CLINICAL PHARMACOLOGY
Mechanism Of Action
ENTRESTO contains a neprilysin inhibitor, sacubitril, and
an angiotensin receptor blocker, valsartan. ENTRESTO inhibits neprilysin
(neutral endopeptidase; NEP) via LBQ657, the active metabolite of the prodrug
sacubitril, and blocks the angiotensin II type-1 (AT1) receptor via valsartan.
The cardiovascular and renal effects of ENTRESTO in heart failure patients are
attributed to the increased levels of peptides that are degraded by neprilysin,
such as natriuretic peptides, by LBQ657, and the simultaneous inhibition of the
effects of angiotensin II by valsartan. Valsartan inhibits the effects of
angiotensin II by selectively blocking the AT1 receptor, and also inhibits
angiotensin II-dependent aldosterone release.
Pharmacodynamics
The pharmacodynamic effects of ENTRESTO were evaluated
after single and multiple dose administrations in healthy subjects and in
patients with heart failure, and are consistent with simultaneous neprilysin
inhibition and renin-angiotensin system blockade. In a 7-day
valsartan-controlled study in patients with reduced ejection fraction (HFrEF),
administration of ENTRESTO resulted in a significant non-sustained increase in
natriuresis, increased urine cGMP, and decreased plasma MR-proANP and NT-proBNP
compared to valsartan.
In a 21-day study in HFrEF patients, ENTRESTO
significantly increased urine ANP and cGMP and plasma cGMP, and decreased
plasma NT-proBNP, aldosterone and endothelin-1. ENTRESTO also blocked the AT1-receptor
as evidenced by increased plasma renin activity and plasma renin
concentrations. In PARADIGM-HF, ENTRESTO decreased plasma NT-proBNP (not a
neprilysin substrate) and increased plasma BNP (a neprilysin substrate) and
urine cGMP compared with enalapril.
QT Prolongation: In a thorough QTc clinical study
in healthy male subjects, single doses of ENTRESTO 194 mg sacubitril/206 mg
valsartan and 583 mg sacubitril/617 mg valsartan had no effect on cardiac
repolarization.
Amyloid-β: Neprilysin is one of multiple
enzymes involved in the clearance of amyloid-β (Aβ) from the brain
and cerebrospinal fluid (CSF). Administration of ENTRESTO 194 mg sacubitril/206
mg valsartan once-daily for 2 weeks to healthy subjects was associated with an
increase in CSF Aβ1-38 compared to placebo; there were no changes in
concentrations of CSF Aβ1-40 or CSF Aβ1-42. The clinical relevance of
this finding is unknown [see Nonclinical Toxicology].
Blood Pressure: Addition of a 50 mg single dose of
sildenafil to ENTRESTO at steady state (194 mg sacubitril/206 mg valsartan mg
once daily for 5 days) in patients with hypertension was associated with
additional blood pressure (BP) reduction (~5/4 mmHg, systolic/diastolic BP)
compared to administration of ENTRESTO alone.
Co-administration of ENTRESTO did not significantly alter
the BP effect of intravenous nitroglycerin.
Pharmacokinetics
Absorption
Following oral administration, ENTRESTO dissociates into
sacubitril and valsartan. Sacubitril is further metabolized to LBQ657. The peak
plasma concentrations of sacubitril, LBQ657, and valsartan are reached in 0.5
hours, 2 hours, and 1.5 hours, respectively. The oral absolute bioavailability
of sacubitril is estimated to be ≥ 60%. The valsartan in ENTRESTO is more
bioavailable than the valsartan in other marketed tablet formulations; 26 mg,
51 mg, and 103 mg of valsartan in ENTRESTO is equivalent to 40 mg, 80 mg, and
160 mg of valsartan in other marketed tablet formulations, respectively.
Following twice-daily dosing of ENTRESTO, steady state levels
of sacubitril, LBQ657, and valsartan are reached in 3 days. At steady state,
sacubitril and valsartan do not accumulate significantly, whereas LBQ657
accumulates by 1.6-fold. ENTRESTO administration with food has no clinically
significant effect on the systemic exposures of sacubitril, LBQ657, or
valsartan. Although there is a decrease in exposure to valsartan when ENTRESTO
is administered with food, this decrease is not accompanied by a clinically
significant reduction in the therapeutic effect. ENTRESTO can therefore be
administered with or without food.
