In addition to cholesterol synthesis in the liver, involving acetyl-CoA via HMG-Reductase pathway (site of action of statins), intestinal cholesterol absorption also adds to the plasma cholesterol levels.

Ezetrol is a newer agent that inhibits selective cholesterol absorption from the intestine without affecting the absorption of fat-soluble vitamins, triglycerides or bile acids. Its action is complementary to the statins and lowers LDL-Cholesterol, lowers triglycerides and raises HDL-Cholesterol. Thus it lowers lipid levels.
Ezetimibe inhibits the intestinal absorption of cholesterol. It is licensed as adjunctive therapy to dietary manipulation in patients with hypercholesterolaemia in combination with a statin or alone (if a statin is inappropriate), in patients with homozygous familial hypercholesterolaemia in combination with a statin, and in patients with homozygous familial sitosterolaemia (phytosterolaemia)

Niaspan is used along with diet and exercise and increases HDL cholesterol while also lowering LDL ("bad") cholesterol. Taken once a day at bedtime, Niaspan has been proven (average effect depends on dose) to:

Increase HDL ("good") cholesterol by ten percent to 26%
Reduce LDL ("bad") cholesterol by three percent to 17%
Reduce triglycerides (TG) by five percent to 35%
The most common side effect is flushing which is usually mild; taking aspirin half an hour beforehand can reduce it. Tachyphylaxis usually develops and the flushing is seen at the time of initiation or on dose increments. Other side effects are gastro intestinal and are mild and well tolerated.
These drugs should be used as add-on therapy and under expert supervision. Currently there are no existing guidelines from NICE to the use of these agents.

Manufacturers have set-up a free phone helpline to patients to advise. Patients when started on Niaspan can be registered with the helpline using free post registration cards.