Mechanism of Action
Omeprazole 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.
Because this enzyme system is regarded as the acid (proton) pump within the
gastric mucosa, omeprazole 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. Animal studies indicate that after rapid disappearance from
plasma, omeprazole can be found within the gastric mucosa for a day or more.
Pharmacodynamics
AntisecretoryActivity
After oral administration, the onset of the antisecretory effect of omeprazole
occurs within one hour, with the maximum effect occurring within two hours.
Inhibition of secretion is about 50% of maximum at 24 hours and the duration
of inhibition lasts up to 72 hours. The antisecretory effect thus lasts far
longer than would be expected from the very short (less than one hour) plasma
half-life, apparently due to prolonged binding to the parietal H+/K+
ATPase enzyme. When the drug is discontinued, secretory activity returns gradually,
over 3 to 5 days. The inhibitory effect of omeprazole on acid secretion increases
with repeated once-daily dosing, reaching a plateau after four days.
Results from numerous studies of the antisecretory effect of multiple doses
of 20 mg and 40 mg of omeprazole in normal volunteers and patients are shown
below. The “max” value represents determinations at a time of maximum
effect (2-6 hours after dosing), while “min” values are those 24
hours after the last dose of omeprazole.
Table 1 : Range of Mean Values from Multiple Studies of the
Mean Antisecretory Effects of Omeprazole After Multiple Daily Dosing
| |
Omeprazole
20 mg |
Omeprazole 40 mg |
| Max |
Min |
Max |
Min |
| % Decrease in Basal Acid Output |
78* |
58-80 |
94* |
80-93 |
| % Decrease in Peak Acid Output |
79* |
50-59 |
88* |
62-68 |
| % Decrease in24-hr. Intragastric Acidity |
|
80-97 |
|
92-94 |
| *Single Studies |
Single daily oral doses of omeprazole ranging from a dose of 10 mg to 40 mg
have produced 100% inhibition of 24-hour intragastric acidity in some patients.
Serum Gastrin Effects
In studies involving more than 200 patients, serum gastrin levels increased
during the first 1 to 2 weeks of once-daily administration of therapeutic doses
of omeprazole in parallel with inhibition of acid secretion. No further increase
in serum gastrin occurred with continued treatment. In comparison with histamine
H2-receptor antagonists, the median increases produced by 20 mg doses
of omeprazole were higher (1.3 to 3.6 fold vs. 1.1 to 1.8 fold increase). Gastrin
values returned to pretreatment levels, usually within 1 to 2 weeks after discontinuation
of therapy.
Enterochromaffin-like (ECL) Cell Effects
Human gastric biopsy specimens have been obtained from more than 3000 patients
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 CLINICAL
PHARMACOLOGY] However, these studies are of insufficient duration and size
to rule out the possible influence of long-term administration of omeprazole
on the development of any premalignant or malignant conditions.
Other Effects
Systemic effects of omeprazole in the CNS, cardiovascular and respiratory systems
have not been found to date. Omeprazole, given in oral doses of 30 or 40 mg
for 2 to 4 weeks, had no effect on thyroid function, carbohydrate metabolism,
or circulating levels of parathyroid hormone, cortisol, estradiol, testosterone,
prolactin, cholecystokinin or secretin.
No effect on gastric emptying of the solid and liquid components of a test
meal was demonstrated after a single dose of omeprazole 90 mg. In healthy subjects,
a single I.V. dose of omeprazole (0.35 mg/kg) had no effect on intrinsic factor
secretion. No systematic dose-dependent effect has been observed on basal or
stimulated pepsin output in humans.
However, when intragastric pH is maintained at 4.0 or above, basal pepsin output
is low, and pepsin activity is decreased.
As do other agents that elevate intragastric pH, omeprazole administered for
14 days in healthy subjects produced a significant increase in the intragastric
concentrations of viable bacteria. The pattern of the bacterial species was
unchanged from that commonly found in saliva. All changes resolved within three
days of stopping treatment.
The course of Barrett's esophagus in 106 patients was evaluated in a U.S. double-blind
controlled study of PRILOSEC 40 mg twice daily for 12 months followed by 20
mg twice daily for 12 months or ranitidine 300 mg twice daily for 24 months.
No clinically significant impact on Barrett's mucosa by antisecretory therapy
was observed. Although neosquamous epithelium developed during antisecretory
therapy, complete elimination of Barrett's mucosa was not achieved. No significant
difference was observed between treatment groups in development of dysplasia
in Barrett's mucosa and no patient developed esophageal carcinoma during treatment.
No significant differences between treatment groups were observed in development
of ECL cell hyperplasia, corpus atrophic gastritis, corpus intestinal metaplasia,
or colon polyps exceeding 3 mm in diameter [See ].
