The Effect of Colestipol on Glycemic Control in Patients with Type 2 Diabetes
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The Effect of Colestipol on Glycemic Control in Patients With Type 2 Diabetes Elizabeth A. Sauter, PharmD; Sindhu Abraham, PharmD, BCPS; Tania G. John, PharmD; Seema Kapadia, PharmD, BCACP; and Judith A. Toth, PharmD, CGP, CDE Using an electronic chart review, the authors investigated the effect of colestipol, a bile acid sequestrant, on glycemic control in patients with type 2 diabetes. iabetes mellitus is a complex cations. In general, every percentage group and the placebo group of disease, characterized by hy- point drop in glycosylated hemoglo- − 0.5% (P = .007). Additionally, in perglycemia, and can be as- bin (A1C) can reduce the risk of mi- participants with a baseline A1C ≥ sociated with abnormalities crovascular complications (ie, eye, 8%, the difference in mean change in D 2 in fat, carbohydrates, and protein kidney, and nerve diseases) by 40%. A1C was − 1.0% (P = .002). Treat- metabolism that result from defects Improved control of LDL-C can re- ment with colesevelam was also in insulin secretion, insulin action, duce cardiovascular complications by associated with a reduction in post- or both. Type 2 diabetes is the most 20% to 50%.2 Current American Dia- prandial glucose (− 31.5 mg/dL, common form of diabetes in the betes Association (ADA) guidelines P = .026) and LDL-C (− 11.7%, United States, accounting for as many recommend an A1C of < 7% and an P = .007). The study authors con- as 90% to 95% of all cases.1 As of LDL-C < 100 mg/dL in patients with cluded that colesevelam may improve 2011, 25.8 million patients were di- diabetes.4 However, to achieve these both glycemic and lipid control in agnosed with diabetes, or 8.3% of the goals, patients with diabetes often patients with type 2 diabetes.5 Fol- U.S. population.2 Type 2 diabetes is need to use multiple medications.1,2 lowing the publication of this trial, more common in African Americans, As a result, recent attention has colesevelam received an FDA indica- Mexican Americans, Native Ameri- shifted to the use of single agents tion as an adjunctive treatment in pa- cans, Asian Americans, Native Ha- with both glucose and lipid-lowering tients with type 2 diabetes, in addition waiians, and other Pacific Islanders, effects. One such class of agents is the to its prior indication for hypercholes- as well as the elderly population.1,3 bile acid sequestrants. To date, both terolemia. Type 2 diabetes is characterized by colesevelam hydrochloride and cho- Another similar trial evaluated the insulin resistance and a relative lack lestyramine have demonstrated A1C use of cholestyramine for dyslipid- of insulin secretion. Insulin is neces- and glucose-lowering effects in clini- emia in patients with type 2 diabetes. sary for the breakdown of sugars and cal trials. The study researchers also examined carbohydrates in the body and plays The Glucose Lowering Effect the effect of cholestyramine on glu- a vital role in the uptake of glucose of Welchol Study (GLOWS) evalu- cose levels as a secondary endpoint. into cells for energy.1 ated the A1C lowering effect of co- This study was a randomized, dou- Uncontrolled diabetes is associ- lesevelam hydrochloride in subjects ble-blind, crossover study of 21 par- ated with numerous complications, with type 2 diabetes who were inad- ticipants receiving cholestyramine including blindness, kidney damage, equately controlled by oral antihyper- 8 g bid vs a placebo for 6 weeks heart disease, and lower-limb am- glycemic agents alone. Participants each. Study participants had type 2 putations. In patients with diabetes, were on a stable dose of metformin diabetes that was well controlled for optimal control of glucose and low- or a sulfonylurea for ≥ 90 days before at least 1 month prior to the initia- density lipoprotein cholesterol (LDL- the initiation of colesevelam. Sixty- tion of cholestyramine, using either C) has been shown to delay or even five study participants who had an insulin or glyburide therapy, and an prevent the development of compli- A1C of 7% to 10% were random- LDL-C of > 130 mg/dL. Addition- ized to receive either colesevelam ally, patients were on a stable dose of 3.75 g/d or placebo for 12 weeks. insulin or glyburide throughout the Dr. Sauter, Dr. Abraham, Dr. John, Dr. Kapadia, After 12 weeks, results demon- duration of the study. After 12 weeks, and Dr. Toth are all clinical pharmacy specialists in the Department of Pharmacy with the Jesse strated a difference in mean change results demonstrated that treatment Brown VA Medical Center in Chicago, Illinois. in A1C between the colesevelam with cholestyramine reduced total MAY 2012 • FEDERAL PRACTITIONER • 23 GLYCEMIC CONTROL Table 1. Data collected using the electronic chart Demographic Age