The comparative effects of lansoprazole, omeprazole, and ranitidine in suppressing gastric acid secretion

Assessing and mitigating pH-mediated DDI risks in drug development - formulation approaches and clinical considerations

pH-mediated drug-drug interactions (DDI) is a prevalent DDI in drug development, especially for weak base compounds with highly pH-dependent solubility. FDA has released a guidance on the evaluation of pH-mediated DDI assessments using in vitro testing and clinical studies. Currently, there is no common practice of ways of testing across the academia and industry. The development of biopredictive method and physiologically-based biopharmaceutics modeling (PBBM) approaches to assess acid-reducing agent (ARA)-DDI have been proven with accurate prediction and could decrease drug development burden, inform clinical design and potentially waive clinical studies. Formulation strategies and careful clinical design could help mitigate the pH-mediated DDI to avoid more clinical studies and label restrictions, ultimately benefiting the patient. In this review paper, a detailed introduction on biorelevant dissolution testing, preclinical and clinical study requirement and PBPK modeling approaches to assess ARA-DDI are described. An improved decision tree for pH-mediated DDI is proposed. Potential mitigations including clinical or formulation strategies are discussed.

A drug-drug interaction study to assess the potential effect of acid-reducing agent, lansoprazole, on quizartinib pharmacokinetics

PURPOSE

Quizartinib, a potent, selective FMS-like tyrosine kinase 3 (FLT3) inhibitor, is currently in phase 3 development for patients with FLT3-internal tandem duplication-mutated acute myeloid leukemia (AML). Acid-reducing agents (ARAs; e.g., proton pump inhibitors) are frequently used during AML treatment. Since quizartinib demonstrates pH-dependent solubility, the effect of lansoprazole coadministration on pharmacokinetics (PK) of quizartinib tablet formulation was assessed.

METHODS

An open-label, parallel-group study randomized 64 healthy adults to single-dose quizartinib 30 mg alone (reference) or lansoprazole (60 mg once daily, days 1-5) + single-dose quizartinib 30 mg (day 5) (test). Plasma concentrations of quizartinib and its active metabolite, AC886, were measured to 504 h postdose; the effect of lansoprazole on quizartinib PK was assessed by analysis of variance.

RESULTS

Quizartinib geometric mean ratios (test/reference) and 90% confidence intervals for maximum observed plasma concentration (Cmax), area under the concentration-time curve to last measurable drug concentration (AUClast), and AUC to infinity were 86.11% (78.4%, 94.6%), 93.96% (79.6%, 110.9%), and 95.30% (80.2%, 113.3%), respectively. Comparisons showed a modest decrease in quizartinib absorption when co-administered with lansoprazole, with lower limits for Cmax and AUClast just below 80-125% limits. Treatment-emergent adverse events were mild or moderate; the most frequent in either treatment group were headache [quizartinib alone: (n = 3) 10%], upper respiratory tract infection [quizartinib alone: (n = 2) 6.7%; lansoprazole + quizartinib: (n = 3) 9.1%], and muscle tightness [quizartinib alone: (n = 2) 6.7%].

CONCLUSIONS

Concomitant lansoprazole had minimal effect on quizartinib PK as a formulated tablet, indicating that quizartinib can be administered with ARAs.

Interchangeable Use of Proton Pump Inhibitors Based on Relative Potency

Although proton pump inhibitors (PPIs) are widely used, their relative potency and ideal dosing regimens remain unclear. We analyzed data from randomized clinical trials that performed pH testing in patients receiving solid-dose PPI formulations (omeprazole, esomeprazole, lansoprazole, pantoprazole, rabeprazole) for a minimum of 5 days. We used omeprazole equivalency and the surrogate biomarker, percentage time pH > 4 over a 24-hour period (pH4time), to compare PPI effectiveness for different PPIs given once, twice, or 3 times daily. We found that increasing strength of once-daily PPIs (9-64 mg omeprazole equivalents) increased pH4time linearly from approximately 10.0 to 15.6 hours; higher doses produced no further increase in pH4time. Increasing the frequency to twice-daily PPI increased pH4time linearly, from approximately 15.8 to 21.0 hours. Three-times daily PPIs performed similarly to twice-daily PPIs. The costs of PPIs varied greatly, but the cost variation was not directly related to potency. We conclude that PPIs can be used interchangeably based on potency. Using twice-daily PPIs is more effective in increasing efficacy increasing once-daily PPI dosage. Omeprazole and lansoprazole (30 mg) and 20 mg of esomeprazole rabeprazole are functionally equivalent.

