The effects of concurrent atorvastatin therapy on the pharmacokinetics of intravenous midazolam

Evaluation of Pharmacokinetic Drug Interactions of the Direct-Acting Antiviral Agents Elbasvir and Grazoprevir with Pitavastatin, Rosuvastatin, Pravastatin, and Atorvastatin in Healthy Adults

BACKGROUND

Many people infected with hepatitis C virus have comorbidities, including hypercholesterolemia, that are treated with statins. In this study, we evaluated the drug-drug interaction potential of the hepatitis C virus inhibitors elbasvir (EBR) and grazoprevir (GZR) with statins. Pitavastatin, rosuvastatin, pravastatin, and atorvastatin are substrates of organic anion-transporting polypeptide 1B, whereas rosuvastatin and atorvastatin are also breast cancer resistance protein substrates.

METHODS

Three open-label, phase I clinical trials in healthy adults were conducted with multiple daily doses of oral GZR or EBR/GZR and single oral doses of statins. Trial 1: GZR 200 mg plus pitavastatin 10 mg. Trial 2: Part 1, GZR 200 mg plus rosuvastatin 10 mg, then EBR 50 mg/GZR 200 mg plus rosuvastatin 10 mg; Part 2, EBR 50 mg/GZR 200 mg plus pravastatin 40 mg. Trial 3: EBR 50 mg/GZR 200 mg plus atorvastatin 10 mg.

RESULTS

Neither GZR nor EBR pharmacokinetics were meaningfully affected by statins. Coadministration of EBR/GZR did not result in clinically relevant changes in the exposure of pitavastatin or pravastatin. However, EBR/GZR increased exposure to rosuvastatin (126%) and atorvastatin (94%). Coadministration of statins plus GZR or EBR/GZR was generally well tolerated.

CONCLUSIONS

Although statins do not appreciably affect EBR or GZR pharmacokinetics, EBR/GZR can impact the pharmacokinetics of certain statins, likely via inhibition of breast cancer resistance protein but not organic anion-transporting polypeptide 1B. Coadministration of EBR/GZR with pitavastatin or pravastatin does not require adjustment of either dose of statin, whereas the dose of rosuvastatin and atorvastatin should be decreased when coadministered with EBR/GZR.

Pharmacokinetic interaction between fimasartan and atorvastatin in healthy male volunteers

Introduction

Major cardiovascular risk factors, including hypertension and dyslipidemia, are often comorbidities, frequently leading to concurrent prescription of angiotensin receptor blockers and 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins). The study’s objective was to evaluate the effect of coadministration of fimasartan and atorvastatin on their pharmacokinetics (PKs).

Subjects and methods

In a randomized, open-label, three-period, six-sequence, crossover, multiple-dose study, 36 healthy subjects received 120 mg fimasartan, 40 mg atorvastatin, or both (based on their assigned sequence) once daily for 7 days in each period, with a 7-day washout between periods. Blood samples for the PK analysis of fimasartan, atorvastatin, and the 2-hydroxy atorvastatin metabolite were collected up to 48 h after the last dose.

Results

The coadministration of fimasartan and atorvastatin was well tolerated and led to an increase in the peak concentration and area under the concentration–time curve at steady state of fimasartan by 2.18-fold (95% confidence interval [CI], 1.79–2.65) and 1.35-fold (95% CI, 1.26–1.43) and those of atorvastatin increased by 1.82-fold (95% CI, 1.51–2.18) and 1.12-fold (95% CI, 1.04–1.22), respectively.

Conclusion

Coadministration increased the systemic exposures of fimasartan and atorvastatin, but the clinical significance of this finding needs to be evaluated with respect to exposure responses and clinical outcomes.

The effect of atorvastatin treatment on serum oxysterol concentrations and cytochrome P450 3A4 activity

AIMS

Atorvastatin is known to both inhibit and induce the cytochrome P450 3A4 (CYP3A4) enzyme in vitro. Some clinical studies indicate that atorvastatin inhibits CYP3A4 but there are no well-controlled longer term studies that could evaluate the inducing effect of atorvastatin. We aimed to determine if atorvastatin induces or inhibits CYP3A4 activity as measured by the 4β-hydroxycholesterol to cholesterol ratio (4βHC : C).

