NEXIUM - Pharmacology Esomeprazole magnesium

Pharmacology refers to the chemical makeup and behavior of NEXIUM (esomeprazole magnesium granule, delayed release).

Description

The active ingredient in the proton pump inhibitor NEXIUM® (esomeprazole magnesium) Delayed-Release Capsules for oral administration and NEXIUM (esomeprazole magnesium) For Delayed-Release Oral Suspension is bis(5-methoxy-2-[(S)-[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H-benzimidazole-1-yl) magnesium trihydrate. Esomeprazole is the S-isomer of omeprazole, which is a mixture of the S- and R- isomers. (Initial U.S. approval of esomeprazole magnesium: 2001). Its molecular formula is (C17H18N3O3S)2Mg x 3 H2O with molecular weight of 767.2 as a trihydrate and 713.1 on an anhydrous basis. The structural formula is:

Figure 1

image 01.jpg

The magnesium salt is a white to slightly colored crystalline powder. It contains 3 moles of water of solvation and is slightly soluble in water. The stability of esomeprazole magnesium is a function of pH; it rapidly degrades in acidic media, but it has acceptable stability under alkaline conditions. At pH 6.8 (buffer), the half-life of the magnesium salt is about 19 hours at 25°C and about 8 hours at 37°C.

NEXIUM is supplied in delayed-release capsules and in packets for a delayed-release oral suspension. Each NEXIUM delayed-release capsule contains 20 mg of esomeprazole (equivalent to 22.3 mg esomeprazole magnesium trihydrate) or 40 mg of esomeprazole (equivalent to 44.5 mg esomeprazole magnesium trihydrate) in the form of enteric-coated granules with the following inactive ingredients: glyceryl monostearate 40-55, hydroxypropyl cellulose, hypromellose, magnesium stearate, methacrylic acid copolymer type C, polysorbate 80, sugar spheres, talc, and triethyl citrate. The capsule shells have the following inactive ingredients: D&C Red #28, D&C Yellow #10, ethyl alcohol, FD&C Blue #1, FD&C Red #40, gelatin, isopropyl alcohol, n-butyl alcohol, polyvinyl pyrrolidone, propylene glycol, shellac, sodium hydroxide, and titanium dioxide.

Each packet of NEXIUM for delayed-release oral suspension contains esomeprazole, in the form of same enteric-coated granules used in NEXIUM delayed-release capsules, and also inactive granules:

  • 2.5 mg esomeprazole (equivalent to 2.8 mg esomeprazole magnesium trihydrate)
  • 5 mg esomeprazole (equivalent to 5.6 mg esomeprazole magnesium trihydrate)
  • 10 mg esomeprazole (equivalent to 11.1 mg esomeprazole magnesium trihydrate)
  • 20 mg esomeprazole (equivalent to 22.3 mg esomeprazole magnesium trihydrate)
  • 40 mg esomeprazole (equivalent to 44.5 mg esomeprazole magnesium trihydrate)

The inactive granules are composed of the following ingredients: citric acid, crospovidone, dextrose, hydroxypropyl cellulose, iron oxide, and xanthan gum. The esomeprazole granules and inactive granules are constituted with water to form a suspension and are given by oral, nasogastric, or gastric administration.

Clinical Pharmacology

mechanism of action

Esomeprazole belongs to a class of antisecretory compounds, the substituted benzimidazoles, that suppress gastric acid secretion by specific inhibition of the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell. Esomeprazole is protonated and converted in the acidic compartment of the parietal cell forming the active inhibitor, the achiral sulphenamide. Because this enzyme system is regarded as the acid (proton) pump within the gastric mucosa, esomeprazole has been characterized as a gastric acid-pump inhibitor, in that it blocks the final step of acid production. This effect is dose-related and leads to inhibition of both basal and stimulated acid secretion irrespective of the stimulus.

pharmacodynamics

Antisecretory Activity

Adults

The effect of esomeprazole on intragastric pH was determined in adult patients with symptomatic GERD in two separate studies. In the first study of 36 patients, NEXIUM 40 mg and 20 mg delayed-release capsules were administered once daily over 5 days as shown in Table 5:

Table 5: Effect of Esomeprazole on Intragastric pH on Day 5 (N=36) Following Once Daily Dosing of NEXIUM Delayed-Release Capsules in Adult Patients with Symptomatic GERD

Parameter

NEXIUM Delayed-Release Capsules

40 mg

20 mg

% Time Gastric pH >4

Gastric pH was measured over a 24-hour period

(Hours)

70%

p< 0.01 NEXIUM 40 mg vs. NEXIUM 20 mg

(16.8 h)

53%

(12.7 h)

Coefficient of variation

26%

37%

Median 24 Hour pH

4.9

4.1

Coefficient of variation

16%

27%

In a second study, the effect on intragastric pH of NEXIUM 40 mg delayed-release capsules administered once daily over a five-day period was similar to the first study, (% time with pH > 4 was 68% or 16.3 hours).

Pediatrics

In infants (1 to 11 months old, inclusive) with GERD given NEXIUM for delayed-release oral suspension 1 mg/kg once daily, the percent time with intragastric pH > 4 increased from 29% at baseline to 69% on Day 7, which is similar to the pharmacodynamic effect in adults.

Serum Gastrin Effects

The effect of esomeprazole on serum gastrin concentrations was evaluated in approximately 2,700 patients in clinical trials of oral esomeprazole for up to 8 weeks and in over 1,300 patients for up to 12 months. The mean fasting gastrin level increased in a dose-related manner. The increase in serum gastrin concentrations reached a plateau within two to three months of therapy and returned to baseline levels within four weeks after discontinuation of therapy.