Identification and characterisation of a salt form of Danirixin with reduced pharmacokinetic variability in patient populations

The natural variability of gastric pH or gastric acid reducing medications can result in lower and more variable clinical pharmacokinetics for basic compounds in patient populations. Progressing alternative salt forms with improved solubility and dissolution properties can minimise this concern. This manuscript outlines a nonclinical approach comprising multiple biopharmaceutical, in vitro and physiologically based pharmacokinetic model (PBPK) modelling studies to enable selection of an alternative salt form for danirixin (DNX, GSK1325756), a pharmaceutical agent being developed for chronic obstructive pulmonary disease (COPD). The hydrobromide salt of DNX was identified as having superior biopharmaceutical properties compared to the free base (FB) form in clinical development and the impact of switching to the hydrobromide salt (HBr) was predicted by integrating the nonclinical data in a PBPK model (using GastroPlus™) to enable simulation of clinical drug exposure with FB and HBr salts in the absence and presence of a gastric acid reducing comedication (omeprazole, a proton pump inhibitor (PPI)). Subsequent investigation of DNX pharmacokinetics in a Phase 1 clinical study comparing FB with HBr salt forms confirmed that DNX HBr had reduced the variability of drug exposure and that exposure was not affected by PPI co-administration with DNX HBr. This case study therefore adds to the surprisingly few examples of a more soluble salt of a weak base translating to an improvement in human pharmacokinetics and illustrates a clear clinical benefit of salt selection during drug development.

The pharmacokinetics and pharmacodynamics of danirixin (GSK1325756)--a selective CXCR2 antagonist --in healthy adult subjects

Background

Excessive neutrophil presence and activation is important in a number of acute and chronic inflammatory diseases. The CXCR2 chemokine receptor is important in controlling the extravasation and activation of neutrophils. Selective antagonism of the CXCR2 receptor is a potential approach to reducing neutrophil migration and activation. Danirixin, is a small molecule, CXCR2 antagonist being evaluated as a potential anti-inflammatory medicine.

Methods

(1) First time in human (FTIH) double-blind, placebo-controlled study to evaluate the safety, pharmacokinetics, and pharmacodynamics of single ascending and repeat oral doses of danirixin in healthy male subjects; (2) single-dose study of age, gender, food, and proton-pump inhibitor effects on the pharmacokinetics of danirixin in healthy adult subjects; and placebo-controlled study of the pharmacokinetics of danirixin in healthy elderly subjects.

Results

There were no serious adverse events and no adverse events considered to be of clinical relevance. There were no withdrawals due to adverse events. Systemic exposure following single doses of danirixin 10 mg, 25 mg, 50 mg, 100 mg, and 200 mg increased with increasing dose. Engagement of pharmacology was demonstrated as inhibition of ex-vivo CXCL1-induced CD11b expression on peripheral blood neutrophils when compared to placebo (approximately 50 % for 50 mg and 100 mg danirixin, and 72 % at 200 mg). There was a 37 % decrease in Cmax and a 16 % decrease in AUC (0-∞) following administration of danirixin in the presence of food. Cmax also decreased by 65 % when danirixin 100 mg was administered following omeprazole 40 mg once daily for 5 days. The AUC (0-∞) and Cmax were 50 % lower in elderly subjects compared with younger subjects.

Conclusion

The dose-dependent inhibition of agonist-induced neutrophil activation following single and repeated once daily oral administration of danirixin suggests that this CXCR2 antagonist may have benefit in neutrophil-predominant inflammatory diseases. Co-administration with food, gastric acid reducing agents, and variable exposure in the elderly have important clinical implications that need to be taken into consideration in subsequent clinical evaluations.

Trial registration

ClinicalTrials.gov identifiers: NCT01209052 and NCT01209104

The pharmacokinetics of conventional and bioenhanced tablet formulations of danirixin (GSK1325756) following oral administration in healthy, elderly, human volunteers

Danirixin (GSK1325756) is a small, high-affinity, selective and reversible CXCR2 antagonist in development for treatment of chronic obstructive pulmonary disease. The objective of the study was to evaluate the relative bioavailability, including the inter-subject variability, of a conventional immediate-release (IR) formulation and two prototype bioenhanced formulations of danirixin during gastric acid suppression in a healthy, elderly population. A single-centre, crossover study in healthy male and female volunteers aged 65–80 years was conducted. Subjects were randomised to receive danirixin 50 mg IR in the fed and fasted states and danirixin 50 mg Bioenhanced Formulation 1 and 2 in the fasted state. All subjects also received omeprazole 20 mg each morning beginning 4 days prior to the first treatment period and continuing through danirixin dosing in the final treatment period. Twenty subjects were randomised and completed the study. Bioenhanced Formulation 2 in the fasted state demonstrated the highest adjusted geometric means for AUC_(0–t), AUC_(0–inf), AUC_(0–24) and C_max. Danirixin IR demonstrated adjusted means that were higher in the fed state compared with the fasted state. For all formulations tested, there was substantial inter-subject variability (CVb >100 % for all formulations). The overall incidences of adverse events (AEs) were 10 % for danirixin IR (both in the fed and fasted states) and 15–20 % for the bioenhanced formulations. The majority of AEs were mild in intensity. There were no serious AEs. Concomitant use of omeprazole resulted in large inter-subject variability in the exposure to danirixin. Bioenhanced formulation strategies could not overcome the effect of omeprazole on exposure and variability between subjects.

