Atorvastatin was first synthesized in 1985 by Bruce Roth, an alumnus of Saint Joseph's University, while he was working for the Parke-Davis Company (since acquired by Warner-Lambert and the Pfizer Company). Although Atorvastatin was the fifth drug in the class of statins to be developed, clinical trials showed that Atorvastatin caused a more dramatic reduction in LDL-C than the other statin drugs. From 1996 to 2012 under the trade name Lipitor, Atorvastatin became the world's best-selling drug of all time, with more than $125 billion in sales over approximately 14.5 years.  When Pfizer's patent on Lipitor expired on November 30, 2011, generic Atorvastatin became available in the United States. Initially, Atorvastatin was manufactured only by generic drugmakers Watson Pharmaceuticals and India's Ranbaxy Laboratories. Prices for the generic version did not drop to the level of other generics—$10 or less for a month's supply—until other manufacturers were able to supply the drug in May 2012.
Primary prevention of heart attack, stroke, and need for revascularization procedures in patients who have risk factors such as age, smoking, high blood pressure, low HDL-C, and a family history of early heart disease, but have not yet developed clinically evident coronary heart disease.
Adult patients taking Atorvastatin for dyslipidemias or for cardiovascular disease prevention may take a dose of Atorvastatin ranging from 10mg-80mg daily.. It is common practice for physicians to begin dosing at 10-20mg daily, and then increase a patient's daily dosage of Atorvastatin according to the patient's response to the medication.
It is recommended that pediatric patients with dyslipidemias begin treatment with 10mg daily Atorvastatin. The maximum recommended dose for children is 20mg/day, however doses may be increased according to the goal of therapy under supervision of a physician.
Atorvastatin may be used in combination with bile acid sequestrants to increase the reduction in cholesterol levels. However, It is not recommended to combine statin drug treatment with certain other cholesterol-lowering drugs, particularly fibrates, because this may increase the risk of myopathy-related adverse effects.
While many statin medications should be administered at bedtime for optimal effect, atorvastatin can be dosed at any time of day, as long as it is continually dosed once daily at the same time.
As stated earlier, myopathy with elevation of creatinine kinase (CK) and rhabdomyolysis are the most serious side effects, although rare at <1%.Headache is the most common side effect, occurring in more than 10% of patients. Side effects that occur in 1–10% of patients taking atorvastatin include:
Atorvastatin and other statins are associated with anecdotal reports of memory loss by consumers, which have been seen in clinical practice in a tiny percentage of users, particularly women. Evidence is conflicting with anecdotal reports contrasting with a well-established association of high cholesterol with dementia. However, it is known that cholesterol synthesis is necessary for normal neuron functioning. According to Pfizer, the manufacturer of Lipitor, clinical trials "do not establish a causal link between Lipitor and memory loss."
Antacids can rarely decrease the plasma concentrations of atorvastatin, but do not affect the LDL-C-lowering efficacy.
Niacin also is proved to increase the risk of myopathy or rhabdomyolysis.
Statins may also alter the concentrations of other drugs, such as warfarin or digoxin, leading to alterations in effect or a requirement for clinical monitoring.
Vitamin D supplementation lowers atorvastatin and active metabolite concentrations, yet synergistically reduces LDL and total cholesterol concentrations.Grapefruit juice components are known inhibitors of intestinal CYP3A4. Co-administration of grapefruit juice with atorvastatin may cause an increase in Cmax and AUC, which can lead to adverse reactions or overdose toxicity.
In clinical trials, drugs that block cholesterol uptake like ezetimibe combine with and complement those that block biosynthesis like atorvastatin or simvastatin in lowering cholesterol or targeting levels of LDL.
The liver is the primary site of action of Atorvastatin, as this is the principal site of both cholesterol synthesis and LDL clearance. It is the dosage of Atorvastatin, rather than systemic drug concentration, which correlates with extent of LDL-C reduction.