Increased gastrin causes enterochromaffin-like cell hyperplasia and increased serum Chromogranin A (CgA) levels. The increased CgA levels may cause false positive results in diagnostic investigations for neuroendocrine tumors [see Warnings and Precautions (5.10)]

Enterochromaffin-like (ECL) Cell Effects

Human gastric biopsy specimens have been obtained from more than 3,000 patients (both pediatrics and adults) treated with omeprazole in long-term clinical trials. The incidence of ECL cell hyperplasia in these studies increased with time; however, no case of ECL cell carcinoids, dysplasia, or neoplasia has been found in these patients [see Nonclinical Toxicology (13.1)]

In over 1,000 patients treated with oral esomeprazole (10 mg, 20 mg or 40 mg/day) for up to 12 months, the prevalence of ECL cell hyperplasia increased with time and dose. No patient developed ECL cell carcinoids, dysplasia, or neoplasia in the gastric mucosa.

Endocrine Effects

Esomeprazole had no effect on thyroid function in adults when given NEXIUM 20 mg or 40 mg delayed-release capsules once daily for 4 weeks. Other effects of esomeprazole on the endocrine system were assessed in studies of omeprazole. Oral doses of omeprazole 30 mg or 40 mg once daily for 2 to 4 weeks had no effect on carbohydrate metabolism, circulating levels of parathyroid hormone, cortisol, estradiol, testosterone, prolactin, cholecystokinin, or secretin.

pharmacokinetics

Absorption

NEXIUM delayed-release capsules and NEXIUM for delayed-release oral suspension. showed similar bioavailability after a single dose (40 mg) administration in 94 healthy male and female subjects under fasting conditions. After oral administration, peak plasma levels (Cmax) of esomeprazole occur at approximately 1.5 hours (Tmax). The Cmax increases proportionally when the dose is increased, and there is a three-fold increase in the area under the plasma concentration-time curve (AUC) from 20 to 40 mg. At repeated once-daily dosing with 40 mg, the systemic bioavailability is approximately 90% compared to 64% after a single dose of 40 mg. The mean exposure (AUC) to esomeprazole increases from 4.32 micromol*hr/L on Day 1 to 11.2 micromol*hr/L on Day 5 after 40 mg once daily dosing.

The AUC after administration of a single 40 mg dose of NEXIUM delayed-release capsules is decreased by 43% to 53% after food intake compared to fasting conditions [see Dosage and Administration (2.3)]. The pharmacokinetics of esomeprazole in adult patients with symptomatic GERD following repeated once daily administration of 20 mg and 40 mg NEXIUM delayed-release capsules over a period of five days are shown in Table 6:

Table 6: Geometric Mean (95% CI) Pharmacokinetic Parameters of Esomeprazole on Day 5 Following Once Daily Dosing of NEXIUM Delayed-Release Capsules in Adult Patients with Symptomatic GERD

NEXIUM delayed-release capsules

Parameter

Values represent the geometric mean, except the Tmax, which is the arithmetic mean; CV = Coefficient of variation

(CV)

40 mg once daily

(n=36)

20 mg once daily

(n=36)

AUC (μmol·h/L)

12.6 (42%)

4.2 (59%)

Cmax (μmol/L)

4.7 (37%)

2.1 (45%)

Tmax (h)

1.6

1.6

t1/2 (h)

1.5

1.2

Esomeprazole is a time-dependent inhibitor of CYP2C19, resulting in autoinhibition and nonlinear pharmacokinetics. The systemic exposure increases in a more than dose proportional manner after multiple oral doses of esomeprazole. Compared to the first dose, the systemic exposure (Cmax and AUC0-24h) at steady state following once a day dosing increased by 43% and 90%, respectively, compared to after the first dose for the 20 mg dose and increased by 95% and 159%, respectively, for the 40 mg dose.

Distribution

Esomeprazole is 97% bound to plasma proteins. Plasma protein binding is constant over the concentration range of 2 to 20 micromol/L. The apparent volume of distribution at steady state in healthy subjects is approximately 16 L.

Elimination

Metabolism

Esomeprazole is extensively metabolized in the liver by the cytochrome P450 (CYP) enzyme system. The metabolites of esomeprazole lack antisecretory activity. The major part of esomeprazole’s metabolism is dependent upon the CYP2C19 isoenzyme, which forms the hydroxy and desmethyl metabolites. The remaining amount is dependent on CYP3A4 which forms the sulphone metabolite.

Excretion

The plasma elimination half-life of esomeprazole is approximately 1 to 1.5 hours. Less than 1% of parent drug is excreted in the urine. Approximately 80% of an oral dose of esomeprazole is excreted as inactive metabolites in the urine, and the remainder is found as inactive metabolites in the feces.

Combination Therapy with Amoxicillin and Clarithromycin

NEXIUM delayed-release capsules 40 mg once daily was given in combination with amoxicillin 1000 mg twice daily and clarithromycin 500 mg twice daily for 7 days to 17 healthy male and female subjects. The mean steady state AUC and Cmax of esomeprazole increased by 70% and 18%, respectively during combination therapy compared to treatment with NEXIUM alone. The observed increase in esomeprazole exposure during co-administration with amoxicillin and clarithromycin is not expected to be clinically relevant.

