Drug and bile acid transporters in rosuvastatin hepatic uptake: function, expression, and pharmacogenetics

BACKGROUND & AIMS: The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins, target liver HMG-CoA and are of proven benefit in the prevention of coronary heart disease. Rosuvastatin is an effective statin notable for liver selectivity and lack of significant metabolism. We assessed the extent and relevance of hepatic transporters to rosuvastatin uptake. METHODS: Transporters involved in rosuvastatin uptake were determined through heterologous expression of multiple human and rat uptake transporters. Human organic anion transporting polypeptide (OATP) 1B1 and sodium-dependent taurocholate cotransporting polypeptide (NTCP) allelic variants were also assessed. Expression of OATP and NTCP messenger RNA and protein was determined from a bank of human liver samples. RESULTS: Multiple OATP family members, including 1B1, 1B3, 2B1, and 1A2, were capable of rosuvastatin transport. Naturally occurring polymorphisms in OATP1B1, including *5, *9, *15, and *18, were associated with profound loss of activity toward rosuvastatin. Interestingly, the major human hepatic bile acid uptake transporter NTCP, but not rat Ntcp, also transported rosuvastatin. Human hepatocyte studies suggested that NTCP alone accounted for approximately 35% of rosuvastatin uptake. Remarkably, NTCP*2, a variant known to have a near complete loss of function for bile acids, exhibited a profound gain of function for rosuvastatin. Quantitative messenger RNA analysis revealed marked intersubject variability in expression of OATPs and NTCP. CONCLUSIONS: Multiple transporters mediate the overall hepatic uptake of rosuvastatin, and NTCP may be a heretofore unrecognized transporter important to the disposition of rosuvastatin and possibly other drugs/statins in clinical use. Accordingly, transporter expression and polymorphisms may be key determinants of intersubject variability in response to statin therapy in general.     

Pitavastatin - pharmacological profile from early phase studies

Pitavastatin has been designed as a synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor with a novel cyclopropyl moiety that results in several differences compared to other statins. These include effective inhibition of cholesterol synthesis and increased lipoprotein lipase expression at lower doses than other statins, and significant high-density lipoprotein-cholesterol and apolipoprotein A1-elevating activity that persists with time. The safety, tolerability and pharmacokinetics of pitavastatin and its major metabolite, pitavastatin lactone, have been investigated in a variety of patient groups with similar results, which suggests dosage adjustments are not required for gender, age or race. In healthy subjects, pitavastatin is well tolerated at the approved doses with no serious adverse events. The bioavailability of pitavastatin is, at 60%, higher than that of any other statin and the majority of the bioavailable fraction of an oral dose is excreted unchanged in the bile. The entero-hepatic circulation of unchanged drug contributes to the prolonged duration of action and allows once-daily, any-time dosing. Pitavastatin is only slightly metabolised by cytochrome P450 (CYP) 2C9 and not at all by CYP3A4. Neither pitavastatin nor its lactone form, have inhibitory effects on CYP, and CYP3A4 inhibitors have no effect on pitavastatin concentrations. Moreover, P-glycoprotein-mediated transport does not play a major role in the drug's disposition and pitavastatin does not inhibit P-glycoprotein activity. Pitavastatin is transported into the liver by several hepatic transporters but OATP1B1 inhibitors have relatively little effect on plasma concentrations compared with other statins. In general, interactions, except with multi-transporter inhibitors like ciclosporin, are not clinically significant. Consequently, pitavastatin has minimal drug-food and drug-drug interactions making it a treatment option in the large group of dyslipidaemic people that require multidrug therapy.     

Pitavastatin: Efficacy and Safety Profiles of A Novel Synthetic HMG‐CoA Reductase Inhibitor

