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Effect of resin surface charge on gastric mucoadhesion and residence of cholestyramine.

Previous studies performed on excised gastric tissue and in healthy volunteers revealed that the ion exchange resin, cholestyramine, exhibits mucoadherent behaviour. This study was designed to elucidate whether surface charge affected this behaviour. Gamma scintigraphy was performed on fasted normal subjects following oral administration of cholestyramine or the cationic exchanger Amberlite(R) IRP-69, either uncoated or polymer-coated to mask their charge. Subjects were fed after 4 h. The initial gastric emptying of all formulations was similar (T(50) values (mean+/-S.E.M.): cholestyramine=85.86+/-9.16 min; IRP-69=76.09+/-9.23 min; polymer-coated cholestyramine=72.0+/-12.64 min; polymer-coated IRP-69=70.25+/-10.57 min: P=0.724). However, after 3 h the emptying pattern of cholestyramine was slower than that of IRP-69. This resulted in greater retention times than IRP-69 (AUC(0-6) values (relative units)=15,200+/-1093 versus 9452+/-811; cholestyramine versus IRP-69: P=0.0004). This effect was reduced by polymer-coating the cholestyramine. Serial images showed that cholestyramine was trapped in the oropharyngeal region and subsequently displaced by the meal, resulting in higher levels of activity remaining at 6 h. Thus, cholestyramine exhibited prolonged gastric residence via mucoadhesion and was distributed throughout the stomach. The surface charge of the resin was found to have a contributory role. These materials may have potential for the delivery of drugs in the topical treatment of the gastric mucosa, for example in the eradication of Helicobacter pylori.

Adolescent↗

Stimulation of pancreatic secretion and growth in the rat after feeding cholestyramine.

The influence of luminal bile salts on pancreatic growth in rats was studied by feeding cholestyramine, an anion-exchange resin that binds luminal bile salts, and by chronic bile diversion. Cholestyramine given in food stimulated pancreatic growth, increasing both its size and deoxyribonucleic acid content. A dose of 0.5% was ineffective, but feeding 2%, 6%, and 10% cholestyramine (wt/wt) gave the same degree of pancreatic enlargement. Cholestyramine feeding also augmented the stimulation of pancreatic growth as seen after feeding raw soybean flour containing active trypsin inhibitor. Feeding cholestyramine increased both the basal pancreatic secretion and the secretory response to exogenous cholecystokinin. If they were fasted overnight, the pancreatic enzyme content of cholestyramine-fed rats was also increased with an equal increase in both trypsin and lipase activity. However, enzyme content after cholestyramine feeding depended on the duration of the feeding and whether or not the animals were fasted before killing. Chronic bile diversion caused pancreatic growth similar to that seen in cholestyramine-fed animals. It is suggested that the pancreatic enlargement seen after cholestyramine feeding and bile diversion is an adaption to increased secretion similar to that seen after feeding soybean trypsin inhibitor.

Animals↗

Enhancement of gallbladder emptying in gallstone patients after oral cholestyramine.

OBJECTIVE: To evaluate whether a low dose of oral cholestyramine improves gallbladder emptying in gallstone patients. METHODS: Gallbladder volumes were assessed by sonography in 36 patients with cholesterol gallstones and 18 healthy controls. On three different days subjects ingested: 1) test meal alone, 2) test meal plus cholestyramine (4 g), and 3) cholestyramine alone (4 g). RESULTS: Fasting gallbladder volume (mean +/- SE, 25.9 +/- 1.8 ml and 19.2 +/- 1.3 ml for patients and controls, respectively, p < 0.05) and postprandial gallbladder residual volume (48.7 +/- 3.9% and 21.6 +/- 2.8% of fasting volume in patients and controls, respectively, p < 0.001) were larger in patients than controls, indicating impaired gallbladder emptying. Gallstone patients were divided into 19 "contractors" and 17 "hypocontractors" (residual gallbladder volume smaller or greater than mean +/- 2 SD of controls). Compared with the test meal alone, the addition of cholestyramine induced a further decrease of residual volume in contractors (from 30.4 +/- 2.1% to 19.8 +/- 1.9%, p < 0.001), hypocontractors (from 69.3 +/- 3.9% to 56.7 +/- 7.4%, p < 0.05), and controls (from 21.6 +/- 2.8% to 5.0 +/- 1.0%, p < 0.0004). Two hours after test meal plus cholestyramine gallbladder volume was still markedly reduced in both patients and controls. Fasting gallbladder volume 24 h after test meal plus cholestyramine was decreased in patients and in controls. The ingestion of cholestyramine alone initiated gallbladder evacuation comparable to that of test meal in both contractors and hypocontractors. CONCLUSIONS: A low dose of cholestyramine in combination with test meal induces a considerable decrement of gallbladder volume compared with test meal alone in gallstone patients. Cholestyramine alone causes a decrease of gallbladder volume which is comparable to that observed in response to test meal alone.

