Colestipol and cholestyramine resin. Comparative effects in familial type II hyperlipoproteinemia

The protective effects of Crocin on testopathy in fat-fed and streptozotocin-treated diabetic rats: An experimental study

Background

Male hypogonadism is associated with type II diabetes mellitus due to testicular dysfunction. Medicinal plants have received considerable attention for the management of diabetes and its complications.

Objective

The aim of present study was to evaluate the anti-diabetic and protective influence of Crocin on testopathy in diabetic rats.

Materials and Methods

In this experimental study, type II of diabetes mellitus was induced by high-fat diet and low dose of streptozotocin. Male Wistar rats (8 weeks, 150–200 gr, 18 rats; n= 6 per group) were divided into a control group (standard diet), diabetic group (streptozotocin+high-fat diet), and treatment group (High-fat diet+streptozotocin+Crocin at 20 mg/kg/day, i.p. for 60 days). After 60 days, animals were euthanized, testis and epididymis were dissected, and weights of testes and sperm count were analyzed. Hematoxylin-eosin-stained was done for histopathological examination. Blood samples were collected for the assessment of serum glucose and cholesterol.

Results

High-fat diet and streptozotocin significantly increased the serum glucose and cholesterol levels as compared to the control group (p≤ 0. 001). Moreover, there was a significant decrease in the weight of right (p= 0.008) and left testes (p≤ 0. 001) and also the total sperm count (p= 0.023) in the diabetic group compared with the control group. Current results also identified that type II diabetes mellitus induced degeneration in the morphology of seminiferous tubules. Application of Crocin could significantly decrease serum glucose and cholesterol levels (p= 0.003). Furthermore, Crocin treatment significantly increased the weight of the right (p= 0.026) and left (p= 0.014) testes and total sperm count (p= 0.000). Also, Crocin could attenuate the pathological changes of the testes in the treatment group.

Conclusion

Present findings concluded that Crocin treatment improved diabetic testopathy and impairment of seminiferous tubules induced by high-fat diet and streptozotocin.

Role of colesevelam in combination lipid-lowering therapy

Hyperlipidemia is associated with an increased risk of cardiovascular events; reducing low-density lipoprotein cholesterol (LDL-C), the primary target for cholesterol-lowering therapy, lowers the risk for such events. Although bile acid sequestrants were the first class of drugs to show a mortality benefit related to LDL-C lowering, statins are now considered first-line pharmacological therapy for reducing LDL-C levels because of their potency and their remarkable record of successful outcomes studies. Nevertheless, a substantial proportion of patients do not achieve LDL-C goals with statin monotherapy. In addition, because of adverse effects (primarily myopathy), some patients may be unwilling to use or unable to tolerate statin therapy at all or may not tolerate a full therapeutic statin dose. Also, statins may increase risk of new-onset diabetes in patients at high risk for diabetes. Thus, there remains a need for other lipid-lowering drugs to be used in combination with or in place of statins. The purpose of this article is to review available data from the literature on the use of colesevelam, a second-generation bile acid sequestrant, in combination with other lipid-lowering agents. Colesevelam has been studied in combination with statins, niacin, fibrates, and ezetimibe (including some three-drug combinations). An additive reduction in LDL-C was seen with all combinations. Other observed effects of colesevelam in combination with other lipid-lowering drugs include reductions in apolipoprotein (apo) B (with statins, fibrates, ezetimibe, statin plus niacin, or statin plus ezetimibe) and high-sensitivity C-reactive protein (with statins), and increases in apo A-I (with statins, ezetimibe, or statins plus niacin). Triglyceride levels remained relatively unchanged when colesevelam was combined with statins, fibrates, ezetimibe, or statin plus ezetimibe, and decreased with the triple combination of colesevelam, statin, and niacin. Colesevelam offset the negative glycemic effects of statins and niacin in subjects with insulin resistance or impaired glucose tolerance. Colesevelam was generally well tolerated when added to other lipid-lowering therapies in clinical trials, with gastrointestinal effects such as constipation being the predominant adverse events. Since colesevelam is not absorbed and works primarily in the intestine, it has a low potential for systemic metabolic drug-drug interactions with other drugs. Colesevelam has been shown to not interact with the lipid-lowering drugs lovastatin and fenofibrate; where interaction may be anticipated, separating dosing times by 4 h reduces the impact of any interaction. Available data confirms that colesevelam has additive cholesterol-lowering effects when used in combination with other lipid-lowering therapies. Furthermore, in some patient populations, the additional glucose-lowering effect of colesevelam may be beneficial in offsetting hyperglycemic effects of other lipid-lowering drugs.

