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Prevacid

Clinical Pharmacology
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Clinical Pharmacology

Lansoprazole, clarithromycin and/or amoxicillin 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 ( ≥ 2.0 µg/mL) was 9.5% (91/960) by E-test and 11.3% (12/106) by agar dilution in the dual and triple therapy clinical trials (M93-125, M93-130, M93-131, M95-392, and M95-399).

Amoxicillin pretreatment susceptible isolates ( ≤ 0.25 µg/mL) occurred in 97.8% (936/957) and 98.0% (98/100) of the patients in the dual and triple therapy clinical trials by E-test and agar dilution, respectively. Twenty-one of 957 patients (2.2%) by E-test and 2 of 100 patients (2.0%) by agar dilution had amoxicillin pretreatment MICs of greater than 0.25 µg/mL. One patient on the 14-day triple therapy regimen had an unconfirmed pretreatment amoxicillin minimum inhibitory concentration (MIC) of greater than 256 µg/mL by E-test and the patient was eradicated of H. pylori (Table 3).

Table 3: Clarithromycin Susceptibility Test Results and Clinical/Bacteriological Outcomesa


Clarithromycin Pretreatment
Results
Clarithromycin Post-treatment
Results
  H. pylori negative -
eradicated
H. pylori positive -
not eradicated
    Post-treatment susceptibility results
    Sb Ib Rb No MIC
Triple Therapy 14-Day (lansoprazole 30 mg b.i.d./amoxicillin 1 gm b.i.d./clarithromycin 500 mg b.i.d.)
(M95-399, M93-131, M95-392)
Susceptibleb 112 105       7
Intermediateb 3 3        
Resistantb 17 6     7 4
Triple Therapy 10-Day (lansoprazole 30 mg b.i.d./amoxicillin 1 gm b.i.d./clarithromycin 500 mg b.i.d.)
(M95-399)
Susceptibleb 42 40 1   1  
Intermediateb            
Resistantb 4 1     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 lansoprazole/amoxicillin/clarithromycin triple therapy will likely have clarithromycin resistant H. pylori. Therefore, for those patients who fail therapy, clarithromycin susceptibility testing should be done when possible. Patients with clarithromycin resistant H. pylori should not be treated with lansoprazole/amoxicillin/clarithromycin triple therapy or with regimens which include clarithromycin as the sole antimicrobial agent.

Brand Name: Prevacid
Generic Name: Lansoprazole
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