Administration, Oral↗

Psyllium for the reduction of cholestyramine-associated gastrointestinal symptoms in the treatment of primary hypercholesterolemia.

OBJECTIVE: To determine if the bulk-forming laxative, psyllium hydrophilic mucilloid (PHM), reduces the gastrointestinal side effects and enhances the cholesterol-lowering efficacy of cholestyramine resin in patients with primary hypercholesterolemia. DESIGN: After a dietary lead-in period and 6 weeks of treatment with cholestyramine, the study followed a double-blinded, placebo-controlled, crossover format. SETTING: Lipid clinic affiliated with a large metropolitan community hospital. PARTICIPANTS: Twenty-seven randomly selected male and female patients with a diagnosis of primary hypercholesterolemia. Entry criteria required a fasting low-density lipoprotein cholesterol (LDL-C) concentration of 4.91 mmol/L (190 mg/dL) or greater and a triglyceride concentration of less than 2.26 mmol/L. Patients using steroids, beta-blockers, thiazide diuretics, and lipid-lowering agents, or having a history of allergy to psyllium or aspartame were excluded. INTERVENTION: The study consisted of four interventional phases of 6 weeks' duration that included (1) dietary stabilization (National Cholesterol Education Program Step I Diet); (2) cholestyramine therapy (4 g twice daily); (3) cholestyramine with study medication (PHM [5.1 g twice daily] or placebo); and (4) cholestyramine with crossover to alternate study medication. MAIN RESULTS: Following the 6-week dietary lead-in phase, four patients were eliminated from the study because their fasting LDL-C concentrations fell below 4.14 mmol/L (160 mg/dL), and one patient was eliminated because testosterone therapy was initiated by his internist. The remaining 22 patients entered the cholestyramine treatment phase. Four left the study within 2 weeks because of intolerable gastrointestinal tract symptoms. The 18 patients who completed this phase demonstrated significant reductions in their plasma total cholesterol (7.27 vs 6.67 mmol/L [281 vs 258 mg/dL]) and LDL-C (5.38 vs 4.63 mmol/L [208 vs 179 mg/dL]) concentrations compared with baseline levels. The addition of PHM to the cholestyramine regimen provided a tendency toward further reductions in total cholesterol and LDL-C levels (6.67 vs 6.46 mmol/L [258 vs 250 mg/dL] and 4.63 vs 4.29 mmol/L [179 vs 166 mg/dL], respectively), although statistical significance was not achieved. Psyllium hydrophilic mucilloid significantly reduced the frequency and severity of constipation, abdominal discomfort, and heartburn. No reports of new gastrointestinal tract symptoms or untoward effects were noted with the addition of PHM. CONCLUSION: These data suggest that the addition of PHM to cholestyramine therapy may improve a patient's compliance by reducing the associated gastrointestinal tract side effects.

Abdominal Pain↗

Comparative effects of simvastatin and cholestyramine in treatment of patients with hypercholesterolaemia.