The pharmacokinetic parameters for amoxicillin and clarithromycin were similar during combination therapy and administration of each drug alone. However, the mean AUC and Cmax for 14-hydroxyclarithromycin increased by 19% and 22%, respectively, during combination therapy compared to treatment with clarithromycin alone. This increase in exposure to 14-hydroxyclarithromycin is not considered to be clinically relevant.

Specific Populations

Geriatric Patients

The AUC and Cmax values of esomeprazole were slightly higher (25% and 18%, respectively) in the elderly as compared to younger subjects at steady state. This increase in exposure is not considered clinically relevant.

Pediatric Patients

1 Month to 11 Months of Age

The pharmacokinetic parameters following repeated dose administration of esomeprazole magnesium 1 mg/kg once daily for 7 to 8 days in 1 month to 11-month-old infants with GERD are summarized in Table 7.

Table 7: Summary of Esomeprazole Pharmacokinetic Parameters Following Once Daily Dosing of Oral Esomeprazole Magnesium for 7 to 8 Days in 1 Month to 1 Year Old Infants with GERD

Parameter

Esomeprazole Magnesium 1 mg/kg Orally Once Daily

AUC (μmol·h/L) (n=7)

Geometric mean

3.51

Css,,max (μmol/L) (n=15)

0.87

t½ (hours) (n=8)

0.93

tmax (hours) (n=15)

Median

3.0

Subsequent pharmacokinetic simulation analyses showed that for pediatric patients 1 month to 11 months of age, a dosage regimen of 2.5 mg once daily (body weight 3 to 5 kg), 5 mg once daily (body weight more than 5 to 7.5 kg) and 10 mg once daily for (body weight more than 7.5 to 12 kg) would achieve comparable steady-state plasma exposures (AUC) to that observed with 10 mg once daily in patients 1 year to 11 year of age and 20 mg once daily in patients 12 years to 18 years of age, as well as adults.

Apparent clearance (CL/F) increases with age in pediatric patients with GERD from 1 month to 2 years of age.

1 Year to 11 Years of Age

The pharmacokinetics of esomeprazole were studied in pediatric patients with GERD aged 1 year to 11 years. Following once daily dosing with NEXIUM for delayed-release oral suspension for 5 days, the total exposure (AUC) for the 10 mg dosage in patients aged 6 years to 11 years was similar to that seen with the 20 mg dosage in adults and adolescents aged 12 years to 17 years. The total exposure for the 10 mg dosage in patients aged 1 year to 5 years was approximately 30% higher than the 10 mg dosage in patients aged 6 years to 11 years. The total exposure for the 20 mg dosage in patients aged 6 years to 11 years was higher than that observed with the 20 mg dosage in patients aged 12 years to 17 years and adults, but lower than that observed with the 40 mg dosage in 12 to 17 year-olds and adults. See Table 8.

Table 8: Summary of PK Parameters in 1 to 11 Year Olds with GERD following 5 Days of Once-Daily Oral Esomeprazole Treatment

Parameter

NEXIUM For Delayed-Release Oral Suspension

1 Year to 5 Years

6 Years to 11 Years

10 mg once daily (N=8)

10 mg once daily (N=7)

20 mg once daily (N=6)

AUC (μmol·h/L)

Geometric mean

4.83

3.70

6.28

Cmax (μmol/L)

2.98

1.77

3.73

tmax (h)

Arithmetic mean

1.44

1.79

1.75

t½λz (h)

0.74

0.88

0.73

Cl/F (L/h)

5.99

7.84

9.22

12 to 17 Years of Age

The pharmacokinetics of NEXIUM were studied in 28 adolescent patients with GERD aged 12 to 17 years inclusive, in a single center study. Patients were randomized to receive NEXIUM 20 mg or 40 mg once daily for 8 days. Mean Cmax and AUC values of esomeprazole were not affected by body weight or age; and more than dose-proportional increases in mean Cmax and AUC values were observed between the two dose groups in the study. Overall, NEXIUM pharmacokinetics in adolescent patients aged 12 to 17 years were similar to those observed in adult patients with symptomatic GERD. See Table 9.

Table 9: Comparison of Esomeprazole Pharmacokinetic Parameters Following Once Daily Dosing of NEXIUM Delayed-Release Capsules in Pediatric Patients 12 Years to 17 Years with GERD and Adults with Symptomatic GERD
Data obtained from two independent studies.

Parameter

NEXIUM Delayed-Release Capsules

12 to 17 Years (N=28)

Adults (N=36)

20 mg once daily

for 8 days

40 mg once daily

for 8 days

20 mg once daily

for 5 days

40 mg once daily

for 5 days

AUC (μmol·h/L)

3.65

13.86

4.2

12.6

Cmax (μmol/L)

1.45

5.13

2.1

4.7

tmax (h)

2.00

1.75

1.6

1.6

t½λz (h)

0.82

1.22

1.2

1.5

Data presented are geometric means for AUC, Cmax and t½λz, and median value for tmax.

Male and Female Patients

The AUC and Cmax values of esomeprazole were slightly higher (13%) in females than in males at steady state when dosed orally This increase in exposure is not considered clinically relevant.

Patients with Renal Impairment

The pharmacokinetics of NEXIUM in patients with renal impairment are not expected to be altered relative to healthy subjects as less than 1% of esomeprazole is excreted unchanged in urine.