The use of 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase inhibitors, statins, has been shown to reduce major cardiovascular events in both primary and secondary prevention, and statins became one of the most widely prescribed classes of drugs throughout the world. Previously, statins have been well tolerated and have shown favorable safety profiles. However, the voluntary withdrawal of cerivastatin from the market because of a disproportionate number of reports of rhabdomyolysis‐associated deaths drew attention to the pharmacokinetic profile of statins, which may possibly have been related to serious drug‐drug interactions. Pitavastatin (NK‐104, previously called itavastatin or nisvastatin, Kowa Company Ltd., Tokyo) is a novel, fully synthetic statin, which has a potent cholesterol‐lowering action. The short‐term and long‐term lipid‐modifying effects of pitavastatin have already been investigated in subjects with primary hypercholesterolemia, heterozygous familial hypercholesterolemia, hypertriglyceridemia, and type‐2 diabetes mellitus accompanied by hyperlipidemia. Within the range of daily doses from 1 to 4 mg, the efficacy of pitavastatin as a lipid‐lowering drug seems to be similar, or potentially superior, to that of atorvastatin. According to the results of pharmacokinetic studies, pitavastatin showed favorable and promising safety profile; it was only slightly metabolized by the cytochrome P450 (CYP) system, its lactone form had no inhibitory effects on the CYP3A4‐mediated metabolism of concomitantly administered drugs; P‐glycoprotein‐mediated transport did not play a major role in its disposition, and pitavastatin did not inhibit P‐glycoprotein activity. It could be concluded that pitavastatin could provide a new and potentially better thera‐peutic choice for lipid‐modifying therapy than do the currently available statins. The ef‐ficacy and safety of higher dose treatment, as well as its long‐term effects in the pre‐vention of coronary artery disease, should be further investigated.     

New insights in bilirubin metabolism and their clinical implications

Bilirubin,a major end product of heme breakdown,is an important constituent of bile,responsible for its characteristic colour.Over recent decades,our understanding of bilirubin metabolism has expanded along with the processes of elimination of other endogenous and exogenous anionic substrates,mediated by the action of multiple transport systems at the sinusoidal and canalicular membrane of hepatocytes.Several inherited disorders characterised by impaired bilirubin conjugation(Crigler-Najjar syndrome typeⅠand typeⅡ,Gilbert syndrome)or transport(Dubin-Johnson and Rotor syndrome)result in various degrees of hyperbilirubinemia of either the predominantly unconjugated or predominantly conjugated type.Moreover,disrupted regulation of hepatobiliary transport systems can explain jaundice in many acquired liver disorders.In this review,we discuss the recent data on liver bilirubin handling based on the discovery of the molecular basis of Rotor syndrome.The data show that a substantial fraction of bilirubin conjugates is primarily secreted by MRP3 at the sinusoidal membrane into the blood,from where they are subsequently reuptaken by sinusoidal membrane-bound organic anion transporting polypeptides OATP1B1 and OATP1B3.OATP1B proteins are also responsible for liver clearance of bilirubin conjugated in splanchnic organs,such as the intestine and kidney,and for a number of endogenous compounds,xenobiotics and drugs.Absence of one or both OATP1B proteins thus may have serious impact on toxicity of commonly used drugs cleared by this system such as statins,sartans,methotrexate or rifampicin.The liverblood cycling of conjugated bilirubin is impaired in cholestatic and parenchymal liver diseases and this impairment most likely contributes to jaundice accompanying these disorders.     

Considerations in the treatment of dyslipidemia associated with chronic kidney failure and renal transplantation

In comparison to the general population, individuals with chronic kidney failure experience an increased risk for atherosclerotic cardiovascular disease attributed predominantly to pronounced abnormalities in lipid metabolism. The emerging consensus is that patients with chronic kidney failure should be treated aggressively for dyslipidemia. Statins reduce the risk of cardiovascular disease in a range of at-risk patients; this class of lipid-lowering drugs should be considered first-line treatment of dyslipidemia observed in renal disease patients. Although the statins share a common lipid-lowering effect, there are differences within this class of drugs. The statins differ in their pharmacokinetic effects, drug interaction profiles, and risk of myotoxicity. This article characterizes the dyslipidemia observed in the renal failure setting and reviews the therapeutic considerations involved in selecting among the statins. Lovastatin, simvastatin, pravastatin, fluvastatin, atorvastatin, and rosuvastatin are the available statins in the United States.     

