| Atorvastatin is a selective, competitive inhibitor of HMG CoA reductase, the rate-limiting enzyme responsible for the conversion of 3 hydroxy-3 methyl-glutaryl-coenzyme A to mevalonate, a precursor of sterols, including cholesterol. Triglycerides and cholesterol in the liver are incorporated into VLDL and released into the plasma for delivery to peripheral tissues. Low-density lipoprotein (LDL) is formed from VLDL and is catabolised primarily through the high affinity LDL receptor.Atorvastatin lowers plasma cholesterol and lipoprotein levels by inhibiting HMG CoA reductase and cholesterol synthesis in the liver and increases the number of hepatic LDL receptors on the cell surface for enhanced uptake and catabolism of LDL.Atorvastatin reduces LDL production and the number of LDL particles. Atorvastatin produces a profound and sustained increase in LDL receptor activity coupled with a beneficial change in the quality of circulating LDL particles.Approximately 70% of circulating inhibitory activity for HMG CoA reductase is attributed to active metabolites (see Section 5.2 Pharmacokinetic Properties).Atorvastatin has been shown to reduce total C, LDL C, apolipoprotein B, and triglycerides while producing variable increases in HDL C in a dose-response study as shown in Table 1 below.TABLE 1. Dose Response in Patients with Primary Hypercholesterolaemia | Lipitor Dose (mg) | N | Total-C | LDL-C | Apo B | TG | HDL-C | Placebo | 12 | 5 | 8 | 6 | -1 | -2 | 10 | 11 | -30 | -41 | -34 | -14 | 4 | 20 | 10 | -35 | -44 | -36 | -33 | 12 | 40 | 11 | -38 | -50 | -41 | -25 | -3 | 80 | 11 | -46 | -61 | -50 | -27 | 3 | Adjusted Mean % Change from Baseline | Atorvastatin produced a variable but small increase in apolipoprotein A1. However, there was no clear dose response effect.Review of the current clinical database of 24 complete studies shows that atorvastatin increases HDL-cholesterol and reduces the LDL/HDL and total cholesterol/HDL ratios.These results are consistent in patients with heterozygous familial hypercholesterolaemia, nonfamilial forms of hypercholesterolaemia, and mixed hyperlipidaemia, including patients with noninsulin-dependent diabetes mellitus.Lipitor is effective in reducing LDL-C in patients with homozygous familial hypercholesterolaemia, a population that has not usually responded to lipid-lowering medication. In a compassionate use study, 41 patients aged 6 to 51 years with homozygous familial hypercholesterolaemia or with severe hypercholesterolaemia, who had 15% reduction in LDL-C in response to previous maximum dose combination drug therapy, received daily doses of 40 to 80 mg of Lipitor. Twenty four patients with homozygous familial hypercholesterolaemia received 80 mg Lipitor. Nineteen of these 24 patients responded with a greater than 15% reduction of LDL-C (mean 26%, range 18% to 42%).Atherosclerosis In the Reversing Atherosclerosis with Aggressive Lipid-Lowering Study (REVERSAL), the effect of atorvastatin 80 mg and pravastatin 40 mg on coronary atherosclerosis was assessed by intravascular ultrasound (IVUS), during angiography, in patients with coronary heart disease. In this randomized, double-blind, multicenter, controlled clinical trial, IVUS was performed at baseline and at 18 months in 502 patients. In the atorvastatin group (n=253), there was no progression of atherosclerosis evaluated by the percentage change in atheroma volume in a pre-defined target vessel with a stenosis between 20% and 50%. The median percent change, from baseline, in total atheroma volume (the primary study criteria) was -0.4% (p=0.98) in the atorvastatin group and +2.7% (p=0.001) in the pravastatin group (n=249). When compared to pravastatin, the effects of atovastatin were statistically significant (p=0.02).In the atorvastatin group, LDL-C was reduced to a mean of 2.04 mmol/L ± 0.8 (78.9 mg/dL + 30) from baseline 3.89 mmol/L + 0.7 (150 mg/dL ± 28) and in the pravastatin group, LDL-C was reduced to a mean of 2.85 mmol/L + 0.7 (110 mg/dL ± 26) from baseline 3.89 mmol/L + 0.7 (150 mg/dL ± 26) (p<0.0001). Atorvastatin also significantly reduced mean TC by 34.1% (pravastatin: -18.4%, p<0.0001), mean TG levels by 20% (pravastatin: -6.8%, p<0.0009), and mean apolipoprotein B by 39.1% (pravastatin: -22.0%, p<0.0001). Atorvastatin