Mechanism of hypolipidemic effect of crocin in rats: Crocin inhibits pancreatic lipase

The hypolipidemic mechanism of crocin, an active ingredient in Gardenia jasminoides Ellis and Crocus sativus L, was examined in rats. In diet-induced hyperlipidemic rats, a 10-day treatment with crocin significantly reduced serum triglyceride, total cholesterol, low density lipoprotein (LDL) cholesterol and very low density lipoprotein (VLDL) cholesterol level in the daily dose range of 25 to 100 mg/kg. Results of the modified fat-loading method indicated that crocin inhibited the absorption of fat and cholesterol and this inhibition is closely related to the hydrolysis of fat. In addition, the modified fat-balance method demonstrated that crocin increased the fecal excretion of fat and cholesterol in rats, but had no influence on the elimination of bile acids. The results of the in situ loop method and enzyme assay indicated that crocin could not directly block the absorption of cholesterol from rat jejunum but could selectively inhibit the activity of pancreatic lipase as a competitive inhibitor. These findings suggest that crocin yielded its hypolipidemic effect by inhibiting pancreatic lipase, leading to the malabsorption of fat and cholesterol.

Common polymorphisms in the CYP7A1 gene do not contribute to variation in rates of bile acid synthesis and plasma LDL cholesterol concentration

Transcriptional regulation of the cholesterol 7alpha-hydroxylase (CYP7AI) gene is of critical importance for bile acid and cholesterol metabolism. We evaluated the physiological significance of two common polymorphisms (-203C/A and -469T/C) in the promoter region of the CYP7AI gene. No evidence was found for physiological differences between either the -203C and -203A alleles or the -469T and -469C alleles in transient transfection studies using native 834bp promoter constructs. Moreover, no association was observed between the CYP7AI promoter polymorphisms and the hepatic cholesterol 7alpha-hydroxylase activity and parameters of bile acid synthesis rates, as analyzed in subjects with gallstone disease. In addition, no relationships were found between the promoter polymorphisms and plasma LDL cholesterol concentration in association studies conducted in three different groups of middle-aged Swedish men. Finally, near complete allelic association was found between the two promoter polymorphisms and the IVS6+363G/A polymorphism at the 3' end of the CYP7AI gene (|D'|=0.98), indicating strong linkage disequilibrium across the whole CYP7AI gene. It is concluded that common polymorphisms of the CYP7A1 gene do not contribute to variation in cholesterol 7alpha-hydroxylase activity, rates of bile acid synthesis and plasma LDL cholesterol concentration in humans.

Linkage between cholesterol 7alpha-hydroxylase and high plasma low-density lipoprotein cholesterol concentrations

Interindividual differences in plasma low-density lipoprotein cholesterol (LDL-C) levels reflect both environmental variation and genetic polymorphism, but the specific genes involved and their relative contributions to the variance in LDL-C are not known. In this study we investigated the relationship between plasma LDL-C concentrations and three genes with pivotal roles in LDL metabolism: the low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), and cholesterol 7alpha-hydroxylase (CYP7). Analysis of 150 nuclear families indicated statistically significant linkage between plasma LDL-C concentrations and CYP7, but not LDLR or APOB. Further sibling pair analyses using individuals with high plasma LDL-C concentrations as probands indicated that the CYP7 locus was linked to high plasma LDL-C, but not to low plasma LDL-C concentrations. This finding was replicated in an independent sample. DNA sequencing revealed two linked polymorphisms in the 5' flanking region of CYP7. The allele defined by these polymorphisms was associated with increased plasma LDL-C concentrations, both in sibling pairs and in unrelated individuals. Taken together, these findings indicate that polymorphism in CYP7 contributes to heritable variation in plasma LDL-C concentrations. Common polymorphisms in LDLR and APOB account for little of the heritable variation in plasma LDL-C concentrations in the general population.

