CHOLESTAGEL Film-coated tablet Ref.[7188] Active ingredients: Colesevelam

Pharmacotherapeutic group: Lipid modifying agent, bile acid sequestrants
ATC code: C10AC04

Mechanism of action

The mechanism of action for the activity of colesevelam, the active substance in Cholestagel, has been evaluated in several in vitro and in vivo studies. These studies have demonstrated that colesevelam binds bile acids, including glycocholic acid, the major bile acid in humans. Cholesterol is the sole precursor of bile acids. During normal digestion, bile acids are secreted into the intestine. A major portion of bile acids is then absorbed from the intestinal tract and returned to the liver via the enterohepatic circulation.

Colesevelam is a non-absorbed, lipid-lowering polymer that binds bile acids in the intestine, impeding their reabsorption. The LDL-C lowering mechanism of bile acid sequestrants has been previously established as follows: As the bile acid pool becomes depleted, the hepatic enzyme, cholesterol 7-α-hydroxylase, is upregulated, which increases the conversion of cholesterol to bile acids. This causes an increased demand for cholesterol in the liver cells, resulting in the dual effects of increasing transcription and activity of the cholesterol biosynthetic enzyme, hydroxymethyl-glutaryl-coenzyme A (HMG-CoA) reductase, and increasing the number of hepatic low-density lipoprotein receptors. A concomitant increase in very low density lipoprotein synthesis can occur. These compensatory effects result in increased clearance of LDL-C from the blood, resulting in decreased serum LDL-C levels.

In a 6-month dose-response study in patients with primary hypercholesterolaemia receiving 3.8 or 4.5 g Cholestagel daily, a 15 to 18% decrease in LDL-C levels was observed, which was evident within 2 weeks of administration. In addition, Total-C decreased 7 to 10%, HDL-C increased 3% and triglycerides increased 9 to 10%. Apo B decreased by 12%. In comparison, in patients given placebo, LDL-C, Total-C, HDL-C and Apo-B were unchanged, while triglycerides increased 5%. Studies examining administration of Cholestagel as a single dose with breakfast, a single dose with dinner, or as divided doses with breakfast and dinner did not show significant differences in LDL-C reduction for different dosing schedules. However, in one study triglycerides tended to increase more when Cholestagel was given as a single dose with breakfast.

In a 6 week study 129 patients with mixed hyperlipidaemia were randomised to fenofibrate 160 mg plus 3.8 g Cholestagel or fenofibrate alone. The fenofibrate plus Cholestagel group (64 patients) demonstrated a 10% reduction on LDL-C levels versus 2% increase for the fenofibrate group (65 patients). Reductions were also seen for non-HDL-C, Total-C and Apo B. A small 5%, non-significant increase in triglycerides was noted. The effects of combination of fenofibrate and Cholestagel on the risks of myopathy or hepatotoxicity are not known.

Multi-centre, randomised, double-blind, placebo-controlled studies in 487 patients demonstrated an additive reduction of 8 to 16% in LDL-C when 2.3 to 3.8 g Cholestagel and a statin (atorvastatin, lovastatin or simvastatin) were administered at the same time.

The effect of 3.8 g Cholestagel plus 10 mg ezetimibe versus 10 mg ezetimibe alone on LDL-C levels was assessed in a multicentre, randomised, double-blind, placebo-controlled, parallel-group study in 86 patients with primary hypercholesterolaemia over a 6-week treatment period. The combination of ezetimibe 10 mg and Cholestagel 3.8 g daily therapy in the absence of a statin resulted in a significant combined effect for LDL-C lowering by 32% demonstrating an additional effect of 11% LDL-C lowering with Cholestagel and ezetimibe compared to ezetimibe alone.

The addition of Cholestagel 3.8 g daily to maximally-tolerated statin and ezetimibe therapy was assessed in a multi-centre, randomised, double-blind, placebo-controlled study in 86 patients with familial hypercholesterolaemia. A total of 85% of the patients were on either atorvastatin (50% of whom received 80 mg dose) or rosuvastatin (72% of whom received 40 mg dose). Cholestagel resulted in a statistically significant LDL-C reduction of 11% and 11% at 6 and 12 weeks vs an increase of 7% and 1% in the placebo group; mean baseline levels were 3.75 mmol/L and 3.86 mmol/L, respectively. Triglycerides in the Cholestagel group increased by 19% and 13% at 6 and 12 weeks vs an increase of 6% and 13% in the placebo group, but the increases were not significantly different. HDL-C and hsCRP levels were also not significantly different compared to placebo at 12 weeks.

Paediatric population

In the paediatric population, the safety and efficacy of 1.9 or 3.8 g/day Cholestagel was assessed in an 8 week multi-centre, randomised, double-blind, placebo-controlled study in 194 boys and postmenarchal girls, aged 10-17 years, with heterozygous FH on a stable dose of statins (47 patients, 24%) or treatment-naïve to lipid-lowering therapy (147 patients, 76%). For all patients, Cholestagel resulted in a statistically significant LDL-C reduction of 11% at 3.8 g/day and 4% at 1.9 g/day, versus a 3% increase in the placebo group. For statin-naïve patients on monotherapy, Cholestagel resulted in a statistically significant LDL-C reduction of 12% at 3.8 g/day and 7% at 1.9 g/day, versus a 1% reduction in the placebo group (see section 4.2). There were no significant effects on growth, sexual maturation, fat-soluble vitamin levels or clotting factors, and the adverse reaction profile for Cholestagel was comparable to that seen with placebo.

Cholestagel has not been compared directly to other bile acid sequestrants in clinical trials.

So far, no studies have been conducted that directly demonstrate whether treatment with Cholestagel as monotherapy or combination therapy has any effect on cardiovascular morbidity or mortality.