Pharmacokinetics
Absorption
PRILOSEC Delayed-Release Capsules contain an enteric-coated granule formulation
of omeprazole (because omeprazole is acid-labile), so that absorption of omeprazole
begins only after the granules leave the stomach. Absorption is rapid, with
peak plasma levels of omeprazole occurring within 0.5 to 3.5 hours. Peak plasma
concentrations of omeprazole and AUC are approximately proportional to doses
up to 40 mg, but because of a saturable first-pass effect, a greater than linear
response in peak plasma concentration and AUC occurs with doses greater than
40 mg. Absolute bioavailability (compared with intravenous administration) is
about 30-40% at doses of 20-40 mg, due in large part to presystemic metabolism.
In healthy subjects the plasma half-life is 0.5 to 1 hour, and the total body
clearance is 500-600 mL/min.
Based on a relative bioavailability study, the AUC and Cmax of PRILOSEC (omeprazole
magnesium) for Delayed-Release Oral Suspension were 87% and 88% of those for
PRILOSEC Delayed-Release Capsules, respectively.
The bioavailability of omeprazole increases slightly upon repeated administration
of PRILOSEC Delayed-Release Capsules.
PRILOSEC Delayed-Release Capsule 40 mg was bioequivalent when administered
with and without applesauce. However, PRILOSEC Delayed-Release Capsule 20 mg
was not bioequivalent when administered with and without applesauce. When administered
with applesauce, a mean 25% reduction in Cmax was observed without a significant
change in AUC for PRILOSEC Delayed-Release Capsule 20 mg. The clinical relevance
of this finding is unknown.
Distribution
Protein binding is approximately 95%.
Metabolism
Omeprazole is extensively metabolized by the cytochrome P450 (CYP) enzyme system.
Excretion
Following single dose oral administration of a buffered solution of omeprazole,
little if any unchanged drug was excreted in urine. The majority of the dose
(about 77%) was eliminated in urine as at least six metabolites. Two were identified
as hydroxyomeprazole and the corresponding carboxylic acid. The remainder of
the dose was recoverable in feces. This implies a significant biliary excretion
of the metabolites of omeprazole. Three metabolites have been identified in
plasma - the sulfide and sulfone derivatives of omeprazole, and hydroxyomeprazole.
These metabolites have very little or no antisecretory activity.
Combination Therapy with Antimicrobials
Omeprazole 40 mg daily was given in combination with clarithromycin 500 mg
every 8 hours to healthy adult male subjects. The steady state plasma concentrations
of omeprazole were increased (Cmax, AUC0-24, and T½ increases
of 30%, 89% and 34% respectively) by the concomitant administration of clarithromycin.
The observed increases in omeprazole plasma concentration were associated with
the following pharmacological effects. The mean 24-hour gastric pH value was
5.2 when omeprazole was administered alone and 5.7 when co-administered with
clarithromycin.
The plasma levels of clarithromycin and 14-hydroxy-clarithromycin were increased
by the concomitant administration of omeprazole. For clarithromycin, the mean
Cmax was 10% greater, the mean Cmin was 27% greater, and the mean AUC0-8
was 15% greater when clarithromycin was administered with omeprazole than
when clarithromycin was administered alone. Similar results were seen for 14-hydroxy-clarithromycin,
the mean Cmax was 45% greater, the mean Cmin was 57% greater, and the mean AUC0-8
was 45% greater. Clarithromycin concentrations in the gastric tissue and mucus
were also increased by concomitant administration of omeprazole.
Table 2: Clarithromycin Tissue Concentrations 2 hours after
Dose1
| Tissue |
Clarithromycin |
Clarithromycin + Omeprazole |
| Antrum |
10.48 ±2.01 (n = 5) |
19.96 ±4.71 (n = 5) |
| Fundus |
20.81 ±7.64 (n = 5) |
24.25 ±6.37 (n = 5) |
| Mucus |
4.15 ±7.74 (n = 4) |
39.29 ±32.79 (n = 4) |
| 1Mean ± SD (μg/g) |
Special Populations
Geriatric Population
The elimination rate of omeprazole was somewhat decreased in the elderly, and
bioavailability was increased. Omeprazole was 76% bioavailable when a single
40 mg oral dose of omeprazole (buffered solution) was administered to healthy
elderly volunteers, versus 58% in young volunteers given the same dose. Nearly
70% of the dose was recovered in urine as metabolites of omeprazole and no unchanged
drug was detected. The plasma clearance of omeprazole was 250 mL/min (about
half that of young volunteers) and its plasma half-life averaged one hour, about
twice that of young healthy volunteers.