Patients with Hepatic Impairment

The steady state pharmacokinetics of esomeprazole obtained after administration of NEXIUM delayed-release capsules 40 mg orally once daily to patients with mild (Child-Pugh Class A, n=4), moderate (Child-Pugh Class B, n=4), and severe (Child-Pugh Class C, n=4) hepatic impairment were compared to those obtained in 36 male and female GERD patients with normal liver function. In patients with mild and moderate hepatic impairment, the AUCs were within the range that could be expected in patients with normal liver function. In patients with severe hepatic impairment the AUCs were 2 to 3 times higher than in the patients with normal liver function [see Use in Specific Populations (8.6)].

Drug Interaction Studies

Effect of Esomeprazole/Omeprazole on Other Drugs

In vitro and in vivo studies have shown that esomeprazole is not likely to inhibit CYPs 1A2, 2A6, 2C9, 2D6, 2E1 and 3A4.

Antiretrovirals

For some antiretroviral drugs, such as rilpivirine, atazanavir and nelfinavir, decreased serum concentrations have been reported when given together with omeprazole [see Drug Interactions (7)].

Rilpivirine:

Following multiple doses of rilpivirine (150 mg, daily) and omeprazole (20 mg, daily), AUC was decreased by 40%, Cmax by 40%, and Cmin by 33% for rilpivirine [see Contraindications (4)].

Nelfinavir:

Following multiple doses of nelfinavir (1250 mg, twice daily) and omeprazole (40 mg daily), AUC was decreased by 36% and 92%, Cmax by 37% and 89% and Cmin by 39% and 75% respectively for nelfinavir and M8.

Atazanavir:

Following multiple doses of atazanavir (400 mg, daily) and omeprazole (40 mg, daily, 2 hours before atazanavir), AUC was decreased by 94%, Cmax by 96%, and Cmin by 95%.

Saquinavir:

Following multiple dosing of saquinavir/ritonavir (1000/100 mg) twice daily for 15 days with omeprazole 40 mg daily co-administered days 11 to 15. The AUC was increased by 82%, Cmax by 75%, and Cmin by 106%. The mechanism behind this interaction is not fully elucidated.

Clopidogrel

In a crossover study, healthy subjects were administered clopidogrel (300 mg loading dose followed by 75 mg per day as the maintenance dosage for 28 days) alone and with esomeprazole (40 mg orally once daily at the same time as clopidogrel) for 29 days. Exposure to the active metabolite of clopidogrel was reduced by 35% to 40% over this time period when clopidogrel and esomeprazole were administered together. Pharmacodynamic parameters were also measured and demonstrated that the change in inhibition of platelet aggregation was related to the change in the exposure to clopidogrel active metabolite [see Warnings and Precautions (5.6) and Drug Interactions (7)].

Mycophenolate Mofetil

Administration of omeprazole 20 mg twice daily for 4 days and a single 1000 mg dose of MMF approximately one hour after the last dose of omeprazole to 12 healthy subjects in a cross-over study resulted in a 52% reduction in the Cmax and 23% reduction in the AUC of MPA [see Drug Interactions (7)].

Cilostazol

Omeprazole acts as an inhibitor of CYP2C19. Omeprazole, given in doses of 40 mg daily for one week to 20 healthy subjects in cross-over study, increased Cmax and AUC of cilostazol by 18% and 26% respectively. The Cmax and AUC of one of the active metabolites, 3,4-dihydro-cilostazol, which has 4 to 7 times the activity of cilostazol, were increased by 29% and 69%, respectively. Co-administration of cilostazol with omeprazole is expected to increase concentrations of cilostazol and the above mentioned active metabolite [see Drug Interactions (7)].

Diazepam

Co-administration of esomeprazole 30 mg and diazepam, a CYP2C19 substrate, resulted in a 45% decrease in clearance of diazepam. Increased plasma levels of diazepam were observed 12 hours after dosing and onwards. However, at that time, the plasma levels of diazepam were below the therapeutic interval, and thus this interaction is unlikely to be of clinical relevance.

Digoxin

Concomitant administration of omeprazole 20 mg once daily and digoxin in healthy subjects increased the bioavailability of digoxin by 10% (30% in two subjects) [see Drug Interactions (7)].

Other Drugs

Concomitant administration of esomeprazole and either naproxen (non-selective NSAID) did not identify any clinically relevant changes in the pharmacokinetic profiles of these NSAIDs.

Effect of Other Drugs on Esomeprazole/Omeprazole

St. John’s Wort

In a cross-over study in 12 healthy male subjects, St. John’s Wort (300 mg three times daily for 14 days) significantly decreased the systemic exposure of omeprazole in CYP2C19 poor metabolizers (Cmax and AUC both decreased by 38%) and extensive metabolizers (Cmax and AUC decreased by 50% and 44%, respectively) [see Drug Interactions (7)].

Voriconazole

Concomitant administration of omeprazole and voriconazole (a combined inhibitor of CYP2C19 and CYP3A4) resulted in more than doubling of the omeprazole exposure. When voriconazole (400 mg every 12 hours for one day, followed by 200 mg once daily for 6 days) was given with omeprazole (40 mg once daily for 7 days) to healthy subjects, the steady-state Cmax and AUC0-24 of omeprazole significantly increased: an average of 2 times (90% CI: 1.8, 2.6) and 4 times (90% CI: 3.3, 4.4), respectively, as compared to when omeprazole was given without voriconazole [see Drug Interactions (7)].

