Colestipol hydrochloride, a new hypolipidemic drug: a two-year study

Association of bowel movement frequency and use of laxatives with the occurrence of symptomatic gallstone disease in a prospective study of women

OBJECTIVES

The authors prospectively examined the association between bowel movement frequency (used as a proxy for intestinal transit), laxative use, and the risk of symptomatic gallstone disease.

METHODS

A total of 79,829 women, aged 36-61 yr, without a history of symptomatic gallstone disease and free of cancer, responded to a mailed questionnaire in 1982 that assessed bowel movement frequency and use of laxatives. Between 1984 and 1996, 4,443 incident cases of symptomatic gallstone disease were documented. Relative risks (RRs) of symptomatic gallstone disease and 95% confidence intervals (CIs) were calculated using logistic regression.

RESULTS

After controlling for age and established risk factors, the multivariate RRs were, compared to women with daily bowel movements, 0.97 (95% CI 0.86-1.08) for women with bowel movements every third day or less, and 1.00 (95% CI 0.91-11.1) for women with bowel movement more than once daily. No trend was evident. As compared to women who never used laxatives in 1982, a significant modest inverse association was seen for monthly laxative use, with a multivariate RR of 0.84 (95% CI 0.72-0.98), and weekly to daily laxative use was associated with a RR of 0.88 (95% CI 0.78-1.02).

CONCLUSIONS

These findings do not support an association between infrequent bowel movements and risk of symptomatic gallstone disease in women, and indicate that simple questions directed at bowel movement frequency are unlikely to enhance our ability to predict risk of symptomatic gallstone disease. The slightly inverse association between use of laxatives and risk of symptomatic gallstone disease may be due to a mechanism that is not related to bowel movement frequency.

Aminated polysaccharides as bile acid sorbents: in vitro study

Dextran, pullulan, and microcrystalline cellulose were cross-linked with 1-chloro-2,3-epoxypropane and reacted with N-(1-chloroethyl)-N,N-diethylamine or N-glycidyl-N,N,N-trialkylammonium chloride in order to obtain sorbents containing tertiary amino and/or quaternary ammonium groups. In vitro equilibrium sorption of cholic acid on these sorbents was studied in comparison with Cholestyramine, and in vitro dissociation of ionic complexes of cholic acid-sorbents was determined under dynamic conditions. The sorption capacity and the affinity of these sorbents for cholic acid were investigated in relation to the nature of the polymeric support, the swelling porosity of sorbent, the basicity of amino groups, and the nature of the substituents at the nitrogen atom. The maximum sorption capacity increases with the increase in amino group content, their basicity, and the length of alkyl substituents at the nitrogen atom. The affinity for cholic acid of all polysaccharide-based sorbents is higher than that of Cholestyramine. Dextran-based sorbents display the highest sorption affinity. It was found that there exists an optimum swelling porosity for the polysaccharide sorbents to attain the highest affinity for cholic acid. The dissociation rate of ionic complexes depends also on the nature of the polysaccharide and the swelling porosity and its lower for sorbents with higher sorption affinity.

Discontinuation of antihyperlipidemic drugs--do rates reported in clinical trials reflect rates in primary care settings?

BACKGROUND

Discontinuation rates for drugs used to treat chronic conditions may affect the success of therapy. However, the discontinuation rates reported in clinical trials may not reflect those in primary care settings.

METHODS

We conducted a cohort study using computerized research files and medical records on 2369 new users of antihyperlipidemic therapy at two health maintenance organizations (HMOs) from 1988 through 1990. The rates of drug discontinuation in these primary care settings were compared with the rates reported in clinical trials published from 1975 through 1993, located with the Medline data base.

RESULTS

In the HMOs, the one-year probability of drug discontinuation was 41 percent for bile acid sequestrants (95 percent confidence interval, 38 to 44 percent), 46 percent for niacin (95 percent confidence interval, 42 to 51 percent), 15 percent for lovastatin (95 percent confidence interval, 11 to 19 percent), and 37 percent for gemfibrozil (95 percent confidence interval, 31 to 43 percent). For the bile acid sequestrants, niacin, and gemfibrozil, the risks of discontinuation were substantially higher in the HMOs than in randomized clinical trials, in which the summary estimates of this risk were 31 percent, 4 percent, and 15 percent, respectively, for trials of one year or longer. The rates of discontinuation in open-label studies were similar to those in the HMOs.