Comparing the acid-suppressive effects of three brands of generic lansoprazole with the original: pharmacokinetic bioequivalence tests do not necessarily guarantee pharmacodynamic equivalence

Generic drugs contain the same active ingredient as an original drug and have their bioequivalence proved by pharmacokinetic tests. However, few studies have been reported on whether these bioequivalence studies infer pharmacodynamic equivalence. In this study, in eight healthy Helicobacter pylori-negative CYP2C19 extensive metabolizers, we compared the acid-suppressive effects of repeated administration of 15 mg of three brands of generic lansoprazole, Taiproton, Tapizol, and Lansoral, with those of the original lansoprazole, Takepron. Median intragastric pH value for 24-h and % pH > 4 for daytime (08:00-20:00 h) and night-time were significantly higher with any lansoprazole formulation, compared with the control (P < 0.05, Wilcoxon signed-rank test). However, during the daytime, % pH > 4 with Tapizol was significantly lower than the original (P < 0.05). Compared with the original, no significantly larger, but no small range of inter-subject variations were observed in these two parameters for each of the three brands of generic lansoprazole (Bartlett test). Pharmacokinetic bioequivalence tests do not necessarily guarantee pharmacodynamic equivalence.

Pharmacology of proton pump inhibitors

The gastric H,K-ATPase is the primary target for the treatment of acid-related diseases. Proton pump inhibitors (PPIs) are weak bases composed of two moieties, a substituted pyridine with a primary pK(a) of about 4.0, which allows selective accumulation in the secretory canaliculus of the parietal cell, and a benzimidazole with a second pK(a) of about 1.0. PPIs are acid-activated prodrugs that convert to sulfenic acids or sulfenamides that react covalently with one or more cysteines accessible from the luminal surface of the ATPase. Because of covalent binding, their inhibitory effects last much longer than their plasma half-life. However, the short half-life of the drug in the blood and the requirement for acid activation impair their efficacy in acid suppression, particularly at night. PPIs with longer half-life promise to improve acid suppression. All PPIs give excellent healing of peptic ulcers and produce good results in reflux esophagitis. PPIs combined with antibiotics eradicate Helicobacter pylori.

Relative potency of proton-pump inhibitors-comparison of effects on intragastric pH

AIM

Comparative potency of proton-pump inhibitors (PPIs) is an important clinical issue. Most available trials have compared the different PPIs at one or a few selected specific dosages, making it difficult to derive quantitative equivalence dosages. Here we derived PPI dose equivalents based on a comprehensive assessment of dose-dependent effects on intragastric pH.

METHODS

All available clinical studies reporting the effects of PPIs on mean 24-h intragastric pH were sought from electronic databases including Medline. Studies included were restricted to those targeting the Caucasian population, and healthy volunteers or gastroesophageal reflux disease (GERD) patients. The dose-effect relationships for mean 24-h intragastric pH and for percentage of time with pH > 4 in 24 h were analyzed for each PPI using pharmacodynamic modeling with NONMEM and a model integrating all available data.

RESULTS

Fifty-seven studies fulfilled the inclusion criteria. Based on the mean 24-h gastric pH, the relative potencies of the five PPIs compared to omeprazole were 0.23, 0.90, 1.00, 1.60, and 1.82 for pantoprazole, lansoprazole, omeprazole, esomeprazole, and rabeprazole, respectively. Compared with healthy volunteers, patients with GERD needed a 1.9-fold higher dose and Helicobacter pylori-positive individuals needed only about 20% of the dose to achieve a given increase in mean 24-h intragastric pH.

CONCLUSION

The present meta-analysis provides quantitative estimates on clinical potency of individual PPIs that may be helpful when switching between PPIs and for assessing the cost-effectiveness of specific PPIs. However, our estimates must be viewed with caution because only a limited dose range has been tested and not exactly the same study conditions were applied for the different substances.

A pharmacokinetic study of etravirine (TMC125) co-administered with ranitidine and omeprazole in HIV-negative volunteers

AIMS

Etravirine is a next-generation non-nucleoside reverse transcriptase inhibitor (NNRTI) with activity against wild-type and NNRTI-resistant HIV. Proton pump inhibitors and H(2)-antagonists are frequently used in the HIV-negative-infected population, and drug-drug interactions have been described with other antiretrovirals. This study evaluated the effect of steady-state omeprazole and ranitidine on the pharmacokinetics of a single dose of etravirine.

