Alimentary Pharmacology & Therapeutics
Esomeprazole induces upper gastrointestinal tract transmucosal permeability increase J. M. MULLIN*, , M. C. VALENZANO*, M. WHITBY*, D. LURIEà, J. D. SCHMIDT , V. JAIN§, O. TULLY§, K. KEARNEY , D. LAZOWICK*, G. MERCOGLIANO & J. J. THORNTON
*The Lankenau Institute for Medical Research, Wynnewood, PA, USA; Division of Gastroenterology, Lankenau Hospital, Wynnewood, PA, USA; àDepartment of Mathematics, St. Joseph’s University, Philadelphia, PA, USA; §Department of Medicine, Lankenau Hospital, Wynnewood, PA, USA Correspondence to: Dr J. M. Mullin, Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood, PA 19096, USA. E-mail:
[email protected]
Publication data Submitted 13 March 2008 First decision 27 March 2008 Resubmitted 8 July 2008, 30 July 2008 Accepted 31 July 2008 Epub Accepted Article 5 August 2008
SUMMARY Background Proton pump inhibitors (PPIs) are one of the most widely used drug classes in the US and are now frontline medications for gastro-oesophageal reflux disease (GERD) and dyspepsia. In a previous work, we observed that a transmucosal, upper gastrointestinal (GI) leak exists in Barrett’s oesophagus (BO) patients. PPI medications are commonly used by Barrett’s patients. Aim To examine if the PPI, esomeprazole, affects the barrier function of the upper GI tract. Methods The sucrose permeability test (SPT) was used to assess the possible effect of the PPI, esomeprazole, on upper GI leak in 37 first-time-presenting GERD patients and 25 healthy controls. Results Esomeprazole induced a significant transmucosal leak in the upper GI tract of patients taking the drug for the first time. The leak occurred quickly, within days of first taking the drug. The leak was also reversed within days of stopping the medication. Conclusions This is the first patient-based study showing that a PPI compromises upper GI barrier function. There are potential implications for transmucosal leak of other medications that a patient on a PPI may be taking, as well as possible leak of endogenous peptides ⁄ proteins. The clinical consequences of this phenomenon are currently unknown, but are potentially important. Aliment Pharmacol Ther 28, 1317–1325
ª 2008 The Authors Journal compilation ª 2008 Blackwell Publishing Ltd doi:10.1111/j.1365-2036.2008.03824.x
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1318 J . M . M U L L I N et al.
INTRODUCTION Proton pump inhibitors (PPIs) are among the most widely prescribed (and over-the-counter purchased) drugs in the US, with over 2 billion dollars being spent yearly on the medications.1, 2 The drugs have even come into use with infants where reflux disease is being more commonly suspected.3, 4 Moreover, their use is very likely to be on the rise, as gastro-oesophageal reflux disease (GERD) is believed to be increasing in frequency.5 GERD is not simply ‘annoying heartburn’ as it is believed to be the early stage of sequelae that can progress to oesophagitis, Barrett’s oesophagus (BO) and oesophageal adenocarcinoma in certain individuals.6 The final condition, oesophageal adenocarcinoma is, in fact, one of the most rapidly rising forms of cancer in the US.7 Some reports contend that proper use of PPIs may inhibit the progression of those sequelae and thereby offer a protective effect regarding cancer of the oesophagus.8 Our research group recently showed that BO patients manifest a transmucosal leak in their upper gastrointestinal (GI) tract.9 In that study, however, we did not collect the complete medication history of the Barrett’s patients at the exact time they performed their permeability testing. We sought to redress that oversight by assessing the effect on upper GI permeability, if any, of common medications that this patient group may routinely take. Nonsteroidal anti-inflammatory drugs (NSAIDs), as an example, are well known to produce upper GI transmucosal leak.10, 11 However, PPIs are the most common medications for the Barrett’s oesophagus patient group. Our hypothesis in evaluating the effect of PPIs on upper GI leak was that these medications would reduce leak, i.e. improve barrier function. They are well known to reduce gross oesophageal inflammation and improve symptoms by reducing the acidity of the refluxed gastric contents.12 We observed increased transmucosal leak in oesophagitis patients in our earlier study.9 We reasoned that any reduction in macroscopic or microscopic inflammation ⁄ ulceration or the cellular ⁄ molecular changes seen in acid-reflux-associated dilation of intercellular spaces13 in a first-timepresenting GERD patient as a result of an 8-week course of a PPI would only serve to improve upper GI barrier function. We utilized the same approach to evaluate mucosal leak clinically as we did in our previous BO study, namely the use of oral sucrose as a probe of upper GI
permeability. Sucrose, a disaccharide, lacks a transport protein in any mammalian cell and can only pass through the upper GI barrier paracellularly, i.e. it must find a pathway between cells, either through leaky tight junctions or through an actual break (e.g. ulceration) in the upper GI mucosa.14, 15 As sucrose is hydrolysed to glucose and fructose on the surface of the duodenum, its leak into the bloodstream must be proximal to this point. Once in the bloodstream, sucrose cannot be reabsorbed by the kidney for similar reasons and thus passes quantitatively into the urine.16 Having test subjects drink a concentrated sucrose solution and collect an overnight urine sample for analysis of upper GI leak has been used in many clinical studies since it was first described.10 This study sought to measure the sucrose (upper GI) leak in healthy controls and in first-time-presenting GERD patients, both before PPI medication was begun and at the time a course of medication was being completed.
