COMPARISON OF ONCE-A-DAY VERSUS TWICE-A-DAY
CLARITHROMYCIN TRIPLE THERAPY
FOR HELICOBACTER PYLORI ERADICATION
MP Collado, MFP Calida, PP Sy
Department of Medicine, Section of Gastroenterology,
Cardinal Santos Medical Center, San Juan, Metro Manila
1
ABSTRACT
Background/ Aim: Eradication therapy with Esomeprazole, Amoxicillin and
Clarithromycin is used extensively, however the efficacy of once-a-day Clarithromycin
have not been determined. This study was conducted to compare the efficacy and safety
profile of once-a-day Clarithromycin triple therapy with the standard triple therapy as a
treatment for Helicobacter pylori (H. pylori) infected patients. Methods: This
randomized, open, parallel-controlled study was conducted at Cardinal Santos Medical
Center from July 2005 to November 2005. A total of 40 consecutive patients who were
H. pylori positive proven by rapid urease test were included and randomly assigned to
once-a-day or twice-a-day Clarithromycin triple therapy. Eighteen patients were
administered with once-a-day Clarithromycin therapy including Esomeprazole 40 mg
b.i.d. and Amoxicillin 1 g b.i.d. for 7 days. Twenty two patients received a standard 7-day
triple therapy consisting of Esomeprazole 40 mg b.i.d., Clarithromycin 500 mg b.i.d. and
Amoxicillin 1 g b.i.d. The eradication rates were evaluated by the (13) C-Urea breath test
at least 4 weeks after completion of a course of treatment. Results: Thirty six patients
completed the trial and 4 patients dropped out. The eradication rates in twice-a-day
therapeutic group and once-a-day therapeutic group (intention to treat [n=22] / per
protocol [n=18]) were 95% / 95% (p=0.832) and 88% / 67% (p=0.02) respectively. Short
lasting and self-limiting side effects including taste disturbance and diarrhea were
reported in 8 patients (36%) in the once-a-day group and 6 patients (33%) in the twice-aday group with odds ratio of 1.75. Conclusion: Once-a-day and twice-a-day
Clarithromycin- based triple therapies were both effective and safe in eradicating H.
pylori in the patient population studied.
2
Category: Stomach and Duodenum
Article: Experimental (Randomized Controlled Trial)
Key Words: Helicobacter pylori
Once-a-day Clarithromycin-based triple therapy
Esomeprazole
Amoxycillin
eradication therapy
side effects
3
INTRODUCTION
Helicobacter pylori (H. pylori) infection, which is presenting 30- 60% of the
population in developed countries and in more than 60% in developing countries, is
established to be a major cause of gastritis, peptic ulcer disease and gastric cancer.1 It is a
serious, chronic, transmissible infectious disease which is preceded by long
asymptomatic periods.
H. pylori resides in the surface of the stomach within the mucus as well as
attached mucus cells. H. pylori can also be found within epithelial cells. These various
niches provide a challenge for antimicrobial therapy. In addition, the gastric lumen is a
hostile environment for antimicrobial therapy because the drugs must penetrate thick
mucus and may need to be active at pH levels below neutral. Despite these difficulties,
relatively effective therapies have been identified, primarily through the process of trial
and error. 2
Currently therapy with proton pump inhibitors such as Esomeprazole and two
antibiotics, Amoxicillin and Clarithromycin is the most frequently prescribed medication
for the eradication of H. pylori.3,
4, 5
Non-recurrence of gastric and duodenal ulcer is
strictly dependent on the success of H. pylori eradication and the persistence of infection
is a negative prognostic marker 6, thus the need for effective H. pylori eradication. An
obstacle to effective therapy is poor compliance with the prescribed medication as with
any other disease requiring multiple drugs for therapy. Simplifying an effective therapy is
ideal using less medication and/ or shorted duration.
Although the modified-release formulation of Clarithromycin (OD tablet)
has demonstrated bioequivalence to the immediate-release formulation (500 mg tablet) 7,
4
the effectiveness of this new formulation in H. pylori eradication has not been
established.
This therapeutic trial is designed to compare the clinical success rate (percentage
of patients with successful cure of H. pylori) and safety of once-daily dosing and the
standard twice-daily regimens of Clarithromycin triple therapy in documented H. pylori
positive patients.