Cholesterol-lowering drug therapy in a patient with receptor-negative homozygous familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is caused by mutations in the gene for the low density lipoprotein (LDL) receptor. It is generally believed that homozygous FH patients do not respond well to lipid-lowering drug therapy with inhibitors of 3-hydroxy-3-methylglutaryl CoA reductase because they cannot respond to an increased demand for hepatic cholesterol by up-regulation of LDL-receptor activity. In this paper we show that serum cholesterol in a homozygous FH patient with a receptor-negative LDL-receptor phenotype was reduced by 30% after treatment with simvastatin alone and by a further 11% with simvastatin in combination with probucol and nicotinic acid. The patient was a true homozygote, with two identical alleles of the LDL receptor gene in which a previously undescribed point mutation in exon 11 introduces a premature termination codon at residue 540 in the protein; the mutant protein is predicted to be truncated in the domain with homology to the epidermal growth factor precursor. Cultured cells from the patient were unable to bind, internalise or degrade LDL by the receptor pathway and there was no immunodetectable LDL receptor protein in the cells. Thus the lipid lowering effect of simvastatin in this individual must involve mechanisms other than stimulation of LDL receptors.

An overview of lipid-lowering drugs

The long term use of lipid-lowering drugs in the treatment of patients with hyperlipoproteinaemia is aimed at reducing plasma concentrations of known atherogenic lipoproteins with a favourable effect on lipid deposition in the arterial wall. A less common aim is to prevent the adverse sequelae of hyperchylomicronaemia in patients with severe hypertriglyceridaemia. The decision to begin drug therapy should be made only after the exclusion of secondary factors and after an adequate trial of diet has failed to produce acceptable concentrations of plasma lipids and lipoproteins. The bile acid sequestrants (cholestyramine and colestipol), nicotinic acid, fenofibrate and inhibitors of hydroxymethylglutaryl coenzyme A (HMG CoA) reductase (e.g. lovastatin or simvastatin) are the most effective drugs for use in patients with primary hypercholesterolaemia; these agents reduce plasma concentrations of total and LDL-cholesterol by 15 to 45%. For those patients with concurrent hypertriglyceridaemia, nicotinic acid, lovastatin or simvastatin, or fenofibrate are the preferred drugs for initial use; bile acid sequestrants frequently exacerbate hypertriglyceridaemia in these patients. Fibric acid derivatives (e.g. clofibrate, gemfibrozil, bezafibrate or fenofibrate) are all effective in the therapy of patients with type III hyperlipoproteinaemia, as is nicotinic acid and I have found lovastatin to be effective also. Gemfibrozil or nicotinic acid are the most effective agents to use in the treatment of patients with severe hypertriglyceridaemia who are at increased risk of abdominal pain and pancreatitis. Combined therapy with drugs which have different mechanisms of action can be effectively used in the treatment of patients with severe hypercholesterolaemia or combined hyperlipidaemia; for the former group, combinations which use bile acid sequestrants, HMG CoA reductase inhibitors and nicotinic acid are the most effective.

Xanthomas and hyperlipidemias

The ability to recognize diverse clinical forms of xanthomas, such as tuberous, planar, eruptive and tendinous, is important in the detection of underlying systemic disease. A variety of primary genetic disorders, as well as numerous secondary conditions such as diabetes, obstructive liver disease, thyroid disease, renal disease, and pancreatitis, can lead to hyperlipoproteinemia that results in the formation not only of xanthomas but also of life-threatening vascular atherosclerosis. An understanding of the pathogenesis of the underlying lipoprotein alterations provides a rational approach to therapy utilizing dietary manipulations and drugs. Such treatment is capable of correcting most disorders of lipid metabolism, and, if appropriate therapy is initiated at the first sign of xanthoma evolution, it may prevent progression of atherosclerosis, provide resolution of xanthomas, and in some instances prevent serious pancreatitis.

