Pharmacokinetic interactions between protease inhibitors and statins in HIV seronegative volunteers: ACTG Study A5047

OBJECTIVE

Lipid lowering therapy is used increasingly in persons with HIV infection in the absence of safety data or information on drug interactions with antiretroviral agents. The primary objectives of this study were to examine the effects of ritonavir (RTV) plus saquinavir soft-gel (SQVsgc) capsules on the pharmacokinetics of pravastatin, simvastatin, and atorvastatin, and the effect of pravastatin on the pharmacokinetics of nelfinavir (NFV) in order to determine clinically important drug-drug interactions.

DESIGN

Randomized, open-label study in healthy, HIV seronegative adults at AIDS Clinical Trials Units across the USA.

METHODS

Three groups of subjects (arms 1, 2, and 3) received pravastatin, simvastatin or atorvastatin (40 mg daily each) from days 1-4 and 15-18. In these groups, RTV 400 mg and SQVsgc 400 mg twice daily were given from days 4-18. A fourth group (arm 4) received NFV 1250 mg twice daily from days 1-14 with pravastatin 40 mg daily added from days 15-18. Statin and NFV levels were measured by liquid chromatography/tandem mass spectrometry.

RESULTS

Fifty-six subjects completed both pharmacokinetic study days. In arms 1-3, the median estimated area under the curves (AUC)(0-24) for the statins were: pravastatin (arm 1, n = 13), 151 and 75 ng.h/ml on days 4 and 18 (decline of 50% in presence of RTV/SQVsgc), respectively (P = 0.005); simvastatin (arm 2, n = 14), 17 and 548 ng.h/ml on days 4 and 18 (increase of 3059% in the presence of RTV/SQVsgc), respectively (P < 0.001); and total active atorvastatin (arm 3, n = 14), 167 and 289 ng.h/ml on days 4 and 18 (increase of 79% in the presence of RTV/SQVsgc), respectively (P < 0.001). In arm 4, the median estimated AUC(0-8) for NFV (24 319 versus 26 760 ng.h/ml; P = 0.58) and its active M8 metabolite (15 565 versus 14 571 ng.h/m; P = 0.63) were not statistically different from day 14 to day 18 (without or with pravastatin).

CONCLUSIONS

Simvastatin should be avoided and atorvastatin may be used with caution in persons taking RTV and SQVsgc. Dose adjustment of pravastatin may be necessary with concomitant use of RTV and SQVsgc. Pravastatin does not alter the NFV pharmacokinetics, and thus appears to be safe for concomitant use.

Efficacy and safety of atorvastatin 10 mg every other day in hypercholesterolemia

OBJECTIVES

The authors sought to evaluate the safety and efficacy of atorvastatin administered every other day in patients with hypercholesterolemia.

BACKGROUND

Statins have efficacy in lowering cholesterol and reducing cardiovascular events but their cost is a major disadvantage. Atorvastatin is the most potent statin and has a long half-life. Therefore, atorvastatin given on alternate days may be reasonable and cost effective, particularly in hypercholesterolemia patients.

METHOD AND RESULT

Sixty patients with hypercholesterolemia despite diet therapy were enrolled into the study. They received atorvastatin 10 mg every other day before bedtime. Duration of treatment was 8 weeks. A lipid profile was determined as baseline, at 4 weeks and again at 8 weeks. Atorvastatin every other day significantly reduced total cholesterol (TC), triglyceride (TG), and LDL-c versus baseline. The TC, TG, and LDL-c levels were lower by 23 per cent, 8 per cent, and 30 per cent. Increase in HDL-c level was not statistically significant. Three patients had drug side effects. One patient had increased serum transaminase and one patient had increased serum muscle enzyme. The other one had somnolence.

CONCLUSIONS

In hypercholesterolemia patients, atorvastatin 10 mg every other day is safe and effective in lowering TC, TG, with LDL-c and a slight increase in HDL-c.

Safety and efficacy of atorvastatin in heart transplant recipients

BACKGROUND

Pravastatin and simvastatin prolong survival and reduce transplant-related coronary vasculopathy, although low-density lipoprotein (LDL) lowering with these agents is only modest. The objective of this study was to assess the safety of moderate dose atorvastatin and its efficacy when prior treatment with another statin had failed to lower LDL to < 100 mg/dl.

