Carl A. Baxter

Reaction development and mechanistic study of a ruthenium catalyzed intramolecular asymmetric reductive amination en route to the dual Orexin inhibitor Suvorexant (MK-4305).

The first example of an intramolecular asymmetric reductive amination of a dialkyl ketone with an aliphatic amine has been developed for the synthesis of Suvorexant (MK-4305), a potent dual Orexin antagonist under development for the treatment of sleep disorders. This challenging transformation is mediated by a novel Ru-based transfer hydrogenation catalyst that provides the desired diazepane ring in 97% yield and 94.5% ee. Mechanistic studies have revealed that CO(2), produced as a necessary byproduct of this transfer hydrogenation reaction, has pronounced effects on the efficiency of the Ru catalyst, the form of the amine product, and the kinetics of the transformation. A simple kinetic model explains how product inhibition by CO(2) leads to overall first-order kinetics, but yields an apparent zero-order dependence on initial substrate concentration. The deleterious effects of CO(2) on reaction rates and product isolation can be overcome by purging CO(2) from the system. Moreover, the rate of ketone hydrogenation can be greatly accelerated by purging of CO(2) or trapping with nucleophilic secondary amines.

Synthesis of Bis-Macrocyclic HCV Protease Inhibitor MK-6325 via Intramolecular sp2–sp3 Suzuki–Miyaura Coupling and Ring Closing Metathesis

A practical asymmetric synthesis of the complex fused bis-macrocyclic HCV protease inhibitor MK-6325 (1) is described. Through the combination of a high yielding and low catalyst loading ring-closing metathesis (RCM) to forge the 15-membered macrocycle with an intramolecular sp(2)-sp(3) Suzuki-Miyaura cross-coupling to append the 18-membered macrocycle, multikilogram access to the unique and challenging architecture of MK-6325 (1) has been achieved.

Prevalence of lipid abnormalities and cholesterol target value attainment in patients with stable coronary heart disease or an acute coronary syndrome in Saudi Arabia

Objectives: To provide an overview of the extent of hyperlipidemia in very high-risk patients, and how lipid-lowering therapy (LLT) is used in a real-world setting. Methods: In this multicenter observational study, data were collected from LLT-treated patients with stable CHD or an ACS in Saudi Arabia between 2013 and 2014. Individuals were included if they were >18 years and had a full lipid profile available, recorded either prior to the baseline physician visit (CHD patients) or within 24-hours of admission to hospital (ACS patients). Results: A total of 737 patients were included in the study, 597 with stable CHD and 140 with ACS. Few patients in either group had an LDL-C level of <70 mg/dl, which is advocated for very high-risk patients (24.3% and 11.4%, respectively). The median distances to this value were 19.0 mg/dl (CHD) and 25.0 mg/dl (ACS). Low doses of statins were being utilized (31 and 24 mg/day for CHD and ACS, respectively), with only minimal intensification for the ACS patients after hospital admission (41 mg/day at follow-up). Conclusions: Achievement of recommended LDL-C levels was poor for patients with stable CHD or an ACS. Statin intensity was low, indicating huge scope for intensifying the treatment of these very high-risk patients.

Use of guideline-recommended management in established coronary heart disease in the observational DYSIS II study

BACKGROUND Guidelines recommend lifestyle modification and medications to control risk factors in coronary heart disease (CHD). Using data from the observational DYSIS II study, we sought to evaluate the use of guideline-recommended treatments at discharge for acute coronary syndromes (ACS) or in the chronic phase for CHD, and participation in rehabilitation/secondary prevention programs. METHODS AND RESULTS Between 2013 and 2014, 10,661 patients (3867 with ACS, 6794 with stable CHD) were enrolled in 332 primary and secondary care centers in 18 countries (Asia, Europe, Middle East). Patients with incident ACS were younger and more likely to be smokers than patients with recurrent ACS or stable CHD (both p < 0.0001). Sedentary lifestyle was common (44.4% of ACS patients; 44.2% of stable CHD patients); 22.8% of ACS patients and 24.3% of stable CHD patients were obese. Prevalence of low high-density lipoprotein cholesterol (<40 mg/dL in men/50 mg/dL in women) was 46.9% in chronic CHD and 55.0% in ACS. Rates of secondary prevention medications were lower among CHD versus ACS (all p < 0.0001): antiplatelet 94.3% vs 98.0%, beta-blocker 72.0% vs 80.0%, lipid-lowering therapy 94.7 vs 97.5%, and angiotensin-converting enzyme inhibitors/angiotensin-receptor blockers 69.4% vs 73.7%, respectively. Attendance at cardiac rehabilitation (16.8% of patients with a first ACS, 10.8% with recurrent ACS) or a secondary prevention program (3.7% of ACS and 11.7% of stable CHD patients) was infrequent. CONCLUSIONS The high prevalence of risk factors in all CHD patients and reduced rates of secondary prevention medications in stable CHD offer areas for improvement. TRANSLATIONAL ASPECTS The findings of DYSIS II may reinforce the importance of adopting a healthy lifestyle and prescribing (by clinicians) and adhering (by patients) to evidence-based medications in the management of CHD, not only during the short term but also over the longer term after a cardiac ischemic event. The results may help to increase the proportion of ACS patients who are referred to cardiac rehabilitation centres.