Pitavastatin - from clinical trials to clinical practice

Managing dyslipidaemia is central to the management of cardiovascular disease. Most statins can reduce the 5-year incidence of major vascular events by 20%. In Europe, however, up to 53% of statin-treated patients fail to attain their low-density lipoprotein-cholesterol (LDL-C) target and residual risk remains high, even when targets are reached. Reasons for this include under-treatment due to insufficient starting doses/failure to uptitrate; poor persistence with therapy due to adverse events (AEs) or drug-drug interactions (DDIs); and failure to treat non-LDL-C risk factors, such as high triglycerides (TGs) and low high-density lipoprotein-C (HDL-C). Phase III and IV studies demonstrate that pitavastatin 1-4 mg has a similar or greater lipid-lowering efficacy to atorvastatin 10-20 mg, simvastatin 20-40 mg and pravastatin 10-40 mg, and is well-tolerated with a low incidence of adverse events (AEs). The SmPC recommends a usual starting dose of 1 mg, with dose-escalation if required. However, since the lower doses (1-2 mg) bring the majority of people with hypercholesterolaemia or combined dyslipidaemia to LDL-C target, the need for pitavastatin uptitration and the risk of under-treatment is low. In addition to reducing LDL-C, pitavastatin has a sustained beneficial effect on other atherogenic lipids, including TGs and HDL-C. Recent studies reveal that pitavastatin reduces coronary atheroma plaque volume as efficiently as atorvastatin and can improve the composition of coronary plaques, effects that are likely to reduce the risk of CV endpoints in patients with acute coronary syndrome. Moreover, pitavastatin has a number of pleiotropic effects that can reduce inflammation and lipid oxidation, improve endothelial function, reduce the metabolic changes associated with adiposity, and improve glucose metabolism and renal function. Compared to other statins, pitavastatin has a unique metabolic profile that could reduce the risk of DDIs, thereby providing a clear benefit in patients receiving polypharmacy. Overall, pitavastatin is a well tolerated and effective treatment for patients with hypercholesterolaemia and combined dyslipidaemia, especially in those with low HDL-C, and it should help improve LDL-C-target attainment rates by reducing the risk of under-treatment, minimising AE rates, and reducing the risk of DDIs in people requiring polypharmacy. Future and ongoing studies will directly compare the effects of pitavastatin vs. other statins on hard clinical endpoints.     

Organic anion transporter 1B1: an important factor in hepatic thyroid hormone and estrogen transport and metabolism

Sulfation is an important pathway in the metabolism of thyroid hormone and estrogens. Sulfation of estrogens is reversible by estrogen sulfatase, but sulfation of thyroid hormone accelerates its degradation by the type 1 deiodinase in liver. Organic anion transporters (OATPs) are capable of transporting iodothyronine sulfates such as T4 sulfate (T4S), T3S, and rT3S or estrogen sulfates like estrone sulfate (E1S), but the major hepatic transporter for these conjugates has not been identified. A possible candidate is OATP1B1 because model substrates for this transporter include the bilirubin mimic bromosulfophthalein (BSP) and E1S, and it is highly and specifically expressed in liver. Therefore, OATP1B1-transfected COS1 cells were studied by analysis of BSP, E1S, and iodothyronine sulfate uptake and metabolism. Two Caucasian populations (155 blood donors and 1012 participants of the Rotterdam Scan Study) were genotyped for the OATP1B1-Val174Ala polymorphism and associated with bilirubin, E1S, and T4S levels. OATP1B1-transfected cells strongly induced uptake of BSP, E1S, T4S, T3S, and rT3S compared with mock-transfected cells. Metabolism of iodothyronine sulfates by cotransfected type 1 deiodinase was greatly augmented in the presence of OATP1B1. OATP1B1-Val174 showed a 40% higher induction of transport and metabolism of these substrates than OATP1B1-Ala174. Carriers of the OATP1B1-Ala174 allele had higher serum bilirubin, E1S, and T4S levels. In conclusion, OATP1B1 is an important factor in hepatic transport and metabolism of bilirubin, E1S, and iodothyronine sulfates. OATP1B1-Ala174 displays decreased transport activity and thereby gives rise to higher bilirubin, E1S, and T4S levels in carriers of this polymorphism.     

Rosuvastatin: a new HMG-CoA reductase inhibitor for the treatment of hypercholesterolemia

Because of their excellent tolerability and their positive impact on lipid parameters, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have become the drugs of first choice for many patients with dyslipidemia. Rosuvastatin is an investigational statin in the U.S. with a number of favorable characteristics, which include low lipophilicity, high hepatocyte selectivity, minimal metabolism, and a low propensity for cytochrome P450 drug interactions. Rosuvastatin has been studied at doses ranging from 1 to 80 mg. In comparative clinical trials, rosuvastatin given at 5 to 10 mg/day reduced low-density lipoprotein cholesterol to a significantly greater extent than atorvastatin 10 mg/day, pravastatin 20 mg/day, and simvastatin 20 mg/day. In addition, rosuvastatin exhibited beneficial effects on other lipid parameters such as high-density lipoprotein cholesterol and triglycerides. Rosuvastatin's safety profile was demonstrated to be similar to those of other statins. Given its favorable pharmacokinetic and pharmacodynamic characteristics, rosuvastatin is likely to become a valuable addition to the statin drug class. The author reviews the pharmacologic and pharmacokinetic properties of this new statin.     