Other Drugs

Co-administration of esomeprazole with oral contraceptives, diazepam, phenytoin, quinidine, naproxen (non-selective NSAID) did not seem to change the pharmacokinetic profile of esomeprazole.

microbiology

NEXIUM, amoxicillin, and clarithromycin triple therapy has been shown to be active against most strains of Helicobacter pylori (H. pylori) in vitro and in clinical infections [see Indications and Usage (1) and Clinical Studies (14)].

Helicobacter pylori: Susceptibility testing of H. pylori isolates was performed for amoxicillin and clarithromycin using agar dilution methodology, and minimum inhibitory concentrations (MICs) were determined.

Pretreatment Resistance: Clarithromycin pretreatment resistance rate (MIC ≥ 1 mcg/mL) to H. pylori was 15% (66/445) at baseline in all treatment groups combined. A total of > 99% (394/395) of patients had H. pylori isolates that were considered to be susceptible (MIC ≤ 0.25 mcg/mL) to amoxicillin at baseline. One patient had a baseline H. pylori isolate with an amoxicillin MIC = 0.5 mcg/mL.

Clarithromycin Susceptibility Test Results and Clinical/Bacteriologic Outcomes: The baseline H. pylori clarithromycin susceptibility results and the H. pylori eradication results at the Day 38 visit are shown in Table 10:

Table 10: Clarithromycin Susceptibility Test Results and Clinical/Bacteriological Outcomes
Includes only patients with pretreatment and post-treatment clarithromycin susceptibility test results

for Triple Therapy (NEXIUM Delayed-Release Capsules 40 mg once daily, Amoxicillin 1000 mg twice daily and Clarithromycin 500 mg twice daily for 10 days)

Clarithromycin

Pretreatment Results

H.  pylori negative

(Eradicated)

H. pylori positive

(Not Eradicated)

Post-treatment susceptibility results

S

Susceptible (S) MIC ≤ 0.25 mcg/mL, Intermediate (I) MIC = 0.5 mcg/mL, Resistant (R) MIC ≥ 1.0 mcg/mL

I

R

No MIC

Susceptible

182

162

4

0

2

14

Intermediate

1

1

0

0

0

0

Resistant

29

13

1

0

13

2

Patients not eradicated of H. pylori following triple therapy with NEXIUM, amoxicillin and clarithromycin will likely have clarithromycin resistant H. pylori isolates. Therefore, clarithromycin susceptibility testing should be done, when possible. Patients with clarithromycin resistant H. pylori should not be re-treated with a clarithromycin-containing regimen.

Amoxicillin Susceptibility Test Results and Clinical/Bacteriological Outcomes:

In patients treated with NEXIUM, amoxicillin and clarithromycin in clinical trials, 83% (176/212) of the patients who had pretreatment amoxicillin susceptible MICs (≤ 0.25 mcg/mL) were eradicated of H. pylori, and 17% (36/212) were not eradicated of H. pylori. Of the 36 patients who were not eradicated of H. pylori, 16 had no post-treatment susceptibility test results and 20 had post-treatment H. pylori isolates with amoxicillin susceptible MICs. Fifteen of the patients who were not eradicated of H. pylori also had post-treatment H. pylori isolates with clarithromycin resistant MICs. There were no patients with H. pylori isolates who developed treatment emergent resistance to amoxicillin.

Susceptibility Test for Helicobacter pylori: For susceptibility testing information about Helicobacter pylori, see Microbiology section in prescribing information for clarithromycin and amoxicillin.

Effects on Gastrointestinal Microbial Ecology: Decreased gastric acidity due to any means, including proton pump inhibitors, increases gastric counts of bacteria normally present in the gastrointestinal tract. Treatment with PPIs may lead to slightly increased risk of gastrointestinal infections such as Salmonella and Campylobacter and possibly Clostridium difficile in hospitalized patients.

pharmacogenomics

CYP2C19, a polymorphic enzyme, is involved in the metabolism of esomeprazole. The CYP2C19*1 allele is fully functional while the CYP2C19*2 and *3 alleles are nonfunctional. There are other alleles associated with no or reduced enzymatic function. Patients carrying two fully functional alleles are extensive metabolizers and those carrying two loss-of-function alleles are poor metabolizers. The systemic exposure to esomeprazole varies with a patient’s metabolism status: poor metabolizers > intermediate metabolizers > extensive metabolizers. Approximately 3% of Caucasians and 15 to 20% of Asians are CYP2C19 poor metabolizers.

Systemic esomeprazole exposures were modestly higher (approximately 17%) in CYP2C19 intermediate metabolizers (IM; n=6) compared to extensive metabolizers (EM; n=17) of CYP2C19. Similar pharmacokinetic differences were noted across these genotypes in a study of Chinese healthy subjects that included 7 EMs and 11 IMs. There is very limited pharmacokinetic information for poor metabolizers (PM) from these studies.

At steady state following once daily administration of esomeprazole 40 mg, the ratio of AUC in poor metabolizers to AUC in the rest of the population (EMs) is approximately 1.5. This change in exposure is not considered clinically meaningful.