The efficacy and safety of 20 mg simvastatin (a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor) and of 16 g cholestyramine daily in the treatment of 34 hypercholesterolaemic patients have been compared after dietary treatment and stratified randomization. The effect of combined treatment with the two drugs was studied in 5 patients with severe hypercholesterolaemia. After 6 weeks of treatment the simvastatin group showed a significantly greater (p less than 0.05) decrease in the mean total plasma cholesterol concentration from 7.88 to 5.48 mmol/l than in the cholestyramine group in whom there was a fall from 7.82 to 6.73 mmol/l. Simvastatin decreased the mean plasma LDL cholesterol concentration from 6.07 to 3.76 mml/l and cholestyramine decreased it from 6.16 to 4.46 mmol/l. Simvastatin also reduced the mean plasma total triglycerides by 24%, VLDL triglycerides by 20% and VLDL cholesterol by 36%, while cholestyramine led to increases in these parameters by 64%, 85% and 63%, respectively. Mean plasma HDL cholesterol concentration and the subfractions HDL2 and HDL3 cholesterol were significantly increased by simvastatin. Simvastatin and cholestyramine reduced the mean plasma apolipoprotein B concentration by 28% and 13%, respectively. The mean plasma apolipoprotein A-I concentration was significantly higher only on simvastatin treatment. Simvastatin did not cause any subjective or objective side effects, while cholestyramine caused gastrointestinal problems in 31% of patients. Small increases in serum alanine aminotransferase (S-ALT) activity were seen with both drugs. Cholestyramine significantly raised the serum alkaline phosphatase (S-ALP) although to a level still within the normal range. It is concluded that 20 mg simvastatin was more effective than 16 g cholestyramine in the treatment of hypercholesterolaemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Effect of cholestyramine and cholecystokinin receptor antagonist CR1505 (loxiglumide) on lower esophageal sphincter pressure in man.

Cholecystokinin (CCK) decreases lower esophageal sphincter pressure (LESP) in man. Cholestyramine, a nonabsorbable bile salt binding resin, stimulates endogenous CCK secretion. We have investigated the effect of oral ingestion of 16 g cholestyramine without and with infusion of the CCK receptor antagonist CR1505 (loxiglumide, 15 mg/kg/90 min) on LESP in seven healthy subjects. LESP was recorded for 90 min, in 10-min intervals, with the pull-through technique using a four-lumen water-perfused catheter. Oral ingestion of cholestyramine resulted in a significant (P < 0.05) decrease in LESP, starting from 10 min and continuing during the entire experiment (basal LESP: 11.8 +/- 2 mm Hg, minimal value reached during cholestyramine: 7.3 +/- 1 mm Hg; P < 0.05). Pretreatment with loxiglumide completely antagonized the effect of cholestyramine on LESP. Infusion of loxiglumide without cholestyramine did not affect basal LESP. It is concluded that: (1) cholestyramine significantly reduces LESP; (2) this reduction in LESP does not occur after pretreatment with loxiglumide, indicating that cholestyramine influences LESP through CCK release; and (3) basal LESP is not regulated by CCK.

Adult↗

Dissociation of cholecystokinin and pancreaticobiliary response to intraduodenal bile acids and cholestyramine in humans.

The role of intraduodenal bile acids in the regulation of cholecystokinin (CCK), pancreatic polypeptide (PP), and secretin as well as exocrine pancreatic and biliary secretion was investigated by means of a duodenal marker perfusion technique in volunteers. The following solutions were perfused: (1) liquid test meal, (2) test meal with 6 g cholestyramine, (3) test meal with 2 g chenodeoxycholic acid (CDC), (4) test meal with 6 g cholestyramine and 2 g CDC, (5) 6 g cholestyramine alone, and (6) 2 g CDC alone. The test meal caused an immediate increase in CCK and PP plasma levels, whereas secretin was not significantly altered. CCK release was further enhanced by addition of cholestyramine, whereas CDC inhibited release. The stimulatory effect of cholestyramine was abolished by CDC. CDC alone and in combination with the test meal stimulated secretin release. The response of PP to the test meal was not altered by addition of either compound. Cholestyramine and CDC alone caused only a very small increase in CCK levels, whereas PP was stimulated to nearly postprandial values. Meal-stimulated pancreatic and biliary secretion was significantly enhanced by cholestyramine, CDC, and the combination of both. CDC and cholestyramine alone each stimulated enzyme and bile secretion to a greater extent than the test meal. We conclude that intraduodenal bile salts are a modulator of postprandial CCK release. Changes in exocrine pancreatic and biliary and PP secretion do not necessarily parallel CCK concentrations, suggesting that different mediators are involved in the observed bile acid-induced changes in humans.