Effects of statin treatments and polymorphisms in UGT1A1 and SLCO1B1 on serum bilirubin levels in Chinese patients with hypercholesterolaemia

ObjectivesIn vitro and animal studies showed that statins could increase bilirubin levels by activation of haem oxygenase-1, whereas the effect of statins on serum bilirubin levels in humans remains controversial. The organic anion transporting polypeptide 1B1 (OATP1B1, gene SLCO1B1) and UDP-glucuronosyltransferase 1A1 (UGT1A1) play an important role in the disposition of bilirubin. This study investigated 1) whether common polymorphisms in UGT1A1 and SLCO1B1 influence bilirubin levels; 2) whether statin treatments affect bilirubin levels; and 3) whether the polymorphisms examined influence the drug effect.MethodsAssociations between common polymorphisms in UGT1A1 and SLCO1B1 and the serum bilirubin levels on no lipid-lowering treatment were analyzed in 379 Chinese patients with hypercholesterolaemia. Effects of simvastatin 40 mg daily and rosuvastatin 10 mg daily on the bilirubin levels were compared in 236 subjects with good compliance to both statins.ResultsThe UGT1A1 polymorphisms associated with reduced enzyme activity were significantly associated with increased baseline bilirubin levels. The bilirubin levels were increased from a geometric mean (95% CI) of 10.9 (10.3–11.4) μmol/L at baseline to 11.6 (11.1–12.0) μmol/L with rosuvastatin and 12.5 (11.9–13.0) μmol/L with simvastatin and the increase was greater with simvastatin (P < 0.001). There was no relationship between polymorphisms in UGT1A1 or SLCO1B1 and changes in bilirubin levels with the two statins.ConclusionsThis study showed that the polymorphisms in UGT1A1, but not SLCO1B1, were associated with serum bilirubin levels in Chinese patients. Statins increased bilirubin levels and this effect was independent of the polymorphisms in UGT1A1 and SLCO1B1.     

Real-World Analyses of the Safety Outcome among a General Population Treated with Statins: An Asian Population-Based Study

Aim: The safety concern of statins is still a major issue for Asians. The aim of this study is to compare the risk of statin-associated adverse events among potent statins. Methods: We included patients from the Taiwan National Health Insurance Research Database who had been treated with atorvastatin, rosuvastatin, or pitavastatin and were without diabetes at baseline. They were classified into three groups: usual-dose statin (atorvastatin 10 mg/d or rosuvastatin 5–10 mg/d), high-dose statin (atorvastatin 20–40 mg/d and rosuvastatin 20 mg/d), and pitavastatin (2–4 mg/d). The primary endpoint is a composite of safety events, including hepatitis, myopathy, and new-onset diabetes mellitus (NODM). We matched age, sex, and year of recruitment among the three groups (n=50,935 in each group) and then used the multivariate Cox proportional hazards model to evaluate the relation between the safety endpoint and different statin groups. Results: After a mean follow-up of 3.08±0.83 years, the safety events occurred in 9.84% in the pitavastatin group, 10.88% in the usual-dose statin group, and 10.49% in high-dose statin group. The multivariate Cox proportional hazards model indicated that usual-dose statin and high-dose statin were associated with a higher risk of the composite safety events compared with pitavastatin (adjusted hazard ratio [aHR]: 1.12, 95% confidence interval [CI]: 1.08–1.17 for usual-dose statin and aHR: 1.06, 95% CI: 1.02–1.10 for high-dose statin). The risks of hepatitis requiring hospitalization and NODM were especially lower in pitavastatin group. Conclusions: Compared with atorvastatin and rosuvastatin, pitavastatin might be associated with a lower risk of safety events in Asians.     