Pediatric Use
The pharmacokinetics of omeprazole have been investigated in pediatric patients
2 to 16 years of age:
Table 3 : Pharmacokinetic Parameters of Omeprazole Following
Single and Repeated Oral Administration in Pediatric Populations Compared with
Adults
Single or Repeated
Oral Dosing/Parameter |
Children†
≤20 kg 2-5 years 10 mg |
Children† >20 kg 6-16 years 20 mg |
Adults‡ (mean 76 kg) 23-29 years
(n=12) |
| Single Dosing |
Cmax*
(ng/mL) |
288
(n=10) |
495
(n=49) |
668 |
AUC*
(ng h/mL) |
511
(n=7) |
1140
(n=32) |
1220 |
| Repeated Dosing |
Cmax*
(ng/mL) |
539
(n=4) |
851
(n=32) |
1458 |
AUC*
(ng h/mL) |
1179
(n=2) |
2276
(n=23) |
3352 |
Note: * = plasma concentration adjusted to
an oral dose of 1 mg/kg.
† Data from single and repeated dose studies
‡Data from a single and repeated dose study Doses of 10, 20 and
40 mg omeprazole as enteric-coated granules |
Following comparable mg/kg doses of omeprazole, younger children (2 to 5 years
of age) have lower AUCs than children 6 to 16 years of age or adults; AUCs of
the latter two groups did not differ. [See DOSAGE AND ADMINISTRATION]
Hepatic Impairment
In patients with chronic hepatic disease, the bioavailability increased to
approximately 100% compared with an I.V. dose, reflecting decreased first-pass
effect, and the plasma half-life of the drug increased to nearly 3 hours compared
with the half-life in normals of 0.5-1 hour. Plasma clearance averaged 70 mL/min,
compared with a value of 500-600 mL/min in normal subjects. Dose reduction,
particularly where maintenance of healing of erosive esophagitis is indicated,
for the hepatically impaired should be considered.
Renal Impairment
In patients with chronic renal impairment, whose creatinine clearance ranged
between 10 and 62 mL/min/1.73 m², the disposition of omeprazole was very
similar to that in healthy volunteers, although there was a slight increase
in bioavailability. Because urinary excretion is a primary route of excretion
of omeprazole metabolites, their elimination slowed in proportion to the decreased
creatinine clearance. No dose reduction is necessary in patients with renal
impairment.
Asian Population
In pharmacokinetic studies of single 20 mg omeprazole doses, an increase in
AUC of approximately four-fold was noted in Asian subjects compared with Caucasians.
Dose reduction, particularly where maintenance of healing of erosive esophagitis
is indicated, for Asian subjects should be considered.
Microbiology Information in H. pylori
Omeprazole and clarithromycin dual therapy and omeprazole, clarithromycin and
amoxicillin triple therapy have been shown to be active against most strains
of Helicobacter pylori in vitro and in clinical infections as described in the
Indications and Usage section.
Helicobacter
Helicobacter pylori- Pretreatment Resistance
Clarithromycin pretreatment resistance rates were 3.5% (4/113) in the omeprazole/clarithromycin
dual therapy studies (4 and 5) and 9.3% (41/439) in omeprazole/clarithromycin/amoxicillin
triple therapy studies (1, 2, and 3).
Amoxicillin pretreatment susceptible isolates (≤0.25 μg/mL) were found
in 99.3% (436/439) of the patients in the omeprazole/clarithromycin/amoxicillin
triple therapy studies (1, 2, and 3). Amoxicillin pretreatment minimum inhibitory
concentrations (MICs) > 0.25 μg/mL occurred in 0.7% (3/439) of the patients,
all of whom were in the clarithromycin and amoxicillin study arm. One patient
had an unconfirmed pretreatment amoxicillin minimum inhibitory concentration
(MIC) of > 256 μg/mL by Etest®.
Table 4 : Clarithromycin Susceptibility Test Results and
Clinical/Bacteriological Outcomes
| Clarithromycin Pretreatment Results |
Clarithromycin Post-treatment Results |
| |
H. pylori negative - eradicated |
H. pylori positive - not eradicated Post-treatment
susceptibility results |
| S b |
I b |
R b |
No MIC |
| Dual Therapy - (omeprazole 40mg once daily/clarithromycin
500 three times daily for 14 days followed by omeprazole 20 mg once daily
for another 14 days) (Studies M93-067, M93-100) |
| Susceptible b |
108 |
72 |
1 |
|
26 |
9 |
| Intermediate b |
1 |
|
|
|
1 |
|
| Resistant b |
4 |
|
|
|
4 |
|
| Triple Therapy - (omeprazole 20 mg twice daily/clarithromycin
500 mg twice daily/amoxicillin 1 g twice daily for 10 days- Studies 126,
127, M96-446; followed by omeprazole 20 mg once daily for another 18 days
- Studies 126, 127) |
| Susceptible b |
171 |
153 |
7 |
|
3 |
8 |
| Intermediateb |
|
|
|
|
|
|
| Resistant b |
14 |
4 |
1 |
|
6 |
3 |
aIncludes only patients with
pretreatment clarithromycin susceptibility test results
bSusceptible (S) MIC 0.25 μg/mL, Intermediate (I) MIC 0.5
- 1.0 μg/mL, Resistant (R) MIC ≥2 μg/mL |
Patients not eradicated of H. pylori following omeprazole/clarithromycin/amoxicillin
triple therapy or omeprazole/clarithromycin dual therapy will likely have clarithromycin
resistant H. pylori isolates. Therefore, clarithromycin susceptibility
testing should be done, if possible. Patients with clarithromycin resistant
H. pylori should not be treated with any of the following: omeprazole/clarithromycin
dual therapy, omeprazole/clarithromycin/amoxicillin triple therapy, or other
regimens which include clarithromycin as the sole antimicrobial agent.
