomy is reported. Nephrectomy was performed because of a large hydronephrosis. Chylous ascites was treated with medium-chain triglycerides, diet and cholestyramine. After 3 days the volume of the abdomen was reduced and on day 8 chylous ascites was not visible clinically or ultrasonographically.

Chylous Ascites↗

Effect of arterial pH and PCO2 on biliary HCO3- secretion in the pig.

The purpose of the present study was to examine the effect of changes in arterial pH and PCO2 on biliary HCO3- secretion. This was done in order to further characterize the various ion transport mechanisms considered responsible for biliary HCO3- secretion in the pig. Experiments were performed on two groups of six pigs. In both groups arterial pH was varied in steps from pH 7.40 to 7.00, both at PCO2 5.5 kPa and PCO2 10 kPa. In group I (n = 6), data were obtained on the effect of arterial pH and PCO2 on ductular HCO3- secretion in bile acid depleted (cholestyramine pretreated), secretin-infused pigs. In group II (n = 6), the effect of pH and PCO2 on canalicular HCO3- secretion was studied in ursodeoxycholic acid (UDCA)-infused pigs (3 mumol min-1 kg-1 body wt). In group I, biliary HCO3- secretion exhibited PCO2-dependent, positive straight line relationships to arterial pH. An increment in biliary HCO3- secretion of 17 (11-24)% was seen during high PCO2 at pH 7.40. In group II, biliary HCO3- secretion exhibited PCO2-dependent, positive curvilinear relationships to arterial pH. A median increment in HCO3- secretion of 37 (20-62)% was seen during elevated PCO2 at arterial pH 7.40. The linear dependence of ductular HCO3- secretion on arterial pH and the effect of elevated PCO2 on HCO3- secretion fit well with findings in other epithelia, where proton transport is thought be driven by a proton pump. A computer simulation provided evidence suggesting that secretin-dependent HCO3- secretion does not involve the action of a Na+/H+ ion exchanger--in contrast to UDCA-dependent HCO3- secretion. It is concluded that ductular and canalicular HCO3- secretion could be mediated by a proton pump and a Na+/H+ ion exchanger in addition to canalicular HCO3- secretion due to solvent drag and diffusion, respectively.

Animals↗

Intragastric distribution of ion-exchange resins: a drug delivery system for the topical treatment of the gastric mucosa.

Previous studies by this group on freeze-dried oral dosage forms containing finely-divided ion-exchange resins revealed prolonged gastric residence and uniform distribution within the stomach. The present study was carried out to ascertain whether this was due to freeze-drying, properties of the radiolabelled ionic exchange resin, or the small dosing volume used. 99mTc-labelled cholestyramine resin was administered in two dosage forms, a freeze-dried tablet which dissolved in the oral cavity (orally dissolving tablet; ODT) and a 1.5 mL aqueous suspension. Two resin particle sizes (20-40 and 90-125 microns) were studied. Oesophageal transit and intragastric distribution and residence were followed by gamma scintigraphy. In a second study, in six subjects, gastric emptying of the water-soluble fraction of the ODT and 1.5 mL of water, was measured using 99mTc diethylenetriaminepentaacetic acid. Oesophageal transit of a water-soluble marker and resin in suspension was rapid, but the transit of the resin in the ODTs was significantly prolonged. Regardless of particle size or dosage form, the resin was evenly distributed throughout the stomach with 20-25% remaining for 5.5 h. In contrast, the water-soluble marker cleared from the stomach rapidly from both dosage forms. We suggest that oral dose forms containing finely-divided ion-exchange resins may form a useful system for topical treatment of the gastric mucosa, for example in targeting to Helicobacter pylori infection.

Adult↗

Effect of bile on Vibrio parahaemolyticus.

Many enteric pathogens are thought to enter a viable but nonculturable state when deprived of nutrients. Virulent strains of the enteric pathogen Vibrio parahaemolyticus are rarely isolated from their low-nutrient aquatic environments, possibly due to their nonculturability. Host factors such as bile may trigger release from dormancy and increase virulence in these strains. In this study, the addition of bile or the bile acid deoxycholic acid to estuarine water-cultured bacteria led to an increase in the direct viable count and colony counts among the virulent strains. This effect was not demonstrated in the nonvirulent strains, and it was reversed by extraction of bile acids with cholestyramine. Bile-treated V. parahaemolyticus had lower levels of intracellular calcium than untreated cells, and this effect coincided with an increase in the number of metabolically active cells. Chelation of intracellular calcium with BAPTA/AM (R. Y. Tsien, Biochemistry 19:2396-2402, 1980) produced similar results. Addition of bile to V. parahaemolyticus cultures in laboratory medium enhanced factors associated with virulence such as Congo red binding, bacterial capsule size, and adherence to epithelial cells. These results suggest that a bile acid-containing environment such as that found in the human host favors growth of virulent strains of V. parahaemolyticus and that bile acids enhance the expression of virulence factors. These effects seem to be mediated by a decrease in intracellular calcium.