Transporters in human platelets: physiologic function and impact for pharmacotherapy

Platelets store signaling molecules (eg, serotonin and ADP) within their granules. Transporters mediate accumulation of these molecules in platelet granules and, on platelet activation, their translocation across the plasma membrane. The balance between transporter-mediated uptake and elimination of signaling molecules and drugs in platelets determines their intracellular concentrations and effects. Several members of the 2 major transporter families, ATP-binding cassette (ABC) transporters and solute carriers (SLCs), have been identified in platelets. An example of an ABC transporter is MRP4 (ABCC4), which facilitates ADP accumulation in dense granules. MRP4 is a versatile transporter, and various additional functions have been proposed, notably lipid mediator release and a role in aspirin resistance. Several other ABC proteins have been detected in platelets with functions in glutathione and lipid homeostasis. The serotonin transporter (SERT, SLC6A4) in the platelet plasma membrane represents a well-characterized example of the SLC family. Moreover, recent experiments indicate expression of OATP2B1 (SLCO2B1), a high affinity transporter for certain statins, in platelets. Changes in transporter localization and expression can affect platelet function and drug sensitivity. This review summarizes available data on the physiologic and pharmacologic role of transporters in platelets.     

The Safety of HMG-CoA Reductase Inhibitors in Special Populations at High Cardiovascular Risk

Controlled clinical studies and clinical experience over many years have proven that virtually all patients benefit from lipid-lowering therapy with statins, even those with normal LDL cholesterol levels. Several recent large outcome trials have further demonstrated the clinical benefits and safety of statins in patients with a wide-range of high risks for cardiovascular disease. Those patients at highest absolute cardiovascular risk generally have the most to gain from statin therapy. A variety of statins are available to lower plasma lipids to guideline levels, but all differ in their pharmacokinetic properties, drug interaction profiles, and risk of myotoxicity. This has been highlighted by the withdrawal of cerivastatin from the market as a result of serious safety concerns. This review examines the safety and effectiveness of statins in special populations at high risk of cardiovascular disease—patients with coronary heart disease, dyslipidaemia, diabetes, hypertension, nephrotic disease, HIV, organ transplant patients and the elderly—with a focus on clinically relevant differences in the properties of individual statins that may influence the risk of drug interactions and side effects.     

Interactions of grapefruit juice and cardiovascular medications: A potential risk of toxicity

Recently, drug interactions with grapefruit juice (GFJ) have received considerable attention from basic scientists, physicians, industry and drug regulatory agencies. GFJ has been shown to inhibit cytochrome P-450 3A4 isoenzyme and P-glycoprotein transporters in the intestine and liver. The GFJ-induced inhibitory effects are considered to be responsible for alterations in drug bioavailability, and pharmacokinetic and pharmacodynamic changes when drugs are ingested concurrently with GFJ. However, little or no interaction is observed when GFJ is taken concomitantly with parentally administered drugs. It is well known that risk factors for cardiovascular disease increase with advancing age, while hepatic metabolic activity decreases in elderly individuals. It is, therefore, possible that the combination of GFJ and cardiovascular medications may pose a health risk, especially in elderly patients. A number of studies have shown interactions of GFJ with cardiovascular drugs such as calcium-channel blockers, angiotensin II receptor antagonists, beta-blockers, and statins. Such interactions are likely to change the pharmacokinetics and pharmacodynamics of these drugs, consequently causing undesirable health effects. Therefore, health care professionals and the public need to be advised of the potential risks associated with the concomitant use of GFJ and interacting medications, especially cardiovascular drugs and agents with a narrow therapeutic index. This review focuses on the adverse interactions of GFJ and cardiovascular medications, and the proposed underlying mechanisms of such interactions.     

Drug interactions with solid tumour-targeted therapies

Drug interactions are an on-going concern in the treatment of cancer, especially when targeted therapies, such as tyrosine kinase inhibitors (TKI) or mammalian target of rapamycin (mTOR) inhibitors, are being used. The emergence of elderly patients and/or patients with both cancer and other chronic co-morbidities leads to polypharmacy. Therefore, the risk of drug–drug interactions (DDI) becomes a clinically relevant issue, all the more so as TKIs and mTOR inhibitors are essentially metabolised by cytochrome P450 enzymes. These DDIs can result in variability in anticancer drug exposure, thus favouring the selection of resistant cellular clones or the occurrence of toxicity. This review provides a comprehensive overview of DDIs that involve targeted therapies approved by the FDA for the treatment of solid tumours for more than 3 years (sorafenib, sunitinib, erlotinib, gefitinib, imatinib, lapatinib, everolimus, temsirolimus) and medicinal herb or drugs. This review also provides some guidelines to help oncologists and pharmacists in their clinical practice.     