METHODS

Data from 185 patients were retrospectively evaluated for adverse events, duration of exposure (person-days), and the mean atorvastatin dose exposure. Changes in lipid parameters, and prednisone and cyclosporine doses were determined.

RESULTS

SAFETY

48 patients received atorvastatin for 24,240 person-days at a mean dose exposure of 21 +/- 10 mg. Rhabdomyolysis, myositis, myalgias, and hepatotoxicity occurred in 0, 2, 2, and 0 patients, respectively. All events occurred at the 10-mg dose, within the first 3 months, and were rapidly reversible with atorvastatin discontinuation.

EFFICACY

Thirty-four patients evaluable for efficacy analyses had a pre-atorvastatin LDL of 145 +/- 38 mg/dl on the following statins: pravastatin (n = 30, 40 +/- 0mg), fluvastatin (n = 3, 33 +/- 12 mg), simvastatin (n = 1, 40 mg). After atorvastatin (21 +/- 9 mg/day) for 133 +/- 67 days, LDL was reduced to 97 +/- 24 mg/dl (relative reduction 31 +/- 20%, p < 0.0001). At the end of the observation period (418 +/- 229 days, atorvastatin final dose 24 +/- 14 mg/day), LDL was further decreased to 88 +/- 23 mg (relative reduction 37 +/- 17%, p < 0.0001).

CONCLUSION

Atorvastatin, when used at moderate doses and with close biochemical and clinical monitoring, appears to be safe and is effective in aggressively lowering LDL in heart transplant recipients when treatment with other statins has failed to achieve LDL goals.

Pharmacokinetic interactions between nelfinavir and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors atorvastatin and simvastatin

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are effective agents in lowering cholesterol and triglycerides and are being used by human immunodeficiency virus-positive patients to treat the lipid elevation that may be associated with antiretroviral therapy. Many HMG-CoA reductase inhibitors and protease inhibitors are metabolized by the same cytochrome P450 enzyme 3A4 (CYP3A4). In addition, many protease inhibitors are potent inhibitors of CYP3A4. Therefore, coadministration of these two classes of drugs may cause significant drug interactions. This open-label, multiple-dose study was performed to determine the interactions between nelfinavir, a protease inhibitor, and two HMG-CoA reductase inhibitors, atorvastatin and simvastatin, in healthy volunteers. Thirty-two healthy subjects received either atorvastatin calcium (10 mg once a day) or simvastatin (20 mg once a day) for the first 14 days of the study. Nelfinavir (1,250 mg twice a day) was added on days 15 to 28. Pharmacokinetic assessment was performed on days 14 and 28. The study drugs were well tolerated. Nelfinavir increased the steady-state area under the plasma concentration-time curve during one dosing period (AUC(tau)) of atorvastatin 74% and the maximum concentration (C(max)) of atorvastatin 122% and increased the AUC(tau) of simvastatin 505% and the C(max) of simvastatin 517%. Neither atorvastatin nor simvastatin appeared to alter the pharmacokinetics of nelfinavir. It is recommended that coadministration of simvastatin with nelfinavir should be avoided, whereas atorvastatin should be used with nelfinavir with caution.

What is the role of intensive cholesterol lowering in the treatment of acute coronary syndromes?

Cholesterol lowering with statins reduces coronary events in a primary-prevention setting and in patients with stable coronary disease. However, where the risk of a coronary event is highest, in the early months after an episode of unstable angina or non-Q-wave infarction, the effect of statin therapy has not been evaluated until recently. The lack of an early benefit in the 3 main statin trials in stable coronary disease may have discouraged this type of investigation. Yet, evidence suggests that intensive cholesterol lowering can rapidly influence several mechanisms intimately related to the pathogenesis of acute coronary syndromes; specifically, improvement in endothelial function, decreased propensity for platelet thrombus formation, and reduced inflammation. Furthermore, 3 nonrandomized, observational studies have recently reported an improved outcome in statin-treated compared with untreated patients after acute coronary syndromes.