CONCLUSIONS

The discontinuation rates reported in randomized clinical trials may not reflect the rates actually observed in primary care settings. The effectiveness and tolerability of antihyperlipidemic medications should be studied further in populations that typically use the agents.

Polymeric sorbents for bile acids. I: Comparison between cholestyramine and colestipol

Isotherms for the sorption of bile acids at 20 degrees C, in tris(hydroxymethyl)aminomethane.HCl(tris) and KH2PO4-NaOH (phosphate) buffers (pH 7.4), indicate that the binding by cholestyramine and colestipol is mainly through ionic linkages, although hydrophobic interactions are also of importance. Cholestyramine has a higher sorption capacity for bile acids, in both buffers, than colestipol. The chloride form of cholestyramine has a higher capacity for cholate in tris buffer than the iodide form. Increased ionic strength of the medium leads to decreased amounts of sorption.

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.

The bile acid binding and hypocholesterolemic action of two water-soluble polymers

The in vitro bile acid binding properties of 2 water-soluble, linear, cationic resins, poly-[(dimethylimino)trimethylene chloride] or 3,3-ione C1, and poly-diallyldimethylammonium chloride) or CAT-FLOC were determined. Both polymers were substantially more active than cholestyramine. All were compared for hypocholesterolemic effect in normo-cholesterolemic dogs. CAT-FLOC and 3,3-ionene C1, administered at 1.8 and 1.2 g/day, respectively, exhibited cholesterol-lowering action equivalent to cholesteryramine given at 12 g/day. The results of this study suggest that effective reduction of plasma cholesterol may be achieved with significantly lower doses of bile acid sequestrants.

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.

Use of combined diet and colestipol in long-term (7--7 1/2 years) treatment of patients with type II hyperlipoproteinemia

Long-term effects of diet and colestipol (a bile acid sequestrant) were studied in 25 patients with familial type II hyperlipoproteinemia. Serum lipids and body weights of an initial group of 30 patients were stabilized by low cholesterol-saturated fat-refined carbohydrate diet and the patients were then randomized into placebo and drug-treatment groups. After explaining that the drug is nontoxic and effective in lowering serum lipids, total cholesterol (C) and low-density lipoprotein cholesterol (LDL-C), colestipol (30 g/day) and diet were given to the 25 patients who remained in the long-term follow-up program. The treatment resulted in highly significant lowering of serum lipids (mg/dl, mean +/- SEM): C and LDL-C from 412.7 +/- 24.4 and 331.1 +/- 22.8 to 270 +/- 11.0 and 188.1 +/- 13.8, respectively (p less than 0.001 in each instance) over 7--7 1/2 years. Although we observed no absolute increase in high density lipoprotein (HDL), the HDL/LDL ratio was elevated. Long-term colestipol and diet treatment reduced the xanthoma size and stabilized serially angiographically visualized atherosclerotic lesions in 21 of the 25 patients who showed a satisfactory hypolipemic response. It did not cause nutritional or metabolic disturbances.

Colestipol hydrochloride for treatment of hypercholesterolemia in a family practice: five-year study

Colestipol hydrochloride (Colestid) lowered the serum cholesterol level significantly more than did placebo in hypercholesterolemic patients (21 colestipol, 19 placebo) treated for up to 5 years. In the 21 colestipol-treated patients, the average decrease in serum cholesterol levels was 19 percent during the first year and 23 percent during the second through fifth years. Seven patients (age range, 44 to 59 years) took colestipol for the full 5 years. The data showed a consistent lowering of the serum cholesterol level. The only side effect was constipation.

Cholesterol-lowering effect of colestipol hydrochloride given twice daily in hypercholesterolemic patients

In a randomized design study in 66 hypercholesterolemic patients, dosages of 10 g of colestipol HCl twice daily lowered serum cholesterol an average of 19% more than placebo therapy. These results are comparable to those in other studies in which the same total daily dose was given in three or four doses. The most common side effect was constipation, reported by 6 patients on colestipol HCl and 3 patients on placebo. No untoward systemic reactions or abnormal laboratory data were seen except for a slight rise in serum alkaline phosphatase during colestipol HCl therapy. The drug was well accepted by most patients.