ABC of oral bioavailability: transporters as gatekeepers in the gut

MDR1 (ABCB1), MRP2 (ABCC2), and BCRP (ABCG2) are members of the family of ATP binding cassette (ABC) transporters. These are plasma membrane transporters that are expressed in various organs. The role of MDR1 and MRP2 in the hepatobiliary system is well defined; both contribute to bile formation by transport of drugs, toxins, and waste products across the canalicular membrane. As they transport exogenous and endogenous substances, they reduce the body load of potentially harmful compounds. The role of ABCG2, which is also expressed in the canalicular membrane of hepatocytes, has not yet been fully characterised. All three proteins are also expressed in the apical membrane of enterocytes where they probably control oral availability of many substances. This important "gatekeeper" function of ABC transporters has been recognised recently and is currently under further investigation. Expression and activity of these transporters in the gut may differ between individuals, due to genetic polymorphisms or pathological conditions. This will lead to individual differences in bioavailability of different drugs, toxins, and (food derived) carcinogens. Recent information on substrates, transport mechanisms, function, and regulation of expression of MDR1, MRP2, and BCRP in different species is summarised in this review.     

Effects of Uremic Serum Residue on OATP1B1‐ and OATP1B3‐Mediated Pravastatin Uptake in OATP‐Expressing HEK293 Cells and Human Hepatocytes

Patients with end‐stage renal disease have increased plasma concentrations of statins, which is a risk factor for rhabdomyolysis, as well as elevated levels of uremic toxins (UTs). We investigated the effects of uremic serum residue and UTs on organic anion‐transporting peptide (OATP1B1)‐ and OATP1B3‐mediated pravastatin uptake. We evaluated the effects of normal serum residue with four UTs (hippuric acid, 3‐carboxy‐4‐methyl‐5‐propyl‐2‐furan propionate, indole‐3‐acetic acid, and 3‐indoxyl sulfate) and uremic serum residue on pravastatin uptake by OATP1B1‐ or OATP1B3‐expressing HEK293 cells. Furthermore, we assessed the contribution of each transporter using cryopreserved human hepatocytes. Uremic serum residue and UTs significantly inhibited OATP1B1‐mediated pravastatin uptake. Uremic serum residue accelerated OATP1B3‐mediated pravastatin uptake, while UTs had no effect. There was no difference in pravastatin uptake between uremic‐ and normal serum residue‐treated hepatocytes. The results suggest that the effects of uremic serum on pravastatin hepatic uptake may be considered negligible in end‐stage renal disease patients.     

Pitavastatin: an overview

Compared to other statins, pitavastatin is a highly potent 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitor and an efficient hepatocyte low-density lipoprotein-cholesterol (LDL-C) receptor inducer. Its characteristic structure (heptenoate as the basic structure, a core quinoline ring and side chains that include fluorophenyl and cyclopropyl moieties) provides improved pharmacokinetics and significant LDL-C-lowering efficacy at low doses. Unlike other statins, the cyclopropyl group on the pitavastatin molecule appears to divert the drug away from metabolism by cytochrome P450 (CYP) 3 A4 and allows only a small degree of clinically insignificant metabolism by CYP2C9. As a result, pitavastatin is minimally metabolized; most of the bioavailable fraction of an oral dose is excreted unchanged in the bile and is reabsorbed by the small intestine ready for enterohepatic recirculation. This process probably accounts for pitavastatin's increased bioavailability relative to most other statins and contributes to its prolonged duration of action. In addition to its potent LDL-C-lowering efficacy, a number of pleiotropic benefits that might lead to a reduction in residual risk have been suggested in vitro. These include beneficial effects on endothelial function, stabilisation of the coronary plaque, anti-inflammatory effects and anti-oxidation. With regard to the clinical safety and efficacy of pitavastatin, the Phase IV Collaborative study of Hypercholesterolemia drug Intervention and their Benefits for Atherosclerosis prevention (CHIBA study) showed similar changes in lipid profile with pitavastatin and atorvastatin in Japanese patients with hypercholesterolemia. However, a subgroup analysis of the CHIBA study showed that pitavastatin produced more significant changes from baseline in LDL-C, TG, and HDL-C in patients with hypercholesterolemia and metabolic syndrome. The clinical usefulness of pitavastatin has been further demonstrated in a number of Japanese patient groups with hypercholesterolemia, including those with insulin resistance, low levels of high-density lipoprotein-cholesterol (HDL-C), high levels of C-reactive protein, and chronic kidney disease. Finally, the Japan Assessment of Pitavastatin and AtorvastatiN in Acute Coronary Syndrome (JAPAN-ACS) study showed that pitavastatin induces plaque regression in patients with ACS, which suggests potential benefits for pitavastatin in reducing CV risk.     