increased mean HDL-C by 2.9% (pravastatin: +5.6%, p=NS). There was a 36.4% mean reduction in CRP in the atorvastatin group compared to a 5.2% reduction in the pravastatin group (p<0.0001).The safety and tolerability profiles of the two treatment groups were comparable.The effect of intensive lipid lowering with atorvastatin on cardiovascular mortality and morbidity was not investigated in this 18-month study. Therefore, the clinical significance of these imaging results with regard to the primary and secondary prevention of cardiovascular events is unknown.Heterozygous Familial Hypercholesterolaemia in Paediatric Patients In a double-blind, placebo controlled study followed by an open-label phase, 187 boys and postmenarchal girls 10-17 years of age (mean age 14.1 years) with heterozygous familial hypercholesterolaemia (FH) or severe hypercholesterolaemia were randomised to atorvastatin (n=140) or placebo (n=47) for 26 weeks and then all received atorvastatin for 26 weeks. Inclusion in the study required 1) a baseline LDL-C level 4.91 mmol/l or 2) a baseline LDL-C 4.14 mmol/l and positive family history of FH or documented premature cardiovascular disease in a first- or second degree relative. The mean baseline LDL-C value was 5.65 mmol/l (range: 3.58-9.96 mmol/l) in the atorvastatin group compared to 5.95 mmol/l (range: 4.14-8.39 mmol/l) in placebo group. The dosage if atorvastatin (once daily) was 10mg for the first 4 weeks and up-titrated to 20mg if the LDL-C level was>3.36 mmol/l. The number of atorvastatin-treated patients who required up-titration to 20mg after Week 4 during the double-blind phase was 80 (57.1%).Atorvastatin significantly decreased plasma levels of total-C, LDL-C, triglycerides, and apolipoprotein B during the 26 week double-blind phase (see Table 2).TABLE 2. Lipid Lowering effects of atorvastatin in adolescent boys and girls with heterozygous familial hypercholesterolaemia or severe hypocholesterolaemia (mean percent change from baseline at endpoint in intention- to-treat-population) | DOSAGE | N | Total-C | LDL-C | HDL-C | TG | Apo B | Placebo | 47 | -1.5 | -0.4 | -1.9 | 1.0 | 0.7 | Atorvastatin | 140 | -31.4 | -39.6 | 2.8 | -12.0 | -34.0 | The mean achieved LDL-C value was 3.38 mmol/l (range: 1.81-6.26 mmol/l) in the atorvastatin group compared to 5.91 mmol/l (range: 3.93-9.96 mmol/l) in the placebo group during the 26-week double-blind phase. In this limited controlled study, there was no detectable effect on growth or sexual maturation in boys or on menstrual length in girls. Atorvastatin has not been studied in controlled clinical trials involving pre-pubertal patients or patients younger than 10 years of age. The safety and efficacy of doses above 20mg have not been studied in controlled trials in children. The long-term efficacy of atorvastatin therapy in childhood to reduce morbidity and mortality in adulthood has not been established.Prevention of Cardiovascular Disease In the Anglo Scandinavian Cardiac Outcomes Trial Lipid Lowering Arm (ASCOT-LLA), the effect of atorvastatin on fatal and non-fatal coronary heart disease was assessed in 10,305 hypertensive patients 40-79 years of age, with no previous myocardial infarction or treatment for angina, and with TC levels 6.5mmol/l (251 mg/dl). Additionally, all patients had at least 3 of the predefined cardiovascular risk factors: male gender, age 55 years, smoking, diabetes, history of CHD in a first degree relative, TC:HDL 6, peripheral vascular disease, left ventricular hypertrophy, prior cerebrovascular event, specific ECG abnormality, proteinuria/albuminuria. In this randomised, double-blind, placebo-controlled study, patients were treated with anti-hypertensive therapy and either atorvastatin 10mg daily (n=5168) or placebo (n=5137). After 3 years treatment with amlodipine or atenolol-based regimen, mean blood pressure fell from 164.2/94.9 to 138.9/80.1 mmHg (atorvastatin) and 164.2/94.3 to 138.9/80.0 mmHg (placebo).After a median of 3.3 years of treatment, there was a statistically significant reduction in the rate of myocardial infarction (a component of the primary endpoint), 1.2% on atorvastatin versus 2.1% on placebo.Fatal and non-fatal ischaemic strokes tended to be lower in the atorvastatin group with a relative