A double-blind trial on the effects of atorvastatin on glycemic control in Japanese diabetic patients with hypercholesterolemia

A double-blind, placebo-controlled, parallel-group study was performed to determine whether atorvastatin, a new HMG-CoA reductase inhibitor, could effectively and safely reduce plasma LDL-cholesterol concentrations in Japanese patients with type-2 diabetes without influencing glycemic control. The subjects were patients with hypercholesterolemia (serum cholesterol concentration > or =5.7 mmol/l (220 mg/dl)) and stable glycemic control. The fasting concentrations of hemoglobin A(1C) (HbA(1C)), fructosamine, and 1,5-anhydroglucitol (1,5-AG) were measured as indices of glycemic control. Plasma lipid concentrations and the safety of the drug were also examined. Forty eligible patients in two groups of 20 each were administered atorvastatin (10 mg/day) or placebo. Neither atorvastatin nor placebo caused a significant change in HbA(1C), fructosamine, or 1,5-AG concentrations. Atorvastatin significantly reduced total cholesterol and LDL-cholesterol concentrations from baseline by 29.7% (p<0.0001) and 41.6% (p<0.0001), respectively. The incidence of clinical adverse events and that of abnormal changes in laboratory test values did not differ between the two groups. In this trial, atorvastatin effectively and safely reduced LDL-cholesterol concentrations in diabetic patients with hypercholesterolemia without influencing glycemic control. These findings are clinically important because there are many diabetic patients with hypercholesterolemia and such patients have a high risk of developing arteriosclerotic disease.

Short term effect of atorvastatin and vitamin E on serum levels of C3, a sensitive marker of the risk of myocardial infarction in men

C3 complement is produced in response to macrophage activation and is a reliable marker of the risk of myocardial infarction in men. This study was designed to ascertain whether the treatment with atorvastatin, a powerful cholesterol lowering drug, and/or vitamin E, a natural antioxidant, may induce a short term decrease in serum C3 in subjects with persistently elevated levels. From an initial random sample of 1100 men aged 55-64 years, 140 subjects with 3 consecutive C3 measurements in the high tertile (>1.19 g/l) were selected. Those with total cholesterol <5.56 mmol/l were double blindly randomized in groups 1 (placebo, N = 28, G1) and 2 (vitamin E 600 IU/day, N= 30, G2). The subjects with total cholesterol values >5.56 mmol/l were randomized in groups 3 (placebo, N= 30, G3), 4 (atorvastatin 10 mg/day, N = 27, G4) and 5 (atorvastatin 10 mg/day + vitamin E 600 IU/day, N = 25, G5). After 3 months C3 levels were substantially unchanged in the first 4 groups, while in G5 a very significant decrement occurred: -0.070 g/l (5.2%); 95% CI 0.043-0.098; p <0.0001. "Normal" levels of C3 (< 1.19 g/l) were reached by 28% of G5 subjects. In G2 and G5 vitamin E levels increased by 60 and 36%, while in G4 they decreased by 23% (p < 0.0001), paralleling cholesterol and triglyceride fall. In all groups a progressive decrease in HDL cholesterol occurred (-17%, p < 0.0001). In conclusion, treatment with atorvastatin plus vitamin E for three months can lower persistently elevated C3 levels.

Effect of niacin and atorvastatin on lipoprotein subclasses in patients with atherogenic dyslipidemia

This study was conducted to determine the efficacy of atorvastatin and niacin on lipoprotein subfractions in patients with atherogenic dyslipidemia. This was a multicenter, randomized, open-label, parallel-design study of patients with total cholesterol >200 mg/dl, triglycerides between 200 and 800 mg/dl, and apolipoprotein B >110 mg/dl. Patients were randomly assigned to atorvastatin 10 mg or immediate release niacin 3,000 mg daily for 12 weeks following a low-fat diet stabilization period. Lipoprotein subclasses were measured by nuclear magnetic resonance spectroscopy. Atorvastatin and niacin both significantly reduced the concentrations of very low-density lipoprotein (VLDL) particles (-31% and -29%, respectively) and small low-density lipoprotein (LDL) particles (-44% and -35%, respectively). Niacin increased the concentration of large LDL (+75%). Atrovastatin reduced the number of LDL particles more than niacin (31% vs 14%). In patients with atherogenic dyslipidemia, both drugs had important effects on lipoprotein subfractions, which contributed to a reduction in coronary heart disease risk. The drugs equally reduced VLDL subclass levels. Niacin shifted the LDL subclass distribution toward the larger particles, more effectively converted patients from LDL phenotype B to phenotype A, and increased levels of the larger and perhaps more cardioprotective high-density lipoprotein particles. In contrast, atorvastatin preferentially lowered the concentration of small LDL particles without increasing levels of large LDL, and more effectively, reduced LDL particle numbers. Atorvastatin had a preferred LDL effect, whereas niacin had a preferred high-density lipoprotein effect.