OBJECTIVES
General
To compare the efficacy and safety of once-a-day Clarithromycin and twice-a-day
Clarithromycin-based triple therapy in the eradication of Helicobacter pylori
Specific
1. To determine the proportion of patients with a negative urea breath test among
patients receiving twice-a-day Clarithromycin versus those receiving once-aday Clarithromycin.
2. To determine the odds ratio of adverse events in both treatment groups
MATERIALS AND METHODS
Study Population
Adult patients of either sex, with duodenal ulcer or erosive / superficial
gastropathy, or both, who were H. pylori positive (as determined by rapid urease test- Cu
test) seen at the Endoscopy Unit of Cardinal Santos Medical Center from July 2005 to
November 2005 were included.
Patients with more than one previous attempt to eradicate H. pylori, those with
active peptic ulcer and active bleeding from gastrointestinal tract were excluded. Other
5
exclusion criteria were regular treatment with non-steroidal anti-inflammatory drugs,
concomitant antimicrobial agents and allergy to any of the study drug.
This study was approved by the Ethics Committee of the Cardinal Santos Medical
Center before commencement of patient enrollment. Informed consent was obtained from
patients before entering the study.
Study Design
This study was a prospective, randomized, open-label, blinded endpoint (PROBE)
trial with parallel-group design. Eligible patients were randomized to 1 of 2 treatment
groups (Table 1) by a process of transparent envelopes. Equivalent number of pieces of
paper, determined based on the calculated sample size, were placed on sealed transparent
envelopes. Each paper will indicate the group allocation of patients who will be included
in the study. Patients were allocated the next transparent envelope once they have
satisfied the inclusion criteria.
TABLE 1. Study Therapy
Therapy
Twice-a-day
therapeutic group (mg)
Once-a- day
therapeutic group (mg)
40
40
Amoxicillin
1000
1000
Clarithromycin
1000
OD tablet
Esomeprazole
NOTE: Esomeprazole and Amoxicillin were administered twice a day daily for 7 days.
The twice-a-day therapeutic group received 500mg of Clarithromycin, twice a day
while patients allocated in the once-a-day therapeutic group received once-a-day
Clarithromycin, both given for 7 days.
6
Assessments
At the first visit (VISIT 1), patient underwent endoscopy with biopsy specimen
taken from the antrum and body, where rapid urease test (Cu test) was performed to
confirm infection. Patients returned for clinic visit (VISIT 2) after the 7-day treatment
period for symptom, adverse event and compliance assessment. (13) C-Urea breath test
(UBT) was performed 4 weeks after the end of treatment (VISIT 3). Eradication was
defined as a negative UBT test 4 weeks after cessation of therapy.
Those patients included in once-a-day therapeutic group with a positive UBT after
4 weeks of therapy (treatment failure) were given the standard treatment for H. pylori for
another week.
Statistics
The primary measure of efficacy was the eradication of H. pylori as determined
by the results of UBT at Visit 3. The two-sample binomial test was used to evaluate the
results. Success rate for once-a-day therapeutic group was set at 94% based on MACH 2
Study.
3
The success rate for twice-a-day therapeutic group was projected at 80% on an
intention to treat basis upon the recommendation of the Maastricht Consensus Report.
8
We calculated that 90 patients would be required to show equivalence between the two
study groups, with a power of 80% with an = 0.05 (two-tailed).
Analysis was performed on an intention to treat (ITT) and per protocol basis. ITT
patients included all those enrolled and randomized to treatment groups. This included
those who took no or incomplete medication or those with delayed exclusions due to lost
to follow-up evaluation (not returning for visit 2 or 3), or had deviated significantly from
7
the study protocol (e.g. intake of interval antibiotics). For the per protocol analysis, these
patients were excluded.
It was assumed that H. pylori had not been eradicated if the patient did not return
for UBT at Visit 3, that is, a worst case analysis.
RESULTS
Patient Population
Forty patients were initially recruited for the ITT analysis. Table 2 shows the
baseline characteristics of the 40 eligible patients. Demographic characteristics were
similar in the two groups, as were symptoms at initial assessment. Of these 40 patients,
36 patients were eligible for inclusion in the per protocol analysis. Two patients who
were excluded had not attended visit 3, the other two patients did not complete the
treatment.