risk reduction of 26% (89 vs. 119 events) and an absolute risk reduction of 0.6%. The difference did not reach pre-defined levels of statistical significance.Women constituted 20% of the trial population and a subgroup analysis did not demonstrate any benefit on the primary endpoint of coronary events (fatal CHD plus non-fatal MI) (RR 1.11, 95% CI 0.58-2.13).In the Collaborative Atorvastatin Diabetes Study (CARDS), the effect of atorvastatin on fatal and nonfatal cardiovascular disease was assessed in 2838 patients with type 2 diabetes 40-75 years of age, without prior history of cardiovascular disease and with LDL 4.14 mmol/l (160 mg/dl) and TG 6.78mmol/l (600mg/dl). Additionally, all patients had at least 1 of the following risk factors: hypertension, current smoking, retinopathy, microalbuminuria or macroalbuminuria.In this randomised, double-blind, multi-centre, placebo-controlled trial, patients were treated with either atorvastatin 10 mg daily (n=1428) or placebo (n=1410) for a median follow-up of 3.9 years.The absolute and relative risk reduction effect of atorvastatin is as follows:Event | Relative
Risk
Reduction
(%) | Absolute
Risk
Reduction1
(%) | No of events (atorvastatin vs.placebo) | p-value | Major cardiovascular events (fatal and non-fatal AMI, silent MI, acute CHD death, unstable angina, CABG, PTCA, revascularisation, stroke) | 37% | 3.2% | 83 vs. 127 | 0.001 | MI (fatal and non-fatal AMI, silent MI) | 42% | 1.9% | 38 vs. 64 | 0.007 | Strokes (Fatal and non-fatal) | 48% | 1.3% | 21 vs. 39 | 0.016 | 1Based on difference in crude events rates occurring over a median follow-up of 3.9 years.AMI= acute myocardial infarction; CABG= coronary artery bypass graft; CHD=coronary heart disease; MI=myocardial infarction; PTCA=percutaneous transluminal coronary angioplasty.Although the relative risk reduction in the primary end-point was similar between men and women, the absolute benefit for the women was less since the primary event rate on placebo was approximately 1/3 of the male event rate.Recurrent StrokeIn the Stroke Prevention by Aggressive Reduction in Cholesterol Levels (SPARCL) study, the effect of atorvastatin 80 mg daily or placebo on stroke was evaluated in 4731 patients who had a stroke or transient ischemic attack (TIA) within the preceding 6 months and no history of coronary heart disease (CHD). Patients were 60% male, 21-92 years of age (average age 63 years) and had an average baseline LDL of 133 mg/dl (3.4 mmol/l). The mean LDL-C was 73 mg/dl (1.9 mmol/l) during treatment with atorvastatin and 129 mg/dL (3.3 mmol/L) during treatment with placebo. Median follow-up was 4.9 years.Atorvastatin 80 mg reduced the risk of the primary endpoint of fatal or non-fatal stroke by 15% (HR 0.85; 95% CI, 0.72-1.00; p=0.05 or 0.84; 95% CI, 0.71-0.99; p=0.03 after adjustment for baseline factors) compared to placebo. All cause mortality was 9.1% (216/2365) for atorvastatin versus 8.9% (211/2366) for placebo.In a post-hoc analysis, atorvastatin 80 mg reduced the incidence of ischemic stroke (218/2365, 9.2% vs. 274/2366, 11.6%, p=0.01) and increased the incidence of haemorrhagic stroke (55/2365, 2.3% vs. 33/2366, 1.4%, p=0.02) compared to placebo.• The risk of haemorrhagic stroke was increased in patients who entered the study with prior haemorrhagic stroke (7/45 for atorvastatin versus 2/48 for placebo; HR 4.06; 95% CI, 0.84-19.57) and the risk of ischemic stroke was similar between groups (3/45 for atorvastatin versus 2/48 for placebo; HR 1.64; 95% CI, 0.27-9.82).• The risk of haemorrhagic stroke was increased in patients who entered the study with prior lacunar infarct (20/708 for atorvastatin versus 4/701 for placebo; HR 4.99; 95% CI, 1.71-14.61), but the risk of ischemic stroke was also decreased in these patients (79/708 for atorvastatin versus 102/701 for placebo; HR 0.76; 95% CI, 0.57-1.02). It is possible that the net risk of stroke is increased in patients with prior lacunar infarct who receive atorvastatin 80 mg/day.All cause mortality was 15.6% (7/45) for atorvastatin versus 10.4% (5/48) in the subgroup of patients with prior haemorrhagic stroke. All cause mortality was 10.9% (77/708) for atorvastatin versus 9.1% (64/701) for placebo in the subgroup of patients with prior lacunar infarct. | |