Adult↗

Cholestyramine as an adsorbent in acute lindane poisoning: a murine model.

STUDY OBJECTIVES: To compare the effectiveness of single-dose cholestyramine versus single-dose activated charcoal in preventing clinical toxicity after acute lindane ingestion. DESIGN: CD-1 mice received lindane by enteral (gavage) and parenteral (intraperitoneal) routes, followed by enteral administration of either cholestyramine (2.25 g/kg) or activated charcoal (2.25 g/kg), with subsequent observation for convulsions and death. MEASUREMENTS: The doses of lindane at which 50% of mice developed convulsions (CD50) and at which 50% of mice died (LD50) were established and compared among control, charcoal-, and cholestyramine-treated groups. RESULTS: For lindane administered by gavage, the differences in the CD50 and LD50 between the control and the activated charcoal groups were not statistically significant. However, a significant difference did exist in both the CD50 and the LD50 between the group receiving cholestyramine and the control group and between the cholestyramine and activated charcoal groups. After IP administration of lindane, the difference in CD50 or LD50 among control, activated charcoal, or cholestyramine groups was not significantly different. CONCLUSION: In the murine model, cholestyramine is more effective than activated charcoal in preventing absorption of lindane, thus preventing convulsions and death. These data support the need for clinical studies to determine whether cholestyramine may be a more effective treatment than activated charcoal for acute lindane ingestions in human beings.

Acute Disease↗

Compliance with and efficacy of treatment with pravastatin and cholestyramine: a randomized study on lipid-lowering in primary care.

OBJECTIVES: Lipid-lowering drugs as 3-hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) reductase inhibitors and cholestyramine are effective in reducing cardiovascular morbidity both in primary and secondary prevention. Patient compliance is an important determinant of the outcome of therapy. This study was designed to compare compliance with tolerance and lipid-lowering effectiveness of pravastatin and/or cholestyramine in primary care. DESIGN: Nine hundred and eighty nine women and 1047 men were randomized to treatment at 100 primary-care centres in Sweden. After dietary intervention, an eligible patient was randomly assigned to one of four programs of daily treatment: group Q, 16 g cholestyramine, group QP, 8 g cholestyramine and 20 mg pravastatin, group P20, 20 mg pravastatin or group P40, 40 mg pravastatin. RESULTS: In group Q, group QP, group P20 and group P40 the reductions in low density lipoprotein (LDL)-cholesterol were 26%, 36%, 27% and 32%. The dose actually taken was 91-95% of the prescribed for the pravastatin treatment groups and 77-88% for the cholestyramine groups. In the pravastatin and cholestyramine groups 76-78% and 44-53%, respectively, completed the trial. Only 8-27% of the patients reached a serum cholesterol target level of 5.2 mmol L-1. There was no difference in lipid-lowering effect between women and men. CONCLUSION: Pravastatin alone is efficacious and compliance is high, independent of dose. Combined treatment with cholestyramine and pravastatin had a better cholesterol lowering effect (although not statistically significant) than 40 mg pravastatin. Despite this, only 8-27% of the patients actually reached a serum cholesterol level of 5.2 mmol L-1. No unexpected serious adverse events were detected in any of the treatment groups. As predicted, the gastrointestinal disturbances were more common on cholestyramine treatment. These two factors suggest that an increase in the dosage of the HMG-CoA reductase inhibitor may be appropriate. Results from other studies indicate that there also might be other positive effects of statin treatment beyond cholesterol lowering.

Adult↗

Treatment of familial hypercholesterolaemia: a controlled trial of the effects of pravastatin or cholestyramine therapy on lipoprotein and apolipoprotein levels.

