Norpid

Uses

Primary hypercholesterolemia (type IIa and IIb) in patients who have not responded adequately to diet and other appropriate measures. Coronary heart disease and elevated plasma cholesterol level.

Norpid is also used to associated treatment for these conditions: Cardiovascular Events, Diabetes Mellitus, Heterozygous Familial Hypercholesterolemia, High Cholesterol, Homozygous Familial Hypercholesterolemia, Mixed Hyperlipidemia, History of coronary heart disease cardiovascular event, History of stroke or other cerebrovascular disease cardiovascular event

How Norpid works

Simvastatin is a prodrug in which the 6-membered lactone ring of simvastatin is hydrolyzed in vivo to generate the beta,delta-dihydroxy acid, an active metabolite structurally similar to HMG-CoA (hydroxymethylglutaryl CoA). Once hydrolyzed, simvastatin competes with HMG-CoA for HMG-CoA reductase, a hepatic microsomal enzyme, which catalyzes the conversion of HMG-CoA to mevalonate, an early rate-limiting step in cholesterol biosynthesis. Simvastatin acts primarily in the liver, where decreased hepatic cholesterol concentrations stimulate the upregulation of hepatic low density lipoprotein (LDL) receptors which increases hepatic uptake of LDL. Simvastatin also inhibits hepatic synthesis of very low density lipoprotein (VLDL). The overall effect is a decrease in plasma LDL and VLDL.

At therapeutic doses, the HMG-CoA enzyme is not completely blocked by simvastatin activity, thereby allowing biologically necessary amounts of mevalonate to remain available. As mevalonate is an early step in the biosynthetic pathway for cholesterol, therapy with simvastatin would also not be expected to cause any accumulation of potentially toxic sterols. In addition, HMG-CoA is metabolized readily back to acetyl-CoA, which participates in many biosynthetic processes in the body.

In vitro and in vivo animal studies also demonstrate that simvastatin exerts vasculoprotective effects independent of its lipid-lowering properties, also known as the pleiotropic effects of statins. This includes improvement in endothelial function, enhanced stability of atherosclerotic plaques, reduced oxidative stress and inflammation, and inhibition of the thrombogenic response.

Statins have also been found to bind allosterically to β2 integrin function-associated antigen-1 (LFA-1), which plays an important role in leukocyte trafficking and in T cell activation.

Dosage

Norpid dosage

The patient should be placed on a standard cholesterol lowering diet before receiving Simvastatin and should continue on this during treatment with Simvastatin. The usual starting dose is 10 mg/day given as a single dose in the evening. Adjustment of dosage, if required, should be made at intervals of not less than four weeks, to a maximum of 40 mg daily given as a single dose in the evening. If LDL-cholesterol levels fall below 2 mmol/L or total plasma cholesterol levels fall below 3.5 mmol/L consideration should be given to reducing the dose of Simvastatin. In hypercholesterolemia, the recommended starting dose is 5-10 mg once a day in the evening and the recommended dosing range is 5-40 mg per day as a single dose in the evening. In patients with coronary heart disease and hypercholesterolemia, the starting dose should be 20 mg once a day in the evening. Because Simvastatin does not undergo significant renal excretion, modification of dosage should not be necessary in patients with renal insufficiency. Safety and effectiveness in children and adolescents have not been established.

Side Effects

Simvastatin is generally well tolerated. Headache, fatigue, insomnia, gastrointestinal effects like nausea, constipation or diarrhoea, flatulence, dyspepsia, abdominal cramps and muscular effects like myalgia, myositis and myopathy have been reported. Rare cases of rhabdomyolysis with acute renal failure secondary to myoglobinuria have been associated with Simvastatin therapy. Hepatitis, pancreatitis, rash, Angio-oedema have also been reported. No potentially life threatening effects have been reported.

Precaution

• If there is a history of liver disease
• Who take high alcohol
• Liver function test should be done before and during treatment
• If serum transaminase rises three times the upper limit of normal, treatment should be discontinued
• Avoid pregnancy during and for one month after treatment

Interaction

Digoxin: Concomitant administration of Simvastatin and Digoxin in normal volunteers resulted in a slight elevation (less than 0.3 µgm/ml) in drug concentrations in plasma compared to concomitant administration of placebo and Digoxin.