METHODS

In this randomized, double-blind, placebo-controlled 6 month study we evaluated the effects of atorvastatin 20 mg day(-1) (n = 15) and placebo (n = 14) on oxysterol concentrations and determined if atorvastatin induces or inhibits CYP3A4 activity as assessed by the 4βHC : C index. The respective 25-hydroxycholesterol and 5α,6α-epoxycholesterol ratios were used as negative controls.

RESULTS

Treatment with atorvastatin decreased 4βHC and 5α,6α-epoxycholesterol concentrations by 40% and 23%, respectively. The mean 4βHC : C ratio decreased by 13% (0.214 ± 0.04 to 0.182 ± 0.04, P = 0.024, 95% confidence interval (CI) of the difference -0.0595, -0.00483) in the atorvastatin group while no significant change occurred in the placebo group. The difference in change of 4βHC : C between study arms was statistically significant (atorvastatin -0.032, placebo 0.0055, P = 0.020, 95% CI of the difference -0.069, -0.0067). The ratios of 25-hydroxycholesterol and 5α,6α-epoxycholesterol to cholesterol did not change.

CONCLUSIONS

The results establish atorvastatin as an inhibitor of CYP3A4 activity. Furthermore, 4βHC : C is a useful index of CYP3A4 activity, including the conditions with altered cholesterol concentrations.

Epidemiology of CYP3A4-mediated clopidogrel drug-drug interactions and their clinical consequences

AIMS

Clopidogrel is a prodrug that needs to be activated to inhibit platelet aggregation. The objective of this study was to evaluate the prevalence and clinical consequences of potential drug-drug interactions of clopidogrel with drugs affecting CYP3A4 activity.

METHODS

Co-administrations of clopidogrel together with well-established CYP3A4 inhibitors, CYP3A4 inducers, and atorvastatin were investigated in a population-based pharmacoepidemiological study utilizing data from the national healthcare registers and in more detail from a university hospital register in Finland. The main outcome measures were all-cause mortality and mortality and morbidity related to thrombosis or bleeding.

RESULTS

In the nationwide analysis, 6.1%, 1.0%, and 20.8% of the clopidogrel-treated patients were exposed to concomitant use of CYP3A4 inhibitors, CYP3A4 inducers, and atorvastatin, respectively. In the survival analysis, the adjusted hazard ratio for overall mortality was 2.29 (P < 0.001) for CYP3A4 inducer users and 0.74 (P = 0.003) for atorvastatin users compared with controls (patients receiving clopidogrel without interacting medication). CYP3A4 inhibitor use seemed to prevent from thrombosis: HR 0.67, P < 0.001. The hospitalizations due to bleedings were rarer in atorvastatin and CYP3A4 inhibitor groups compared with controls. Thrombosis complications leading to hospitalizations were more often seen in the atorvastatin group than in the control group.

CONCLUSIONS

No uniform untoward effect of concomitant CYP3A4 inhibitor use on the clinical efficacy of clopidogrel was found. In patients receiving concomitant atorvastatin and clopidogrel, the antithrombotic effect of clopidogrel was moderately attenuated, but the combination significantly reduced the overall mortality. CYP3A4 inhibitors and atorvastatin may reduce bleedings in clopidogrel users.

Drug-drug interactions in cardiovascular catheterizations and interventions

Patients presenting for invasive cardiovascular procedures are frequently taking a variety of medications aimed to treat risk factors related to heart and vascular disease. During the procedure, antithrombotic, sedative, and analgesic medications are commonly needed, and after interventional procedures, new medications are often added for primary and secondary prevention of ischemic events. In addition to these prescribed medications, the use of over-the-counter drugs and supplements continues to rise. Most elderly patients, for example, are taking 5 or more prescribed medications and 1 or more supplements, and they often have some degree of renal insufficiency. This polypharmacy might result in drug-drug interactions that affect the balance of thrombotic and bleeding events during the procedure and during long-term treatment. Mixing of anticoagulants, for instance, might lead to periprocedural bleeding, and this is associated with an increase in long-term adverse events. Furthermore, the range of possible interactions with thienopyridine antiplatelets is of concern, because these drugs are essential to immediate and extended interventional success. The practical challenges in the field are great-some drug-drug interactions are likely present yet not well understood due to limited assays, whereas other interactions have well-described biological effects but seem to be more theoretical, because there is little to no clinical impact. Interventional providers need to be attentive to the potential for drug-drug interaction, the associated harm, and the appropriate action, if any, to minimize the potential for medication-related adverse events. This review will focus on drug-drug interactions that have the potential to affect procedural success, either through increases in immediate complications or compromising longer-term outcome.