Alterations in human serum alkaline phosphatase and its isoenzymes by hypolipidemic agents: colestipol and clofibrate

Total serum alkaline phosphatase (TSAP) determinations were done as part of the biochemical screening in comparative studies of lipid lowering agents in type lla hyperlipoproteinemic patients. TSAP determinations were made by using a modification of the Bessey-Lowry method and the Statland method. Increases in TSAP following colestipol treatment of 20% (P less than 0.05) and 32% (P less than 0.005) were seen by using the respective methods. Isoenzymatic determinations were done by employing the Statland method and all fractions were increased from baseline levels during colestipol therapy. Clofibrate was associated with 34% (P less than 0.005) and 28% (P less than 0.005) reductions in TSAP activity by using the respective methods; significant reductions in both "bone" and "other" isoenzymatic components occurred. Gamma-glutamyltransferase (gamma GT) results did not consistently reflect TSAP or "liver" isoenzyme results.

Treatment of the arthropathy of familial hypercholesterolaemia

A 29-year-old woman suffering from the arthropathy of familial hypercholesterolaemia was treated with a fat-modified low-cholesterol diet and colestipol. Symptomatic improvement occurred in association with a moderate reduction in the plasma cholesterol concentration. The pathogenesis of the musculoskeletal features of this disease is reviewed, and the implications of this patient's therapeutic response are explored.

Reduction of serum cholesterol in heterozygous patients with familial hypercholesterolemia. Additive effects of compactin and cholestyramine

We studied the effects of the bile acid sequestrant cholestyramine, alone and in combination with the experimental agent compactin (ML-236B), a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on serum levels of lipoproteins in 10 heterozygous patients with familial hypercholesterolemia. After cholestyramine treatment alone for 2 to 16 months, serum total and low-density lipoprotein cholesterol decreased by 20 and 28 per cent, respectively. With the addition of compactin for 12 weeks there was a 39 per cent total decrease in serum cholesterol from the control value--from 356 +/- 14 to 217 +/- 10 mg per deciliter (9.27 +/- 0.36 to 5.64 +/- 0.26 mmol per liter [mean +/- S.E.M.]; P less than 0.001)--and a 53 per cent decrease in low-density lipoprotein cholesterol--from 263 +/- 13 to 125 +/- 10 mg per deciliter (6.84 +/- 0.34 to 3.25 +/- 0.26 mmol per liter; P less than 0.001). High-density lipoprotein cholesterol, which had increased during cholestyramine treatment, remained at its higher level. No adverse effects were observed. If long-term safety can be demonstrated, the compactin-cholestyramine regimen may prove useful in heterozygous familial hypercholesterolemia. prove useful in heterozygous familial hypercholesterolemia.

Ciprofibrate in the therapy of type II hypercholesterolemia. A double-blind trial

The hypolipidemic efficacy of ciprofibrate was evaluated in patients with type II hypercholesterolemia. Patients were randomized to placebo or ciprofibrate (50 mg or 100 mg/day) and, after a 6-week baseline period, received medication for a period of 12 weeks. Blood samples were analyzed every 2 weeks. Twenty patients completed the study (4 on placebo, 7 on 50 mg/day, and 9 on 100 mg/day ciprofibrate). The drug was well tolerated in all patients. Lipid values in the patients on active drug decreased and attained stable values after 4 weeks of treatment. Compared to baseline values, total and LDL cholesterol decreased 11% and 13% on the 50-mg dose whereas HDL increased 8%. Plasma triglyceride fell by 22%. In patients receiving 100 mg ciprofibrate, total and LDL cholesterol fell by 20% (334 leads to 269 mg/dl) and 24% (262 leads to 198 mg/dl), respectively. HDL increased 9.8% (51 leads to 56 mg/dl) and triglyceride decreased by 30% (102 leads to 69 mg/dl). Values in the placebo group remained stable. We conclude that once daily therapy with 100 mg ciprofibrate, is effective in reducing LDL levels in patients with type II hypercholesterolemia (mainly heterozygous FH) and that this decrease is paralleled by small rises in HDL.