Atorvastatin undergoes rapid absorption when taken orally, with an approximate time to maximum plasma concentration (Tmax) of 1–2 h. The absolute bioavailability of the drug is about 14%, but the systemic availability for HMG-CoA reductase activity is approximately 30%. Atorvastatin undergoes high intestinal clearance and first-pass metabolism, which is the main cause for the low systemic availability. Administration of atorvastatin with food produces a 25% reduction in Cmax (rate of absorption) and a 9% reduction in AUC (extent of absorption), although food does not affect the plasma LDL-C-lowering efficacy of atorvastatin. Evening dose administration is known to reduce the Cmax and AUC by 30% each. However, time of administration does not affect the plasma LDL-C-lowering efficacy of atorvastatin.
Atorvastatin is highly protein bound (≥98%).
The primary proposed mechanism of atorvastatin metabolism is through cytochrome P4503A4hydroxylation to form active ortho- and parahydroxylated metabolites, as well as various beta-oxidation metabolites. The ortho- and parahydroxylated metabolites are responsible for 70% of systemic HMG-CoA reductase activity. The ortho-hydroxy metabolite undergoes further metabolism via glucuronidation. As a substrate for the CYP3A4 isozyme, it has shown susceptibility to inhibitors and inducers of CYP3A4 to produce increased or decreased plasma concentrations, respectively. This interaction was tested in vitro with concurrent administration of erythromycin, a known CYP3A4 isozyme inhibitor, which resulted in increased plasma concentrations of atorvastatin. It is also an inhibitor of cytochrome 3A4.
Atorvastatin is primarily eliminated via hepaticbiliary excretion, with less than 2% recovered in the urine. Bile elimination follows hepatic and/or extrahepatic metabolism. There does not appear to be any entero-hepatic recirculation. Atorvastatin has an approximate elimination half-life of 14 h. Noteworthy, the HMG-CoA reductase inhibitory activity appears to have a half-life of 20–30 h, which is thought to be due to the active metabolites. Atorvastatin is also a substrate of the intestinal P-glycoprotein efflux transporter, which pumps the drug back into the intestinal lumen during drug absorption.
In hepatic insufficiency, plasma drug concentrations are significantly affected by concurrent liver disease. Patients with A-stage liver disease show a four-fold increase in both Cmax and AUC. Patients with B-stage liver disease show a 16-fold increase in Cmax and an 11-fold increase in AUC.
Geriatric patients (>65 years old) exhibit altered pharmacokinetics of atorvastatin compared to young adults, with mean AUC and Cmax values that are 40% and 30% higher, respectively. Additionally, healthy elderly patients show a greater pharmacodynamic response to atorvastatin at any dose; therefore, this population may have lower effective doses.
Several genetic polymorphisms have been found to be associated with a higher incidence of undesirable side effects of atorvastatin. This phenomenon is suspected to be related to increased plasma levels of pharmacologically active metabolites, such as atorvastatin lactone and p-hydroxyatorvastatin. Atorvastatin and its active metabolites may be monitored in potentially susceptible patients using specific chromatographic techniques.
Pack and tablet of Atorvastatin (Lipitor) 40mg
Atorvastatin calcium tablets are marketed by Pfizer under the trade name Lipitor for oral administration. Tablets are white, elliptical, and film-coated. Pfizer also packages the drug in combination with other drugs, such as with Caduet. Pfizer recommends that patients do not break tablets in half to take half-doses, even when this is recommended by their doctors. In some countries, atorvastatin calcium is made in tablet form by generic drug makers under various brand names including Stator, Atorvastatin Teva, Litorva, Torid, Atoris, Atorlip,Mactor, Lipvas, Sortis, Torvast, Torvacard, Totalip, and Tulip.
On 23 November 2012, Indian drugmaker Ranbaxy Laboratories Ltd. voluntarily recalled 10-, 20- and 40-mg doses of its generic version of atorvastatin in the United States, a development that could further dent its image in the world's largest prescription drug market, in which the company faced an earlier ban. (The 80-mg dose of atorvastatin was not recalled.) Controlled by Japan's Daiichi Sankyo Co., Ranbaxy has had a troubled history in the United States, where in 2009 the Food and Drug Administration banned shipments from some of its manufacturing plants to the United States.
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