The effect of aggressive versus standard lipid lowering by atorvastatin on diabetic dyslipidemia: the DALI study: a double-blind, randomized, placebo-controlled trial in patients with type 2 diabetes and diabetic dyslipidemia

OBJECTIVE

In patients with type 2 diabetes, intensive glucose regulation, although effective for microangiopathy, has not been shown to have unambiguous preventive effects on the occurrence of cardiovascular disease. Patients with diabetes show a characteristic dyslipidemia (high triglyceride level, low HDL cholesterol level). Aggressive reduction of triglycerides might be an effective method to reduce the cardiovascular risk in these patients.

RESEARCH DESIGN AND METHODS

A double-blind, placebo-controlled, randomized study to assess the effect of 30 weeks of administration of atorvastatin 10 and 80 mg on plasma triglyceride levels in 217 patients with type 2 diabetes and fasting triglyceride levels between 1.5 and 6.0 mmol/l.

RESULTS

Administration of atorvastatin 10 and 80 mg resulted in significant reductions (25 and 35%, respectively) of plasma triglyceride levels (both P < 0.001). The difference between 10 and 80 mg was not statistically significant (P > 0.5). Atorvastatin 10 mg provided significant reductions from baseline in total cholesterol (-30%, P < 0.001), LDL cholesterol (-40%, P < 0.001), and apolipoprotein B (-31%, P < 0.001), and significantly increased HDL cholesterol from baseline by 6% (P < 0.005). Atorvastatin 80 mg had a similar effect on HDL cholesterol (+5.2%, P < 0.005) but significantly decreased total cholesterol (-40%, P < 0.001), LDL cholesterol (-52%, P < 0.001), and apolipoprotein B (-40%, P < 0.001) more than atorvastatin 10 mg (P < 0.005). The side effects of atorvastatin 10 and 80 mg were similar and did not differ from the patients receiving placebo.

CONCLUSIONS

Administration of 10- and 80-mg doses of atorvastatin provides similar, significant reductions from baseline in triglyceride levels in patients with type 2 diabetes. A higher dose of atorvastatin improves cholesterol-related parameters. Both doses were well tolerated in this patient population.

Use of intravascular ultrasound to compare effects of different strategies of lipid-lowering therapy on plaque volume and composition in patients with coronary artery disease

BACKGROUND

We studied whether lipid-lowering therapy with atorvastatin (target LDL cholesterol [LDL-C] <100 mg/dL) compared with a moderate treatment regimen that used other lipid-lowering drugs led to a lesser progression of atherosclerosis and to different changes in plaque echogenicity in patients with coronary artery disease.

METHODS AND RESULTS

This study was a 12-month, open-label, randomized, multicenter trial, which used serial 3D intracoronary ultrasound to calculate plaque volume and plaque echogenicity. After transcatheter therapy, 131 patients were randomized (atorvastatin n=65, usual care n=66). The target plaque had to be a minor lesion (ie, a diameter stenosis of <50% on angiography). After 12 months, mean LDL-C was reduced from 155 to 86 mg/dL in the atorvastatin group and from 166 to 140 mg/dL in the usual care group. Mean absolute plaque volume showed a larger increase in the usual care group compared with the atorvastatin group (usual care 9.6+/-28.1 mm(3), atorvastatin 1.2+/-30.4 mm(3); P=0.191). The hyperechogenicity index of the plaque increased to a larger extent for the atorvastatin group than for the usual care group, with a significant treatment effect for the percent change (atorvastatin 42.2%, usual care 10.1%; P=0.021).

CONCLUSIONS

One year of lipid-lowering therapy to <100 mg/dL LDL-C most likely led to a slowdown of plaque growth of minor lesions. The significantly larger increase in plaque hyperechogenicity is most likely due to a change in plaque composition.

Effects of low doses of simvastatin and atorvastatin on high-density lipoprotein cholesterol levels in patients with hypercholesterolemia

BACKGROUND

Simvastatin 40 to 80 mg/d has been found to increase high-density lipoprotein cholesterol (HDL-C) levels significantly more than atorvastatin at equipotent doses (ie, 20-80 mg/d). Data on the effects of lower doses of the 2 drugs on HDL-C levels are conflicting.