The efficacy and safety of a new, selective inhibitor of cholesterol synthesis, pravastatin, and the bile acid-binding resin, cholestyramine, were compared in a randomized, double-blind study of 120 patients with familial hypercholesterolaemia. After a run-in period of 8-10 weeks with assessment of dietary habits, the patients were treated with pravastatin + placebo, placebo + cholestyramine, or placebo alone. Active pravastatin therapy was initiated with 10 mg b.i.d. for 6 weeks, and was increased to 20 mg b.i.d. for the following 6 weeks. Cholestyramine was given at 24 g d-1, or the highest tolerable dose. After 6 weeks of therapy, serum total and LDL cholesterol levels were reduced by 17% and 21%, respectively, on pravastatin treatment, whereas the corresponding reductions with cholestyramine treatment were 24% and 30%, respectively. With an increased dose of pravastatin, serum and LDL cholesterol concentrations were reduced by 23% and 28%, respectively, after 12 weeks; the effect of cholestyramine was unchanged. HDL cholesterol levels increased in response to pravastatin, by 7% and 9% after 6 and 12 weeks, respectively. Concomitant changes in the concentrations of apolipoproteins B and AI were observed. Three patients discontinued the study because of side-effects: two subjects were treated with pravastatin and one was given placebo. The prevalence of side-effects (including laboratory abnormalities) was 35% for pravastatin, 30% for placebo, and 53% (significantly higher) for cholestyramine. We conclude that pravastatin, in a 40 mg daily dose, is as effective as cholestyramine in lowering LDL cholesterol in familial hypercholesterolaemia. Since the frequency of side-effects is higher with cholestyramine, pravastatin offers a promising alternative for the therapy of this genetic disease.

Adult↗

Effects of therapy with cholestyramine on progression of coronary arteriosclerosis: results of the NHLBI Type II Coronary Intervention Study.

In the National Heart, Lung and Blood Institute Type II Coronary Intervention Study, patients with Type II hyperlipoproteinemia and coronary artery disease (CAD) were placed on a low-fat, low-cholesterol diet and then were randomly allocated to receive either 6 g cholestyramine four times daily or placebo. This double-blind study evaluated the effects of cholestyramine on the progression of CAD as assessed by angiography. Diet alone reduced the low-density lipoprotein cholesterol 6% in both groups. After randomization, low-density lipoprotein cholesterol decreased another 5% in the placebo group and 26% in the cholestyramine-treated group. Coronary angiography was performed in 116 patients before and after 5 years of treatment. CAD progressed in 49% (28 of 57) of the placebo-treated patients vs 32% (19 of 59) of the cholestyramine-treated patients (p less than .05). When only definite progression was considered, 35% (20 of 57) of the placebo-treated patients vs 25% (15 of 59) of the cholestyramine-treated patients exhibited definite progression; the difference was not statistically significant. However, when this analysis was performed with adjustment for baseline inequalities of risk factors, effect of treatment was more pronounced. Of lesions causing 50% or greater stenosis at baseline, 33% of placebo-treated and 12% of cholestyramine-treated patients manifested lesion progression (p less than .05). Similar analyses with other end points (percent of baseline lesions that progressed, lesions that progressed to occlusion, lesions that regressed, size of lesion change, and all cardiovascular end points) all favored the cholestyramine-treated group, but were not statistically significant. Thus, although the sample size does not allow a definitive conclusion to be drawn, this study suggests that cholestyramine treatment retards the rate of progression of CAD in patients with Type II hyperlipoproteinemia.

Adult↗

Effects of cholestyramine and diet on small intestinal histomorphometry in rats.

Reports on the effects of cholestyramine on small intestinal structure of rats have produced contradictory data about changes in mucosal histomorphometry, perhaps due to interacting effects of dietary composition. In order to identify effects of cholestyramine and diet on structure of the small intestines, 40 male rats were divided into 4 groups of 10 and fed 1 of each of the following diets for 1 month: standard diet, purified fiber-free diet, standard diet + 2% cholestyramine, or purified fiber-free diet + 2% cholestyramine. Serum concentrations of cholesterol and triglycerides were moderately increased in rats fed the purified fiber-free diet versus the standard diet. Neither total length nor weight of small intestine were affected by either diet or cholestyramine. Mucosal weight was affected by interactions between cholestyramine and diet, indicating that outcome depended upon modulating effects of both variables. Significant interactions were similarly detected among the variables of anatomic site, diet, and cholestyramine for many histomorphometric parameters of intestinal mucosa. Cholestyramine reduced total mucosal thickness in both jejunum and ileum and reduced villus height and villus:crypt ratio in the ileum.