Distribution
Sacubitril, LBQ657 and valsartan are highly bound to
plasma proteins (94% to 97%). Based on the comparison of plasma and CSF
exposures, LBQ657 crosses the blood brain barrier to a limited extent (0.28%).
The average apparent volumes of distribution of valsartan and sacubitril are 75
and 103 L, respectively.
Metabolism
Sacubitril is readily converted to LBQ657 by esterases;
LBQ657 is not further metabolized to a significant extent. Valsartan is
minimally metabolized; only about 20% of the dose is recovered as metabolites.
A hydroxyl metabolite has been identified in plasma at low concentrations ( <
10%).
Elimination
Following oral administration, 52% to 68% of sacubitril
(primarily as LBQ657) and ~13% of valsartan and its metabolites are excreted in
urine; 37% to 48% of sacubitril (primarily as LBQ657), and 86% of valsartan and
its metabolites are excreted in feces. Sacubitril, LBQ657, and valsartan are
eliminated from plasma with a mean elimination half-life (T½) of
approximately 1.4 hours, 11.5 hours, and 9.9 hours, respectively.
Linearity/Nonlinearity
The pharmacokinetics of sacubitril, LBQ657, and valsartan
were linear over an ENTRESTO dose range of 24 mg sacubitril/26 mg valsartan to
194 mg sacubitril/206 mg valsartan.
Drug Interactions
Effect of Co-administered Drugs on ENTRESTO
Because CYP450 enzyme-mediated metabolism of sacubitril
and valsartan is minimal, coadministration with drugs that impact CYP450
enzymes is not expected to affect the pharmacokinetics of ENTRESTO. Dedicated
drug interaction studies demonstrated that coadministration of furosemide,
warfarin, digoxin, carvedilol, a combination of levonorgestrel/ethinyl
estradiol, amlodipine, omeprazole, hydrochlorothiazide (HCTZ), metformin,
atorvastatin, and sildenafil, did not alter the systemic exposure to
sacubitril, LBQ657 or valsartan.
Effect of ENTRESTO on Co-administered Drugs
In vitro data indicate that sacubitril inhibits OATP1B1
and OATP1B3 transporters. The effects of ENTRESTO on the pharmacokinetics of
coadministered drugs are summarized in Figure 1.
Figure 1: Effect of ENTRESTO on Pharmacokinetics of
Coadministered Drugs
Specific Populations
Effect of specific populations on the pharmacokinetics of
LBQ657 and valsartan are shown in Figure 2.
Figure 2: Pharmacokinetics of ENTRESTO in Specific
Populations
Note: Child-Pugh Classification was used for hepatic
impairment.
Animal Toxicology And/Or Pharmacology
The effects of ENTRESTO on amyloid-β concentrations
in CSF and brain tissue were assessed in young (2 to 4 years old) cynomolgus
monkeys treated with ENTRESTO (24 mg sacubitril/26 mg valsartan/kg/day) for 2
weeks. In this study, ENTRESTO affected CSF Aβ clearance, increasing CSF
Aβ 1-40, 1-42, and 1-38 levels in CSF; there was no corresponding increase
in Aβ levels in the brain. In addition, in a toxicology study in
cynomolgus monkeys treated with ENTRESTO at 146 mg sacubitril/154 mg
valsartan/kg/day for 39-weeks, there was no amyloid-β accumulation in the
brain.
Clinical Studies
Dosing in clinical trials was based on the total amount
of both components of ENTRESTO, i.e., 24/26 mg, 49/51 mg and 97/103 mg were
referred to as 50 mg, 100 mg, and 200 mg, respectively.
PARADIGM-HF
PARADIGM-HF was a multinational, randomized, double-blind
trial comparing ENTRESTO and enalapril in 8,442 adult patients with symptomatic
chronic heart failure (NYHA class II–IV) and systolic dysfunction (left
ventricular ejection fraction ≤ 40%). Patients had to have been on an ACE
inhibitor or ARB for at least four weeks and on maximally tolerated doses of
beta-blockers. Patients with a systolic blood pressure of < 100 mmHg at
screening were excluded.
The primary objective of PARADIGM-HF was to determine
whether ENTRESTO, a combination of sacubitril and a RAS inhibitor (valsartan),
was superior to a RAS inhibitor (enalapril) alone in reducing the risk of the
combined endpoint of cardiovascular (CV) death or hospitalization for heart
failure (HF).