Effect of atorvastatin on CYP2C9 metabolic activity as measured by the formation rate of losartan metabolite in hypercholesterolaemic patients

HMG-CoA reductase inhibitors (statins) have a potential to interact with substrates of the drug-metabolizing enzyme cytochrome P450 2C9 (CYP2C9). This may lead to concentration-dependent toxicity such as skeletal muscle side effects. Atorvastatin, a widely used statin, is presently inadequately investigated in vivo with regard to effects on CYP2C9 activity in human beings. The aim of this study was to determine the effect of atorvastatin on the activity of CYP2C9 in a group of Turkish hypercholesterolaemic patients. We prospectively investigated the atorvastatin effect on CYP2C9 activity in a sample of Turkish hypercholesterolaemia patients (11 women, 7 men) who commenced atorvastatin (10 mg/day). Losartan was used as a probe drug to determine CYP2C9 metabolic activity. A single 25-mg oral dose of losartan was given to the patients before, on the first day and after the fourth week of the atorvastatin treatment. Urinary concentrations of losartan and its metabolite, E3174, were measured by high-pressure liquid chromatography (HPLC). Urinary losartan/E3174 ratios were used as an index of CYP2C9 activity. As the baseline enzyme activity may influence the extent of drug-drug interactions, the CYP2C9*2 and 2C9*3 alleles were identified by using PCR-RFLP. In the patients with the CYP2C9*1*1 genotype (n = 12), atorvastatin treatment did not cause a significant change in losartan/E3174 ratios (medians; 95% CI) neither after the first day (0.73; 0.34-1.61) nor at the fourth week (0.71; 0.36-1.77) of the treatment as compared with the baseline activity (0.92; 0.57-1.74, p = 0.38). Similarly, no significant change in the baseline CYP2C9 activity (0.91; 0.30-1.60) was observed in patients with the CYP2C9*1*2 genotype as compared with those of the first day (1.08; 0.08-2.72) and fourth week (0.64; 0.0-3.82) of the atorvastatin treatment (n = 4, p = 0.86). These observations in a hypercholesterolaemic patient sample suggest that atorvastatin does not have a significant effect on enzymes encoded by the CYP2C9*1*1 and CYP2C9*1*2 genotypes when co-administered with a CYP2C9 substrate, losartan.

effect of atorvastatin on the pharmacokinetics of diltiazem and its main metabolite, desacetyldiltiazem, in rats

The purpose of this study was to investigate the effect of atorvastatin, HMG-CoA reductase inhibitor, on the pharmacokinetics of diltiazem and its active metabolite, desacetyldiltiazem, in rats. Pharmacokinetic parameters of diltiazem and desacetyldiltiazem were determined in rats after oral administration of diltiazem (15 mg x kg(-1)) to rats pretreated with atorvastatin (0.5 or 2.0 mg x kg(-1)). Compared with the control (given diltiazem alone), the pretreatment of atorvastatin significantly altered the pharmacokinetic parameters of diltiazem. The peak concentration (Cmax) and the areas under the plasma concentration-time curve (AUC) of diltiazem were significantly (p < 0.05, 0.5 mg x kg(-1); p < 0.01, 2.0 mg x kg(-1)) increased in the presence of atorvastatin. The AUC of diltiazem was increased by 1.40-fold in rats pretreated with 0.5 mg x kg(-1) atorvastatin, and 1.77-fold in rats pretreated with 2.0 mg x kg(-1) atorvastatin. Consequently, absolute bioavailability values of diltiazem pretreated with atorvastatin (8.4-10.6%)were significantly higher (p < 0.05) than that in the control group (6.6%). Although the pretreatment of atorvastatin significantly (p < 0.05) increased the AUC of desacetyldiltiazem, metabolite-parent AUC ratio (M.R.) in the presence of atorvastatin (0.5 or 2.0 mg x kg(-1)) was significantly decreased compared to the control group, implying that atorvastatin could be effective to inhibit the metabolism of diltiazem. In conclusion, the concomitant use of atorvastatin significantly enhanced the oral exposure of diltiazem in rats.