Amoxicillin Susceptibility Test Results and Clinical/Bacteriological Outcomes
In the triple therapy clinical trials, 84.9% (157/185) of the patients in the
omeprazole/clarithromycin/amoxicillin treatment group who had pretreatment amoxicillin
susceptible MICs (≤0.25 μg/mL) were eradicated of H. pylori and
15.1% (28/185) failed therapy. Of the 28 patients who failed triple therapy,
11 had no post-treatment susceptibility test results and 17 had post-treatment
H. pylori isolates with amoxicillin susceptible MICs. Eleven of the patients
who failed triple therapy also had post-treatment H. pylori isolates
with clarithromycin resistant MICs.
Susceptibility Test for Helicobacter pylori
The reference methodology for susceptibility testing of H. pylori is
agar dilution MICs1. One to three microliters of an inoculum equivalent
to a No. 2 McFarland standard (1 x 107 - 1 x 108 CFU/mL
for H. pylori ) are inoculated directly onto freshly prepared antimicrobial
containing Mueller-Hinton agar plates with 5% aged defibrinated sheep blood
(≥2 weeks old). The agar dilution plates are incubated at 35°C in a microaerobic
environment produced by a gas generating system suitable for campylobacters.
After 3 days of incubation, the MICs are recorded as the lowest concentration
of antimicrobial agent required to inhibit growth of the organism. The clarithromycin
and amoxicillin MIC values should be interpreted according to the following
criteria:
Table 5
| Clarithromycin MIC (μg/mL) a |
Interpretation |
| ≤0.25 |
Susceptible(S) |
| 0.5 |
Intermediate(I) |
| >1.0 |
Resistant(R) |
| Amoxicillin MIC (μg/mL) a,b |
Interpretation |
| ≤0.25 |
Susceptible(S) |
a These are tentative breakpoints
for the agar dilution methodology and they should not be used to interpret
results obtained using alternative methods.
b There were not enough organisms with MICs > 0.25 μg/mL
to determine a resistance breakpoint. |
Standardized susceptibility test procedures require the use of laboratory control
microorganisms to control the technical aspects of the laboratory procedures.
Standard clarithromycin and amoxicillin powders should provide the following
MIC values:
| Microorganism |
Antimicrobial Agent |
MIC (μg/mL) a |
| H. pylori ATCC 43504 |
Clarithromycin |
0.016- 0.12 (μg/mL) |
| H. pylori ATCC 43504 |
Amoxicillin |
0.016- 0.12 (μg/mL) |
| aThese are quality control ranges
for the agar dilution methodology and they should not be used to control
test results obtained using alternative methods. |
Animal Toxicology and/or Pharmacology
Reproductive Toxicology Studies
Reproductive studies conducted with omeprazole in rats at oral doses up to
138 mg/kg/day (about 56 times the human dose on a body surface area basis) and
in rabbits at doses up to 69 mg/kg/day (about 56 times the human dose on a body
surface area basis) did not disclose any evidence for a teratogenic potential
of omeprazole. In rabbits, omeprazole in a dose range of 6.9 to 69.1 mg/kg/day
(about 5.5 to 56 times the human dose on a body surface area basis) produced
dose-related increases in embryo-lethality, fetal resorptions, and pregnancy
disruptions. In rats, dose-related embryo/fetal toxicity and postnatal developmental
toxicity were observed in offspring resulting from parents treated with omeprazole
at 13.8 to 138.0 mg/kg/day (about 5.6 to 56 times the human doses on a body
surface area basis).
Clinical Studies
Duodenal Ulcer Disease
Active Duodenal Ulcer- In a multicenter, double-blind, placebo-controlled study
of 147 patients with endoscopically documented duodenal ulcer, the percentage
of patients healed (per protocol) at 2 and 4 weeks was significantly higher
with PRILOSEC 20 mg once daily than with placebo (p≤0.01).
Treatment of Active Duodenal Ulcer % of Patients Healed
| |
PRILOSEC 20 mg a.m.
(n = 99) |
Placebo a.m.