Nonclinical Toxicology

carcinogenesis, mutagenesis, impairment of fertility

The carcinogenic potential of NEXIUM was assessed using studies of omeprazole, of which esomeprazole is an enantiomer. In two 24-month oral carcinogenicity studies in rats, omeprazole at daily doses of 1.7, 3.4, 13.8, 44, and 140.8 mg/kg/day (about 0.4 to 34 times the human dose of 40 mg/day expressed on a body surface area basis) produced gastric ECL cell carcinoids in a dose-related manner in both male and female rats; the incidence of this effect was markedly higher in female rats, which had higher blood levels of omeprazole. Gastric carcinoids seldom occur in the untreated rat. In addition, ECL cell hyperplasia was present in all treated groups of both sexes. In one of these studies, female rats were treated with 13.8 mg omeprazole/kg/day (about 3.4 times the human dose of 40 mg/day on a body surface area basis) for 1 year, then followed for an additional year without the drug. No carcinoids were seen in these rats. An increased incidence of treatment-related ECL cell hyperplasia was observed at the end of 1 year (94% treated vs. 10% controls). By the second year the difference between treated and control rats was much smaller (46% vs. 26%) but still showed more hyperplasia in the treated group. Gastric adenocarcinoma was seen in one rat (2%). No similar tumor was seen in male or female rats treated for 2 years. For this strain of rat no similar tumor has been noted historically, but a finding involving only one tumor is difficult to interpret. A 78-week mouse carcinogenicity study of omeprazole did not show increased tumor occurrence, but the study was not conclusive.

Esomeprazole was negative in the Ames mutation test, in the in vivo rat bone marrow cell chromosome aberration test, and the in vivo mouse micronucleus test. Esomeprazole, however, was positive in the in vitro human lymphocyte chromosome aberration test. Omeprazole was positive in the in vitro human lymphocyte chromosome aberration test, the in vivo mouse bone marrow cell chromosome aberration test, and the in vivo mouse micronucleus test.

The potential effects of esomeprazole on fertility and reproductive performance were assessed using omeprazole studies. Omeprazole at oral doses up to 138 mg/kg/day in rats (about 34 times the human dose of 40 mg/day on a body surface area basis) was found to have no effect on reproductive performance of parental animals.

animal toxicology & / or pharmacology

Reproduction Studies

Reproduction studies have been performed in rats at oral doses up to 280 mg/kg/day (about 68 times an oral human dose of 40 mg on a body surface area basis) and in rabbits at oral doses up to 86 mg/kg/day (about 42 times an oral human dose of 40 mg on a body surface area basis) and have revealed no evidence of impaired fertility or harm to the fetus due to esomeprazole [see Use in Specific Populations (8.1) ].

Juvenile Animal Study

A 28-day toxicity study with a 14-day recovery phase was conducted in juvenile rats with esomeprazole magnesium at doses of 70 to 280 mg /kg/day (about 17 to 68 times a daily oral human dose of 40 mg on a body surface area basis). An increase in the number of deaths at the high dose of 280 mg/kg/day was observed when juvenile rats were administered esomeprazole magnesium from postnatal day 7 through postnatal day 35. In addition, doses equal to or greater than 140 mg/kg/day (about 34 times a daily oral human dose of 40 mg on a body surface area basis), produced treatment-related decreases in body weight (approximately 14%) and body weight gain, decreases in femur weight and femur length, and affected overall growth. Comparable findings described above have also been observed in this study with another esomeprazole salt, esomeprazole strontium, at equimolar doses of esomeprazole.

Clinical Studies

healing of ee in adults

The healing rates of NEXIUM delayed-release capsules 40 mg, NEXIUM delayed-release capsules 20 mg, and omeprazole delayed-release capsules 20 mg (the approved dose for this indication) once daily were evaluated in adult patients with endoscopically diagnosed EE in four multicenter, double-blind, randomized studies. The healing rates at Weeks 4 and 8 were evaluated and are shown in Table 11:

Table 11: EE Healing Rate (Life-Table Analysis) in Adults with EE Treated with NEXIUM Delayed-Release Capsules or Omeprazole Delayed-Release Capsules Once Daily in Four Clinical Studies

Study

No. of Patients

Treatment Groups

EE healing rates

Significance Level

log-rank test vs. omeprazole 20 mg.

Week 4

Week 8

1

588

NEXIUM 20 mg

68.7%

90.6%

N.S.

588

Omeprazole 20 mg

69.5%

88.3%

2

654

NEXIUM 40 mg

75.9%

94.1%

p < 0.001

656

NEXIUM 20 mg

70.5%

89.9%

p < 0.05

650

Omeprazole 20 mg

64.7%

86.9%

3

576

NEXIUM 40 mg

71.5%

92.2%

N.S.

572

Omeprazole 20 mg

68.6%

89.8%

4

1216

NEXIUM 40 mg

81.7%

93.7%

p < 0.001

1209

Omeprazole 20 mg

68.7%

84.2%

N.S. = not significant (p > 0.05).

In these same studies of patients with EE, sustained heartburn resolution and time to sustained heartburn resolution were evaluated and are shown in Table 12:

Table 12: Sustained Resolution
Defined as 7 consecutive days with no heartburn reported in daily patient diary.

of Heartburn in Adults with EE Treated with NEXIUM Delayed-Release Capsules or Omeprazole Delayed-Release Capsules Once Daily in Four Clinical Studies

Cumulative Percent

Defined as the cumulative proportion of patients who have reached the start of sustained resolution.

with Sustained Resolution

Study

No. of Patients

Treatment Groups

Day 14

Day 28

Significance Level

log-rank test vs. omeprazole 20 mg.

1

573

NEXIUM 20 mg

64.3%

72.7%

N.S.

555

Omeprazole 20 mg

64.1%

70.9%

2

621

NEXIUM 40 mg

64.8%

74.2%

p <0.001

620

NEXIUM 20 mg

62.9%

70.1%

N.S.

