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Ranexa

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Ranexa

CLINICAL PHARMACOLOGY

Mechanism of Action

The mechanism of action of ranolazine's antianginal effects has not been determined. Ranolazine has anti-ischemic and antianginal effects that do not depend upon reductions in heart rate or blood pressure. It does not affect the rate-pressure product, a measure of myocardial work, at maximal exercise. Ranolazine at therapeutic levels can inhibit the cardiac late sodium current (INa). However, the relationship of this inhibition to angina symptoms is uncertain.

The QT prolongation effect of ranolazine on the surface electrocardiogram is the result of inhibition of IKr, which prolongs the ventricular action potential.

Pharmacodynamics

Hemodynamic Effects

Patients with chronic angina treated with RANEXA in controlled clinical studies had minimal changes in mean heart rate ( < 2 bpm) and systolic blood pressure ( < 3 mm Hg). Similar results were observed in subgroups of patients with CHF NYHA Class I or II, diabetes, or reactive airway disease, and in elderly patients.

Electrocardiographic Effects

Dose and plasma concentration-related increases in the QTc interval [see WARNINGS AND PRECAUTIONS], reductions in T wave amplitude, and, in some cases, notched T waves, have been observed in patients treated with RANEXA. These effects are believed to be caused by ranolazine and not by its metabolites. The relationship between the change in QTc and ranolazine plasma concentrations is linear, with a slope of about 2.6 msec/1000 ng/mL, through exposures corresponding to doses several-fold higher than the maximum recommended dose of 1000 mg twice daily. The variable blood levels attained after a given dose of ranolazine give a wide range of effects on QTc. At Tmax following repeat dosing at 1000 mg twice daily, the mean change in QTc is about 6 msec, but in the 5% of the population with the highest plasma concentrations, the prolongation of QTc is at least 15 msec. In cirrhotic subjects with mild or moderate hepatic impairment, the relationship between plasma level of ranolazine and QTc is much steeper [see CONTRAINDICATIONS].

Age, weight, gender, race, heart rate, congestive heart failure, diabetes, and renal impairment did not alter the slope of the QTc-concentration relationship of ranolazine.

No proarrhythmic effects were observed on 7-day Holter recordings in 3,162 acute coronary syndrome patients treated with RANEXA. There was a significantly lower incidence of arrhythmias (ventricular tachycardia, bradycardia, supraventricular tachycardia, and new atrial fibrillation) in patients treated with RANEXA (80%) versus placebo (87%), including ventricular tachycardia ≥ 3 beats (52% versus 61%). However, this difference in arrhythmias did not lead to a reduction in mortality, a reduction in arrhythmia hospitalization, or a reduction in arrhythmia symptoms.

Pharmacokinetics

Ranolazine is extensively metabolized in the gut and liver and its absorption is highly variable. For example, at a dose of 1000 mg twice daily, the mean steady-state Cmax was 2600 ng/mL with 95% confidence limits of 400 and 6100 ng/mL. The pharmacokinetics of the (+) R- and (-) S-enantiomers of ranolazine are similar in healthy volunteers. The apparent terminal half-life of ranolazine is 7 hours. Steady state is generally achieved within 3 days of twice-daily dosing with RANEXA. At steady state over the dose range of 500 to 1000 mg twice daily, Cmax and AUC0-τ increase slightly more than proportionally to dose, 2.2- and 2.4-fold, respectively. With twicedaily dosing, the trough:peak ratio of the ranolazine plasma concentration is 0.3 to 0.6. The pharmacokinetics of ranolazine is unaffected by age, gender, or food.

Absorption and Distribution

After oral administration of RANEXA, peak plasma concentrations of ranolazine are reached between 2 and 5 hours. After oral administration of 14C-ranolazine as a solution, 73% of the dose is systemically available as ranolazine or metabolites. The bioavailability of ranolazine from RANEXA tablets relative to that from a solution of ranolazine is 76%. Because ranolazine is a substrate of P-gp, inhibitors of P-gp may increase the absorption of ranolazine.

Food (high-fat breakfast) has no important effect on the Cmax and AUC of ranolazine. Therefore, RANEXA may be taken without regard to meals. Over the concentration range of 0.25 to 10 μg/mL, ranolazine is approximately 62% bound to human plasma proteins.