After discontinuing their existing ACE inhibitor or ARB
therapy, patients entered sequential single-blind run-in periods during which
they received enalapril 10 mg twice-daily, followed by ENTRESTO 100 mg
twice-daily, increasing to 200 mg twice daily. Patients who successfully
completed the sequential run-in periods were randomized to receive either
ENTRESTO 200 mg (N=4,209) twice-daily or enalapril 10 mg (N=4,233) twice-daily.
The primary endpoint was the first event in the composite of CV death or
hospitalization for HF. The median follow-up duration was 27 months and
patients were treated for up to 4.3 years.
The population was 66% Caucasian, 18% Asian, and 5%
Black; the mean age was 64 years and 78% were male. At randomization, 70% of
patients were NYHA Class II, 24% were NYHA Class III, and 0.7% were NYHA Class
IV. The mean left ventricular ejection fraction was 29%. The underlying cause
of heart failure was coronary artery disease in 60% of patients; 71% had a
history of hypertension, 43% had a history of myocardial infarction, 37% had an
eGFR < 60 mL/min/1.73m², and 35% had diabetes mellitus. Most patients were
taking beta-blockers (94%), mineralocorticoid antagonists (58%), and diuretics
(82%). Few patients had an implantable cardioverter-defibrillator (ICD) or
cardiac resynchronization therapy-defibrillator (CRT-D) (15%).
PARADIGM-HF demonstrated that ENTRESTO, a combination of
sacubitril and a RAS inhibitor (valsartan), was superior to a RAS inhibitor
(enalapril), in reducing the risk of the combined endpoint of cardiovascular
death or hospitalization for heart failure, based on a time-to-event analysis
(hazard ratio [HR]: 0.80, 95% confidence interval [CI], 0.73, 0.87, p < 0.0001).
The treatment effect reflected a reduction in both cardiovascular death and
heart failure hospitalization; see Table 2 and Figure 3. Sudden death accounted
for 45% of cardiovascular deaths, followed by pump failure, which accounted for
26%.
ENTRESTO also improved overall survival (HR 0.84; 95% CI
[0.76, 0.93], p = 0.0009) (Table 2). This finding was driven entirely by a
lower incidence of cardiovascular mortality on ENTRESTO.
Table 2: Treatment Effect for the Primary Composite
Endpoint, its Components, and All-cause Mortality
|
ENTRESTO
N=4,187
n (%) |
Enalapril
N=4,212
n (%) |
Hazard Ratio (95% CI) |
p-value |
Primary composite endpoint of cardiovascular death or heart failure hospitalization |
914 (21.8) |
1,117 (26.5) |
0.80 (0.73, 0.87) |
< 0.0001 |
Cardiovascular death as first event |
377 (9.0) |
459 (10.9) |
|
|
Heart failure hospitalization as first event |
537 (12.8) |
658 (15.6) |
|
|
Number of patients with events: * |
Cardiovascular death** |
558 (13.3) |
693 (16.5) |
0.80 (0.71, 0.89) |
|
Heart failure hospitalizations |
537 (12.8) |
658 (15.6) |
0.79 (0.71, 0.89) |
|
All-cause mortality |
711 (17.0) |
835 (19.8) |
0.84 (0.76, 0.93) |
0.0009 |
*Analyses of the components of the primary composite
endpoint were not prospectively planned to be adjusted for multiplicity
**Includes subjects who had heart failure hospitalization prior to death |
The Kaplan-Meier curves presented below (Figure 3) show
time to first occurrence of the primary composite endpoint (3A), and time to
occurrence of cardiovascular death at any time (3B) and first heart failure hospitalization
(3C).
Figure 3: Kaplan-Meier Curves for the Primary
Composite Endpoint (A), Cardiovascular Death (B), and Heart Failure
Hospitalization (C)
A wide range of demographic characteristics, baseline
disease characteristics, and baseline concomitant medications were examined for
their influence on outcomes. The results of the primary composite endpoint were
consistent across the subgroups examined (Figure 4).
Figure 4: Primary Composite Endpoint (CV Death or HF Hospitalization)
- Subgroup Analysis
Note: The figure above presents effects in various
subgroups, all of which are baseline characteristics. The 95% confidence limits
that are shown do not take into account the number of comparisons made, and may
not reflect the effect of a particular factor after adjustment for all other
factors. Apparent homogeneity or heterogeneity among groups should not be
over-interpreted.