Darapladib

Plaque rupture is responsible for the clinical events of ischemic death, myocardial infarction, acute coronary syndromes and ischemic strokes. Lipoprotein-associated phospholipase A2 (Lp-PLA2) seems to play a major role in the development of such high-risk lesions, in both the coronary and carotid arteries. Darapladib is a selective inhibitor of Lp-PLA2.

In vitro: Darapladib potently inhibited Lp-PLA2 with an IC50 of 270 pM. A lack of selectivity against other secretory PLA2s postulated to play a role in atherogenesis had been demonstrated. The percentage inhibition achieved when 1 μM darapladib was evaluated against human secretory PLA2s IIA, V and X, was 0, 0 and 8.7%, respectively [1].

In vivo: Inhibition of lp-PLA2 by darapladib led to attenuation of inflammation in vivo and decreased plaque formation in ApoE-deficient mice, suggesting an anti-atherogenic role during the progression of atherosclerosis [2].

Clinical trial: Darapladib produced sustained inhibition of plasma Lp-PLA2 activity in patients receiving intensive atorvastatin therapy. IL-6 and hs-CRP changes after 12 weeks of darapladib 160 mg suggested a possible reduction in inflammatory burden [3].

References:
[1] Bui QT, Wilensky RL.  Darapladib. Expert Opin Investig Drugs. 2010;19(1):161-8.
[2] Wang WY, Zhang J, Wu WY, Li J, Ma YL, Chen WH, Yan H, Wang K, Xu WW, Shen JH, Wang YP.  Inhibition of lipoprotein-associated phospholipase A2 ameliorates inflammation and decreases atherosclerotic plaque formation in ApoE-deficient mice. PLoS One. 2011;6(8):e23425.
[3] Mohler ER 3rd, Ballantyne CM, Davidson MH, Hanefeld M, Ruilope LM, Johnson JL, Zalewski A; Darapladib Investigators.  The effect of darapladib on plasma lipoprotein-associated phospholipase A2 activity and cardiovascular biomarkers in patients with stable coronary heart disease or coronary heart disease risk equivalent: the results of a multicenter, randomized, double-blind, placebo-controlled study. J Am Coll Cardiol. 2008;51(17):1632-41.

Darapladib, a Lipoprotein-Associated Phospholipase A2 Inhibitor, Reduces Rho Kinase Activity in Atherosclerosis.[Pubmed:26847282]

Yonsei Med J. 2016 Mar;57(2):321-7.

PURPOSE: Increased lipoprotein-associated phospholipase A2 (Lp-PLA2) activity and Rho kinase activity may be associated with atherosclerosis. The principal aim of this study was to examine whether Darapladib (a selective Lp-PLA2 inhibitor) could reduce the elevated Lp-PLA2 and Rho kinase activity in atherosclerosis. MATERIALS AND METHODS: Studies were performed in male Sprague-Dawley rats. The atherosclerosis rats were prepared by feeding them with a high-cholesterol diet for 10 weeks. Low-dose Darapladib (25 mg.kg(-)(1).d(-)(1)) and high-dose Darapladib (50 mg.kg(-)(1).d(-)(1)) interventions were then administered over the course of 2 weeks. RESULTS: The serum levels of triglycerides, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), high-sensitivity C-reactive protein (hs-CRP), and Lp-PLA2, significantly increased in atherosclerosis model groups, as did Rho kinase activity and cardiomyocyte apoptosis (p<0.05 vs. sham group), whereas nitric oxide (NO) production was reduced. Levels of TC, LDL-C, CRP, Lp-PLA2, and Rho kinase activity were respectively reduced in Darapladib groups, whereas NO production was enhanced. When compared to the low-dose Darapladib group, the reduction of the levels of TC, LDL-C, CRP, and Lp-PLA2 was more prominent in the high-dose Darapladib group (p<0.05), and the increase of NO production was more prominent (p<0.05). Cardiomyocyte apoptosis of the high-dose Darapladib group was also significantly reduced compared to the low-dose Darapladib group (p<0.05). However, there was no significant difference in Rho kinase activity between the low-dose Darapladib group and the high-dose Darapladib group (p>0.05). CONCLUSION: Darapladib, a Lp-PLA2 inhibitor, leads to cardiovascular protection that might be mediated by its inhibition of both Rho kinase and Lp-PLA2 in atherosclerosis.

Retinal pathology is associated with increased blood-retina barrier permeability in a diabetic and hypercholesterolaemic pig model: Beneficial effects of the LpPLA2 inhibitor Darapladib.[Pubmed:28301218]

Diab Vasc Dis Res. 2017 May;14(3):200-213.

Using a porcine model of diabetes mellitus and hypercholesterolaemia, we previously showed that diabetes mellitus and hypercholesterolaemia is associated with a chronic increase in blood-brain barrier permeability in the cerebral cortex, leading to selective binding of immunoglobulin G and deposition of amyloid-beta1-42 peptide in pyramidal neurons. Treatment with Darapladib (GlaxoSmithKline, SB480848), an inhibitor of lipoprotein-associated phospholipase-A2, alleviated these effects. Here, investigation of the effects of chronic diabetes mellitus and hypercholesterolaemia on the pig retina revealed a corresponding increased permeability of the blood-retina barrier coupled with a leak of plasma components into the retina, alterations in retinal architecture, selective IgG binding to neurons in the ganglion cell layer, thinning of retinal layers due to cell loss and increased glial fibrillary acidic protein expression in Muller cells, all of which were curtailed by treatment with Darapladib. These findings suggest that chronic diabetes mellitus and hypercholesterolaemia induces increased blood-retina barrier permeability that may be linked to altered expression of blood-retina barrier-associated tight junction proteins, claudin and occludin, leading to structural changes in the retina consistent with diabetic retinopathy. Additionally, results suggest that drugs with vascular anti-inflammatory properties, such as Darapladib, may have beneficial effects on eye diseases strongly linked to vascular abnormalities such as diabetic retinopathy and age-related macular degeneration.