Effects of an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase on serum lipoproteins and ubiquinone-10-levels in patients with familial hypercholesterolemia

We studied the effects of ML-236B, a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, on serum levels of lipoproteins and ubiquinone-10-in seven heterozygous patients with familial hypercholesterolemia. ML-236B was given at doses of 30 to 60 mg per day for 24 weeks. Serum cholesterol decreased from 390 +/- 9 to 303 +/- 8 mg per deciliter (101 +/- 0.2 to 7.88 +/- 0.2 mmol per liter, mean +/- S.E.M.; p less than 0.001) and serum triglyceride decreased from 137 +/- 18 to 87 +/- 9 mg per deciliter (1.55 +/- 0.20 to 0.98 +/- 0.01 mmol per liter; p less than 0.05). Intermediate-density-lipoprotein (DL) cholesterol, IDL triglyceride, low-density-lipoprotein (LDL) cholesterol, and LDL triglyceride decreased significantly (p less than 0.01, P less than 0.001, and P less than 0.001, respectively). However, there were no significant changes in very-low-density-lipoprotein (VLDL) cholesterol and triglyceride or high-density-lipoprotein (HDL) cholesterol. Serum ubiquinone-10 levels did not change, and LDL levels of ubiquinone-10 decreased by 50 per cent, from 0.39 +/- 0.07 to 0.20 +/- 0.01 microgram per milliliter (P less than 0.05). No adverse effects were observed. We conclude that ML-236B is effective in lowering serum cholesterol without lowering serum ubiquinone-10 in heterozygous patients with familial hypercholesterolemia.

Effect of colestipol and clofibrate on plasma lipid and lipoproteins in type IIa hyperlipoproteinemia

The effects of 2.0 g of clofibrate and 15, 20 and 30 g of colestipol on plasma lipid and lipoprotein levels were evaluated in adult patients with Type IIa hyperlipoproteinemia. Clofibrate treatment was associated with decreases in 11.0% in plasma cholesterol. 15.2% in LDL cholesterol, 26.1% in triglycerides, and an 11.3% increase in HDL cholesterol. The reductions in total cholesterol with the various doses of colestipol ranged from 11.9 to 17.8% and reductions in LDL cholesterol ranged from 16.1 to 27.3%. Colestipol treatment was not associated with any significant change in HDL cholesterol levels and minor increases in triglycerides. The addition of clofibrate to patients receiving colestipol resulted in a significant increase in HDL cholesterol and a decrease in triglycerides, but no additional reduction in total or LDL cholesterol.

Effects of colestipol, clofibrate, and placebo on plasma lipoproteins of patients with hypercholesterolemia

To evaluate the effectiveness of colestipol and clofibrate in patients with hypercholesterolemia and normal concentrations of triglycerides, 27 patients were randomized into three groups, and colestipol, clofibrate, and avicel powder placebo were compared for effects on concentration of total plasma lipid and lipoprotein cholesterol and triglyceride in a single blind protocol over 8 mo. Mean pretreatment values for low density lipoprotein (LDL)-cholesterol and very low density lipoprotein (VLDL) triglyceride were 250 mg/dl and 68 mg/dl, respectively. Colestipol (30 g/day) lowered total- and LDL-cholesterol by 25% and 31%k, respectively, while VLDL-triglyceride rose. Overall clofibrate lowered total- and LDL-cholesterol by 13% and 12% while lowering VLDL-triglyceride 21% and VLDL cholesterol by 50%. For clofibrate, certain patients showed a more pronounced effect than others: in seven of nine patients clofibrate lowered both mean total- and LDL-cholesterol by 17% (range 8% to 31%) and 19% (range 10%--44%) respectively, whereas two patients did not respond to clofibrate. High density lipoproteins were not affected by either colestipol or clofibrate in these patients. Thus, while colestipol was more consistently effective, certain hypercholesterolemic patients responded equally well to clofibrate with substantial lowering of total-, LDL-, and VLDL-cholesterol.