Coumarin derivatives: Slightly enhance the anticoagulant effect of Warfarin (mean changes in p rothrombin time less than two seconds) in normal volunteers maintained in a state of low therapeutic anticoagulation.

Others: In clinical studies, Simvastatin was used concomitantly with ACE inhibitors, beta-blockers, calcium channel blockers, diuretics and NSAIDs without evidence of clinically significant adverse interactions.

Volume of Distribution

Rat studies indicate that when radiolabeled simvastatin was administered, simvastatin-derived radioactivity crossed the blood-brain barrier.

Elimination Route

Peak plasma concentrations of both active and total inhibitors were attained within 1.3 to 2.4 hours post-dose. While the recommended therapeutic dose range is 10 to 40 mg/day, there was no substantial deviation from linearity of AUC with an increase in dose to as high as 120 mg. Relative to the fasting state, the plasma profile of inhibitors was not affected when simvastatin was administered immediately before a test meal.

In a pharmacokinetic study of 17 healthy Chinese volunteers, the major PK parameters were as follows: Tmax 1.44 hours, Cmax 9.83 ug/L, t1/2 4.85 hours, and AUC 40.32ug·h/L.

Simvastatin undergoes extensive first-pass extraction in the liver, the target organ for the inhibition of HMG-CoA reductase and the primary site of action. This tissue selectivity (and consequent low systemic exposure) of orally administered simvastatin has been shown to be far greater than that observed when the drug is administered as the enzymatically active form, i.e. as the open hydroxyacid.

In animal studies, after oral dosing, simvastatin achieved substantially higher concentrations in the liver than in non-target tissues. However, because simvastatin undergoes extensive first-pass metabolism, the bioavailability of the drug in the systemic system is low. In a single-dose study in nine healthy subjects, it was estimated that less than 5% of an oral dose of simvastatin reached the general circulation in the form of active inhibitors.

Genetic differences in the OATP1B1 (Organic-Anion-Transporting Polypeptide 1B1) hepatic transporter encoded by the SCLCO1B1 gene (Solute Carrier Organic Anion Transporter family member 1B1) have been shown to impact simvastatin pharmacokinetics. Evidence from pharmacogenetic studies of the c.521T>C single nucleotide polymorphism (SNP) showed that simvastatin plasma concentrations were increased on average 3.2-fold for individuals homozygous for 521CC compared to homozygous 521TT individuals. The 521CC genotype is also associated with a marked increase in the risk of developing myopathy, likely secondary to increased systemic exposure. Other statin drugs impacted by this polymorphism include rosuvastatin, pitavastatin, atorvastatin, lovastatin, and pravastatin.

For patients known to have the above-mentioned c.521CC OATP1B1 genotype, a maximum daily dose of 20mg of simvastatin is recommended to avoid adverse effects from the increased exposure to the drug, such as muscle pain and risk of rhabdomyolysis.

Evidence has also been obtained with other statins such as rosuvastatin that concurrent use of statins and inhibitors of Breast Cancer Resistance Protein (BCRP) such as elbasvir and grazoprevir increased the plasma concentration of these statins. Further evidence is needed, however a dose adjustment of simvastatin may be necessary. Other statin drugs impacted by this polymorphism include fluvastatin and atorvastatin.

Half Life

4.85 hours

Elimination Route

Following an oral dose of 14C-labeled simvastatin in man, 13% of the dose was excreted in urine and 60% in feces.

Pregnancy & Breastfeeding use

Category X: Studies in animals or human beings have demonstrated foetal abnormalities or there is evidence of foetal risk based on human experience or both, and the risk of the use of the drug in pregnant women clearly outweighs any possible benefit. The drug is contraindicated in women who are or may become pregnant.

Contraindication

Simvastatin should not be used in-

• Active liver disease
• Pregnant and breast feeding mother
• Women of child bearing age unless they have been adequately protected by contraception
• Hypersensitivity to any component of the preparation
• Patients with the homozygous familial hypercholesterolemia who have a complete absence of LDL receptors

Acute Overdose

There are no data available on overdose. No antidote is available. General measures should be adopted and liver function should be monitored.

Storage Condition

Store in a cool, dry place, Away from light keep out of reach of children.

Innovators Monograph

You find simplified version here Norpid