METHODS

In an open-label, randomized, one-way, three-period crossover trial, HIV-negative volunteers randomly received a single dose of 100 mg etravirine alone (treatment A); 11 days of 150 mg ranitidine b.i.d. (treatment B); and 11 days of 40 mg omeprazole q.d. (treatment C). A single dose of 100 mg etravirine was co-administered on day 8 of sessions 2 and 3. Each session was separated by a 14-day wash-out.

RESULTS

Nineteen volunteers (seven female) participated. When a single dose of etravirine was administered in the presence of steady-state ranitidine, etravirine least squares means ratios (90% confidence interval) for AUC(last) and C(max) were 0.86 (0.76, 0.97) and 0.94 (0.75, 1.17), respectively, compared with administration of etravirine alone. When administered with steady-state omeprazole, these values were 1.41 (1.22, 1.62) and 1.17 (0.96, 1.43), respectively. Co-administration of a single dose of etravirine and ranitidine or omeprazole was generally safe and well tolerated.

CONCLUSIONS

Ranitidine slightly decreased etravirine exposure, whereas omeprazole increased it by approximately 41%. The increased exposure of etravirine when co-administered with omeprazole is attributed to CYP2C19 inhibition. Considering the favourable safety profile of etravirine, these changes are not clinically relevant. Etravirine can be co-administered with proton pump inhibitors and H(2) antagonists without dose adjustments.

Safety of Proton Pump Inhibitors in Community-Dwelling Older Adults

Objective:

To describe proton pump inhibitor (PPI)–related adverse effects in community-dwelling older adults.

Data Sources:

Articles were identified via PubMed (1966–March 2008) using the terms proton pump inhibitor, adverse drug effects, safety, pneumonia, fractures, Clostridium difficile, and vitamin B12. Clinical trials, meta-analyses, and drug evaluations published in English were selected. Articles excluding patients over 65 years of age or those involving solely institutionalized patients were excluded.

Study Selection and Data Extraction:

Twelve studies were selected, 10 of which were case–control or population-based studies. Three of 4 studies investigating the association of PPI use with C. difficile infection found a positive association. Many participants in these studies had no history of antibiotic exposure prior to infection. Three studies found a significant relationship between community-acquired pneumonia and PPI therapy, with a possible dose–response relationship. Two studies found an increased risk of fracture with PPI use, with a possible dose–response relationship. Two of 3 included studies found an association between vitamin B12 deficiency and PPI therapy.

Data Synthesis:

The majority of studies found significant associations between PPI use and the development of C. difficile infection, pneumonia, fractures, and vitamin B12 deficiency, all of which are plausible based on the mechanisms of action of PPIs. With a lack of randomized controlled trials, the underlying causes of these adverse effects remain controversial.

Conclusions:

Cause and effect between PPI use and C. difficile infection, pneumonia, fractures, and vitamin B12 deficiency has not been established. Well-designed, prospective, randomized studies are required to confirm whether there are risks associated with long-term PPI use. Until the results of such studies become available, PPI use should be reviewed for appropriateness at regular intervals in individual patients, as the consequences of these complications in the elderly could be devastating.

Interactions between protease inhibitors and acid-reducing agents: a systematic review

OBJECTIVE

The purpose of this article is to provide a systematic review of the available pharmacokinetic and clinical data on drug interactions between protease inhibitors (PIs) and acid-reducing agents, and their clinical relevance.

METHODS

A literature search was performed using Medline and EMBASE, abstracts of the previous 2 years of major conferences were searched and the drug information service of the manufacturer of every currently available PI was contacted. All data were summarized, and verified by at least two authors.

RESULTS

A total of 1231 references were identified, 22 of which were studies of pharmacokinetic interactions between PIs and acid-suppressive agents and a further 12 of which provided pharmacokinetic and/or clinical data.

CONCLUSIONS

Many pharmacokinetic studies show a lack of a drug interaction between at least one acid-reducing agent and most PIs. Little clinical information is available, except on interactions between atazanavir and acid-reducing agents. This is probably a consequence of the complexity of the interaction.

Use of acid-suppressing drugs and the risk of bacterial gastroenteritis

BACKGROUND & AIMS

Gastric acid is a defense mechanism against gastrointestinal infections caused by ingested bacteria. Studies have suggested that the use of acid-suppressing drugs may increase the risk of gastroenteritis (GE).

METHODS

Patients aged 20-74 years with an episode of acute bacterial GE (n = 6414) were identified. A control group from the same study population without a diagnosis of GE (n = 50,000) was frequency-matched by age, sex, and calendar year to the case group. Unconditional logistic regression was used to calculate the adjusted relative risk (RR) of GE in patients using proton pump inhibitors (PPIs) or histamine-2 receptor antagonists (H2RAs).