626

Omeprazole 20 mg

56.5%

66.6%

3

568

NEXIUM 40 mg

65.4%

73.9%

N.S.

551

Omeprazole 20 mg

65.5%

73.1%

4

1187

NEXIUM 40 mg

67.6%

75.1%

p <0.001

1188

Omeprazole 20 mg

62.5%

70.8%

N.S. = not significant (p> 0.05)

In these four studies, the range of median days to the start of sustained resolution (defined as 7 consecutive days with no heartburn) was 5 days for NEXIUM 40 mg, 7 to 8 days for NEXIUM 20 mg and 7 to 9 days for omeprazole 20 mg.

There are no comparisons of 40 mg of NEXIUM with 40 mg of omeprazole in clinical trials assessing either healing or symptomatic relief of EE.

maintenance of healing of ee in adults

Two multicenter, randomized, double-blind placebo-controlled 4-arm studies were conducted in adult patients with endoscopically confirmed, healed EE to evaluate NEXIUM delayed-release capsules 40 mg (n=174), 20 mg (n=180), 10 mg (n=168) or placebo (n=171) once daily over six months of treatment.

No additional clinical benefit was seen with NEXIUM 40 mg over NEXIUM 20 mg. NEXIUM 40 mg once daily is not a recommended regimen for the maintenance of healing of EE in adults.

The percentages of patients that maintained healing of EE at the various time points are shown in the Figures 2 and 3:

Figure 2: Maintenance of Healing Rates of EE in Adults by Month (Study 177)

image 02.jpg

s= scheduled visit

Figure 3: Maintenance of EE Healing Rates in Adults by Month (Study 178)

image 03.jpg

s= scheduled visit

Patients remained in remission significantly longer and the number of recurrences of EE was significantly less in patients treated with NEXIUM compared to placebo.

In both studies, the proportion of patients on NEXIUM who remained in remission and were free of heartburn and other GERD symptoms was well differentiated from placebo.

In a third multicenter open label study of 808 patients treated for 12 months with NEXIUM 40 mg, the percentage of patients that maintained healing of EE was 93.7% for six months and 89.4% for one year.

symptomatic gerd in adults

Two multicenter, randomized, double-blind, placebo-controlled studies were conducted in a total of 717 adult patients comparing four weeks of treatment with NEXIUM delayed-release capsules 20 mg or 40 mg once daily versus placebo for resolution of GERD symptoms. Patients had at least a 6-month history of heartburn episodes, no EE by endoscopy, and heartburn on at least four of the seven days immediately preceding randomization.

The percentage of patients that were symptom-free of heartburn was significantly higher in the NEXIUM groups compared to placebo at all follow-up visits (Weeks 1, 2, and 4).

No additional clinical benefit was seen with NEXIUM 40 mg over NEXIUM 20 mg. NEXIUM 40 mg once daily is not a recommended regimen for the treatment of symptomatic GERD in adults.

The percent of patients symptom-free of heartburn by day are shown in the Figures 4 and 5:

Figure 4: Percent of Patients Symptom-Free of Heartburn by Day (Study 225)

image 04.jpg

Figure 5: Percent of Patients Symptom-Free of Heartburn by Day (Study 226)

image 05.jpg

In three European symptomatic GERD trials, NEXIUM 20 mg and 40 mg and omeprazole 20 mg were evaluated. No significant treatment related differences were seen.

pediatric gerd

1 to 11 Years of Age

In a multicenter, parallel-group study, 109 pediatric patients with a history of endoscopically-proven GERD (1 year to 11 years of age; 53 female; 89 Caucasian, 19 Black, 1 Other) were treated with NEXIUM for delayed-release oral suspension once daily for up to 8 weeks to evaluate safety and tolerability. Dosing by patient weight was as follows:

  • weight < 20 kg: once daily treatment with NEXIUM for delayed-release oral suspension 5 mg or 10 mg
  • weight ≥ 20 kg: once daily treatment with NEXIUM for delayed-release oral suspension 10 mg or 20 mg

Of the 109 patients, 53 had EE at baseline (51 had mild, 1 moderate, and 1 severe esophagitis). Although most of the patients who had a follow up endoscopy at the end of 8 weeks of treatment healed, spontaneous healing cannot be ruled out because these patients had low grade EE prior to treatment, and the trial did not include a concomitant control.

12 Years to 17 Years of Age

In a multicenter, randomized, double-blind, parallel-group study, 149 adolescent patients (12 to 17 years of age; 89 female; 124 Caucasian, 15 Black, 10 Other) with clinically diagnosed GERD were treated with NEXIUM delayed-release capsules 20 mg or 40 mg once daily for up to 8 weeks to evaluate safety and tolerability. Patients were not endoscopically characterized as to the presence or absence of EE..

risk reduction of nsaid-associated gastric ulcer

Two multicenter, double-blind, placebo-controlled studies were conducted in adult patients at risk of developing gastric and/or duodenal ulcers associated with continuous use of non-selective and COX-2 selective NSAIDs. A total of 1429 patients were randomized across the 2 studies. Patients ranged in age from 19 to 89 (median age 66 years) with 71% female, 29% male; 83% Caucasian, 5% Black, 4% Asian, and 8% Others. At baseline, the patients in these studies were endoscopically confirmed not to have ulcers but were determined to be at risk for ulcer occurrence due to their age (at least 60 years) and/or history of a documented gastric or duodenal ulcer within the past 5 years. Patients receiving NSAIDs and treated with NEXIUM delayed-release capsules 20 mg or 40 mg once daily experienced significant reduction in gastric ulcer occurrences relative to placebo treatment at 26 weeks. See Table 13. No additional benefit was seen with NEXIUM 40 mg over NEXIUM 20 mg. NEXIUM 40 mg once daily is not a recommended regimen for the risk reduction of NSAID-associated gastric ulcer in adults. These studies did not demonstrate significant reduction in the development of NSAID-associated duodenal ulcer due to the low incidence.