A randomized, double-blind trial comparing the efficacy and safety of pitavastatin versus pravastatin in patients with primary hypercholesterolemia

Pitavastatin (p-INN) is a novel and fully synthetic 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, with a cholesterol-lowering action stronger than that of other statins currently in use. A 12-week, multi-center, randomized, double-blind, controlled study was conducted to confirm the efficacy and safety of pitavastatin compared with pravastatin, an agent for using to reduce low density lipoprotein cholesterol (LDL-C) in hypercholesterolemic patients. Patients were recruited at 43 institutes in Japan. Following more than 4 weeks run-in period, 240 patients were randomized to receive 2 mg of pitavastatin or 10 mg of pravastatin daily. At 12 weeks post-randomization, the pitavastatin group showed significantly lower LDL-C levels by -37.6% from baseline compared with -18.4% in the pravastatin group (P<0.05). Pitavastatin also significantly lowered total cholesterol (TC) by -28.2% compared with -14.0% of pravastatin (P<0.05). The LDL-C target level of <140 mg/dl was attained in 75% of the patients treated with pitavastatin, compared with 36% of those in the pravastatin group (P<0.05). Pitavastatin also significantly reduced triglycerides (TG), apo B, C-II and C-III, compared with pravastatin, and increased HDL-C, apo A-I and A-II, to the same extent of pravastatin. Safety was assessed by monitoring adverse events and measuring clinical laboratory parameters. The adverse event profile was similar for both treatment groups and neither treatment caused clinically relevant laboratory abnormalities. These results indicated that pitavastatin was more effective than pravastatin, and both drugs were well-tolerated in the treatment of hypercholesterolemia.     

Rosuvastatin: A Highly Effective New HMG‐CoA Reductase Inhibitor

Rosuvastatin, a new statin, has been shown to possess a number of advantageous pharmacological properties, including enhanced HMG‐CoA reductase binding characteristics, relative hydrophilicity, and selective uptake into/activity in hepatic cells. Cytochrome P450 (CYP) metabolism of rosuvastatin appears to be minimal and is principally mediated by the 2C9 enzyme, with little involvement of 3A4; this finding is consistent with the absence of clinically significant pharmacokinetic drug‐drug interactions between rosuvastatin and other drugs known to inhibit CYP enzymes. Dose‐ranging studies in hypercholesterolemic patients demonstrated dose‐dependent effects in reducing low‐density lipoprotein cholesterol (LDL‐C) (up to 63%), total cholesterol, and apolipoprotein (apo) B across a 1‐ to 40‐mg dose range and a significant 8.4% additional reduction in LDL‐C, compared with atorvastatin, across the dose ranges of the two agents. Rosuvastatin has also been shown to be highly effective in reducing LDL‐C, increasing high‐density lipo‐protein cholesterol (HDL‐C), and producing favorable modifications of other elements of the atherogenic lipid profile in a wide range of dyslipidemic patients. In patients with mild to moderate hypercholesterolemia, rosuvastatin has been shown to produce large decreases in LDL‐C at starting doses, thus reducing the need for subsequent dose titration, and to allow greater percentages of patients to attain lipid goals, compared with available statins. The substantial LDL‐C reductions and improvements in other lipid measures with rosuvastatin treatment should facilitate achievement of lipid goals and reduce the requirement for combination therapy in patients with severe hypercholesterolemia. In addition, rosuvastatin's effects in reducing triglycerides, triglyceride‐containing lipoproteins, non‐HDL‐C, and LDL‐C and increasing HDL‐C in patients with mixed dyslipidemia or elevated triglycerides should be of considerable value in enabling achievement of LDL‐C and non‐HDL‐C goals in the numerous patients with combined dyslipidemias or metabolic syndrome who require lipid‐lowering therapy. Rosuvastatin is well tolerated alone, and in combination with fenofibrate, extended‐release niacin, and cholestyramine, and has a safety profile similar to that of currently marketed statins. A large, long‐term clinical trials program is under way to investigate the effects of rosuvastatin on atherosclerosis and cardiovascular morbidity and mortality.