(n = 48) |
| Week 2 |
*41 |
13 |
| Week 4 |
*75 |
27 |
| *(p≤0.01) |
Complete daytime and nighttime pain relief occurred significantly faster (p≤0.01)
in patients treated with PRILOSEC 20 mg than in patients treated with placebo.
At the end of the study, significantly more patients who had received PRILOSEC
had complete relief of daytime pain (p≤0.05) and nighttime pain (p≤0.01).
In a multicenter, double-blind study of 293 patients with endoscopically documented
duodenal ulcer, the percentage of patients healed (per protocol) at 4 weeks
was significantly higher with PRILOSEC 20 mg once daily than with ranitidine
150 mg b.i.d. (p < 0.01).
Treatment of Active Duodenal Ulcer % of Patients Healed
| |
PRILOSEC
20 mg a.m.
(n = 145) |
Ranitidine
150 mg twice daily
(n = 148) |
| Week 2 |
42 |
34 |
| Week 4 |
*82 |
63 |
| *(p < 0.01) |
Healing occurred significantly faster in patients treated with PRILOSEC than
in those treated with ranitidine 150 mg b.i.d. (p < 0.01).
In a foreign multinational randomized, double-blind study of 105 patients with
endoscopically documented duodenal ulcer, 20 mg and 40 mg of PRILOSEC were compared
with 150 mg b.i.d. of ranitidine at 2, 4 and 8 weeks. At 2 and 4 weeks both
doses of PRILOSEC were statistically superior (per protocol) to ranitidine,
but 40 mg was not superior to 20 mg of PRILOSEC, and at 8 weeks there was no
significant difference between any of the active drugs.
Treatment of Active Duodenal Ulcer % of Patients Healed
| |
PRILOSEC
20 mg
(n = 34) |
40 mg
(n = 36) |
Ranitidine
150 mg twice daily
(n = 35) |
| Week 2 |
*83 |
*83 |
53 |
| Week 4 |
*97 |
*100 |
82 |
| Week 8 |
100 |
100 |
94 |
| *(p ≤ 0.01) |
H. pylori Eradication in Patients with Duodenal Ulcer Disease
Triple Therapy(PRILOSEC/clarithromycin/amoxicillin)- Three U.S., randomized,
double-blind clinical studies in patients with H. pylori infection and
duodenal ulcer disease (n = 558) compared PRILOSEC plus clarithromycin plus
amoxicillin with clarithromycin plus amoxicillin. Two studies (1 and 2) were
conducted in patients with an active duodenal ulcer, and the other study (3)
was conducted in patients with a history of a duodenal ulcer in the past 5 years
but without an ulcer present at the time of enrollment. The dose regimen in
the studies was PRILOSEC 20 mg twice daily plus clarithromycin 500 mg twice
daily plus amoxicillin 1 g twice daily for 10 days; or clarithromycin 500 mg.
twice daily plus amoxicillin 1 g twice daily for 10 days. In studies 1 and 2,
patients who took the omeprazole regimen also received an additional 18 days
of PRILOSEC 20 mg once daily. Endpoints studied were eradication of H. pylori
and duodenal ulcer healing (studies 1 and 2 only). H. pylori status
was determined by CLOtest®, histology and culture in all three studies.
For a given patient, H. pylori was considered eradicated if at least
two of these tests were negative, and none was positive.
The combination of omeprazole plus clarithromycin plus amoxicillin was effective
in eradicating H. pylori .
Table 6 : Per-Protocol and Intent-to-Treat H. pylori
Eradication Rates % of Patients Cured [95% Confidence Interval]
| |
PRILOSEC + amoxicillin
Per- Protocol † |
+clarithromycin
Intent-to- Treat ‡ |
Clarithromycin
Per- Protocol † |
+ amoxicillin
Intent- to-Treat ‡ |
| Study 1 |
*77 [64, 86] |
*69 [57, 79] |
43 [31, 56] |
37 [27, 48] |
| (n = 64) |
(n = 80) |
(n = 67) |
(n = 84) |
| Study 2 |
*78 [67, 88] |
*73 [61, 82] |
41 [29, 54] |
36 [26, 47] |
| (n = 65) |
(n = 77) |
(n = 68) |
(n = 83) |
| Study 3 |
*90 [80, 96] |
*83 [74, 91] |
33 [24, 44] |
32 [23, 42] |
| (n = 69) |
(n = 84) |
(n = 93) |
(n = 99) |
† Patients were included in the analysis
if they had confirmed duodenal ulcer disease (active ulcer, studies 1
and 2; history of ulcer within 5 years, study 3) and H. pylori infection
at baseline defined as at least two of three positive endoscopic tests
from CLOtest®, histology, and/or culture. Patients were included in
the analysis if they completed the study. Additionally, if patients dropped
out of the study due to an adverse event related to the study drug, they
were included in the analysis as failures of therapy. The impact of eradication
on ulcer recurrence has not been assessed in patients with a past history
of ulcer.