Effect of colestipol on sterol metabolism in the rat

Sterol metabolism studies using isotopic and chromatographic techniques were performed on rats fed diets supplemented with colestipol (Upjohn). Compared to controls, colestipol altered sterol metabolism dramatically. Bile acid output increased from 7.0 mg/day to 12.2 mg/day (0.42% colestipol) and 39.6 mg/day (1.67% colestipol). Daily fecal neutral sterol output and daily endogenous neutral sterol output increased 36% and 55%, respectively, on the 1.67% colestipol diet. Cholesterol absorption was reduced by colestipol feeding. Cholesterol balance increased dramatically with 1.67% colestipol administration (43.5 mg/day vs -1.0 mg/day in controls). Colestipol exerts its effect by binding bile acids and by bile acid depletion interfering with cholesterol absorption.

Colestipol: a review of its pharmacological properties and therapeutic efficacy in patients with hypercholesterolaemia

Colestipol is an anion exchange resin with bile acid sequestering properties resembling those of cholestyramine, another lipid-lowering binding resin. In daily doses of 15 to 30g colestipol reduces total plasma cholesterol concentrations (primarily low density lipoprotein cholesterol) by about 15 to 30%, but plasma triglyceride concentrations may be unchanged or in some patients increased. Thus, like cholestyramine, colestipol is of benefit in patients with primary hypercholesterolaemia without associated hypertriglyceridaemia (type IIa hyperlipoproteinaemia). Colestipol is odourless and tasteless, and is said by some to be more readily tolerated by patients than cholestyramine, leading to improved compliance, but such data has not been documented in most studies. Side effects of colestipol treatment are primarily gastrointestinal in nature since the drug is essentially unabsorbed. As with cholestyramine, colestipol may bind with other concomitantly administered drugs reducing their absorption or enterohepatic recirculation; dosage intervals of other concurrent medications should be adjusted to minimise the potential for such an interaction.

Long-term trial with colestipol plus clofibrate in familial hypercholesterolemia

Twenty subjects with familial hypercholesterolemia (12 Type IIa and 8 Type IIb), previously treated with Colestipol for 16 months, were subjected to therapy with Colestipol (15 g/day) + clofibrate (2 g/day) for 15 months. During the second treatment period these patients continued to follow the isocaloric hypocholesterolemic diet initiated during the original trial. In Type IIa patients, the association of these drugs enhanced the decrease in plasma cholesterol levels. The total mean decrease was -40 +/- 17 mg/dl (P less than 0.05). In Type IIb patients, on the other hand, the association of clofibrate with Colestipol induced an increase in plasma cholesterol levels. The total mean increase was +24 +/- 7 mg/dl (P less than 0.05). A markedly significant decrease in plasma triglyceride levels was observed in this group (- 107 +/- 30; P less than 0.01). These results seem to indicate that, in Type IIa, clofibrate increased the resin's hypocholesterolemic effect. In Type IIb, on the other hand, the association of these drugs did not seem to be indicated since a marked hypotriglyceridemic effect was accompanied by an increase in plasma cholesterol levels. These results are briefly discussed in the light of recent data obtained on the effects of Colestipol and clofibrate on lipoprotein metabolism.

Cholestyramine and ileal by-pass in the treatment of familial hypercholesterolaemia

A comparison was made of the therapeutic effectiveness of cholestyramine and an ileal by-pass operation as hypocholesterolaemic measures in thirteen patients with familial xanthomatotic type II hypercholesterolaemia. Serum cholesterol and faecal steroids were measured before and at the end of a 10 day course of cholestyramine (32 g/day), and subsequently after an ileal by-pass operation. The mean decrease in serum cholesterol caused by cholestyramine (-17%) was significantly less than that caused by the surgical procedure (-33%). The increase in faecal steroid excretion, mainly as bile acids, was lower with cholestyramine (1.261 g/day) than after the ileal exclusion (2.176 g/day) and a positive correlation was found between the decrease in serum cholesterol and the increase in the faecal elimination of steroids of cholesterol origin. However, even though the increase in faecal steroids with cholestyramine was positively correlated with that resulting from ileal by-pass, the correlation between the corresponding changes in serum cholesterol level was not significant. The findings indicate that ileal by-pass decreases serum cholesterol and increases faecal elimination of cholesterol more effectively than cholestyramine, and that the decrease in the serum cholesterol level induced by ileal exclusion is not consistently predictable by the serum cholesterol response to the preceding cholestyramine treatment.

