Zocor Review Article
Zocor, also known as Simvastatin, is a cholesterol-lowering drug. Your doctor may prescribe Simvastatin in addition to a cholesterol-lowering diet if your blood cholesterol level is too high, and if you have been unable to lower it by diet alone. In people with high cholesterol and heart disease, Simvastatin reduces the risk of heart attack, stroke and "mini-stroke" (transient ischemic attack) and can stave off the need for bypass surgery or angioplasty to clear clogged arteries.
Zocor is a hypolipidemic drug, which means that it lowers the lipid level in the blood. It is a member of the statin group of drugs. Zocor is mainly used for the treatment of hyperlipidemia or hypercholesterolemia (high level of cholesterol in blood). FDA approved Zocor in 1997. Continue reading...
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|40 mg forte
|80 mg max
Generic Name: simvastatin.
Product Brand Name: Zocor.
Product Manufacturer: Merck & Co. Inc.
The generic name of Zocor is simvastatin. Simvastatin is synthetically derived by fermentation of Aspergillus terreus. It belongs to the statin group of drugs. Statins work by inhibiting an enzyme, namely, HMG-CoA reductase or 3-hydroxy-3-methyl-glutaryl-CoA reductase or HMGCR. HMGCR is a rate-controlling enzyme in the metabolic pathway, which produces cholesterol and other similar biochemical agents. HMGCR controls the amount of cholesterol being synthesized in the human body. Inhibition of HMGCR inhibits the metabolic pathway that produces cholesterol endogenously, thus lowering the overall blood cholesterol level and lowering the risk of cardiovascular disease.
Cholesterol is an animal sterol that is synthesized in the liver and in the intestine. It is the most abundant steroid of fat in the animal tissue. Dietary sources of cholesterol are cheese, egg, chicken, red meat, beef, pork etc. Two types of cholesterol are found in human body, LDL (low-density lipoprotein) and HDL (high-density lipoprotein). HDL is often called “good cholesterol” and LDL is called “bad cholesterol”. When LDL concentration increases and HDL concentration decreases in the human body, it causes hypercholesterolemia.
In 1990, a clinical trial was performed in Scandinavia, namely, Scandinavian simvastatin survival study (4s). This study was done to assess the effect of simvastatin in regard to mortality and morbidity in patients with coronary artery disease. A total of 4444 patients were recruited through 94 clinics in Denmark, Finland, Iceland, Norway, and Sweden. All the patients had angina pectoris or previous myocardial infarction history, as well as moderate hypercholesterolemia with cholesterol levels between 5.5 mmoles/L and 8.0 mmoles/L. Out of 4444 patients, 2223 were started on placebo and 2221 were started on simvastatin. Simvastatin was started at 20 mg/day and was titrated up to 40 mg/day. This was the double-blind period. After this most patients in both groups were treated with open-label prescription of simvastatin. In the placebo group, 1,967 patients survived the double-blind period. Out of these 1,967 patients, 97 (4.9%) died within the following two years. In the simvastatin group 2039 patients survived the double-blind period, out of which 74 (3.6%) patients died within the following two years.
The total number of deaths in the placebo group and the simvastatin groups were 353 (15.9%) and 256 (11.5%) respectively. Cancer deaths were 3.1% in the placebo group compared to 2.3% in the simvastatin group. After this study, it was concluded that coronary heart disease patients can be treated with simvastatin for up to eight years safely to yield survival benefit (Pedersen, et al, 2000).
In 2011, a randomized clinical trial of simvastatin and aspirin was performed on patients with pulmonary arterial hypertension (PAH). The objective was to determine whether aspirin and simvastatin are effective for treating PAH. After six months of double-blind and placebo controlled trial, neither aspirin nor simvastatin showed any significant effect on the patients. The results did not support routine treatment of PAH with simvastatin (Kawut, et al, 2011).
Another clinical study took place in the year 2011 to determine if HMG-CoA reductase inhibitors like simvastatin can slow down the progression of Alzheimer’s disease. Previous studies suggested that lowering cholesterol levels can reduce amyloid disposition in the central nervous system which can benefit the patients of Alzheimer’s disease. The study was double-blind and placebo-controlled. A total of 406 individuals were on this trial for 18 months. The results were disappointing. Simvastatin lowered the cholesterol/lipid level in the individuals but that did not improve Alzheimer’s disease or slow the progression of the disease (Sano, et al, 2011).
Simvastatin was also in trial for treating individuals with erectile dysfunction secondary to endothelial dysfunction. After seven months of a placebo-controlled double-blind study, the individuals showed no significant improvement regarding the international index of erectile dysfunction, though their hormone levels were unaltered and serum cholesterol was improved (Mastalir, et al, 2011).
The patients with relapsing-reemitting multiple sclerosis (RR MS) are generally treated with interferon beta-1, but this medicine is only partly effective. Simvastatin is a statin group drug that has anti-inflammatory effect. So, simvastatin was tried as an add-on drug in a clinical trial with RR MS patients. It was a placebo-controlled, double-blind, randomised trial. A total of 307 patients were enrolled in this study, 151 of which were on interferon beta plus simvastatin, and another 156 were on interferon beta and placebo. At the end of the study, no significant improvement in simvastatin add-on therapy was found (Sorensen, et al, 2011).
Statistics of cardiovascular - related deaths:
According to the WHO fact sheet, 30% of the total global deaths occur from cardiovascular diseases. WHO also reports that high blood cholesterol causes more or less 4.4 million deaths each year.
Mechanisms of action of simvastatin:
Simvastatin reportedly has two mechanisms to reduce the level of cholesterol in blood plasma.