Bacterial Adhesion↗

Testis-specific transcription initiation sites of rat farnesyl pyrophosphate synthetase mRNA.

A variety of rat tissues were screened at low stringency with a rat farnesyl pyrophosphate (FPP) synthetase cDNA. In testis, an FPP synthetase-related RNA was detected that was larger than the liver FPP synthetase mRNA and was present at very high levels comparable with liver FPP synthetase RNA levels obtained from rats fed diets supplemented with cholestyramine and mevinolin. Sequence analysis of testis cDNA clones, together with primer extension and S1 nuclease experiments, indicated that testis FPP synthetase transcripts contain an extended 5' untranslated region. The 5' extension contained one or two out-of-frame upstream ATGs, depending on the site of transcription initiation. Protein in vitro translation studies indicated that the extended 5' untranslated region may play a role in regulating the translation of the FPP synthetase polypeptide in rat testis. Southern blot analysis with a probe containing both testis and liver 5' untranslated sequences provided evidence that both liver and testis transcripts derive from the same gene. The data suggest that an upstream testis-specific promoter results in the abundant production of FPP synthetase transcripts that are translated at low efficiency; another promoter functions in liver and other somatic tissues and directs the regulated synthesis of shorter discrete transcripts.

Amino Acid Sequence↗

Molecular cloning and sequence of a cholesterol-repressible enzyme related to prenyltransferase in the isoprene biosynthetic pathway.

Differential hybridization and molecular cloning have been used to isolate CR39, a cDNA which hybridizes to a 1.2-kilobase (kb) mRNA in rat liver. The level of CR39 mRNA was increased seven- to ninefold over normal levels by dietary cholestyramine and mevinolin and decreased about fourfold compared with normal levels by cholesterol feeding or administration of mevalonate. Similar changes in the mRNA levels of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and HMG-CoA synthase were observed under the various conditions. In vitro translation of either CR39 hybrid selected RNA or 1.2-kb CR39 RNA generated by an SP6 in vitro transcription system produced a polypeptide of 39,000 daltons. As deduced from the nucleotide sequence of a full-length CR39 cDNA, the rat CR39 polypeptide contained 344 amino acids and had a molecular weight of 39,615. The predicted amino acid composition and submit molecular weight of the rat CR39 were very similar to those of prenyltransferases isolated from chicken, pig, and human. The sequence of amino acid residues 173 through 203 in the rat CR39 polypeptide showed that 17 out of 30 matched an active-site peptide of avian liver prenyltransferase. Thus, alterations in the rate of cholesterogenesis resulted in the coordinate regulation of three mRNAs encoding HMG-CoA reductase, HMG-CoA synthase, and CR39, the latter being tentatively identified as prenyltransferase.

Amino Acid Sequence↗

The 14C-glycocholate test in diabetic diarrhoea.

Twenty-four insulin-dependent diabetics, including seven with diabetic diarrhoea, were studied by means of the 14C-glycocholate (14C-GCA) test and various tests for autonomic dysfunction. The breath component of het test was abnormal in four of the seven patients with diarrhoea and one of the other diabetics. Three patients with diarrhoea and a positive breath test result responded to antibiotics, whereas two with diarrhoea and a negative test result did not. High faecal 14C, suggesting bile acid malabsorption, was found in only one patient with diarrhoea and he had previously failed to respond to cholestyramine. These results suggest that bacterial overgrowth in the small intestine does occur in some but not all patients with diabetic diarrhoea and that the 14C-GCA test can predict the response to antibiotics. All the patients with diabetic diarrhoea had good evidence of autonomic dysfunction.

Anti-Bacterial Agents↗

Idiopathic bile acid catharsis.

In the course of extensive routine screening for bile acid malabsorption a few patients were detected in whom chronic diarrhoea was apparently induced by excess bile acid loss which was neither associated with demonstrable conventional ileopathy nor with any other disorder allied to diarrhoea. In three patients subjected to scrutiny the results obtained were in harmony with a concept of idiopathic bile acid catharsis. Ingestion of cholestyramine was followed by immediate relief, but the diarrhoea recurred whenever this treatment was withdrawn. It it suggested that idiopathic bile acid catharsis should be suspected in patients with unexplained chronic diarrhoea and especially in those with a diagnosis of irritable colon with diarrhoea.