‡ Patients were included in the analysis if they had documented
H. pylori infection at baseline and had confirmed duodenal ulcer
disease. All dropouts were included as failures of therapy.
*(p < 0.05) versus clarithromycin plus amoxicillin. |
Dual Therapy (PRILOSEC/clarithromycin)
Four randomized, double-blind, multi-center studies (4, 5, 6, and 7) evaluated
PRILOSEC 40 mg once daily plus clarithromycin 500 mg three times daily for 14
days, followed by PRILOSEC 20 mg once daily, (Studies 4, 5, and 7) or by PRILOSEC
40 mg once daily (Study 6) for an additional 14 days in patients with active
duodenal ulcer associated with H. pylori . Studies 4 and 5 were conducted
in the U.S. and Canada and enrolled 242 and 256 patients, respectively. H.
pylori infection and duodenal ulcer were confirmed in 219 patients in Study
4 and 228 patients in Study 5. These studies compared the combination regimen
to PRILOSEC and clarithromycin monotherapies. Studies 6 and 7 were conducted
in Europe and enrolled 154 and 215 patients, respectively. H. pylori infection
and duodenal ulcer were confirmed in 148 patients in study 6 and 208 patients
in Study 7. These studies compared the combination regimen with omeprazole monotherapy.
The results for the efficacy analyses for these studies are described below.
H. pylori eradication was defined as no positive test (culture or histology)
at 4 weeks following the end of treatment, and two negative tests were required
to be considered eradicated of H. pylori . In the per-protocol analysis,
the following patients were excluded: dropouts, patients with missing H.
pylori tests post-treatment, and patients that were not assessed for H.
pylori eradication because they were found to have an ulcer at the end of
treatment.
The combination of omeprazole and clarithromycin was effective in eradicating
H. pylori .
Table 7 : H. pylori Eradication Rates (Per-Protocol
Analysis at 4 to 6 Weeks) % of Patients Cured [95% Confidence Interval]
| |
PRILOSEC + Clarithromycin |
PRILOSEC |
Clarithromycin |
| U.S. Studies |
| Study 4 |
74 [60, 85] † ‡ |
0 [0, 7] |
31 [18, 47] |
| (n = 53) |
(n = 54) |
(n = 42) |
| Study 5 |
64 [51, 76] † ‡ |
0 [0, 6] |
39 [24, 55] |
| (n = 61) |
(n = 59) |
(n = 44) |
| Non U.S. Studies |
| Study 6 |
83 [71, 92] ‡ |
1 [0, 7] |
N/A |
| (n = 60) |
(n = 74) |
|
| Study 7 |
74 [64, 83] ‡ |
1 [0, 6] |
N/A |
| (n = 86) |
(n = 90) |
|
† Statistically significantly
higher than clarithromycin monotherapy (p < 0.05)
‡ Statistically significantly higher than omeprazole
monotherapy (p < 0.05) |
Ulcer healing was not significantly different when clarithromycin was added
to omeprazole therapy compared with omeprazole therapy alone.
The combination of omeprazole and clarithromycin was effective in eradicating
H. pylori and reduced duodenal ulcer recurrence.
Table 8: Duodenal Ulcer Recurrence Rates by H. pylori Eradication
Status % of Patients with Ulcer Recurrence
| |
H. pylori eradicated# |
H. pylori not eradicated# |
U.S. Studies †
6 months post-treatment |
| Study 4 |
*35 |
60 |
| (n = 49) |
(n = 88) |
| Study 5 |
*8 |
60 |
| (n = 53) |
(n = 106) |
Non U.S. Studies ‡
6 months post-treatment |
| Study 6 |
*5 |
46 |
| (n = 43) |
(n = 78) |
| Study 7 |
*6 |
43 |
| (n = 53) |
(n = 107) |
| 12 months post-treatment |
| Study 6 |
*5 |
68 |
| (n = 39) |
(n = 71) |
#H. pylori eradication status assessed
at same time point as ulcer recurrence
† Combined results for PRILOSEC + clarithromycin, PRILOSEC,
and clarithromycin treatment arms
‡ Combined results for PRILOSEC + clarithromycin and
PRILOSEC treatment arms
*(p≤0.01) versus proportion with duodenal ulcer recurrence
who were not H. pylori eradicated |
Gastric Ulcer
In a U.S. multicenter, double-blind, study of omeprazole 40 mg once daily,
20 mg once daily, and placebo in 520 patients with endoscopically diagnosed
gastric ulcer, the following results were obtained.