RESULTS

Current use of PPIs was associated with an increased risk of bacterial GE compared with nonuse, regardless of the treatment duration (RR, 2.9; 95% confidence interval [CI], 2.5-3.5), whereas no association was observed with H2RA use (RR, 1.1; 95% CI, 0.9-1.4). Doubling the PPI dose further increased the risk of developing bacterial GE (RR, 5.0; 95% CI, 2.7-9.3). The effect of PPI use did not vary significantly with regard to treatment indication. The increased risk associated with PPI use was similar for both omeprazole (RR, 3.0; 95% CI, 2.5-3.7) and lansoprazole (RR, 2.1; 95% CI, 1.4-3.0), whereas neither cimetidine nor ranitidine showed any increased risk. Campylobacter (n = 4124) and Salmonella (n = 1885) were the 2 species most frequently responsible for GE episodes in the case group. When analyzed separately, both species reproduced the increased risk associated with PPI use and not H2RA use. Clostridium GE cases were rare (n = 31).

CONCLUSIONS

This study suggests that gastric acid suppression induced by PPIs but not H2RAs is associated with an increased risk of Campylobacter and Salmonella GE.

Drug interactions between proton pump inhibitors and antiretroviral drugs

Gastroesophageal reflux disease and other related symptoms are common comorbidities for HIV-infected patients. Therefore, concurrent use of proton pump inhibitors and antiretrovirals is a common practice in the clinical setting. However, this practice may alter antiretroviral pharmacokinetics and lead to treatment failure due to inadequate drug exposure. Clinician awareness of these complex interactions is essential for optimal HIV management. This review summarizes the current knowledge on the interactions between proton pump inhibitors and antiretrovirals, and makes recommendations for the coadministration of proton pump inhibitors.

Relationship between intragastric acid control and healing status in the treatment of moderate to severe erosive oesophagitis

AIM

To assess the relationship between the percentage of time intragastric pH >4.0 and healing of erosive oesophagitis.

METHODS

In this proof-of-concept study, adults with endoscopically verified Los Angeles grade C or grade D erosive oesophagitis were randomly assigned to oral esomeprazole 10 or 40 mg once daily for 4 weeks. On day 5, patients underwent 24-h pH monitoring. At 4 weeks, erosive oesophagitis healing status was endoscopically assessed. Investigators scored gastro-oesophageal reflux disease symptoms on a 4-point scale [none to severe (0-3)] before and 4 weeks after treatment. The percentage of time intragastric pH was >4.0 and healing status were correlated and tested for significance using a Spearman rank correlation (r).

RESULTS

103 patients had evaluable data (mean age, 48.7 years; 65% men). Mean percentages of time with intragastric pH >4.0 on day 5 in patients with healed and unhealed erosive oesophagitis were 61% and 42%, respectively (P = 0.0002), indicating that erosive oesophagitis healing rates were positively related to the percentage of time intragastric pH was >4.0. Greater intragastric acid control correlated with lower final daytime and night-time heartburn and acid regurgitation symptom scores (r = -0.029, -0.029 and -0.021; P = 0.003, 0.003 and 0.032, respectively).

CONCLUSION

A positive relationship between intragastric acid control and erosive oesophagitis healing was demonstrated.

Comparison of the effects of single and repeated oral doses of lansoprazole and rabeprazole on ambulatory 24-hour intragastric pH in healthy volunteers

BACKGROUND

As the comparative pharmacokinetics and pharmacodynamics of lansoprazole and rabeprazole have not previously been studied, we set out in this study to compare the pharmacokinetics and pharmacodynamics of single and repeated daily doses of lansoprazole 15 mg and 30 mg with those of rabeprazole 10 mg and 20 mg.

METHODS

This was an open-label, randomised, crossover, two-centre study in 72 healthy volunteers. Each subject received each of the four treatments for 5 days, with 2-week washout periods. Continuous 24-hour intragastric pH and pharmacokinetics were studied on days 1 and 5.

RESULTS

Mean 24-hour pH and percentage time for pH > 4 were not significantly different between lansoprazole 30 mg and rabeprazole 20 mg. Mean 24-hour pH and percentage time for pH > 4 were significantly greater after lansoprazole 30 mg and rabeprazole 20 mg than after lansoprazole 15 mg and rabeprazole 10 mg, respectively. Lansoprazole resulted in greater acid suppression during hours 0-5 on days 1 and 5, whereas rabeprazole had greater suppression during hours 11-24 on day 5. Time to maximum plasma concentration was significantly shorter for lansoprazole on both days.

CONCLUSION

Lansoprazole had a consistently faster onset of action, whereas rabeprazole had a greater effect during the evening hours after 5 days of administration.

Coadministration of esomeprazole with fosamprenavir has no impact on steady-state plasma amprenavir pharmacokinetics

OBJECTIVES

To evaluate the drug interaction between fosamprenavir (FPV) and esomeprazole (ESO) after repeated doses in healthy adults.

