Aliment Pharmacol Ther 2004; 19: 1105–1110.
Effect of splitting the dose of esomeprazole on gastric acidityand nocturnal acid breakthrough
J . H A M M E R & B . S C H M I D TUniversita¨tsklinik fu¨r Innere Medizin IV, Abteilung fu¨r Gastroenterologie und Hepatologie, Vienna, Austria
Results: Median gastric 24-h pH was higher during 2
· 20 mg esomeprazole on day 2 (P < 0.01), no
Background: Twice-daily dosing is increasingly used to
differences were detected on day 6. Night-time gastric
improve gastric acid control, although not all proton-
pump inhibitors are more effective when doses are split.
2 · 20 mg esomeprazole on all study days (P < 0.05).
Standard dose esomeprazole provides better gastric acid
Nocturnal acid breakthrough was observed on all study
control than other standard dose proton-pump inhibitors.
days in subjects receiving 1 · 40 mg, but in only 85%
Aims: To compare the effect of standard dose esomep-
(first night), 64% (second night), and 45% of subjects
razole (1 · 40 mg) with 20 mg b.d. on gastric acidity.
(sixth night) with 2 · 20 mg (P < 0.05).
Methods: Thirteen healthy subjects participated in this
Conclusion: Splitting the esomeprazole dose improves
crossover study, receiving esomeprazole 2 · 20 mg and
initial acid suppression, this effect starts at the first
1 · 40 mg for 7 days in random order with a washout
night. Maximal benefit is achieved on day 2, while the
period of at least 7 days. Gastric 24-h pH was measured
effect on night-time acid control is detectable during the
has improved remarkably over the last decades, there
are still patients and conditions that do not respond
The prevalence of abnormal oesophageal acid exposure
adequately to currently available therapy regimens.5, 6
of the oesophagus increases across the spectrum of
Healing of reflux oesophagitis and relief of symptoms is
gastro-oesophageal reflux disease (GERD), as one pro-
directly related to the percentage of time that the gastric
gresses from non-erosive reflux disease through erosive
pH is maintained above a pH of 4.0 over a 24 h
oesophagitis to Barrett’s oesophagus.1 Therapy of acid-
period.7–9 Several regimens have been used to improve
related disorders of the oesophagus aims to reduce acid
the degree of intragastric pH control, including pre-
load of the oesophagus by suppressing gastric acid
scription of an additional dose of histamine type 2
production.2 Earlier generations of proton-pump inhib-
receptor antagonists or splitting the dose of the PPI.
itors (PPIs) in standard doses once daily have achieved
The night-time interval may require special considera-
80–85% symptom relief and healing in GERD, while
tion.10 During the night period, patients with GERD and
newer agents achieve healing and symptom relief in
also healthy subjects continue to secrete acid and
even higher percentages, reaching up to 95%.3, 4
decrease the intragastric pH < 4 for at least 1
However, while therapy of gastric acid-related disorders
continuous hour, even when taking PPI such asomeprazole or lansoprazole twice daily.11, 12
The literature on the effect of splitting the PPI dose on
Correspondence to: Dr J. Hammer, Universita¨tsklinik fu¨r Innere Medizin IV,
gastric acidity is divergent for the different PPIs. Gastric
Wa¨hringer Gu¨rtel 18–20, 1090 Vienna, Austria. E-mail: [email protected]
acid control with omeprazole 40 mg once daily could be
significantly improved when the dose was divided and
taken before breakfast and dinner.11, 13 Lansoprazole,which has been proven to be similar effective as
A dual electrode antimony pH catheter (diameter
omeprazole when given once daily, has been less
2.1 mm), connected to a Flexilog 2000 ambulatory pH
effective with split dosing when compared with omep-
recorder (Oakfield Instrument, Ltd, Oxfordshire, England,
razole twice daily. Finally, splitting the dose of pantop-
Great Britain, UK), was used to continuously record pH
razole did not have any benefit on gastric acidity over a
values at 4-s intervals. The electrodes were calibrated
prior to each recording as per the recommendations of the
Recent studies have suggested that esomeprazole
manufacturer in buffers of pH 1.1 and 7.0 at room tem-
(ESO), the S-isomer of omeprazole, improves gastric
perature. The electrodes were positioned 15 cm apart on
acid control as well as healing of GERD compared with
the tube. The tube was introduced into the subject’s
other PPIs that are currently available on the mar-
stomach via the intranasal route. The position of the
ket.15–21 The pharmacological difference to the racemic
electrodes were obtained by determining the pH-step
mixture, omeprazole, is due to a decreased first-pass
between the stomach and the oesophagus with the prox-
elimination and decreased systemic clearance that
imal electrode; thereafter, the tube was 5 cm withdrawn.