Animals↗

Low-dose combined therapy with fluvastatin and cholestyramine in hyperlipidemic patients.

OBJECTIVE: To compare the low-density lipoprotein (LDL) cholesterol-lowering efficacy of low-dose combinations of cholestyramine and fluvastatin. DESIGN: Randomized, double-blind, parallel group, placebo-controlled trial with a 24-week double-blind treatment period divided into three phases. SETTING: Office-based clinics. PATIENTS: Hypercholesterolemic, with LDL cholesterol of 4.14 mmol/L or greater (> or = 160 mg/dL) and plasma triglycerides of 3.39 mmol/L or less (< or = 300 mg/dL). Four hundred sixty patients were screened; 224 patients were randomized into a double-blind treatment period; 203 completed the study; 6 dropped out because of adverse events. INTERVENTION: Patients were treated with 10 mg or 20 mg of fluvastatin alone, 8 g or 16 g of cholestyramine alone, or combinations of these fluvastatin and cholestyramine dosages (six treatment groups). MEASUREMENTS: Changes in lipid variables, particularly LDL cholesterol. RESULTS: The 10-mg and 20-mg fluvastatin monotherapy groups showed considerable reductions in LDL cholesterol initially (-20.1% [SD, 8.8%] and -20.2% [SD, 10.1%], respectively); these reductions were maintained. Reductions in LDL cholesterol that resulted from the addition of cholestyramine, 8 g/d, to 10 mg of fluvastatin and 20 mg of fluvastatin were greater than those observed with monotherapy (10-mg fluvastatin--[10-mg fluvastatin plus cholestyramine], 9.1%; 95% CI, 3.8% to 14.4%) and 20-mg fluvastatin--[20-mg fluvastatin plus cholestyramine], 11.6%; CI, 6.5% to 16.8%). The increase in cholestyramine dose to 16 g/d in the three combination groups provided only a modest additional response. CONCLUSIONS: Low-density lipoprotein cholesterol reductions of about 25% to 30% can be achieved with low-dose combination therapy with fluvastatin and cholestyramine. The addition of low-dose resin appears to produce greater overall cholesterol reduction than does a simple doubling of the fluvastatin dosage. The low-dose combination treatment was highly successful in achieving the goals of the National Cholesterol Education Program guidelines.

Anticholesteremic Agents↗

Cholestyramine therapy for dyslipidemia in non-insulin-dependent diabetes mellitus. A short-term, double-blind, crossover trial.

OBJECTIVE: To assess clinical efficacy and tolerability of cholestyramine therapy in patients with dyslipidemia and non-insulin-dependent diabetes mellitus (NIDDM). DESIGN: A randomized, double-blind, crossover study of cholestyramine (8 g twice daily) compared with placebo for a period of 6 weeks each. SETTING: Metabolic Unit and the Lipid and Diabetes Clinics at the Department of Veterans Affairs Medical Center, Dallas, Texas. PATIENTS: 21 patients with NIDDM that was well controlled using either glyburide or insulin therapy and with low-density lipoprotein (LDL) cholesterol levels more than 3.36 mmol/L (130 mg/dL) and fasting plasma triglyceride levels less than 3.4 mmol/L (300 mg/dL). MEASUREMENTS: During the last week of each period, for 5 consecutive days fasting plasma lipids and lipoproteins were measured, and plasma glucose levels were determined at 3, 7, and 11 a.m. and at 4 and 8 p.m. Daily urinary glucose excretion was measured for 3 days and glycosylated hemoglobin concentrations were determined on days 28 and 38 of the study periods. RESULTS: In this short-term study, when compared with placebo, cholestyramine reduced total cholesterol by 18% (95% CI, 14% to 22%) and LDL cholesterol by 28% (CI, 21% to 35%). Although cholestyramine therapy increased plasma triglyceride levels by 13.5% (CI, 1% to 26%), very-low density lipoprotein cholesterol and high-density lipoprotein cholesterol levels remained unchanged. Cholestyramine therapy improved glycemic control; mean plasma glucose values were lower by 13% (CI, 5% to 21%), a median reduction in urinary glucose excretion of 0.22 g/d was observed (P < 0.001), and a tendency to lower glycosylated hemoglobin concentration was noted. The doses of glyburide and insulin did not change during the study, and body weight remained stable. Constipation was the main side effect, and two patients dropped out of the study because of cholestyramine intolerance. CONCLUSIONS: In carefully selected male patients with NIDDM and high LDL cholesterol and normal triglyceride levels, cholestyramine therapy effectively reduces LDL levels and also may improve glycemic control. The long-term efficacy of cholestyramine therapy in patients with NIDDM needs further evaluation.