OBJECTIVE

The purpose of this study was to investigate the effects of simvastatin 20 mg/d and atorvastatin 10 mg/d on HDL-C levels in patients with hypercholesterolemia.

METHODS

Patients with primary hypercholesterolemia (total cholesterol [TC] >250 mg/dL) who were not taking any lipid-lowering agents and who were following a low-fat diet were randomized to receive 1 of 2 treatments: simvastatin 20 mg/d or atorvastatin 10 mg/d. Serum TC, triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and HDL-C levels were measured using standard methods after 2 months of therapy. In a secondary analysis, lipids and lipoprotein cholesterol were measured after 1 year in patients who continued treatment.

RESULTS

Of the 240 patients enrolled (108 men and 132 women; age range, 23-77 years, mean [SEM] 56.7 [0.69]), 235 completed the study. After 2 months of therapy, TC, LDL-C, and serum TG levels decreased significantly versus baseline in both groups (P < 0.001), with no significant differences between treatment groups. HDL-C levels increased by 9.0% (P < 0.001 vs baseline) in the simvastatin group and by 4.3% (P < 0.02) in the atorvastatin group. The difference between the 2 groups in the percentage increase in HDL-C was statistically significant (P < 0.05). In 113 patients who continued treatment, HDL-C levels at 1 year were still significantly higher than baseline levels in the simvastatin group (6.3%, P = 0.034), but not in the atorvastatin group (2.8%, P = 0.587).

CONCLUSIONS

The findings from this study suggest that the HDL-C-increasing effect of simvastatin 20 mg is significantly greater than that of atorvastatin 10 mg. Since increasing HDL-C levels is thought to lower the risk for atherosclerosis and coronary heart disease, these results warrant further investigation.

Atorvastatin

Atorvastatin (Lipitor, Pfizer) is a safe and effective 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitor (statin). It is the most potent currently available statin in terms of lowering low-density lipoprotein (LDL) and total cholesterol levels. It was the first statin shown to lower triglycerides in patients with isolated hypertriglyceridaemia. It has a good safety profile. In common with other statins, it has non-lipid-lowering effects including improving endothelial function, antiproliferative actions on smooth muscle and reducing platelet aggregation. It also has anti-inflammatory effects and may reduce plasma glucose levels. Clinical trial evidence with this statin is currently limited. It did slightly reduce events in the AVERT trial comparing patients receiving coronary angioplasty with those receiving high-dose atorvastatin therapy and in the MIRACL study reduced ischemia in patients with acute coronary syndromes. Other end point trials are in progress.

Statin induced myopathy does not show up in MIBI scintigraphy

Statin induced myopathy is the most commonly seen side effect in users of this family of drugs. Their different forms present with either creatine phosphokinase (CK) elevation or not, signs of in vivo oxidation injury or not or a combination of both. The pathogenetic background, however, still remains obscure. As MIBI, beside myocardial and tumour scintigraphy, is useful in detecting muscle metabolic abnormalities, an increased uptake of MIBI in the diseased muscular segments could be expected. We investigated seven patients (five males, two females; aged 36-56 years) with statin induced myopathy with either elevated CK, isoprostanes or muscle pains at varying combinations. MIBI whole-body imaging was done immediately, the patients still being on the respective statin. Sixteen patients (six males, 10 females) suffering from lung or breast cancer and being on statins served as controls. No uptake abnormalities in any muscular segment either in the patients or the control group were seen. Thus, MIBI scintigraphy is not useful, apparently, in diagnosing and eventually localizing statin induced myopathy. These findings indicate that MIBI scintigraphy is of no help for diagnosis and gaining further insight into statin induced myopathy.

Linear IgA bullous dermatosis induced by atorvastatin

Linear IgA bullous dermatosis (LABD) is an autoimmune blistering skin disease characterized by circulating IgA antibodies binding the basement membrane zone. In most cases the origin is not clear, but in a minority of cases LABD is drug induced. We describe a patient in whom linear IgA disease developed shortly after beginning therapy with atorvastatin. In Western blotting analysis we detected IgA and IgG class antibodies targeting a 97-kd protein. To our knowledge this is the first reported case of atorvastatin-induced LABD.