Metabolism and Excretion

Ranolazine is metabolized mainly by CYP3A and, to a lesser extent, by CYP2D6. Following a single oral dose of ranolazine solution, approximately 75% of the dose is excreted in urine and 25% in feces. Ranolazine is metabolized rapidly and extensively in the liver and intestine; less than 5% is excreted unchanged in urine and feces. The pharmacologic activity of the metabolites has not been well characterized. After dosing to steady state with 500 mg to 1500 mg twice daily, the four most abundant metabolites in plasma have AUC values ranging from about 5 to 33% that of ranolazine, and display apparent half-lives ranging from 6 to 22 hours.

Drug Interactions

Effect of other drugs on ranolazine

In vitro data indicate that ranolazine is a substrate of CYP3A and, to a lesser degree, of CYP2D6. Ranolazine is also a substrate of P-glycoprotein.

Strong CYP3A Inhibitors

Plasma levels of ranolazine with RANEXA 1000 mg twice daily are increased by 220% when coadministered with ketoconazole 200 mg twice daily [see CONTRAINDICATIONS].

Moderate CYP3A Inhibitors

Plasma levels of ranolazine with RANEXA 1000 mg twice daily are increased by 50 to 130% by diltiazem 180 to 360 mg, respectively. Plasma levels of ranolazine with RANEXA 750 mg twice daily are increased by 100% by verapamil 120 mg three times daily [see DRUG INTERACTIONS].

Weak CYP3A Inhibitors

The weak CYP3A inhibitors simvastatin (20 mg once daily) and cimetidine (400 mg three times daily) do not increase the exposure to ranolazine in healthy volunteers.

CYP3A Inducers

Rifampin 600 mg once daily decreases the plasma concentrations of ranolazine (1000 mg twice daily) by approximately 95% [see CONTRAINDICATIONS].

CYP2D6 Inhibitors

Paroxetine 20 mg once daily increased ranolazine concentrations by 20% in healthy volunteers receiving RANEXA 1000 mg twice daily. No dose adjustment of RANEXA is required in patients treated with CYP2D6 inhibitors.

Digoxin

Plasma concentrations of ranolazine are not significantly altered by concomitant digoxin at 0.125 mg once daily.

Effect of ranolazine on other drugs

In vitro ranolazine and its O-demethylated metabolite are weak inhibitors of CYP3A and moderate inhibitors of CYP2D6 and P-gp. In vitro ranolazine is an inhibitor of OCT2.

CYP3A Substrates

The plasma levels of simvastatin, a CYP3A substrate, and its active metabolite are increased by 100% in healthy volunteers receiving 80 mg once daily and RANEXA 1000 mg twice daily [see DRUG INTERACTIONS]. Mean exposure to atorvastatin (80 mg daily) is increased by 40% following co-administration with RANEXA (1000 mg twice daily) in healthy volunteers.

However, in one subject the exposure to atorvastatin and metabolites was increased by ~400% in the presence of RANEXA.

Diltiazem

The pharmacokinetics of diltiazem is not affected by ranolazine in healthy volunteers receiving diltiazem 60 mg three times daily and RANEXA 1000 mg twice daily.

P-gp Substrates

Ranolazine increases digoxin concentrations by 50% in healthy volunteers receiving RANEXA 1000 mg twice daily and digoxin 0.125 mg once daily [see DRUG INTERACTIONS].

CYP2D6 Substrates

RANEXA 750 mg twice daily increases the plasma concentrations of a single dose of immediate release metoprolol (100 mg), a CYP2D6 substrate, by 80% in extensive CYP2D6 metabolizers with no need for dose adjustment of metoprolol. In extensive metabolizers of dextromethorphan, a substrate of CYP2D6, ranolazine inhibits partially the formation of the main metabolite dextrorphan.

OCT2 Substrates

In subjects with type 2 diabetes mellitus, the exposure to metformin is increased by 40% and 80% following administration of ranolazine 500 mg twice daily and 1000 mg twice daily, respectively. If co-administered with RANEXA 1000 mg twice daily, do not exceed metformin doses of 1700 mg/day [see DRUG INTERACTIONS].

Reproductive Toxicology Studies

Animal reproduction studies with ranolazine were conducted in rats and rabbits.

There was an increased incidence of misshapen sternebrae and reduced ossification of pelvic and cranial bones in fetuses of pregnant rats dosed at 400 mg/kg/day (2 times the MRHD on a surface area basis). Reduced ossification of sternebrae was observed in fetuses of pregnant rabbits dosed at 150 mg/kg/day (1.5 times the MRHD on a surface area basis). These doses in rats and rabbits were associated with an increased maternal mortality rate.