results in an increase of the area under the plasma
Twenty-four hour ambulatory intragastric and distal
concentration–time curve; this in turn is related to a
oesophageal pH recording was performed after an
prolonged availableness at the proton pump.22, 23 ESO
overnight fast on days 1, 2 and 6 during both study
is readily absorbed, the highest plasma concentration is
series. Subjects were allowed to follow their daily
being reached after approximately 1.5 h. Up to an
routine. They were instructed to take the meals always
ingested amount of 40 mg, plasma concentrations
at the same time during the study period with a similar
increase proportional to the ingested dose. Like all other
composition and calorie content according to their
PPIs, the antisecretory effect lasts longer than the
individual preferences. The compositions of the meals
plasma half-life. All PPI, including ESO, increase their
were chosen individually by the study subjects.
inhibitory effect on the proton pump within the firsttreatment days until the effect reaches a plateau after
The effect of drugs on gastric acidity can be quantified
Subjects were asked to participate in two series, receiving
by 24-h pH monitoring. In the present study, we
1 · 40 mg or 2 · 20 mg ESO, respectively, over a 7-day
hypothesized that the effect of once daily ESO on gastric
period with a washout phase between study series of at
acidity can be further improved by splitting the dose.
least 7 days and up to 3 weeks. The order of the two series
We expected that especially night-time acid secretion
was determined at random. Subjects were instructed to
would be affected by a twice daily regimen.
ingest the drugs with a small amount of water approxi-mately 15–30 min before breakfast (1 · 40 mg and firstdose of 20 mg b.d.) and dinner (second dose of 20 mg
b.d.). The first dose was given in the study centre afterpositioning of the pH-tube and was dissolved in 125 mL
of water. As soon as the tube was in position, the
Thirteen healthy volunteers (seven female, six male;
pH-recording was started. The tube was left in position for
mean age 30.6 years, range: 20–52 years) were recrui-
48 h (days 1 and 2). At the end of day 2, the tube was
ted by public advertisement. None had a history of
gently removed. Subjects returned to the study centre on
gastrointestinal complaints and abdominal surgery
day 6, when the pH tube was repositioned for another
(except appendectomy and cholecystectomy) and none
used medication on a regular basis. Subjects were notallowed to use any medication during the study period.
All subjects tested negative for Helicobacter pylori withthe [13C] urea breath test. Subjects signed an informed
Data collected from the Flexilog 2000 were downloaded
consent for the protocol that was approved by the Ethics
onto an IBM-compatible computer that utilized Flexilog
Committee of the University Hospital of Vienna, Austria.
software (Oakfield Instrument, Ltd) to analyse the data.
Ó 2004 Blackwell Publishing Ltd, Aliment Pharmacol Ther 19, 1105–1110
E S O M E P R AZ O L E D O S E S P L I T T I N G
From the oesophageal and gastric recordings, the
in acid suppression were detected on day 6 (P > 0.05).
median pH and the percentage of time with a pH above
Gastric acid suppression with 2 · 20 mg ESO treatment
4 were calculated for three time periods: the daytime
was comparable on days 2 and 6 (P > 0.05).
interval (08:00–20:00 hours), the night-time interval(22:00–07:00 hours) and the full 24 h. Nocturnal acid
breakthrough was defined as a trop in gastric pH under4 that lasted longer than 1 h.
During daytime hours, 2 · 20 mg ESO increased the
Gastric pH values were also converted to acid concen-
median gastric pH (P < 0.05) and percentage time with
trations and these concentrations were then plotted for
gastric pH > 4 (P < 0.01) and decreased gastric AUC of
the total 24 h period as well as for the day- and night-
acidity on day 2 (P < 0.05), but not on day 1 and day 6
time intervals for each of the doses and study days.
Integration of the area under the resulting curves (AUC)
During night-time, gastric acid suppression was signi-
was performed using the trapezoid rule and provided an
ficantly improved by 2 · 20 mg ESO compared with
estimate of the 24-h intragastric acidity.
1 · 40 mg on all study days (Table 1). Nocturnal acid
Comparisons between study days were performed using
breakthrough was observed in all subjects receiving
Student’s t-test for paired observations. The proportion
1 · 40 mg on all study days. Each individual subject
of subjects with nocturnal acid breakthrough was
had between 1 and 3 episodes of nocturnal acid
compared using McNemar’s test for paired proportions.
A P-value of <0.05 was considered significant.
During 2 · 20 mg ESO, nocturnal acid breakthrough
was observed in only 85% (first night), 64% (secondnight), and 45% of subjects (sixth night) (P < 0.05 vs.