information Gender Race Baseline information A1C (within the 6 months Lipids (LDL-C, TGs, HDL-C) prior to initiation of LFTs (within normal limits [WNL] vs elevated) colestipol) After initiation of A1C (at least 3 months after starting colestipol) colestipol Lipids (LDL-C, TGs, HDL-C) (at least 4 weeks after starting colestipol) LFTs (WNL vs elevated) Any subsequent values for the above parameters following dose titration of colestipol for up to 6 months Adverse effects Medication intolerance as documented in the progress notes Medication Colestipol information • Initial dose • Maximum tolerated dose • Date of initiation • Date of discontinuation (if applicable) Concomitant oral antihyperglycemic medications (including sulfonylureas, biguanides, insulin, thiazolidinediones, α-glucosidase inhibitors, meglitinides, dipeptidyl pepti- dase-4 inhibitors, glucagon-like peptide-1 agonists, and dopamine agonists) • Dose when colestipol was started • Dosage changes since colestipol was started • Date of initiation • Date of discontinuation (if applicable) Concomitant lipid-lowering medications (including HMG-CoA reductase inhibitors, nicotinic acid, intestinal absorption inhibitors, fish oil, and fibric acid derivatives) • Dose when colestipol was started • Dosage changes since colestipol was started • Date of initiation • Date of discontinuation (if applicable) Medication Determined by the refill history in the electronic medical record and documentation compliance of nonadherence in the progress notes Patient education Counseling regarding the proper administration of colestipol in relation to other medications to minimize any possible interference with absorption (take other medications at least 1 hour before or 4 hours after colestipol) as documented in the progress notes or stated on the medication label cholesterol by 18% and LDL-C by that cholestyramine therapy effec- monotherapy, which does not com- 28%, when compared with placebo. tively reduced LDL-C and may also ply with the current clinical approach In addition, cholestyramine therapy improve glycemic control in patients in the United States of using bile acid improved glycemic control. Mean with diabetes.6 sequestrants as adjunctive therapy in plasma glucose levels decreased by It is important to note that there patients with diabetes. In other coun- 13%; a mean reduction in urinary glu- is 1 additional agent in this class of tries, colestilan has been proven effec- cose excretion of 0.22 g/d was noted, medications: Colestilan. However, this tive in reducing both A1C and fasting as well as a decrease in A1C values of agent is not approved in the United plasma glucose in patients with type 2 0.5%. The study authors concluded States and has been evaluated only as diabetes.7 Continued on page 27 24 • FEDERAL PRACTITIONER • MAY 2012 GLYCEMIC CONTROL Continued from page 24 Patient charts reviewed (239) Excluded Included (189) (50) Non- < 3 months No type 2 Antihyperglycemic No A1C adherence therapy diabetes changes (42) (8) (13) (30) (96) Figure 1. Study design. In general, bile acid sequestrants tory action increases LDL-C clearance demonstrated beneficial effects on act by binding bile acids, forming a from the blood, resulting in lowered both LDL-C and A1C in patients with complex that is then excreted in the LDL-C levels.8,9 type 2 diabetes, the specific effect of feces, thus preventing reabsorption The mechanism by which bile acid colestipol on glycemic control has yet in the intestines. This action also re- sequestrants exert their glycemic ef- to be evaluated. Currently, colestipol sults in partial removal of bile acids fects is not fully understood. One is FDA approved for the treatment of from the enterohepatic circulation, proposed mechanism is that bile acid primary hypercholesterolemia, and which prevents its reabsorption. This sequestrants cause a reduction in glu- it is the bile acid sequestrant that is leads to the depletion of serum bile cose absorption or a change in the currently on the formulary at Jesse acids, which activates cholesterol time course of glucose absorption in Brown VAMC. 7 alpha-hydroxylase to convert cho- the gastrointestinal tract. Another the- lesterol into bile acids. Consequently, ory is that by interrupting the entero- METHODS a demand for cholesterol in the liver hepatic pathway of bile metabolism, The purpose of this study was to is increased, resulting in increased bile acid sequestrants deactivate the evaluate the effect of colestipol on 3-hydroxy-3-methyl-glutaryl-CoA farnesoid X receptor. This receptor is glycemic control in patients with (HMG-CoA) reductase transcription a bile acid-activated nuclear receptor type 2 diabetes in a veteran popula- and activity, and an increased num- that plays a significant role in the me- tion. This study was an Institutional ber of LDL-C receptors.