METHODS

Subjects received ESO 20 mg once daily (qd) for 7 days followed by either ESO 20 mg qd + FPV 1400 mg twice daily (bid) or ESO 20 mg qd + FPV 700 mg bid + ritonavir (RTV) 100 mg bid for 14 days in arms 1 and 2, respectively. After a 21- to 28-day washout, subjects received either FPV 1400 mg bid for 14 days (arm 1) or FPV 700 mg bid + RTV 100 mg bid for 14 days (arm 2). Pharmacokinetic sampling was conducted on the last day of each treatment.

RESULTS

Simultaneous coadministration of ESO 20 mg qd with either FPV 1400 mg bid or FPV 700 mg bid + RTV 100 mg bid had no effect on steady-state amprenavir pharmacokinetics. The only effect on plasma ESO exposure was a 55% increase in area under the plasma concentration-time curve during a dosing interval, tau[AUC0-tau], after coadministration of ESO 20 mg qd with FPV 1400 mg bid.

CONCLUSIONS

FPV 1400 mg bid or FPV 700 mg bid + RTV 100 mg bid may be coadministered simultaneously with ESO without dose adjustment. However, the impact of staggered administration of proton pump inhibitors (PPI) on plasma amprenavir exposure is unknown at present.

The impact of reflux composition on mucosal injury and esophageal function

The components of refluxed gastric juice are known to cause mucosal injury, but their effect on esophageal function is less appreciated. Our aim was to determine the effect of acid and/or bile on mucosal injury and esophageal function. From 1993-2004, 402 patients with reflux symptoms had 24-hour pH and Bilitec monitoring, manometry, and endoscopy with biopsies. Mucosal injury (esophagitis or Barrett's esophagus) and esophageal function (lower esophageal sphincter [LES] characteristics and body contractility) in patients with acid reflux, bile reflux, or both were compared with patients without reflux. Reflux was present in 273/402 patients; of these, 37 (13.5%) had increased exposure to bile, 82 (30.0%) had increased exposure to acid, and 154 (56.4%) had increased exposure to both. Mucosal injury was most common with increased mixed acid and bile exposure, followed by acid alone, and was uncommon with bile alone (P < 0.0001). Functional deterioration paralleled mucosal injury (P < 0.0001). Mixed acid and bile exposure was present in more than half of patients with reflux and was associated with the most severe mucosal injury and the greatest deterioration of esophageal function. This suggests that composition of gastric juice is the primary determinant of inflammatory mucosal injury and subsequent loss of esophageal function.

Fosamprenavir

Fosamprenavir is one of the most recently approved HIV-1 protease inhibitors (PIs) and offers reductions in pill number and pill size, and omits the need for food and fluid requirements associated with the earlier-approved HIV-1 PIs. Three fosamprenavir dosage regimens are approved by the US FDA for the treatment of HIV-1 PI-naive patients, including fosamprenavir 1,400 mg twice daily, fosamprenavir 1,400 mg once daily plus ritonavir 200mg once daily, and fosamprenavir 700 mg twice daily plus ritonavir 100mg twice daily. Coadministration of fosamprenavir with ritonavir significantly increases plasma amprenavir exposure. The fosamprenavir 700 mg twice daily plus ritonavir 100mg twice daily regimen maintains the highest plasma amprenavir concentrations throughout the dosing interval; this is the only approved regimen for the treatment of HIV-1 PI-experienced patients and is the only regimen approved in the European Union. Fosamprenavir is the phosphate ester prodrug of the HIV-1 PI amprenavir, and is rapidly and extensively converted to amprenavir after oral administration. Plasma amprenavir concentrations are quantifiable within 15 minutes of dosing and peak at 1.5-2 hours after fosamprenavir dosing. Food does not affect the absorption of amprenavir following administration of the fosamprenavir tablet formulation; therefore, fosamprenavir tablets may be administered without regard to food intake. Amprenavir has a large volume of distribution, is 90% bound to plasma proteins and is a substrate of P-glycoprotein. With <1% of a dose excreted in urine, the renal route is not an important elimination pathway, while the principal route of amprenavir elimination is hepatic metabolism by cytochrome P450 (CYP) 3A4. Amprenavir is also an inhibitor and inducer of CYP3A4. Furthermore, fosamprenavir is commonly administered in combination with low-dose ritonavir, which is also extensively metabolised by CYP3A4, and is a more potent CYP3A4 inhibitor than amprenavir. This potent CYP3A4 inhibition contraindicates the coadministration of certain CYP3A4 substrates and requires others to be co-administered with caution. However, fosamprenavir can be co-administered with many other antiretroviral agents, including drugs of the nucleoside/nucleotide reverse transcriptase inhibitor, non-nucleoside reverse transcriptase inhibitor and HIV entry inhibitor classes. Coadministration with other HIV-1 PIs continues to be studied.The extensive fosamprenavir and amprenavir clinical drug interaction information provides guidance on how to co-administer fosamprenavir and fosamprenavir plus ritonavir with many other commonly co-prescribed medications, such as gastric acid suppressants, HMG-CoA reductase inhibitors, antibacterials and antifungal agents.