Adult↗

Comparative effects of simvastatin and cholestyramine on plasma lipoproteins and CETP in humans.

Cholesteryl ester transfer protein (CETP) mediates neutral lipid transport in plasma, resulting in a net transfer of cholesteryl ester from high density lipoprotein to very low density lipoprotein. CETP gene expression is regulated by cholesterol, and plasma CETP level increases in patients with hyperlipidemia and with cholesterol feeding. Simvastatin, unlike cholestyramine, reduces hydroxymethylglutaryl coenzyme A reductase activity and may decrease a cellular pool of cholesterol, which is regulatory for CETP gene expression. The effects of simvastatin and cholestyramine on plasma lipids and CETP in 24 male and 19 female patients with primary hypercholesterolemia were compared. Following a four-week placebo period, patients were randomly assigned to receive either simvastatin or cholestyramine. Medication was increased in a stepwise fashion (from 10 to 40 mg for simvastatin and from 8 to 24 g for cholestyramine) as required at six-week intervals to maintain a low density lipoprotein cholesterol (LDL-C) level below 3.4 mmol/L. At the end of the 18-week study, the mean dose of simvastatin was 28.6 mg/day and of cholestyramine 19.3 g/day. Simvastatin was more effective than cholestyramine in lowering LDL-C (-36.8% versus -27. 2%; P=0.031) and triglycerides (-8.5% versus +12.5%; P=0.045). Plasma CETP level decreased by 14.8% following treatment with simvastatin (P=0.003) but did not change following cholestyramine treatment. This study demonstrates that, compared with cholestyramine, simvastatin results in more favourable improvements in the plasma lipoprotein profile and also lowers plasma levels of CETP.

Adolescent↗

[Pravastatin, cholestyramine and gemfibrozil in long-term therapy of primary hypercholesterolemia. An open randomized comparative study].

In this open controlled clinical trial the lipid-lowering effect, the tolerance and clinical safety of the new hydrophilic HMG-CoA reductase inhibitor pravastatin and cholestyramine were compared in the treatment of 45 patients with primary hypercholesterolaemia over a period of 16 weeks. Following a dietary lead-in of six weeks, patients were randomized at a ratio of 3:2 to receive either pravastatin 10 mg b.i.d. or cholestyramine 8 g b.i.d. The dose of pravastatin was increased to 40 mg per day after eight weeks of treatment and after 16 weeks cholestyramine 8 g b.i.d. was added. Two thirds of the patients in the cholestyramine group were switched to gemfibrocil 900 mg. At the end of the 48 week treatment period the mean reduction rates of total cholesterol, LDL-cholesterol and triglycerides for the pravastatin combination compared to cholestyramine (in brackets values for gemfibrocil) were -30, -35 and -17% versus -17 (-19), -25 (-22) and +27 (-24)%. Pravastatin lead to an increase of the HDL concentration of approximately 8%, gemfibrocil to approximately 13%, whilst cholestyramine alone did not change this lipid fraction. The reduction of total cholesterol and LDL-cholesterol was associated with a decrease in the apolipoprotein B concentration. However, the apolipoprotein AI and AII levels remained unchanged. Due to the absence of clinically relevant side effects and laboratory abnormalities coupled with the excellent compliance in this study, pravastatin proved to be a convincing therapeutic alternative to cholestyramine and gemfibrocil. The combination therapy of pravastatin and cholestyramine offers a potentially highly efficacious and safe therapeutic regimen for the future.