METHODS Recruitment Healthy controls were recruited without regard to gender or ethnicity from an age range of 18–80. Criteria for exclusion from the study were: (i) prior GI surgery; (ii) current GI disease; (iii) diabetes; and (iv) renal insufficiency. The last two exclusions related to the nature of the sucrose permeability test (SPT). Before testing, all subjects signed an informed consent approved by the Lankenau Hospital Institutional Review Board. Previous work by our group showed that GERD without mucosal abnormalities (as evidenced in previous endoscopic examination) did not result in an observed mucosal leak to sucrose.9 Those GERD patients, unlike those in this study, had long-standing GERD and were already under the medical care of a gastroenterologist before entering the study. The GERD patients in this study were recruited from a primary care practice, to which they were presenting for the first time with their disease. These patients were PPI- and H-2 blocker-naı¨ve or had not taken such medications for at least a 30 day period (only antacids were allowed in that time frame). The upper GI tracts of these current patients would thus not have had the opportunity to heal from damage ensuing from their chronic reflux until they were recruited ª 2008 The Authors, Aliment Pharmacol Ther 28, 1317–1325 Journal compilation ª 2008 Blackwell Publishing Ltd
P R O T O N P U M P I N H I B I T O R S A N D G I M U C O S A L L E A K 1319
into our study and placed on PPI medication. With the exception of their GERD, these patients met the above criteria at the time of their recruitment and were recruited in a manner similar to that of healthy controls. Several days after performing their initial SPT, these patients, who had not been previously endoscoped, were given an upper endoscopy examination at study expense and then began their 8 week course of esomeprazole.
Sucrose permeability testing All patients and healthy controls consumed in their homes a chilled solution of 100 g of sucrose in 200 cc of water containing 5 g of a citric acid-based flavouring agent at bedtime. GERD patients undergoing upper endoscopy had these exams performed only after the first SPT was completed (and at least 6 weeks before the second test) so as not to have scope trauma or mucosal biopsies skew the permeability measurements. After drinking the sucrose solution, an 8 h (overnight) urine sample was collected in a container with 5 mL of 10% thymol in isopropanol as antimicrobial preservative. Total urine volume and specific gravity were measured and recorded. The concentration of sucrose in the urine sample was then measured by an enzymatic ⁄ spectrophotometric assay after prior desalting of the urine sample by anion and cation exchange resins.9, 10, 17 Total amount of sucrose in the urine in mg was determined by multiplying the urine volume in ml by the sucrose concentration in mg ⁄ mL. This amount of sucrose equates to the number of mg of sucrose, which leaked from the upper GI lumen.