Table 13: Cumulative Percentage of Patients at Least 60 Years of Age Taking NSAIDS Without Gastric Ulcers at 26 Weeks in Two Randomized Placebo-Controlled Studies

Study

No. of Patients

Treatment Group

% of Patients Remaining Gastric Ulcer Free

%= Life Table Estimate. Significant difference from placebo (p<0.01).

1

191

194

184

NEXIUM 20 mg

NEXIUM 40 mg

Placebo

95.4

96.7

88.2

2

267

271

257

NEXIUM 20 mg

NEXIUM 40 mg

Placebo

94.7

95.3

83.3

h. pylori eradication in adult patients with duodenal ulcer disease

Two multicenter, randomized, double-blind studies were conducted in adult patients using a 10-day treatment regimen of triple therapy (NEXIUM, amoxicillin and clarithromycin). The first study (191) compared NEXIUM delayed-release capsules 40 mg once daily in combination with amoxicillin 1000 mg twice daily and clarithromycin 500 mg twice daily to NEXIUM delayed-release capsules 40 mg once daily plus clarithromycin 500 mg twice daily. The second study (193) compared NEXIUM delayed-release capsules 40 mg once daily in combination with amoxicillin 1000 mg twice daily and clarithromycin 500 mg twice daily to NEXIUM delayed-release capsules 40 mg once daily. H. pylori eradication rates, defined as at least two negative tests and no positive tests from CLOtest®, histology and/or culture, at 4 weeks post-therapy were significantly higher in the NEXIUM, amoxicillin and clarithromycin group than in the NEXIUM and clarithromycin group or the NEXIUM alone group. The results are shown in Table 14:

Table 14:H. pylori Eradication Rates at 4 Weeks after 10 Day Treatment Regimen % of Adult Patients Cured [95% Confidence Interval] (Number of Patients)

Study

Treatment Group

Per-Protocol

Patients were included in the analysis if they had H. pylori infection documented at baseline, had at least one endoscopically verified duodenal ulcer ≥ 0.5 cm in diameter at baseline or had a documented history of duodenal ulcer disease within the past 5 years, and were not protocol violators. Patients who dropped out of the study due to an adverse reaction related to the study drug were included in the analysis as not H. pylori eradicated.

Intent-to-Treat

Patients were included in the analysis if they had documented H. pylori infection at baseline, had at least one documented duodenal ulcer at baseline, or had a documented history of duodenal ulcer disease, and took at least one dose of study medication. All dropouts were included as not H. pylori eradicated.

191

NEXIUM plus amoxicillin and clarithromycin

84%

p < 0.05 compared to NEXIUM plus clarithromycin.

[78, 89]

(n=196)

77%

[71, 82]

(n=233)

NEXIUM plus clarithromycin

55%

[48, 62]

(n=187)

52%

[45, 59]

(n=215)

193

NEXIUM plus amoxicillin and clarithromycin

85%

p < 0.05 compared to NEXIUM alone.

[74, 93]

(n=67)

78%

[67, 87]

(n=74)

NEXIUM

5%

[0, 23]

(n=22)

4%

[0, 21]

(n=24)

The percentage of patients with a healed baseline duodenal ulcer by 4 weeks after the 10-day treatment regimen in the NEXIUM, amoxicillin and clarithromycin group was 75% (n=156) and 57% (n=60) respectively, in the 191 and 193 studies (per-protocol analysis).

pathological hypersecretory conditions including zollinger-ellison syndrome

In a multicenter, open-label dose-escalation study of 21 adult patients (15 males and 6 females, 18 Caucasian and 3 Black, mean age of 56 years) with pathological hypersecretory conditions, such as Zollinger-Ellison Syndrome, NEXIUM significantly inhibited gastric acid secretion. The initial dosage of NEXIUM delayed-release capsules was 40 mg twice daily in 19 patients and 80 mg twice daily in 2 patients. Total daily doses ranging from 80 mg to 240 mg for 12 months maintained gastric acid output below the target levels of 10 mEq/h in patients without prior gastric acid-reducing surgery and below 5 mEq/hr in patients with prior gastric acid-reducing surgery. At the Month 12 final visit, 18/20 (90%) patients had Basal Acid Output (BAO) under satisfactory control (median BAO = 0.17 mmol/hr). Of the 18 patients evaluated with a starting dose of NEXIUM 40 mg twice daily, 13 (72%) had their BAO controlled with the original dosing regimen at the final visit. See Table 15.

Table 15: Adequate Acid Suppression at Final Visit by Dose Regimen in Adult Patients with Pathological Hypersecretory Conditions

NEXIUM dose at the Month 12 visit

BAO under adequate control at the Month 12 visit (N=20)

One patient was not evaluated.

40 mg twice daily

13/15

80 mg twice daily

4/4

80 mg three times daily

1/1

This drug label information is as submitted to the Food and Drug Administration (FDA) and is intended for informational purposes only. If you think you may have a medical emergency, immediately call your doctor or dial 911. You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
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