Adult↗

Mevinolin and cholestyramine inhibit the direct synthesis of low density lipoprotein apolipoprotein B in miniature pigs.

Previous studies established that following simultaneous injection of 125I-labeled homologous very low density lipoproteins (VLDL) and 131I-labeled homologous low density lipoproteins (LDL) into miniature pigs, a large proportion of LDL apolipoprotein B (apoB) was synthesized directly, independent of VLDL or intermediate density lipoprotein (IDL) apoB catabolism. The possibility that cholestyramine alone (a bile acid sequestrant) or in combination with mevinolin (a cholesterol synthesis inhibitor) could regulate the direct LDL apoB synthetic pathway was investigated. 125I-labeled VLDL and 131I-labeled LDL were injected into miniature pigs (n = 8) during a control period and following 18 days of cholestyramine treatment (1.0 g kg-1d-1) or following 18 days of treatment with cholestyramine and mevinolin (1.2 mg kg-1d-1). ApoB in each lipoprotein fraction was selectively precipitated using isopropanol in order to calculate specific activity. In control experiments, LDL apoB specific activity curves reached their peak values well before crossing the VLDL or IDL apoB curves. However, cholestyramine treatment resulted in LDL apoB curves reaching maximal values much closer to the point of intersection with the VLDL or IDL curves. Kinetic analyses demonstrated that cholestyramine reduced total LDL apoB flux by 33%, which was due entirely to inhibition of the LDL apoB direct synthesis pathway since VLDL-derived apoB was unaffected. In addition, the LDL apoB pool size was reduced by 30% and the fractional catabolic rate of LDL apoB was increased by 16% with cholestyramine treatment. The combination of mevinolin and cholestyramine resulted in an even more marked inhibition of the direct LDL apoB synthesis pathway (by 90%), and in two animals this pathway was completely abolished. This inhibition was selective as VLDL-derived LDL apoB synthesis was not significantly different. LDL apoB pool size was reduced by 60% due primarily to the reduced synthesis as well as a 40% greater fractional removal rate. These results are consistent with the idea that cholestyramine and mevinolin increase LDL catabolism by inducing hepatic apoB, E receptors. We have now shown that the direct synthesis of LDL apoB is selectively inhibited by these two drugs.

Animals↗

Fluvastatin efficacy and tolerability in comparison and in combination with cholestyramine.

The aim of this study was to investigate the new synthetic HMG-CoA reductase inhibitor, fluvastatin, for efficacy, safety and tolerability in comparison to cholestyramine. One hundred fifty one primary hypercholesterolaemic patients participated in this double-blind, parallel-group, randomized study. During the first 12 weeks of the study, fluvastatin (20 mg and 40 mg daily) was compared with cholestyramine (16 g per day). In the subsequent, 6-week part of the study, the comparative efficacy, safety and tolerability of 20 mg fluvastatin, combined with cholestyramine (4 g, 8 g, or 16 g) were assessed. Fluvastatin (40 mg) reduced LDL cholesterol by 28.0%, triglycerides by 10.5% and increased HDL cholesterol by 3.7%. Cholestyramine (16 g) reduced LDL cholesterol by 35.0%, but raised triglycerides and HDL cholesterol by 12.3% (p < 0.01) and 3.7% respectively. The combination of fluvastatin 20 mg and cholestyramine (4 g, 8 g and 16 g) induced the following reductions in LDL cholesterol: 30.4%, 35.6% and 46.6% respectively. There was no significant change in triglycerides in either group although HDL cholesterol was raised by 4.9%, 8.3% and 7.2% respectively. One patient treated with fluvastatin and two treated with cholestyramine were withdrawn from the study due to elevation of liver transaminases. The most frequent subjective adverse effects in both treatment groups were mild, transient gastrointestinal complaints. Thus, fluvastatin was effective as a lipid-lowering agent; the effect was further enhanced when fluvastatin was combined with cholestyramine.

Anticholesteremic Agents↗