What is potent acid inhibition, and how can it be achieved?

The clinical response to antisecretory treatment correlates directly with the degree of inhibition of acid secretion achieved. Acid inhibition able to maintain the intragastric pH at a value greater than 4 for at least 16 h/day seems to heal even the most refractory acid-related diseases. It has also been shown that the degree of inhibition of acid secretion in response to antisecretory treatment depends on the genetic characteristics of the patient and on the presence of Helicobacter pylori infection. A possible definition of potent (or profound) acid inhibition is, therefore, the achievement of the aforementioned level of control of acid secretion regardless of patient characteristics or of the presence of H. pylori infection. Antisecretory drugs differ in their ability to reach potent acid inhibition. As far as the comparative efficacy of different drugs for inhibiting acid secretion is concerned, proton pump inhibitors are more efficient in inhibiting gastric acid secretion than histamine (H2) receptor antagonists. Among the different proton pump inhibitors, esomeprazole 40 mg/day exhibits greater antisecretory potency than the others at standard doses. Rabeprazole 20 mg/day and lansoprazole 30 mg/day exhibit a more rapid onset of action than omeprazole 20 mg/day or pantoprazole 40 mg/day.

Head-to-head comparison of H2-receptor antagonists and proton pump inhibitors in the treatment of erosive esophagitis: a meta-analysis

AIM

To systematically evaluate the efficacy of H(2)-receptor antagonists (H(2)RAs) and proton pump inhibitors in healing erosive esophagitis (EE).

METHODS

A meta-analysis was performed. A literature search was conducted in PubMed, Medline, Embase, and Cochrane databases to include randomized controlled head-to-head comparative trials evaluating the efficacy of H(2)RAs or proton pump inhibitors in healing EE. Relative risk (RR) and 95% confidence interval (CI) were calculated under a random-effects model.

RESULTS

RRs of cumulative healing rates for each comparison at 8 wk were: high dose vs standard dose H(2)RAs, 1.17 (95%CI, 1.02-1.33); standard dose proton pump inhibitors vs standard dose H(2)RAs, 1.59 (95%CI, 1.44-1.75); standard dose other proton pump inhibitors vs standard dose omeprazole, 1.06 (95%CI, 0.98-1.06). Proton pump inhibitors produced consistently greater healing rates than H(2)RAs of all doses across all grades of esophagitis, including patients refractory to H(2)RAs. Healing rates achieved with standard dose omeprazole were similar to those with other proton pump inhibitors in all grades of esophagitis.

CONCLUSION

H(2)RAs are less effective for treating patients with erosive esophagitis, especially in those with severe forms of esophagitis. Standard dose proton pump inhibitors are significantly more effective than H(2)RAs in healing esophagitis of all grades. Proton pump inhibitors given at the recommended dose are equally effective for healing esophagitis.

Helicobacter pylori infection influences symptomatic response to anti-secretory therapy in patients with GORD--crossover comparative study with famotidine and low-dose lansoprazole

BACKGROUND AND AIM

Helicobacter pylori infection was reported to affect gastric acid secretion. We investigated the heartburn symptoms of patients with gastro-oesophageal reflux disease during sequential treatment with 40 mg of famotidine or 15 mg of lansoprazole to clarify whether H. pylori infection influences symptomatic response to anti-secretory therapy.

SUBJECTS AND METHODS

The subjects were 33 gastro-oesophageal reflux disease patients, who had already been treated with a full dose of H2 receptor antagonist. First, famotidine at 20 mg b.i.d. was administered to the patients for 8 weeks. Second, famotidine was replaced with 15 mg of lansoprazole once in the morning for 8 weeks. Finally, 20 mg of famotidine was administered b.i.d. for 8 weeks instead of lansoprazole. Gastro-oesophageal reflux disease symptoms were assessed using an original visual analogue scale.

RESULTS

The sequential symptomatic responses to famotidine and lansoprazole administration indicated that gastro-oesophageal reflux disease symptoms of patients during low-dose lansoprazole treatment were significantly less than those during famotidine treatment. Remission of symptoms was obtained significantly more often by famotidine therapy in patients with H. pylori infection than in patients without H. pylori infection.

CONCLUSION

Low-dose lansoprazole is more effective than full-dose famotidine for the control of symptoms in patients with gastro-oesophageal reflux disease, and H. pylori infection influences the symptomatic response to H2 receptor antagonists.