Effects of colestipol hydrochloride and neomycin sulfate on cholesterol turnover in the rat

Three groups of male rats were fed diets containing the bile acid sequestrant colestipol hydrochloride (1%), neomycin sulfate (0.25%), or basic diet during the test. After 15 days, each rat was injected IV with 3.9 muCi cholesterol-1,2(-3)H complexed with serum lipoproteins; specific radioactivity of the total serum cholesterol was measured at several time intervals for a period of 7 weeks. Computer analysis of the data indicated that the turnover of cholesterol could best be fitted by a three-pool model. In pool 1, colestipol HC1 caused a significant increase in production rate (10.09 to 15.96 mg/day) and the excretion rate constant (0.53 to 0.79 day-1) of cholesterol without significantly altering the size of the pool or serum cholesterol concentrations. These results are compatible with an agent capable of binding bile acids in the rat but do not cause a decrease of the sterol pool because of an adequate compensatory increase in cholesterol biosynthesis. Neomycin SO4 caused a significant reduction in serum cholesterol (9%) without altering turnover parameters and apparently exerts its hypocholesterolemia by some mechanism other than bile acid sequestration.

Treatment of hypercholesterolemia with Secholex. A long-term clinical trial and comparison with cholestyramine

The efficacy of an anion-exchange gel, Secholex, as a hypocholesterolemic agent was assessed in 46 patients in 4 different studies and the effects were compared with those of cholestyramine. All patients had severe Type II-a or II-b hyperlipoproteinemia. In short-term metabolic studies Secholex (15 g/day) and cholestyramine (16 g/day) decreased serum cholesterol levels and increased total fecal sterol output and serum methyl sterol concentration to a similar extent, but cholestyramine was more effective than Secholex in increasing fecal bile acid excretion. In crossover studies, the two drugs appeared to be equally effective in lowing serum cholesterol levels but the patients mostly preferred Secholex. Twenty patients were treated with Secholex over a two-year period. The average decrease in serum cholesterol levels from the mean pretreatment value of 406 mg/100 ml was 15% during the first year, and 13% during the second year. In 5 patients the serum cholesterol was permanently lowered by more than 20% (good responders), while in 7 patients the average reduction of serum cholesterol level during Secholex administration was less than 10% (non-responders). The serum triglyceride level was slightly decreased by Secholex in Type II-b patients but was unaltered in Type II-a patients. At the end of the treatment period, serum iron and vitamin B12 levels were normal but the serum folic acid concentration was reduced in eight of 20 patients. A dose--response study indicated that a similar cholesterol-lowering effect was obtained with daily doses of 9 and 15 g of Secholex. It is concluded that Secholex is a relatively safe drug which effectively reduces serum cholesterol levels in two-thirds of patients with severe hypercholesterolemia.

Results of colestipol therapy in Type II hyperlipoproteinemia

Twenty-five patinets with well defined Type ii hyperlipoproteinemia were treated with a divided 15 g daily dose of colestipol, a bile acid sequestrant, for periods of up to 20 months. The patients were divided into 3 groups: Those with no obvious sequelae, those with arcus corneae, xanthomas, and/or xanthelasmas only, and those with atherosclerotic complications. Colestipol lowered plasma cholesterol in all 3 groups, but reduced it to normal or near-normal levels in only 9 of the 25 patients (36%). The response of plasma triglycerides was highly varible; the mean for each group was elevated by the drug. Colestipol was well-tolerated and its effect did not diminish with time. It is a useful drug in the treatment of hypercholesterolemia.

Clofibrate-induced low density liporotein elevation. Therapeutic implications and treatment by colestipol resin