Predictors of LDL-cholesterol target value attainment differ in acute and chronic coronary heart disease patients: Results from DYSIS II Europe

Background Patients with coronary heart disease (CHD) and survivors of acute coronary syndrome (ACS) are at very high risk for adverse cardiovascular events. Lowering low-density lipoprotein cholesterol (LDL-C) can reduce the risk, with effective lipid-lowering therapy (LLT) readily available; however, dyslipidemia remains prevalent throughout Europe. Design The observational Dyslipidemia International Study II (DYSIS II) aimed to identify unmet treatment needs in adult ACS and CHD patients. Data for the seven participating European countries are presented herein. Methods The study was carried out from December 2012 to November 2014. Use of LLT and attainment of European-guideline-recommended LDL-C targets were assessed. For ACS patients, changes in lipid levels and LLT were evaluated 4 months post-hospitalization. Results Of the 4344 patients enrolled, 2946 were attending a physician visit for the assessment of stable CHD, while 1398 had been hospitalized for an ACS event. In both patient sets, mean LDL-C levels were high (89.5 and 112.5 mg/dl, respectively) and <70 mg/dl target attainment extremely poor. The mean daily statin dosage (normalized to atorvastatin potency) was 27 ± 20 mg for CHD and 22 ± 17 mg for ACS patients. Treatment was intensified slightly for ACS subjects after hospitalization, with the dosage reaching 35 ± 24 mg/day. LDL-C target attainment was higher by the end of the 4-month follow up (30.9% and 41.5% for patients on LLT and without LLT at baseline, respectively; p < 0.05). Conclusion Elevated blood cholesterol levels are highly prevalent across Europe, with low numbers of coronary patients reaching their recommended LDL-C target. While use of LLT is widespread, there is significant scope for intensifying treatment.

Low-density lipoprotein cholesterol target attainment in patients with stable or acute coronary heart disease in the Asia-Pacific region: results from the Dyslipidemia International Study II

Background As mortality due to cardiovascular disease increases throughout the world, accurate data on risk factors such as hyperlipidemia are required. This is lacking in the Asia-Pacific region. Design The observational Dyslipidemia International Study (DYSIS) II was established to quantify the extent of hyperlipidemia in adults with acute and stable coronary heart disease globally. Methods Patients with stable coronary heart disease or hospitalised with an acute coronary syndrome were enrolled across nine Asia-Pacific countries from July 2013 to October 2014. Lipid-lowering therapy and low-density lipoprotein cholesterol target attainment (<70 mg/dL) were assessed. The acute coronary syndrome cohort was followed up 4 months post-discharge. Results Of the 4592 patients enrolled, 2794 had stable coronary heart disease and 1798 were admitted with an acute coronary syndrome. In the coronary heart disease cohort, the mean low-density lipoprotein cholesterol level was 86.9 mg/dL, with 91.7% using lipid-lowering therapy and 31% achieving low-density lipoprotein cholesterol of less than 70 mg/dL. In the acute coronary syndrome cohort at admission, the corresponding values were 103.2 mg/dL, 63.4% and 23.0%, respectively. Target attainment was significantly higher in lipid-lowering therapy-treated than non-treated patients in each cohort (32.6% vs. 12.9% and 31.1% vs. 9.0%, respectively). Mean atorvastatin-equivalent dosages were low (20 ± 15 and 22 ± 18 mg/day, respectively), with little use of non-statin adjuvants (13.0% and 6.8%, respectively). Low-density lipoprotein cholesterol target attainment had improved by follow-up for the acute coronary syndrome patients, but remained low (41.7%). Conclusions Many patients in Asia at very high risk of recurrent cardiovascular events had a low-density lipoprotein cholesterol level above the recommended target. Although lipid-lowering therapy was common, it was not used to its full potential.

Body mass index impacts the choice of lipid-lowering treatment with no correlation to blood cholesterol - Findings from 52 916 patients in the Dyslipidemia International Study (DYSIS)