Adult↗

Clinical, biochemical, and histological studies of osteomalacia, osteoporosis, and parathyroid function in chronic liver disease.

Twenty of 32 patients with either chronic cholestatic or hepatocellular liver disease had bone pain or recent fractures. On bone biopsy five patients had normal bone, 15 had osteomalacia, five had osteoporosis, and seven had a combination of osteomalacia and osteoporosis. In the presence of osteoporosis, osteomalacia was minimal or absent. There was no biochemical, radiological, or histological evidence of excess parathyroid activity. No significant correlations were demonstrated between the plasma and urinary biochemical findings and the presence of either osteoporosis or osteomalacia and bone biopsy was essential for correct diagnosis. There was no statistical relationship between low serum 25-hydroxy vitamin D values and the presence of osteomalacia. Bone disease was not prevented by regular intramuscular vitamin D2, although biochemical changes were improved. Drugs such as corticosteroids and cholestyramine may be important aetiological factors in hepatic osteodystrophy.

Adult↗

Benign recurrent intrahepatic cholestasis: studies of bilirubin kinetics, bile acids, and cholangiography.

Three patients with benign recurrent intrahepatic cholestasis are described. They had had between five and 16 attacks of cholestasis. Between attacks the liver function tests, including serum bile acids, were normal. Serial serum bilirubin and bile acid estimations during the cholestasis in one patient revealed a consistent discrepancy between the serum bilirubin and bile acid concentrations during three consecutive attacks. In the other two patients the serum concentrations of bile acids and bilirubin varied in parallel. Analysis of the individual serum bile acids did not reveal high concentrations of any 'toxic' bile acid. In one patient, plasma bromsulphthalein (BSP) curves were obtained during both remission and cholestatic periods. The 45 minute retention was slightly increased (10.8%) during remission. During the cholestasis, the 45 minute retention (25%) and the fractional extraction coefficient (Ke=0.069 min-1) were markedly abnormal. The hepatic clearance of unconjugated radiobilirubin was normal at all times in this patient, although during cholestasis, conjugated bilirubin reflexed from the liver to the plasma and was then cleared slowly with a half life of approximately 12 hours. Treatment with corticosteroids, cholestyramine, and phenobarbitone was unsatisfactory.

Adult↗

75Se HCAT test in the detection of bile acid malabsorption in functional diarrhoea and its correlation with small bowel transit.

The purpose of this study was to evaluate whether bile acid malabsorption assessed by the 75SeHCAT test, had a pathogenetic role in functional chronic diarrhoea and to ascertain whether the small bowel transit time (SBTT) could be correlated with the 75SeHCAT test results. The test was based on the counting of the abdominal retention of a 75-selenium labelled homotaurocholic acid. The 75SeHCAT test was carried out in a control group of 23 healthy adults and in 46 patients, 38 of whom were suffering from irritable bowel syndrome (IBS) of diarrhoeic form and eight patients who had undergone cholecystectomy and were suffering from chronic diarrhoea. Faecal bile acid loss was determined in nine patients, and in 14, serum bile acid increase after a standard meal was measured. In 17, SBTT was studied by hydrogen breath test after lactulose administration (21 g in 300 ml water). In 15 patients, choledochocaecal transit time was estimated by Tc99m-HIDA (111 MBq) cholescintigraphy. In 20 of 46 subjects, 75SeHCAT retention was below normal level, and in 19 cholestyramine administration relieved diarrhoea. 75SeHCAT results were related to faecal bile acid loss, while no correlation was found with serum bile acids and SBTT. The data suggest a possible wider use of the 75SeHCAT test in chronic diarrhoea to estimate bile acid malabsorption in irritable bowel syndrome, diarrhoeic form, and provide an effective treatment. In our patients small bowel transit velocity does not seem to be a pathogenetic factor of bile acid malabsorption.

Adolescent↗

Primary bile acid diarrhoea without an ileal carrier defect: quantification of active bile acid transport across the ileal brush border membrane.