Comparison of efficacy and safety of atorvastatin (10mg) with simvastatin (10mg) at six weeks. ASSET Investigators

The 6-week efficacy and safety of atorvastatin versus simvastatin was determined during a 54-week, open-label, multicenter, parallel-arm, treat-to-target study. In all, 1,424 patients with mixed dyslipidemia (triglyceride 200 to 600 mg/dl [2.26 to 6.77 mmol/L]) were stratified to 1 of 2 groups (diabetes or no diabetes). Patients were then randomized to receive either atorvastatin 10 mg/ day (n = 730) or simvastatin 10 mg/day (n = 694). Efficacy was determined by measuring changes from baseline in lipid parameters including low-density lipoprotein (LDL) cholesterol, total cholesterol, triglycerides, and apolipoprotein B. Compared with simvastatin, atorvastatin produced significantly greater (p < 0.0001) reductions from baseline in LDL cholesterol (37.2% vs 29.6%), total cholesterol (27.6% vs 21.5%), triglycerides (22.1% vs 16.0%), the ratio of LDL cholesterol to high-density lipoprotein (HDL) cholesterol (41.1% vs 33.7%), and apolipoprotein B (28.3% vs 21.2%), and a comparable increase from baseline in HDL cholesterol (7.4% vs 6.9%). Atorvastatin was also significantly (p < 0.0001) more effective than simvastatin at treating the overall patient population to LDL cholesterol goals (55.6% vs 38.4%). Fewer than 6% of patients in either treatment group experienced drug-attributable adverse events, which were mostly mild to moderate in nature. Diabetic patients treated with either statin had safety characteristics similar to nondiabetics, with atorvastatin exhibiting superior efficacy to simvastatin. In conclusion, atorvastatin, at a dose of 10 mg/day, is more effective than simvastatin 10 mg/day at lowering lipids and reaching LDL cholesterol goals in patients with mixed dyslipidemia. Both statins are well tolerated with safety profiles similar to other members of the statin class.

Effect of atorvastatin 15 mg/week on serum lipids in patients with hypercholesterolemia

Atorvastatin 15 mg/week was administered to 21 patients with hypercholesterolemia for 2 months. The mean low-density lipoprotein concentration decreased by 20% after treatment.

Fibrinogen response with simvastatin versus atorvastatin in familial hypercholesterolemia

The clinical and biochemical determinants of the fibrinogen response to simvastatin or atorvastatin therapy were assessed in 130 patients with severe polygenic or familial hypercholesterolemia treated in a randomized open-trial format design. Hyperfibrinogenemia was associated with atorvastatin, baseline fibrinogen, and initial concentration and change in concentration of apolipoprotein B or low-density lipoprotein cholesterol.

Influence of age on the pharmacokinetics of vapiprost, a thromboxane A2 receptor antagonist, and platelet aggregation: comparison of pharmacokinetics by routine approach and population pharmacokinetics

The effects of a single-dose oral administration of a thromboxane A2 receptor antagonist, vapiprost (SN-309), on pharmacokinetic profile and inhibition of platelet aggregation were investigated in six healthy elderly volunteers (age: 65-72 years) and the influence of age on these parameters was studied by comparison with the results obtained in phase-I data involving healthy young participants. Although direct comparison of pharmacokinetic parameters was inappropriate because of different models, high Cmax and AUC values were obtained on comparison with the young. The inhibition of platelet aggregation in platelet rich plasma induced by U-46619 or collagen was rapidly established and remained suppressed for more than 8 h, although the effect was short-acting compared with the inhibition period in the young. This suggests that dose adjustment in the elderly is unnecessary In addition to a routine pharmacokinetic approach to determine the time-profile of vapiprost, population pharmacokinetics were studied using data from 51 volunteers in five clinical trials including the two above-mentioned studies. By fitting 812 plasma-monitoring points into the two-compartment model, the effects of several factors including age on parameters were investigated, based on the nonlinear mixed effect model. Clearance in the elderly attenuated 82.2% of that in the young, the distribution volume varied with platelet counts and delayed absorption was observed in volunteers with, rather than without, food intake. Closer bridging studies with other countries have resulted in the current local situation of abbreviating phase-III studies. Consequently to clarify the pharmacokinetic profile of the elderly in Japan and other countries, the population pharmacokinetics approach based on the data in the various phase I-II trials is useful.