A high body mass index (BMI) is associated with increased cardiovascular risk. We sought to identify whether BMI influences the choice of lipid‐lowering treatment in a large, real‐world cohort of 52 916 patients treated with statins. The Dyslipidemia International Study (DYSIS) is a cross‐sectional, observational, multicentre study in statin‐treated patients ≥45 years of age from 30 countries; 1.1% were underweight (BMI < 18.5 kg/m2), 33.1% had normal weight (BMI 18.5‐24.9 kg/m2), 41.5% were overweight (BMI 25‐29.9 kg/m2), 17.1% had class I obesity (BMI 30.0‐34.9 kg/m2), 5.0% had class II obesity (BMI 35‐39.9 kg/m2), and 2.1% had class III obesity (≥40 kg/m2). BMI correlated with high‐density lipoprotein cholesterol (HDL‐C) and triglycerides (Spearmans ρ: −0.147 and 0.170, respectively; P < 0.0001 for both); however, there was no correlation with low‐density lipoprotein cholesterol (LDL‐C; ρ: 0.003; P = 0.51). Statin intensity increased with increasing BMI (ρ: 0.13; P < 0.001), an association that held after adjustment for comorbidities (OR: 2.4; 95% CI: 2.0‐3.0) on BMI ≥ 30 kg/m2 for atorvastatin equivalent ≥40 mg/d.

Contemporary data on treatment practices for low-density lipoprotein cholesterol in 6794 patients with stable coronary heart disease across the world

DYSIS II CHD was a longitudinal, observational study in 6794 patients from 18 countries. They were attending an outpatient physician appointment for coronary heart disease (CHD). 6370 patients (93.8%) were on active lipid lowering therapy (LLT). The mean atorvastatin dose equivalent was 25 mg per day and 10.5% received ezetimibe in combination with a statin. The mean low-density lipoprotein cholesterol (LDL-C) level was 88 mg/dL, with 29.4% of patients displaying a level below the 70 mg/dL target for very high-risk subjects. Conclusion While more than 90% of patients with CHD were on lipid lowering drugs, only three out of ten patients achieved their LDL-C target value.

Contemporary data on treatment practices for low-density lipoprotein cholesterol in 3867 patients who had suffered an acute coronary syndrome across the world

DYSIS II ACS was a longitudinal, observational study in 3867 patients from 18 countries. They were being hospitalized after suffering an acute coronary syndrome. Evaluations were performed at the time of admission and again 120±15 days following the date of admission (the follow-up time point). 2521 patients were on active lipid lowering treatment (LLT) at admission. Mean atorvastatin dose was 22 mg per day and 2.7% received ezetimibe in combination with a statin. At discharge from hospital, 3767 patients received LLT expressed as a mean atorvastatin dose of 36 mg per day with 4.8% receiving ezetimibe on top of a statin. After 120 days, intensity in lipid lowering treatment was reduced to 32 mg per day with 4.9% of the patients receiving ezetimibe and a statin. Of note, during this 4-month follow up period, only 32% of all patients received laboratory lipid testing. 37% attained the low density lipoprotein cholesterol (LDL-C) target value of <70 mg/dl after 120 days. There are differences in the therapy administered as well as in the switch strategies when comparing the data from the respective countries studied. Conclusions Only one in three patients achieved the LDL-C target value following only marginal improvements in atorvastatin dose or combination therapy after an ACS event.

Ezetimibe in high-risk, previously treated statin patients: a systematic review and network meta-analysis of lipid efficacy

PurposeWhile statins are used as first-line treatments for high-risk patients with hypercholesterolemia, statin monotherapy is often insufficient to achieve target low-density lipoprotein cholesterol (LDL-C) levels. Second-line treatment options include up-titration of statin dose, switching to a more potent statin, or combination therapy, e.g., with ezetimibe. The aim of this study was to evaluate the efficacy of adding ezetimibe to simvastatin, atorvastatin, or rosuvastatin monotherapy versus doubling the dosage or switching to a higher-potency statin in a population of patients with hypocholesterolemia at high risk of cardiovascular disease (CVD) and who had been previously treated with a statin.MethodsA systematic literature search was performed and evidence bases were established for populations of atorvastatin-, simvastatin-, and rosuvastatin-experienced patients using eligible randomized controlled trials (RCTs). Based on the available data, we constructed networks of evidence and conducted a Bayesian network meta-analysis (NMA) within each statin population. The primary outcome of interest was percent change from baseline in LDL-C. Changes in total cholesterol were explored as a secondary outcome.FindingsAcross all patient populations, 35 RCTs were identified and included in the evidence base. Among patients on simvastatin therapy, the addition of ezetimibe resulted in a mean difference (MD) in LDL-C of − 13.62% (95% CrI − 19.99, − 6.91; see table below) compared to doubling the starting dose of simvastatin. In the population of patients on atorvastatin therapy, the addition of ezetimibe resulted in an MD in LDL-C of − 14.71% (95% CrI − 16.46, − 12.95) compared to doubling the starting dose of atorvastatin. The addition of ezetimibe to rosuvastatin resulted in an MD in LDL-C of − 14.96% (95% CrI − 17.79, − 12.11), compared to doubling the starting rosuvastatin dose. Similar trends were observed for changes in total cholesterol.ImplicationsGiven the available data, the addition of ezetimibe to ongoing simvastatin, atorvastatin, or rosuvastatin monotherapy offers greater reduction in LDL-C among patients at high risk of CVD compared to doubling the initial statin dose.