Clinical Studies

Chronic Stable Angina

CARISA (Combination Assessment of Ranolazine In Stable Angina) was a study in 823 chronic angina patients randomized to receive 12 weeks of treatment with twice-daily RANEXA 750 mg, 1000 mg, or placebo, who also continued on daily doses of atenolol 50 mg, amlodipine 5 mg, or diltiazem CD 180 mg. Sublingual nitrates were used in this study as needed.

In this trial, statistically significant (p < 0.05) increases in modified Bruce treadmill exercise duration and time to angina were observed for each RANEXA dose versus placebo, at both trough (12 hours after dosing) and peak (4 hours after dosing) plasma levels, with minimal effects on blood pressure and heart rate. The changes versus placebo in exercise parameters are presented in Table 1. Exercise treadmill results showed no increase in effect on exercise at the 1000 mg dose compared to the 750 mg dose.

Table 1 : Exercise Treadmill Results (CARISA)

Study Mean Difference from Placebo (sec) CARISA
(N = 791)
RANEXA Twice-daily Dose 750 mg 1000 mg
Exercise Duration
  Trough 24a 24a
  Peak 34b 26a
Time to Angina
  Trough 30a 26a
  Peak 38b 38b
Time to 1 mm ST-Segment Depression
  Trough 20 21
  Peak 41b 35b
a p-value ≤ 0.05
b p-value ≤ 0.005

The effects of RANEXA on angina frequency and nitroglycerin use are shown in Table 2.

Table 2 : Angina Frequency and Nitroglycerin Use (CARISA)

    Placebo RANEXA 750 mga RANEXA 1000 mga
Angina Frequency (attacks/week) N 258 272 261
Mean 3.3 2.5 2.1
p-value vs placebo 0.006 < 0.001
Nitroglycerin Use (doses/week) N 252 262 244
Mean 3.1 2.1 1.8
p-value vs placebo 0.016 < 0.001
a Twice daily

Tolerance to RANEXA did not develop after 12 weeks of therapy. Rebound increases in angina, as measured by exercise duration, have not been observed following abrupt discontinuation of RANEXA.

RANEXA has been evaluated in patients with chronic angina who remained symptomatic despite treatment with the maximum dose of an antianginal agent. In the ERICA (Efficacy of Ranolazine In Chronic Angina) trial, 565 patients were randomized to receive an initial dose of RANEXA 500 mg twice daily or placebo for 1 week, followed by 6 weeks of treatment with RANEXA 1000 mg twice daily or placebo, in addition to concomitant treatment with amlodipine 10 mg once daily. In addition, 45% of the study population also received long-acting nitrates. Sublingual nitrates were used as needed to treat angina episodes. Results are shown in Table 3. Statistically significant decreases in angina attack frequency (p = 0.028) and nitroglycerin use (p = 0.014) were observed with RANEXA compared to placebo. These treatment effects appeared consistent across age and use of long-acting nitrates.

Table 3 : Angina Frequency and Nitroglycerin Use (ERICA)

    Placebo RANEXAa
Angina Frequency (attacks/week) N 281 277
Mean 4.3 3.3
Median 2.4 2.2
Nitroglycerin Use (doses/week) N 281 277
Mean 3.6 2.7
Median 1.7 1.3
a 1000 mg twice daily

Gender

Effects on angina frequency and exercise tolerance were considerably smaller in women than in men. In CARISA, the improvement in Exercise Tolerance Test (ETT) in females was about 33% of that in males at the 1000 mg twice-daily dose level. In ERICA, where the primary endpoint was angina attack frequency, the mean reduction in weekly angina attacks was 0.3 for females and 1.3 for males.

Race

There were insufficient numbers of non-Caucasian patients to allow for analyses of efficacy or safety by racial subgroup.

Lack of Benefit in Acute Coronary Syndrome

In a large (n = 6,560) placebo-controlled trial (MERLIN-TIMI 36) in patients with acute coronary syndrome, there was no benefit shown on outcome measures. However, the study is somewhat reassuring regarding proarrhythmic risks, as ventricular arrhythmias were less common on ranolazine [see CLINICAL PHARMACOLOGY], and there was no difference between RANEXA and placebo in the risk of all-cause mortality (relative risk ranolazine:placebo 0.99 with an upper 95% confidence limit of 1.22).

REFERENCES

M.A. Suckow et al. The anti-ischemia agent ranolazine promotes the development of intestinal tumors in APC (min/+) mice. Cancer Letters 209(2004):165-9.

Last reviewed on RxList: 11/25/2013
This monograph has been modified to include the generic and brand name in many instances.

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