Treatment of Gastric Ulcer % of Patients Healed (All Patients
Treated)
| |
PRILOSEC
20 mg once daily
(n = 202) |
PRILOSEC
40 mg. once daily
(n = 214) |
Placebo
(n = 104) |
| Week 4 |
47.5** |
55.6** |
30.8 |
| Week 8 |
74.8** |
82.7**,+ |
48.1 |
**(p < 0.01) PRILOSEC 40 mg or 20 mg
versus placebo
+(p < 0.05) PRILOSEC 40 mg versus 20 mg |
For the stratified groups of patients with ulcer size less than or equal to
1 cm, no difference in healing rates between 40 mg and 20 mg was detected at
either 4 or 8 weeks. For patients with ulcer size greater than 1 cm, 40 mg was
significantly more effective than 20 mg at 8 weeks.
In a foreign, multinational, double-blind study of 602 patients with endoscopically
diagnosed gastric ulcer, omeprazole 40 mg once daily, 20 mg once daily, and
ranitidine 150 mg twice a day were evaluated.
Treatment of Gastric Ulcer % of Patients Healed (All Patients
Treated)
| |
PRILOSEC
20 mg once daily
(n = 200) |
PRILOSEC
40 mg once daily
(n = 187) |
Ranitidine
150 twice daily
(n = 199) |
| Week 4 |
63.5 |
78.1**,++ |
56.3 |
| Week 8 |
81.5 |
91.4**,++ |
78.4 |
** (p < 0.01) PRILOSEC 40 mg
versus ranitidine
++ (p < 0.01) PRILOSEC 40 mg versus 20 mg |
Gastroesophageal Reflux Disease (GERD)
Symptomatic GERD
A placebo-controlled study was conducted in Scandinavia to compare the efficacy
of omeprazole 20 mg or 10 mg once daily for up to 4 weeks in the treatment of
heartburn and other symptoms in GERD patients without erosive esophagitis. Results
are shown below.
% Successful Symptomatic Outcomea
| |
PRILOSEC
20 mg a.m. |
PRILOSEC
10 mg a.m. |
Placebo a.m. |
| All patients |
46*,† |
31† |
13 |
| (n = 205) |
(n = 199) |
(n = 105) |
| Patients with confirmed GERD |
56*,† |
36† |
14 |
| (n = 115) |
(n = 109) |
(n = 59) |
aDefined as complete resolution
of heartburn
*(p <0.005) versus 10 mg
† (p <0.005) versus placebo |
Erosive Esophagitis
In a U.S. multicenter double-blind placebo controlled study of 20 mg or 40
mg of PRILOSEC Delayed-Release Capsules in patients with symptoms of GERD and
endoscopically diagnosed erosive esophagitis of grade 2 or above, the percentage
healing rates (per protocol) were as follows:
| Week |
20 mg PRILOSEC
(n = 83) |
40 mg PRILOSEC
(n = 87) |
Placebo
(n = 43) |
| 4 |
39** |
45** |
7 |
| 8 |
74** |
75** |
14 |
| ** (p<0.01) PRILOSEC versus placebo. |
In this study, the 40 mg dose was not superior to the 20 mg dose of PRILOSEC
in the percentage healing rate. Other controlled clinical trials have also shown
that PRILOSEC is effective in severe GERD. In comparisons with histamine H2-receptor
antagonists in patients with erosive esophagitis, grade 2 or above, PRILOSEC
in a dose of 20 mg was significantly more effective than the active controls.
Complete daytime and nighttime heartburn relief occurred significantly faster
(p < 0.01) in patients treated with PRILOSEC than in those taking placebo
or histamine H2- receptor antagonists.
In this and five other controlled GERD studies, significantly more patients
taking 20 mg omeprazole (84%) reported complete relief of GERD symptoms than
patients receiving placebo (12%).
Long Term Maintenance Of Healing of Erosive Esophagitis
In a U.S. double-blind, randomized, multicenter, placebo controlled study,
two dose regimens of PRILOSEC were studied in patients with endoscopically confirmed
healed esophagitis. Results to determine maintenance of healing of erosive esophagitis
are shown below.
| |
PRILOSEC
20 mg once daily
(n = 138) |
Life Table Analysis
PRILOSEC
20 mg 3 days per week
(n = 137) |
Placebo
(n = 131) |
| Percent in endoscopic remission at 6 months |
*70 |
34 |
11 |
| *(p < 0.01) PRILOSEC 20 mg once daily
versus PRILOSEC 20 mg 3 consecutive days per week or placebo. |
In an international multicenter double-blind study, PRILOSEC 20 mg daily and
10 mg daily were compared with ranitidine 150 mg twice daily in patients with
endoscopically confirmed healed esophagitis. The table below provides the results
of this study for maintenance of healing of erosive esophagitis.
