Absorption
The pharmacokinetics of esomeprazole in healthy subjects following administration of esomeprazole 20 mg and 40 mg once daily as intravenous infusion over 30 minutes for 5 days are shown in Table 8.
Table 8: Geometric Mean (95% CI) Pharmacokinetic Parameters of Esomeprazole Following Dosing for 5 Days
Parameter
| Esomeprazole 20 mg (n=24)
| Esomeprazole 40 mg (n=38)
|
AUC (micromol*h/L)
| 5.1 (4.0:6.6)
| 16.2 (14.5:18.2)
|
Cmax (micromol/L))
| 3.9 (3.2:4.7)
| 7.5 (6.9:8.1)
|
t1/2 (h)
| 1.1 (0.9:1.2)
| 1.4 (1.3:1.5)
|
Following intravenous administration of esomeprazole in 24 healthy subjects as a loading dose of 80 mg over 30 minutes followed by a continuous infusion of 8 mg/hour for 23.5 hours (for a total of 24 hours), esomeprazole pharmacokinetic parameters [geometric mean value (95% CI)] were as follows: AUCt 111.1 micromol*h/L (100.5, 122.7 micromol*h/L), Cmax 15.0 micromol/L (13.5, 16.6 micromol/L), and steady state plasma concentration (Css) 3.9 micromol/L (3.5, 4.5 micromol/L). In another study of healthy Caucasian subjects administered the same treatment regimen.
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
Esomeprazole is excreted as metabolites primarily in urine but also in feces. Less than 1% of parent drug is excreted in the urine. Esomeprazole is completely eliminated from plasma, and there is no accumulation during once daily administration. The plasma elimination half-life of esomeprazole following intravenous administration of esomeprazole is approximately 1.1 to 1.4 hours and is prolonged with increasing doses.
The plasma clearance (CL) is approximately 5.9 to 7.2 L/h during administration of esomeprazole as an intravenous infusion of 80 mg over 30 minutes followed by a continuous infusion of 8 mg/hour for 23.5 hours.
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
The pharmacokinetics of esomeprazole were evaluated in 50 pediatric patients birth to 17 years of age, inclusive (of which 44 pediatric patients were 1 month to 17 years) in a randomized, open-label, multi-national, multiple dose study of 20 mg esomeprazole administered as a once-daily 3-minute intravenous injection. Esomeprazole plasma AUC values were 183% and 60% higher in pediatric patients aged 6 to 11 years and 12 to 17 years, respectively, compared to adults.
Subsequent pharmacokinetic analyses predicted the following dosage regimens would achieve comparable steady-state plasma exposures (AUC0-24) to those observed in adult patients administered 20 mg of esomeprazole once daily: 0.5 mg/kg once daily for pediatric patients 1 month to 11 months of age, 10 mg once daily for pediatric patients 1 year to 17 years with body weight less than 55 kg, and 20 mg once daily for pediatric patients 1 year to 17 years with body weight of 55 kg and greater. Increasing the infusion duration from 3 minutes to 10 minutes or 30 minutes was predicted to produce steady-state Cmax values that were comparable to those observed in adult patients at the 40 mg and 20 mg esomeprazole doses, respectively [see Use in Specific Populations (8.4)].
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. Similar differences have been seen for intravenous administration of esomeprazole. This increase in exposure is not considered clinically relevant.
Patients with Renal Impairment
The pharmacokinetics of esomeprazole 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 40 mg orally once daily to 4 patients each with mild (Child-Pugh Class A), moderate (Child-Pugh Class B), and severe (Child-Pugh Class C) 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)].
There are no pharmacokinetic data available for esomeprazole administered as continuous intravenous administration in patients with liver impairment. The pharmacokinetics of intravenous omeprazole 80 mg infused over 30 minutes, followed by 8 mg/hour over 47.5 hours in patients with mild (Child-Pugh Class A; n=5), moderate (Child-Pugh Class B; n=4) and severe (Child-Pugh Class C; n=3) liver impairment were compared to those obtained in 24 male and female healthy subjects. In patients with mild and moderate liver impairment, omeprazole clearance and steady state plasma concentration was approximately 35% lower and 50% higher, respectively, than in healthy subjects. In patients with severe liver impairment, the omeprazole clearance was 50% of that in healthy subjects and the steady state plasma concentration was double that in healthy subjects [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 (1,250 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 (1,000/100 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), Drug Interactions (7)].
Mycophenolate Mofetil
Administration of omeprazole 20 mg twice daily for 4 days and a single 1,000 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 decreased by 37.5% and 37.9%, respectively) and extensive metabolizers (Cmax and AUC decreased by 49.6% and 43.9%, 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.