Review article: The role of statins in reducing perioperative cardiac risk: physiologic and clinical perspectives

PURPOSE

To review the pathobiology and clinical implications of coronary vulnerable atherosclerotic plaques (VAPs), to discuss the role of statin therapy in VAP stabilization, and the potential benefits of perioperative statin therapy (PST) in reducing perioperative risk of acute coronary syndromes (ACSs).

SOURCE

MEDLINE search using "perioperative", "cardiac morbidity", "atherosclerosis", "vulnerable plaque", "statins" and combinations of these terms as keywords. The reference lists of relevant articles were further reviewed to identify additional citations.

PRINCIPAL FINDINGS

The nonstenotic, yet rupture-prone VAP causes most myocardial infarctions (MIs) and other ACSs, both in the nonsurgical and surgical patients. Large clinical trials in both primary and secondary prevention and in patients with ACSs have demonstrated that statin therapy will reduce cardiovascular morbidity and mortality across a broad spectrum of patient subgroups. These trials also suggest, and laboratory investigations establish, that statins possess favourable vascular effects independent of cholesterol reduction. Statins appear to interfere specifically with the pathophysiologic mechanisms implicated in atherothrombotic disease. Statins reduce vascular inflammation, improve endothelial function, stabilize VAPs, and reduce platelet aggregability and thrombus formation. Recent studies have shown that PST is associated with a reduced incidence of perioperative and long-term cardiovascular complications in high-risk patients. Combined therapy with statins and ss-blockers is a conceptually valid strategy targeting critical steps in the pathogenesis of an ACS.

CONCLUSION

Emerging evidence for the efficacy and safety of PST is promising, especially when combined with ss-blocker therapy in patients at highest risk. Confirmation of this early evidence awaits the results of ongoing and future prospective randomized controlled trials.

Combination of Clopidogrel and Statins: A Hypothetical Interaction or Therapeutic Dilemma?

BACKGROUND

The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) and clopidogrel are frequently used in the treatment of patients with various cardiovascular disorders. The possibility of a drug-drug interaction between certain statins and clopidogrel has been extensively investigated in the literature recently. Investigators have proposed that the use of statins that are metabolized by the cytochrome P450 (CYP) system may diminish the conversion of clopidogrel to its active form by inhibiting the CYP3A4 isoenzyme. This inhibition could result in a decreased antiplatelet effect of clopidogrel, which could translate into an increased risk of cardiovascular events.

METHODS

We performed a MEDLINE search of the literature from 1993-2005 to evaluate and discuss the existing data on a possible interaction between clopidogrel and statins and to provide clinicians with relevant and practical recommendations. Additional studies were identified from the bibliographies of the reviewed literature.

RESULTS

Several articles were discovered that discuss this potential drug-drug interaction. Whereas some studies indicated that there was not a relevant interaction between statins and clopidogrel, other studies demonstrated that the concomitant administration of some statins with clopidogrel resulted in diminished platelet inhibition activity of clopidogrel.

CONCLUSIONS

Although the interaction between certain statins and clopidogrel seems to be a pharmacologic certainty, the clinical relevance of this interaction needs further clarification. While investigators continue to evaluate the clinical relevance, we provide several recommendations for clinicians responsible for treating patients who require combination therapy with statins and clopidogrel.