Life Table Analysis
| |
PRILOSEC
20 mg once daily
(n = 131) |
PRILOSEC
10 mg once daily
(n = 133) |
Ranitidine
150 mg twice daily
(n = 128) |
| Percent in endoscopic remission at 12 months |
*77 |
‡ 58 |
46 |
*(p = 0.01) PRILOSEC 20 mg once daily. versus
PRILOSEC 10 mg.once daily or Ranitidine.
‡ (p = 0.03) PRILOSEC 10 mg.once daily. versus Ranitidine.
|
In patients who initially had grades 3 or 4 erosive esophagitis, for maintenance
after healing 20 mg daily of PRILOSEC was effective, while 10 mg did not demonstrate
effectiveness.
Pathological Hypersecretory Conditions
In open studies of 136 patients with pathological hypersecretory conditions,
such as Zollinger-Ellison (ZE) syndrome with or without multiple endocrine adenomas,
PRILOSEC Delayed-Release Capsules significantly inhibited gastric acid secretion
and controlled associated symptoms of diarrhea, anorexia, and pain. Doses ranging
from 20 mg every other day to 360 mg per day maintained basal acid secretion
below 10 mEq/hr in patients without prior gastric surgery, and below 5 mEq/hr
in patients with prior gastric surgery.
Initial doses were titrated to the individual patient need, and adjustments
were necessary with time in some patients [See DOSAGE AND ADMINISTRATION]
PRILOSEC was well tolerated at these high dose levels for prolonged periods
(> 5 years in some patients). In most ZE patients, serum gastrin levels were
not modified by PRILOSEC. However, in some patients serum gastrin increased
to levels greater than those present prior to initiation of omeprazole therapy.
At least 11 patients with ZE syndrome on long-term treatment with PRILOSEC developed
gastric carcinoids. These findings are believed to be a manifestation of the
underlying condition, which is known to be associated with such tumors, rather
than the result of the administration of PRILOSEC. [See ADVERSE REACTIONS]
Pediatric GERD
Symptomatic GERD
The effectiveness of PRILOSEC for the treatment of nonerosive GERD in pediatric
patients 1 to 16 years of age is based in part on data obtained from 125 pediatric
patients in two uncontrolled Phase III studies. [See Use
in Specific Populations]
The first study enrolled 12 pediatric patients 1 to 2 years of age with a history
of clinically diagnosed GERD. Patients were administered a single dose of omeprazole
(0.5 mg/kg, 1.0 mg/kg, or 1.5 mg/kg) for 8 weeks as an open capsule in 8.4%
sodium bicarbonate solution. Seventy-five percent (9/12) of the patients had
vomiting/ regurgitation episodes decreased from baseline by at least 50%.
The second study enrolled 113 pediatric patients 2 to 16 years of age with
a history of symptoms suggestive of nonerosive GERD. Patients were administered
a single dose of omeprazole (10 mg or 20 mg, based on body weight) for 4 weeks
either as an intact capsule or as an open capsule in applesauce. Successful
response was defined as no moderate or severe episodes of either pain-related
symptoms or vomiting/regurgitation during the last 4 days of treatment. Results
showed success rates of 60% (9/15; 10 mg omeprazole) and 59% (58/98; 20 mg omeprazole),
respectively.
Healing of Erosive Esophagitis
In an uncontrolled, open-label dose-titration study, healing of erosive esophagitis
in pediatric patients 1 to 16 years of age required doses that ranged from 0.7
to 3.5 mg/kg/day (80 mg/day). Doses were initiated at 0.7 mg/kg/day. Doses were
increased in increments of 0.7 mg/kg/day (if intraesophageal pH showed a pH
of < 4 for less than 6% of a 24-hour study). After titration, patients remained
on treatment for 3 months. Forty-four percent of the patients were healed on
a dose of 0.7 mg/kg body weight; most of the remaining patients were healed
with 1.4 mg/kg after an additional 3 months' treatment. Erosive esophagitis
was healed in 51 of 57 (90%) children who completed the first course of treatment
in the healing phase of the study. In addition, after 3 months of treatment,
33% of the children had no overall symptoms, 57% had mild reflux symptoms, and
40% had less frequent regurgitation/vomiting.
Maintenance of Healing of Erosive Esophagitis
In an uncontrolled, open-label study of maintenance of healing of erosive esophagitis
in 46 pediatric patients, 54% of patients required half the healing dose. The
remaining patients increased the healing dose (0.7 to a maximum of 2.8 mg/kg/day)
either for the entire maintenance period, or returned to half the dose before
completion. Of the 46 patients who entered the maintenance phase, 19 (41%) had
no relapse. In addition, maintenance therapy in erosive esophagitis patients
resulted in 63% of patients having no overall symptoms.
REFERENCES
1. National Committee for Clinical Laboratory Standards. Methods
for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically-Fifth
Edition. Approved Standard NCCLS Document M7-A5, Vol, 20, No. 2, NCCLS, Wayne,
PA, January 2000.
Last updated on RxList: 4/15/2008