TABLE 2. Pretreatment Clinical and Demographic Characteristics
Mean Age (years)
Range
Sex
Men
(%)
Women (%)
Diagnosis
Duodenal Ulcer (%)
Erosive / Superficial
Gastropathy
(%)
Twice-a-day
Therapeutic group
N = 22
Once-a-day
Therapeutic group
N = 18
60.2
40 – 80
58.9
38 – 84
13 (59)
9 (41)
10 (55)
8 (45)
6
4
(27)
16 (73)
8
(22)
14 (78)
Efficacy
The proportion of patients in whom H. pylori was successfully eradicated for the
per protocol and the intention to treat patient populations are shown in Table 3. In the
ITT population, both groups are found to have equal performance using binomial test for
proportion with p-value of 0.832. Evaluating the results using the per protocol analysis
showed a p value of 0.02.
TABLE 3. Proportion of patients with negative Urea Breath Test 7 days after treatment
Twice-a-day
Therapeutic group
Once-a-day
Therapeutic group
Intention to treat
Negative (%)
N = 22
20 (95)
N = 18
16 (88)
Per protocol
Negative (%)
N = 21
20 (95)
N = 15
10 (67)
UBT Result
Safety
The safety analysis was done on all 38 patients who had taken at least one dose of
the medications. The most frequently reported adverse events were diarrhea and taste
disturbance (Table 4).
Eight patients experienced diarrhea while 6 patients reported taste disturbance.
Both groups were equal in terms of the occurrence of adverse effects, using the binomial
test for proportions.
Odds ratio was used to determine occurrence of adverse effects on both groups
which revealed a value of 1.75. However, no patients withdrew from the study as a result
of an adverse event.
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TABLE 4. Patients Experiencing Adverse Events in Each Treatment Group
Twice-a-day
Therapeutic group
N = 22
Once-a-day
Therapeutic group
N = 18
Diarrhea
4
4
Taste disturbance
4
2
Total (%)
8 (36)
6 (33)
Adverse Event
DISCUSSION
This study has shown that once-a-day Clarithromycin and twice-a-day
Clarithromycin triple therapy, given for 7 days effectively eradicates H. pylori. The
proportion of patients in once-a-day therapeutic group in whom H. pylori was
successfully eradicated was comparable with twice-a-day therapeutic group in the ITT
population, having a success rate of 88%. This eradication rate is consistent with other
studies using Clarithromycin and proton-pump inhibitor triple therapies. 4, 5,
9, 10
However,
unlike many studies reported in Europe 3, per protocol eradication rates above 90% were
not achieved for the once-a-day therapeutic group which was only 67%. The higher
number of patients excluded in the once-a-day therapeutic group might have influenced
this result.
The results suggests that giving once-a-day or twice-a-day Clarithromycin triple
therapy results in significantly equivalent eradication efficacies, although there was a
trend for lesser eradication rate for once-a-day therapeutic group in the per protocol
population. The use, however, of fewer tablets has perceived increased compliance value.
10
It has been suggested that eradication rates vary between patients subgroups. In
particular, patients with non-ulcer dyspepsia have been reported to have lower eradication
rates than patients with ulcer disease.11, 12 In this study, a majority of the patients in oncea-day and twice-a-day therapeutic group ( 78% and 73% respectively) showed high
eradication rates in both intention to treat and per protocol populations despite being
diagnosed with non-ulcer dyspepsia.
The use of Urea Breath Test (UBT) as assessment for the primary outcome of this
study has been proven to have a very high sensitivity as reported by previous trials
3, 9
reporting a 95% agreement between UBT and histological assessments. This test is a
highly sensitive method for assessing H. pylori status both before and after therapy and
that the reliability of the method is such that a single post-therapy UBT is sufficient in
most cases.13
The number of patients reporting adverse effects was relatively similar in both
groups, with calculated Odds ratio of 1.75 which was relatively small since statistically
both groups have the same performance. No patients withdrew from the study because of
these side effects, thus the treatments were generally well tolerated. The high incidence
of taste related adverse events is a frequently reported occurrence with Clarithromycin
and was thought to be dose-dependent.3 That however was not observed in our study.
Diarrhea and GIT disturbances is also a well documented side effect of Amoxicillin, a
broad-spectrum penicillin antibiotic.14 Reports of this adverse event among our study
patients were consistent with current knowledge of treatment with these drugs.
11
CONCLUSION
Once-a-day and twice-a-day Clarithromycin- based triple therapies were both
effective and safe in eradicating H. pylori in the patient population studied.
RECOMMENDATIONS
Calculated sample size must be achieved to determine absolute comparability
between the treatment groups.
Data concerning the pretreatment antimicrobial sensitivities, which were not
included in this study, may also proved useful in providing conclusive results.
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