RESULTS First-time-presenting GERD patients who were either PPI- and H-2 blocker-naı¨ve or refraining from those medications for at least 30 days were recruited for this study. As previously mentioned, this was in contrast to our earlier study which utilized GERD patients who had been previously diagnosed and under the care of a gastroenterologist.9 Demographic criteria for this entire study’s healthy controls and GERD population are shown in Table 1, which summarizes age, gender and ethnicity profiles. The first-time-presenting GERD patients were asked to perform an initial SPT before beginning an 8-week course of esomeprazole capsules (Nexium; AstraZeneca, London, UK) at a dose of 40 mg ⁄ day, to be taken each morning before breakfast. A 4-week follow-up interview was performed with all patients to assess symptom resolution and all reported a significant symptom improvement with mild, if any, side effects. Within 3 days before their 8week medication course was completed, all patients performed a second and final SPT. The numerical differences between the result of their second SPT and the result of their first test are shown for each of 26 first-time-presenting GERD patients in Figure 1. A total of 37 patients were recruited and completed the test, but 11 were removed from consideration because their initial SPT result showed a leak >200 mg [suggesting a possible ongoing pathology or undisclosed (secondary) drug complication that could skew the results of the test].10 As can be seen, of the remaining 26 patients, 21 (84%) showed increased sucrose leak in their second test at the end of their course of esomeprazole. Fourteen of 21 in fact showed increased leak above the 200 mg threshold level that
Materials The sucrose solutions were a generous gift of Perk Scientific, Inc. (Yeadon, PA, USA). Enzymatic reagents for determination of urine glucose and sucrose concentrations (invertase, hexokinase and glucose-6-phosphate dehydrogenase) as well as cofactors (ATP and NADP) were products of Sigma Aldrich Chemical Co. (St Louis, MO, USA).
Table 1. Patient demographics across all studies Gender distribution
Per cent Caucasian
24–70 years [48]
48% male
64%
21–67 years [36]
62% male
82%
Age range Gastro-oesophageal reflux disease population (26) Nondisease (healthy control) group (34)
Statistics In comparing pre- and post-PPI sucrose leak levels, a paired Student’s t-test was used. The data so tested did fit a Gaussian distribution. ª 2008 The Authors, Aliment Pharmacol Ther 28, 1317–1325 Journal compilation ª 2008 Blackwell Publishing Ltd
The number in parenthesis represents the number of patients in that group. The number in brackets is the mean age of that group.
1320 J . M . M U L L I N et al. Effect of 8 week esomeprazole therapy on transmucosal sucrose leak
800 600 400
Increased leak
1000
200 0 –200 –400 –600
Decreased leak
Increase or decrease in sucrose leak in total mg
1200
Figure 1. Induction of upper gastrointestinal leak after an 8 week trial of proton pump inhibitors (PPIs). Sucrose permeability tests (SPTs) at the end of an 8-week course of esomeprazole minus the corresponding gastro-oesophageal reflux disease patient’s permeability test before beginning esomeprazole are shown for 26 patients. Each bar represents the result for one patient. Ascending bars indicate that the post-esomeprazole leak was greater (21 of 26). Descending bars indicate that the post-esomeprazole leak was smaller (five of 26). Results shown derive from the total amount of sucrose (mg) in an overnight urine sample as described in Methods. A total of 37 patients completed the 8-week course of therapy and both SPTs, but the results of 11 were removed from consideration because the magnitude of their initial permeability test was >200 mg and suggested that an effect of a medication (other than a PPI) and ⁄ or a pathophysiological condition was complicating the interpretation.
others have believed indicate pathophysiology. The average initial sucrose leak was 72 9 mg (S.E.M.) vs. a mean final sucrose leak of 325 56 mg, an increase of 451%. This difference is statistically significant (P = 0.001, Student’s t-test; similar results were obtained by the nonparametric Wilcoxon Signed Ranks Test). If all 37 patients who entered and completed the study are included (without regard to the magnitude of the initial leak), the average initial leak is 179 mg (39 mg) vs. a final leak of 307 mg (44 mg), a 171% increase, which is also statistically significant (P = 0.04; Table 2). Nine of these 11 patients removed from the study had either medical complications such as hiatal hernia, oesophagitis or gastritis or medication use such as ibuprofen or aspirin that could contribute to a higher than normal initial sucrose leak. A second study with healthy control subjects was begun to reduce the (disease) variables that may be at play in working with a GERD population and simultaneously assess the time course with which a PPI leak may establish. As described in Methods, a volunteer
Table 2. Summary of pre-esomeprazole sucrose leak vs. sucrose leak once on esomeprazole
All patients Patient subset
Initial leak value (mg)
Final leak value (mg)
Significance P (n)
178.5 39.0 72.8 9.0
306.8 43.8 324.7 55.9
0.04 (37) 0.001(26)
The average ( standard error) baseline sucrose leak measurement (pre-esomeprazole) and the sucrose leak at the end of 8 weeks of esomeprazole therapy are shown for all patients successfully finishing the study (n = 37) and only those patients whose initial sucrose leak is