Predictors of Nonuse of a High-Potency Statin After an Acute Coronary Syndrome: Insights From the Stabilization of Plaques Using Darapladib-Thrombolysis in Myocardial Infarction 52 (SOLID-TIMI 52) Trial.[Pubmed:28077384]

J Am Heart Assoc. 2017 Jan 11;6(1). pii: JAHA.116.004332.

BACKGROUND: High-potency statins reduce cardiovascular events after acute coronary syndromes but remain underused in clinical practice. We examined predictors of nonuse of high-potency statins after acute coronary syndromes. METHODS AND RESULTS: The Stabilization of pLaques usIng Darapladib-Thrombolysis in Myocardial Infarction (SOLID-TIMI 52) trial enrolled patients after an acute coronary syndrome in 36 countries between 2009 and 2011. Statin use was strongly encouraged throughout the trial, and statin potency was at the discretion of the treating physician. A high-potency statin was defined as >/=40 mg atorvastatin, >/=20 mg rosuvastatin, or 80 mg simvastatin daily. Predictors of nonuse of high-potency statins were examined using logistic regression. Of the patients included (n=12 446), 11 850 (95.2%) were treated with a statin at baseline after acute coronary syndrome (median 14 days), but only 5212 (41.9%) were on a high-potency statin. Selected patient factors associated with nonuse of high-potency statins included age >/=75 years (odds ratio 1.39, 95% CI 1.24-1.56), female sex (odds ratio 1.11, 95% CI 1.02-1.22), renal dysfunction (odds ratio 1.17, 95% CI 1.03-1.32), and heart failure during hospital admission (odds ratio 1.43, 95% CI 1.27-1.62). At 3 months after baseline, only 49% of patients had low-density lipoprotein cholesterol <70 mg/dL. Among the 5490 patients (59%) who were not on a high-potency statin at 3 months, lower low-density lipoprotein cholesterol was a predictor of nonuse of a high-potency statin after a median of 2.3 years (odds ratio 1.15 for 10 mg/dL decrease, 95% CI 1.11-1.19). CONCLUSION: Despite the widespread use of statins after acute coronary syndromes, most patients are not treated with high-potency statins early and late after the event, including patients at the highest risk of recurrent cardiovascular events. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01000727.

Single and Multiple Dose Pharmacokinetics, Pharmacodynamics and Safety of the Novel Lipoprotein-Associated Phospholipase A2 Enzyme Inhibitor Darapladib in Healthy Chinese Subjects: An Open Label Phase-1 Clinical Trial.[Pubmed:26465780]

PLoS One. 2015 Oct 14;10(10):e0139862.

BACKGROUND AND OBJECTIVES: Darapladib is a lipoprotein-associated phospholipase A2 (Lp-PLA2) inhibitor. This study evaluated the pharmacokinetics, pharmacodynamics and safety of Darapladib in healthy Chinese subjects. METHODS: Twenty-four subjects received Darapladib 160 mg orally, approximately 1 hour after a standard breakfast, as a single dose and once daily for 28 days. Non-compartmental methods were used to determine the single and multiple dose pharmacokinetics of Darapladib and its metabolite SB-553253. Repeat dose Lp-PLA2 activity and safety were evaluated. RESULTS: Systemic exposure (AUC(0-T), Cmax geometric mean (CVb%)) of Darapladib was higher after multiple-dosing (519 ng.h/mL (33.3%), 34.4 ng/mL (49.9%)) compared to single-dose administration (153 ng.h/mL (69.0%), 17.9 ng/mL (55.2%). The steady-state accumulation ratio was less than unity (Rs = 0.80), indicating time-dependent pharmacokinetics of Darapladib. Darapladib steady-state was reached by Day 14 of once daily dosing. Systemic exposure to SB-553253 was lower than Darapladib with median (SB-553253: Darapladib) ratios for AUC(0-tau) of 0.0786 for single dose and 0.0532 for multiple dose administration. On Day 28, pre-dose and maximum inhibition of Lp-PLA2 activity was approximately 70% and 75% relative to the baseline value, respectively and was dependent of Darapladib concentration. The most common adverse events (>/= 21% subjects) were abnormal faeces, abnormal urine odour, diarrhoea and nasopharyngitis. CONCLUSION: Darapladib 160 mg single and repeat doses were profiled in healthy Chinese subjects. Single dose systemic exposure to Darapladib in healthy Chinese subjects was consistent with that observed previously in Western subjects whereas steady-state systemic exposure was approximately 65% higher in Chinese than Western subjects. The Lp-PLA2 activity and adverse event profile were similar in healthy Chinese and previous reports in Western subjects. Ethnic-specific dose adjustment of Darapladib is not considered necessary for the Chinese population. TRIAL REGISTRATION: ClinicalTrials.gov NCT02000804.