The statins (or HMG-CoA reductase inhibitors) form a class of hypolipidemic drugs used to lower cholesterol levels in people with or at risk of cardiovascular disease.
The commercially available natural statin is Red yeast rice
Statin development and structure
Statins can be roughly subdivided into two groups: the natural compounds derived from fungal fermentation (type 1), that include mevastatin, lovastatin, simvastatin and pravastatin, and the fully synthetic compounds (type 2), that include fluvastatin, atorvastatin, rosuvastatin, cerivastatin and pitavastatin.
METABOLIC EFFECTS:
All statins, independent of their structural differences, bind to HMG-CoA reductase at nanomolar concentrations, leading to competitive displacement of the natural substrate HMG-CoA. This competitive inhibition results in a failure to catalyse the conversion of HMG-CoA to l-mevalonate, which in turn prevents the downstream biosynthesis of cholesterol.
- Cholesterol lowering
- Not only is cholesterol synthesis reduced, but also low intracellular-cholesterol concentrations activate sterol-responsive-element-binding proteins, leading to increased transcription of the gene encoding the LDL receptor and subsequent expression of the receptor at the cell surface. As LDL-receptor-mediated uptake of LDL cholesterol by the liver is a key factor in determining circulating levels, this further reduces blood LDL cholesterol. A reduction in circulating cholesterol is a primary clinical objective when treating hypercholesterolaemia, as it removes one of the main risk factors for atherosclerosis
- ABC transporter
- Coenzyme Q
NON GENOMIC EFFECTS:
- Decrease the isoprenoids farnesyl pyrophosphate and geranylgeranyl pyrophosphate which serve as essential adjuncts in the post-translational modification of numerous key proteins such as the small GTPases RAS, RAC and RAS homologue (RHO). This post-translational modification enables these signalling proteins to associate with membranes. These small GTP-binding proteins have a role in different cell functions, so the immune response will be modified independently of their lipid-lowering effect.
GENOMIC MECHANISM:
- Cholesterol synthesis and fatty acid synthesis are controlled by a common family of transcription factors designated sterol regulatory element binding proteins (SREBPs). This SREBP activates the transcription of genes involved in cholesterol and fatty acid synthesis by binding to sterol regulatory elements (SREs) or to palindromic sequences called E-boxes within their promoter regions.
- SCAP is a multiple membrane-spanning protein containing a consensus sequence for a sterol-sensing domain which is shared by HMG CoA reductase. SCAP has been suggested to function as a cholesterol sensor.
- SREBP precursor and SCAP form a complex on the rough endoplasmic reticulum membrane.
- When sterol is depleted, the SREBP-SCAP complex targets to golgi. Here site-1 protease, activated by auto-catalysis, cleaves SREBP at the loop region, followed by the second cleavage in the first membrane spanning region by site-2 protease to liberate the N-terminal of SREBP.
- When sterol is abundant, SREBP-SCAP complex is retained at the rough ER and no cleavage occurs. In the neighboring (usually 15 bases around the SRE) sequence of SREBP target gene promoters, NF-Y site or Sp1 site is usually found. NF-Y and Sp1 directly bind to SREBP and seem involved in recruitment of basic transcription machinery including CBP.
- In some SREBP target genes, SREBP activation of gene expression can be negatively regulated by Yin Yang-1 zinc finger transcription factor (YY1). YY1 can repress SREBP activation of HMG CoA synthase, FPP synthase, and LDL receptor genes by displacing NF-Y, which is essential for SREBP activation of these genes.
Fibrillazione: statine riducono rischio nelle donne
L'uso delle statine nelle donne coronaropatiche in età postmenopausale riduce il rischio di fibrillazione atriale del 55 percento. Oltre alle loro proprietà ipocolesterolemizzanti, le statine presentano anche proprietà antiinfiammatorie, e dato che recenti ricerche suggeriscono che l'infiammazione svolga un ruolo chiave nella fisiopatologia della fibrillazione atriale, è possibile che la terapia statinica possa aiutare a tenere sotto controllo l'aritmia. Diversi studi hanno infatti già investigato il possibile ruolo delle statine contro la fibrillazione atriale, ma si è trattato eminentemente di studi sul sesso maschile, e nessuno di essi ha esaminato specificamente l'uso delle statine per questa indicazione nelle donne. Rimane da accertare se questa terapia possa davero alleviare il carico totale derivante dalla fibrillazione atriale. (Heart 2009; 95: 693-4 e 704-8)
Infarto: beta-bloccanti ostacolano statine
I livelli di CRP risultano molto più ampiamente ridotti con la sola somministrazione di statine che con l'aggiunta di beta-bloccanti dopo un infarto acuto., il che indica che questi ultimi farmaci attenuino l'effetto antiinfiammatorio delle statine. E' stato confermato che vari tipi di statine sono in grado di attenuate l'intenso incremento dell'attività infiammatoria a livello sistemico che si osserva durante la fase acuta dell'infarto miocardico, ma non era finora noto che questo effetto terapeutico delle statine potesse essere ostacolato dalla concomitante somministrazione di altri farmaci, come i beta-bloccanti. La significatività del dato rilevato permane anche tenendo conto di elementi come età o sesso del paziente e livelli base di CRP. (Am J Cardiol 2009; 103: 461-3)
Molecular multitasking: statins lead to more arteries, less plaque 2000
Are Statin Side Effects Worth The Price In The Fight Against Heart Disease? 2011
Side Effects?
Relation of statin use with non-melanoma skin cancer: prospective results from the Women's Health Initiative. 2016
Effect of Statin Treatment vs Usual Care on Primary Cardiovascular Prevention Among Older AdultsThe ALLHAT-LLT Randomized Clinical Trial, july 2017
Conclusions and Relevance: No benefit was found when pravastatin was given for primary prevention to older adults with moderate hyperlipidemia and hypertension, and a nonsignificant direction toward increased all-cause mortality with pravastatin was observed among adults 75 years and older.
The ALLHAT-LLT was conducted from February 1994 to March 2002 at 513 clinical sites.
and why it has been published 15 years after?
Statins linked to 20,000 side effects and 227 deaths Sunday Express 2015
Two million people are given statins needlessly, new research shows Sunday Express 2015