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Tomkin G.H.,Diabetes Institute of Ireland
Expert Review of Cardiovascular Therapy | Year: 2010

The enormous burden of vascular disease is likely to expand rapidly as sedentary obesity and diabetes increase. Although cholesterol plays a major role in atherosclerosis and LDL is the major carrier of cholesterol in the blood, the importance of the postprandial triglyceride-rich lipoproteins in the development of atherosclerosis is gaining recognition. The role of HDL-cholesterol is also receiving more attention. These changes have been forced upon us by the realization that statins, which primarily lower LDL-cholesterol, only reduce the risk of atherosclerosis by 30%, suggesting that 70% of the risk still has to be explained and treated. In diabetes, abnormality in the metabolism of the triglyceride-rich lipoproteins and the inter-relationship with HDL-cholesterol appears to be of primary importance in atherosclerotic risk. Postprandial studies are difficult to carry out, which is one reason why large studies have not so far been performed. The important new findings in chylomicron metabolism suggest new treatments for the future. © 2010 Expert Reviews Ltd.

Tomkin G.H.,Diabetes Institute of Ireland | Tomkin G.H.,Trinity College Dublin | Owens D.,Trinity College Dublin
Expert Opinion on Investigational Drugs | Year: 2014

Introduction: There is great need for new drugs to reduce cholesterol in those patients who have not achieved target levels on statins as well as those who are statin intolerant.Areas covered: In this review, the authors discuss the new antisense oligotide inhibitor of apo B synthesis, mipomersen; pro-protein convertase subtilisin/kexin type 9 (PCSK9) inhibitors and cholesterol ester transport protein (CETP) inhibitors. Furthermore, the authors discuss cholesterol absorption and chylomicron synthesis with an emphasis on microsomal triglyceride transfer protein (MTP) inhibitors, which inhibit very-low-density lipoprotein production in the liver and chylomicron inhibition in the intestine. Finally, the authors also discuss Apo A1- and adenosine triphosphate-binding cassette transporter A1 (ABCA1)-promoting drugs. A literature review was performed through PubMed using the terms atherosclerosis, hypercholesterolemia, Apo B inhibition, PSCK9, CETP inhibitors, MTP inhibitors, apo A1 mimetics and ABCA1.Expert opinion: So far, research suggests that PCSK9 inhibitors will be successful with mipomersen being used for those patients who do not respond well or who are still not at target. However, it is difficult to see where CETP inhibitors will fit in except with patients who have very low high-density lipoprotein. The MTP inhibitor lomitapide is currently only licensed for familial homozygous hypercholesterolemia but the intestinal inhibitors may have a future, particularly in familial combined hyperlipidemia. The future will be most exciting. © Informa UK, Ltd.

Tomkin G.H.,Diabetes Institute of Ireland | Tomkin G.H.,Trinity College Dublin | Owens D.,Diabetes Institute of Ireland | Owens D.,Trinity College Dublin
International Journal of Vascular Medicine | Year: 2012

The B-containing lipoproteins are the transporters of cholesterol, and the evidence suggests that the apo B48-containing postprandial chylomicron particles and the triglyceride-rich very low density lipoprotein (VLDL) particles play an important part in the development of the plaque both directly and indirectly by their impact on LDL composition. The ratio of dietary to synthesised cholesterol is variable but tightly regulated: hence intervention with diet at best reduces serum cholesterol by <20 andusually <10. Statins are the mainstay of cholesterol reduction therapy, but they increase cholesterol absorption, an example of the relationship between synthesis and absorption. Inhibition of cholesterol absorption with Ezetimibe, an inhibitor of Niemann Pick C1-like 1 (NPC1-L1), the major regulator of cholesterol absorption, increases cholesterol synthesis and hence the value of adding an inhibitor of cholesterol absorption to an inhibitor of cholesterol synthesis. Apo B48, the structural protein of the chylomicron particle, is synthesised in abundance so that the release of these particles is dependent on the amount of cholesterol and triglyceride available in the intestine. This paper will discuss cholesterol absorption and synthesis, chylomicron formation, and the effect of postprandial lipoproteins on factors involved in atherosclerosis. © 2012 Gerald H. Tomkin and Daphne Owens.

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