Cholesterol in the blood
When the levels of cholesterol in the blood are too high (6.5 mmol l-1 or higher), the condition is called hypercholesterolaemia. Doctors use cholesterol-lowering drugs to treat hypercholesterolaemia when dietary modification has failed to bring the patient's level back down to normal.Because cholesterol (like all other lipids) is insoluble in water, it is carried in the blood bound to a protein structure, forming molecules called lipoproteins. The two types of lipoprotein that are particularly important in atherosclerosis and CHD are low density lipoproteins (LDL) and high density lipoproteins (HDL). LDL transports cholesterol from the liver (where cholesterol is synthesised) to peripheral tissues of the body, whereas HDL removes excess cholesterol from peripheral tissues, taking it back to the liver to be broken down. Epidemiological studies have associated higher levels of LDL-cholesterol and lower levels of HDL-cholesterol in the blood with increased risk of CHD, which is why LDL-cholesterol is also known as 'bad' cholesterol.The current armoury of cholesterol-lowering drugs include statins, nicotinic acid (niacin) derivatives, bile acid sequestrants (resins) and fibrates. Statins, niacin derivatives and resins are more effective in lowering LDL cholesterol than fibrates, but fibrates increase HDL cholesterol to a greater extent than the others. Statins, being the most recently developed of these drugs, present the greatest market opportunity in the industry and represent an important step forward in managing high blood cholesterol levels. They have recently been at the forefront of debate in the medical field, due to emerging evidence from studies which suggests that they do improve survival rates. This evidence has spurred their sales to among the fastest growing drugs in the world.
The first statin to be introduced in the UK was Zocor (simvastatin), which was launched in May 1989 by Merck Sharp and Dohme (MSD). This was followed by Lipostat (pravastatin, or pravachol in the US) in September 1990 from BMS. In January 1994, Sandoz launched Lescol (fluvastatin), which is the first totally synthetic HMG-CoA reductase inhibitor. Lovastatin (Mevacor), is also a Merck product, but it is not marketed in the UK. Lovastatin is produced from the fungus Aspergillus terreus and simvastatin and pravastatin are produced by chemical modifications of lovastatin. Parke Davis, a subsidiary of the US company Warner Lambert, has just entered into a worldwide promotion agreement with Pfizer for the newly-developed drug atorvastatin. Bayer's drug cerivastatin has been in development for a number of years and is currently awaiting registration. Credited to the Royal Society of Chemistry