Plasma lipid and lipoprotein responses to clofibrate were assessed in fifteen hypertriglyceridemic patients for the purpose of ascertaining low-density lipoprotein (LDL) changes. Subjects were grouped into either Type IV (11) or IIB (4) subgroups according to initial LDL level. Clofibrate was without effect on LDL in the IIB group, but consistent, often large, elevations were noted in Type IV cases (mean increase, 37.6%, P less than 0.001). In the IIB subgroup, addition of the bile-acid sequestrant, colestipol, lowered LDL (27.8%, P less 0.02) and total cholesterol (21.3%, P less 0.01) below pre-treatment values. In the Type IV subgroup, LDL fell to 19.5% above baseline (P great than 0.05). Significant LDL elevations induced by clofibrate in three of six subjects were restored to initial levels. In both groups, triglycerides and very-low density lipoproteins (VLDL) were not affected. The efficacy of colestipol in reducing LDL levels, expressed as either absolute or percentage reductions, increased as a function of increasing post-clofibrate LDL concentration (r = 0.84, P less than 0.001). In these subjects the level of LDL after treatment with clofibrate depended upon their LDL level prior to drug therapy, the effect of clofibrate on this level, and lipoprotein phenotype. Thus colestipol was most effective in IIB subjects, Type IV subjects with the lowest baseline VLDL and hence reciprocally highest LDL, and Type IV individuals who exhibited the largest LDL induction by clofibrate. The reported ineffectiveness of clofibrate on mortality and morbidity in patients with established coronary heart disease might be related to elevations and infrequent reductions of LDL. From the perspective of lipoprotein lowering, the combination with colestipol appears more favorable.

Long-term effects of colestipol (U-26,597 A) on plasma lipids in familial type II hyperbetalipoproteinaemia

Results related to long term treatment with Colestipol (a new resin sequestering bile acids) in 23 subjects with familial hypercholesterolaemia, 12 with Type IIA, 8 with Type IIB and 3 homozygotes are reported. Patients were given 15 g/day active drug for a period of 12 months and a double dose (30 g/day) for a successive period of 4 months along with a low cholesterol, low saturated fat, polyunsaturated fat-rich diet. Mean cholesterol decrease was --42 +/- 18 mg/dl (P less than 0.05) after 12 months of 15 g/day Colestipol and --69 +/- 17 mg/dl (P less than 0.01) after the following 4 months of 30 g/day Colestipol. The difference between the two periods of treatment (15 g and 30 g/day was not statistically significant. A slight but not significant increase in triglyceride levels was observed. Serum uric acid showed a significant increase throughout the entire period of treatment. No malabsorption syndrome or signs of toxicity were seen. Most frequent side effects were constipation, nausea, and metheorism which, with the exception of 4 cases which were withdrawn from the study, were reported as being transitory and mild.

The effects of colestipol resin and of colestipol plus clofibrate on the turnover of plasma cholesterol in man

Studies were conducted to determine the effects of colestipol hydrochloride, a new bile acid-sequestrant resin, on some of the parameters of cholesterol turnover and metabolism in man. Three normal volunteers and eight hyperlipidemic patients participated in three sets of cholesterol turnover studies carried out at intervals of approximately 1 yr. The effects of colestipol were assessed by comparing the results obtained before therapy with those obtained on repeat study after several months of resin therapy. Colestipol treatment significantly reduced the serum cholesterol concentration (mean reduction 21%), and produced a large increase in the production rate of cholesterol (mean 86%) and in the turnover rate of cholesterol in pool 1 (mean 46%). The values of the intercompartmental rate constants and of the size of the rapidly exchangeable pool were unchanged with therapy. The turnover studies were carried out for 12-13 wk, and were analyzed according to a two-pool model. Although long-term studies of cholesterol turnover conform to a three-pool, rather than a two-pool model, the present studies probably provide a valid estimate of the effects of therapy on certain parameters, namely the production rate, the size, and the turnover rate of pool 1. Repeated studies in four untreated subjects showed a striking constancy with time for the kinetic parameters for each subject. The production rate was particularly constant from year to year for a given subject, and showed a pooled standard deviation of only 3%. The findings suggest that the total body turnover of cholesterol is under close homeostatic control in an integrated manner. Combined drug therapy with colestipol plus clofibrate further reduced the serum cholesterol level in three of four patients, and reduced the triglyceride level in all four patients. Addition of clofibrate to the treatment program produced only small decreases in the production rate, which were not significantly different from the small decreases seen in two patients who were continued (and restudied) on colestipol alone. The findings do not support the suggestion that clofibrate can block the increased rate of cholesterol synthesis and turnover resulting from bile acid-sequestrant treatment. The effects on serum lipids, however, make the combined drug therapy potentially quite useful.