1 · 40 mg ESO) (Table 1) During the sixth night, foursubjects still had 1 episode of nocturnal acid break-
through and two had 2 episodes (Figure 2b).
increased the median gastric 24 h pH (P < 0.01) and
percentage time with gastric pH > 4 (P < 0.05) on day 2and decreased gastric AUC of acidity on day 1 (P < 0.01)
On all study days no differences in oesophageal acid
and day 2 (P < 0.01) (Table 1, Figure 1). No differences
parameters were found with the two different regimens
Table 1. Parameters of gastric acidity in subjects treated with 1 · 40 and 2 · 20 mg esomeprazole on day 1, day 2 and day 6. Data aregiven as mean ± s.d.
P-value 1 · 40 mg 2 · 20 mg P-value 1 · 40 mg 2 · 20 mg
Percentage time pH > 4.0 36.0 (20.3) 44.4 (20.6) N.S.
Percentage time pH > 4.0 50.1 (25.3) 36.9 (15.9) N.S.
Percentage time pH > 4.0 29.7 (15.7) 46.3 (22.4) 0.05
Ó 2004 Blackwell Publishing Ltd, Aliment Pharmacol Ther 19, 1105–1110
acid breakthrough is present in a high proportion ofhealthy subjects at baseline and that a once daily dose ofESO could not eliminate this phenomenon. Splitting the
dose had a significant effect on nocturnal acid control,
and this effect increased from day 1 to day 6, the end of
Acid-induced injury of the oesophagus depends on the
pH of the refluxate and the healing rate of erosive
oesophagitis by acid inhibitors is directly related to theduration of suppression of gastric acid secretion
Figure 1. Time (h) per 24-h period with a pH above 4. Dataare given as mean ± S.E.M., shaded area ¼ 1 · 40 mg
achieved over a 24-h period.7, 9 Several recent studies
esomeprazole, white area ¼ 2 · 20 mg esomeprazole. *P < 0.05
have demonstrated that ESO suppresses gastric acidity
more potently than other PPIs.15, 16 Our data demon-strated that by splitting the daily dose, gastric acid
control can further be improved. The maximal 24 h
gastric acidity that has been achieved on day 6 during
once daily dosing, has already been achieved on the
Splitting the dose of omeprazole has also been shown
to provide superior intragastric pH control whencompared with a double dose given once daily, whereas
such a benefit has not been documented for other
PPIs.11, 13, 14 The differences in PPI effect might be due
to a variable reversibility of binding to the proton pump
among the PPIs.24, 25 Proton-pump inhibition was
generally thought to be irreversible, but this has
recently been challenged. Binding of omeprazole for
instance, seems to be reversed in vivo, while binding of
pantoprazole to the proton pump seems to be truly
irreversible, suggesting a longer duration of acid
Figure 2. Number of nocturnal acid breakthrough episodes
suppression with pantoprazole treatment; thus, the rate
during the 3 study days; (a) during 1 · 40 mg esomeprazole,
of recovery of the proton pump might be higher with
omeprazole, leaving more proton pumps susceptible foranother application 12 h after the morning dose. Thus,
of ESO. Median 24-h pH in the oesophagus remained at
the reversibility of binding of omeprazole and ESO might
a level above 6.5 during all three measurement days
be of some clinical benefit by allowing the option to split
and remained above 6.3 during the night-time periods,
the dose whereby the effect on gastric acid suppression
Oesophageal acid exposure was not significantly
different among the two ESO regimens in our study.
It should be noted that subjects in this study did not
The results of the present study demonstrate that gastric
have gastro-oesophageal reflux, thus intra-oesophageal
acid suppression with ESO, the most potent PPI
pH measurement were not expected to be abnormal and
currently on the market, can further be improved in
in fact, there was very little nocturnal reflux in our
the initial period of the treatment when the daily dose is
study group. Future clinical studies have to demonstrate
divided into a morning and an evening dose. The
whether also oesophageal acid exposure in patients with
beneficial effect was more pronounced during the night
gastro-oesophageal reflux disease can be reduced signi-
period and was detectable already in the first night of
ficantly by splitting the ESO dose. In the present study,
treatment. Our study has also confirmed that nocturnal
we have evaluated the effect of splitting the ESO dose on
Ó 2004 Blackwell Publishing Ltd, Aliment Pharmacol Ther 19, 1105–1110
E S O M E P R AZ O L E D O S E S P L I T T I N G
gastric acid suppression during the initial week of
treatment. It cannot be inferred from our data whether
1 Van Herawaarden MA, Samsom M, Smout AJPM. Excess
the effect of splitting the dose persists longer than the
gastrooesophageal reflux in patients with hiatus hernia is
caused by mechanisms other than transient LES relaxations.