1. By competitively inhibiting the enzyme HMGCR, which is responsible for a rate-limiting step in the synthesis of cholesterol in liver.
2. By increasing the expression of LDL receptors on targeted tissue as a result of the first mechanism (1.), thus enhancing the removal of LDL from plasma (Saeb-Parsy, 1999).
When statins bind to the active site of HMGCR, they change the conformation of the enzyme. This prevents the enzyme from attaining a functional structure. The binding of the drug is reversible and its affinity for the enzyme is in the nanomolar range, whereas normal substrates have affinity in the micromolar range.
As a result of decreasing blood cholesterol levels (due to HMGCR inhibition), an enzyme named protease gets activated. Protease slices the sterol regulatory element binding proteins (SREBPs) from the endoplasmic reticulum of the cell. SREBPs signal the gene expression of LDL receptors. Thus, the reduction of cholesterol in liver cells leads to expression of LDL receptors in liver cells. As a result, the level of circulating LDL decreases. (Stancu and Sima, 2001)
• The recommended starting dose is 10 or 20 mg once a day and taken in the evening.
• The recommended starting dose for patients at high risk of Coronary Heart Disease is 40 mg/day.
• The recommended starting dose for adolescents (10-17 years of age) with Heterozygous familial hypercholesterolemia (HeFH) is 10 mg per day; the maximum recommended dose for these patients is 40 mg/day.
Use of the 80 mg dose of simvastatin should be avoided. It should be restricted to patients who were already taking this dose for 12 months or more and have shown no signs of muscle toxicity.
Patients taking the 40 mg dose of simvastatin but are unable to reduce their LDL-C levels sufficiently, should be placed on an alternative therapy. Avoid increasing the dose of simvastatin to more than 40 mg.
Uses of Zocor:
1. It reduces the risk of coronary heart disease and myocardial infarction.
2. It reduces the levels of total cholesterol, low-density lipoprotein cholesterol, apolipoprotein B, and triglycerides. For increasing high-density lipoprotein cholesterol in patients with several types of hyperlipidemia.
3. It acts as a prophylaxis against acute coronary syndrome and atrial fibrillation before heart surgery (Frishman and Sica, 2011)
2. Stomach ache, constipation, flatulence, diarrhea, and nausea.
3. Upper respiratory infection
4. Problems urinating, change in the colour of urine, muscle pain and cramps, skin rash, skin itching, etc, are also reported to be seen in some patients (Frishman, et al, 2005)
Precautions and Safety:
Ingestion of grapefruit juice should be avoided while taking simvastatin as it can lead to high plasma level concentration of simvastatin, causing adverse effects.
Simvastatin interacts significantly with macrolide antibiotics like azithromycin, antifungal drugs like ketoconazole, HIV-protease inhibitor drugs, and calcium channel blockers like verapamil.
Several new clinical trials have been taking place on this drug. FDA has recently limited the use of the 80 mg dose of simvastatin as it increases the risk of muscle damage. Zocor is a cost-effective drug for lowering lipid level in blood, but it should not be taken during pregnancy and it is not available over-the-counter.
Frishman WH, Cheng-Lai A, Nawarskas J, 2005, Current Cardiovascular Drugs, Birkh?user, page 307
Frishman WH, Sica DA, M.D, 2011, Cardiovascular Pharmacotherapeutics, Cardiotext Publishing, page 347
Mastalir ET, Carvalhal GF, Portal VL, 2011, The effect of simvastatin in penile erection: a randomized, double-blind, placebo-controlled clinical trial (Simvastatin treatment for erectile dysfunction-STED TRIAL), Int J Impot Res.
Kawut SM, Bagiella E, Lederer DJ, Shimbo D, Horn EM, Roberts KE, Hill NS, Barr RG, Rosenzweig EB, Post W, Tracy RP, Palevsky HI, Hassoun PM, Girgis RE; ASA-STAT Study Group, 2011, Randomized clinical trial of aspirin and simvastatin for pulmonary arterial hypertension: ASA-STAT, Circulation;123(25):2985-93.
Pedersen TR, Wilhelmsen L, Faergeman O, Strandberg TE, Thorgeirsson G, Troedsson L, Kristianson J, Berg K, Cook TJ, Haghfelt T, Kjekshus J, Miettinen T, Olsson AG, Py?r?l? K, Wedel H., 2000, Follow-up study of patients randomized in the Scandinavian simvastatin survival study (4S) of cholesterol lowering, Am J Cardiol.86(3):257-62.
Saeb-Parsy K, 1999, Instant pharmacology, John Wiley and Sons, page 294-295
Sano M, Bell KL, Galasko D, Galvin JE, Thomas RG, van Dyck CH, Aisen PS, 2011, A randomized, double-blind, placebo-controlled trial of simvastatin to treat Alzheimer disease, Neurology. 77(6):556-63.
Sorensen PS, Lycke J, Er?linna JP, Edland A, Wu X, Frederiksen JL, Oturai A, Malmestr?m C, Stenager E, Sellebjerg F, Sondergaard HB; SIMCOMBIN study investigators, 2011, Simvastatin as add-on therapy to interferon β-1a for relapsing-remitting multiple sclerosis (SIMCOMBIN study): a placebo-controlled randomised phase 4 trial, Lancet Neurol;10(8):691-701.
Stancu C, Sima A, 2001, Statins: mechanism of action and effects, J.Cell.Mol.Med. Vol 5, No 4, page. 378-387.
Tighe DA, Tran MT, Donovan J, 2010, Cardiology Drug Guide 2010, Jones & Bartlett Learning, page 238-241.
Zocor Review Article