Comparison of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) as inhibitors of cytochrome P450 2C8

Statins are involved in different types of drug interactions. Our objective was to study the effect of statins on cytochrome P450 (CYP) 2C8-mediated paclitaxel 6 alpha-hydroxylation by incubating paclitaxel and statins (0--100 microM) with pooled human liver microsomes. Simvastatin, lovastatin, atorvastatin and fluvastatin were the most potent inhibitors of CYP2C8 activity with K(i) (IC(50)) values of 7.1 (9.6) muM, 8.4 (15) microM, 16 (38) microM and 19 (37) microM, respectively. Cerivastatin, simvastatin acid and lovastatin acid were less potent inhibitors with K(i) (IC(50)) values ranging from 32 to 55 (30--67) microM. Rosuvastatin and pravastatin showed no appreciable effect on CYP2C8 activity even at 100 microM. In conclusion, all the statins tested, except rosuvastatin and pravastatin, had a significant inhibitory effect on the activity of CYP2C8 in vitro. Because many of the statins accumulate in the liver and because also their metabolites may inhibit CYP2C8 activity, in vivo studies are needed to investigate a possible interaction of simvastatin, lovastatin, atorvastatin and fluvastatin with CYP2C8 substrate drugs.

Effect of atorvastatin and fluvastatin on the metabolism of midazolam by cytochrome P450 in vitro

We have investigated the effects of the statins atorvastatin and fluvastatin on the cytochrome P450 3A4 enzyme (CYP 3A4)-mediated metabolism of midazolam in vitro, using pooled human liver microsomes. Midazolam was metabolised by human hepatic microsomes with a Michaelis-Menten constant (K(m)) of 5.25 (SD 1.2) micromol.l(-1). Atorvastatin was a moderate competitive inhibitor of CYP 3A4 with an inhibitory constant (K(i)) of 12.4 (95% CI 4.65-20.06) micromol.l(-1). Fluvastatin was a weak non-competitive inhibitor of CYP 3A4 with a K(i) of 94.3 (95% CI 55.01-133.5) micromol.l(-1). Both atorvastatin and fluvastatin inhibit the CYP 3A4-mediated metabolism of midazolam in vitro.

Clinical pharmacokinetics of atorvastatin

Hypercholesterolaemia is a risk factor for the development of atherosclerotic disease. Atorvastatin lowers plasma low-density lipoprotein (LDL) cholesterol levels by inhibition of HMG-CoA reductase. The mean dose-response relationship has been shown to be log-linear for atorvastatin, but plasma concentrations of atorvastatin acid and its metabolites do not correlate with LDL-cholesterol reduction at a given dose. The clinical dosage range for atorvastatin is 10-80 mg/day, and it is given in the acid form. Atorvastatin acid is highly soluble and permeable, and the drug is completely absorbed after oral administration. However, atorvastatin acid is subject to extensive first-pass metabolism in the gut wall as well as in the liver, as oral bioavailability is 14%. The volume of distribution of atorvastatin acid is 381L, and plasma protein binding exceeds 98%. Atorvastatin acid is extensively metabolised in both the gut and liver by oxidation, lactonisation and glucuronidation, and the metabolites are eliminated by biliary secretion and direct secretion from blood to the intestine. In vitro, atorvastatin acid is a substrate for P-glycoprotein, organic anion-transporting polypeptide (OATP) C and H+-monocarboxylic acid cotransporter. The total plasma clearance of atorvastatin acid is 625 mL/min and the half-life is about 7 hours. The renal route is of minor importance (<1%) for the elimination of atorvastatin acid. In vivo, cytochrome P450 (CYP) 3A4 is responsible for the formation of two active metabolites from the acid and the lactone forms of atorvastatin. Atorvastatin acid and its metabolites undergo glucuronidation mediated by uridinediphosphoglucuronyltransferases 1A1 and 1A3. Atorvastatin can be given either in the morning or in the evening. Food decreases the absorption rate of atorvastatin acid after oral administration, as indicated by decreased peak concentration and increased time to peak concentration. Women appear to have a slightly lower plasma exposure to atorvastatin for a given dose. Atorvastatin is subject to metabolism by CYP3A4 and cellular membrane transport by OATP C and P-glycoprotein, and drug-drug interactions with potent inhibitors of these systems, such as itraconazole, nelfinavir, ritonavir, cyclosporin, fibrates, erythromycin and grapefruit juice, have been demonstrated. An interaction with gemfibrozil seems to be mediated by inhibition of glucuronidation. A few case studies have reported rhabdomyolysis when the pharmacokinetics of atorvastatin have been affected by interacting drugs. Atorvastatin increases the bioavailability of digoxin, most probably by inhibition of P-glycoprotein, but does not affect the pharmacokinetics of ritonavir, nelfinavir or terfenadine.