Unexplained bile acid malabsorption associated with diarrhoea that responds to cholestyramine was first described in 1973 but convincing evidence of the proposed mechanism--a defective active ileal bile acid transport--has never been substantiated. Active bile acid transport was quantified in vitro using brush border membrane vesicles prepared from terminal ileal biopsy specimens from 10 patients who fulfilled the criteria of idiopathic bile acid diarrhoea. They were recruited from 181 patients with bile acid malabsorption of various causes. Transport was quantified as in vitro Na+ dependent bile acid transport (INBAT), expressed as pmol taurocholate/mg brush border membrane protein/15 seconds, and in vitro Na+ dependent bile acid local transport capacity (INBALTC), expressed as pmol taurocholate/g ileal biopsy tissue/15 seconds. The lowest INBAT and INBALTC values in the 10 patients with idiopathic bile acid diarrhoea were well above the 10th centile values of a control group of 132 patients. Both INBAT (mean (range) 88 (30-136)) and INBALTC (158 (85-268)) values were significantly higher in the 10 patients than in the control group (INBAT: mean (range) 63 (1-244), INBALTC: mean (range) 98 (1-408)). Quantification of active ileal bile acid transport in these 10 patients with idiopathic bile acid malabsorption suggests that a genetic (carrier) defect is rare in adults.

Adult↗

Inhibition of methanogenesis by human bile.

The factors that regulate methanogenesis in humans have not been established. The presence of bile acid, which is lost into the colon from the small intestine, may be an important regulatory factor of methanogenesis. To examine this possibility, the effect of human bile on methane production by faecal cultures, and the in vivo effect of biliary diversion on breath methane excretion in a methanogenic choledochostomy patient, were investigated. Faecal suspensions (0.1%) from five methanogenic humans were incubated anaerobically with bile (0.3-30%) from three choledochostomy patients, and headspace methane measured by gas chromatography. All biles inhibited headspace methane. Inhibition of methanogenesis was dose dependent, plateaued at 10-30% bile concentration, and was abolished by 0.6% cholestyramine. The maximum inhibition by bile, median (range), was 38 (0.9-56)% of control methane values. Reversal of the bile fistula in the fourth choledochostomy patient converted that subject from methanogenic to 'non-methanogenic' status, It is concluded that inhibition of methanogens in the caecum by bile acid could significantly reduce the number of methanogens in the colon. This and the effect of transit time could explain much of the known epidemiology of 'non-methanogenesis', which has been related to obesity, (comparatively) fast colonic transit in healthy persons, and to small intestinal Crohn's disease.

Bile↗

Primary ileal villous atrophy is often associated with microscopic colitis.

Three cases of apparent primary villous atrophy of the terminal ileum in women with chronic diarrhoea are reported. Eight cases have previously been reported in the literature. Clinical characteristics are the presence of severe chronic secretory diarrhoea with episodes of hypokalaemia combined with signs of ileal malabsorption and/or efficacy of cholestyramine. Diagnosis is based on ileoscopy and histology. An association with microscopic colitis was present in the three patients and in four cases in the literature. The pathogenesis of primary ileal villous atrophy remains unknown and may involve dysimmunity. Its association with microscopic colitis may indicate a common pathogenesis or support the hypothesis that the faecal stream or bile salts play a role in the pathogenesis of microscopic colitis.

Adult↗

Assessment of long-term plasma exchange for familial hypercholesterolaemia.

The effectiveness of repeated plasma exchange with 2 to 4 litres of plasma protein fraction as long-term treatment for familial hypercholesterolaemia has been evaluated in six severely affected patients receiving conventional cholesterol lowering treatment. Cell-separator mediated exchange at monthly intervals for one to two years reduced mean serum cholesterol levels from 18.5 mmol/l (715 mg/dl) to 12.4 mmol/l (480 mg/dl) in two female homozygotes but failed to influence xanthomata or prevent a two- to threefold increase in their left ventricular aortic systolic pressure gradients. More effective reduction of mean serum cholesterol levels from 15.7 mmol/l (608 mg/dl) to 8.6 mmol/l (333 mg/dl) in two male homozygotes by plasma exchange at fortnightly intervals for two to three years was accompanied by resolution of xanthomata and by stabilisation of aortocoronary lesions. In two male heterozygotes with angina, coronary angiographic appearances were unaltered or improved after one to two years of thrice-monthly plasma exchange, which reduced mean serum cholesterol levels from 6.4 mmol/l (248 mg/dl) to 4.7 mmol/l (182 mg/dl). We conclude that plasma exchange every one to two weeks, combined with oral nicotinic acid and/or cholestyramine, retards the rate of progression of atheroma in homozygotes and possibly induces regression in heterozygotes.

Adult↗