A series of observations have demonstrated that an
Gastroenterology 2000; 119: 1439–46.
increase in nocturnal acid production occurs in
2 Tutuian R, Castell DO. Management of gastroesophageal
reflux disease. Am J Med Sci 2003; 326: 309–18.
subjects with GERD as well as in healthy subjects.10
3 Kahrilas PJ, Falk GW, Johnson DA, et al. Esomeprazole
This also occurs in the presence of PPI therapy and it
improves healing and symptom resolution as compared with
has been suggested that this so called nocturnal acid
omeprazole in reflux oesophagitis patients: a randomized
breakthrough might be responsible for nocturnal
controlled trial. Aliment Pharmacol Ther 2000; 14: 1249–58.
oesophageal acid exposure and persisting symptoms
4 Castell DO, Kahrilas PJ, Richter JE, et al. Esomeprazole
of GERD, although this concept has been questioned
(40 mg) compared with lansoprazole (30 mg) in the treat-ment of erosive esophagitis. Am J Gastroenterol 2002; 97:
recently.26 Studies have suggested that addition of H2
receptor antagonists at bedtime to an existing b.d. PPI
5 Hatlebakk JG, Katz PO, Castell DO. Medical therapy. Man-
regimen is more effective than PPI therapy alone in
agement of the refractory patient. Gastroenterol Clin North
reducing nocturnal acid breakthrough.27 However,
the effect of H2 receptor antagonists on nocturnal
6 Katz PO. Lessons learned from intragastric pH monitoring.
J Clin Gastroenterol 2001; 33: 107–13.
acid is only temporary and is not detectable after
7 Pursnani KG, Mohiuddin MA, Geisinger KR, Weinbaum G,
1 week of treatment.26, 28 In contrast, our findings
Katzka DA, Castell DO. Experimental study of acid burden
suggest that splitting the ESO dose improves gastric
and acute oesophagitis. Br J Surg 1998; 85: 677–80.
night-time acid control and this effect increases
8 Smith JL, Opekun AR, Larkai E, Graham DY. Sensitivity of the
during the first week. After 1 week of treatment, less
esophageal mucosa to pH in gastroesophageal reflux disease.
than half of the subjects remained to have nocturnal
9 Bell NJ, Burget D, Howden CW, Wilkinson J, Hunt RH. Appro-
acid breakthrough. The present study does not allow
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to conclude whether the proportion of subjects with
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nocturnal acid breakthrough would further decrease
10 Peghini PL, Katz PO, Bracy N, Castell DO. Nocturnal recovery
during longer ESO application with a split dose
of gastric acid secretion with twice daily dosing of proton
pump inhibitors. Am J Gastroenterol 1998; 93: 763–7.
11 Hatlebakk JG, Katz PO, Kuo B, Castell DO. Nocturnal gastric
It has to be pointed out that our study was conducted
acidity and acid breakthrough on different regimens of
in healthy subjects, thus should be extrapolated with
omeprazole 40 mg daily. Aliment Pharmacol Ther 1998; 12:
caution to patients with acid-related disorders. Our
subjects were all tested H. pylori-negative. It has been
12 Katz PO, Hatlebakk JG, Castell DO. Gastric acidity and acid
shown that PPI therapy in H. pylori-negative healthy
breakthrough with twice-daily omeprazole or lansoprazole.
subjects is associated with a higher rate of nocturnal
Alimen Pharmacol Ther 2000; 14: 709–14.
13 Kuo B, Castell DO. Optimal dosing of omeprazole 40 mg daily:
acid breakthrough compared with H. pylori-positive
effects on gastric and esophageal pH and serum gastrin in
subjects,29 possibly because the presence of H. pylori
healthy controls. Am J Gastroenterol 1996; 91: 1532–8.
infection leads to a more profound suppression of acid
14 Moennikes H, Weber S, Tebbe J, et al. Comparison of pan-
toprazole 20 mg twice daily with 40 mg once daily on
In conclusion, splitting the dose of ESO improves acid
intragastric pH in healthy volunteers. Gastroenterology1998; 114: A232.
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15 Miner P Jr, Katz PO, Chen Y, Sostek M. Gastric acid control
dosing, maximal 24-h acid suppression is already
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achieved on the second day of treatment, while night-
and rabeprazole: a five-way crossover study. Am J Gast-
time acid control as well as acid breakthrough improved
continuously within the first week of treatment by
16 Hatlebakk JG. Review article: gastric acidity – comparison of
esomeprazole with other proton pump inhibitors. AlimentPharmacol Ther 2003; 17 (Suppl. 1): 10–5.
17 Ro¨hss K, Wilder-Smith CH, Claar-Nilsson, Lundin C, Hassel-
gren G. Esomeprazole 40 mg provides more effective acidcontrol than standard doses of all other proton pump inhib-
There was no financial support required for this study.
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18 Castell DO, Kahrilas PF, Richter JE, et al. Esomeprazole
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Ó 2004 Blackwell Publishing Ltd, Aliment Pharmacol Ther 19, 1105–1110
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