Efficacy and safety of lansoprazole in adolescents with symptomatic erosive and non-erosive gastroesophageal reflux disease

OBJECTIVES

To assess the efficacy and safety of lansoprazole in the treatment of adolescents with symptomatic, endoscopically proven, non-erosive gastroesophageal reflux disease and erosive esophagitis.

METHODS

Adolescents between 12 and 17 years of age with esophagitis were enrolled in this open-label trial and treated with lansoprazole 15 mg (non-erosive) or 30 mg (erosive) once daily for 8 weeks. If unhealed at week 8, those with erosive esophagitis were treated with an additional 4 weeks of lansoprazole 30 mg once daily.

RESULTS

Lansoprazole produced a significant reduction from baseline in the median percentage of days with reflux symptoms (91 to 43% in the 64 adolescents with non-erosive disease and 85 to 16% in the 23 adolescents with erosive esophagitis, P < or = 0.001 for each comparison). At week 8, mucosal healing had occurred in 95% (21 of 22) of those with erosive esophagitis. Treatment-related adverse events were reported by 19% of patients with non-erosive and 4% of patients with erosive esophagitis. Headache (7%), abdominal pain (5%), nausea (3%) and dizziness (3%) were the most frequently reported adverse events. One patient discontinued treatment early because of dizziness and vomiting. An elevation in mean serum gastrin from baseline (59 pg/mL at pretreatment to 80 pg/mL at final visit) was observed.

CONCLUSION

Lansoprazole 15 mg or 30 mg once daily reduced symptoms of gastroesophageal reflux in adolescents with non-erosive gastroesophageal reflux disease and erosive esophagitis, respectively. Lansoprazole 30 mg once daily for 8 weeks was effective in healing erosive esophagitis. Both treatment regimens were considered safe.

Cost-minimization analysis of treatment of gastroesophageal reflux disease. Implications of varying holding time on conclusions

Gastroesophageal reflux disease (GERD), is a common disorder. The most effective medical treatment for GERD is a proton pump inhibitor (PPI). The aim of this study was to specify the most inexpensive PPI therapy for GERD, and to examine the implications of varying outcome measure, holding time, on the conclusions about the cost-effectiveness of the treatments. Proton pump inhibitors that have holding time of intragastric pH>4 for at least 11h in 24h period (esomeprazole, lansoprazole, omeprazole and rabeprazole), were included. In this cost-minimization analysis (CMA), data on holding times were gathered from scientific publications listed in MEDLINE, prices of proton pump inhibitors from the Finnish database of drug prices and the treatment dosages were taken from the official guide of drug therapies in Finland. A decision tree was applied and the probabilities utilized were acquired from three expert physicians. The cost-minimization analysis was performed in three settings. At first, drugs that had a holding time (pH>4) of 11h or more were included. Secondly, drugs that had a holding time of 12h or more were included, and thirdly, a holding time of 13h or more was required. In the first analysis, the least expensive PPI treatment was lansoprazole (average cost of 138.89 per patient). In the second analysis, least expensive treatment was rabeprazole (193.81 per patient), and in the third, rabeprazole again (193.81 per patient). Esomeprazole and omeprazole were not among two of the least expensive alternatives in any of the settings. Which proton pump therapy turns out to be the least expensive for GERD, depends on the length of the holding time desired. Varying the holding time of the drug had a profound effect on the conclusions about the cost-effectiveness of the alternative treatments.

Evaluation of the pharmacokinetics and pharmacodynamics of intravenous lansoprazole

AIM

To compare the pharmacokinetics and pharmacodynamics of lansoprazole 30 mg administered intravenously in 0.9% NaCl or in polyethylene glycol, or orally.

METHODS

Twenty-nine subjects received lansoprazole orally on days 1-7 and intravenous lansoprazole in NaCl on days 8-14. Blood samples were collected on days 1, 7, 8 and 14. Fasting basal acid output and pentagastrin-stimulated maximal acid output were determined on days -1, 8, 9 and 15. Thirty-six different subjects received one of four regimen sequences: intravenous lansoprazole in NaCl, intravenous in polyethylene glycol, per orally, or intravenous placebo, each for 5 days. Twenty-four hour intragastric pH was recorded on days 1 and 5.

RESULTS

Intravenous and per oral lansoprazole for 7 days produced equivalent basal acid output and maximal acid output suppression. Pharmacokinetics and mean pH values with intravenous lansoprazole in NaCl or polyethylene glycol were equivalent. Both produced mean pH and percentages of time pH above 3, 4, 5 and 6 that were significantly greater than did per orally.

CONCLUSIONS

Intravenous lansoprazole inhibits acid secretion as effectively in NaCl as in polyethylene glycol, and its onset of action is faster than per oral lansoprazole.

Double-blind, randomized controlled study to assess the effects of lansoprazole 30 mg and lansoprazole 15 mg on 24-h oesophageal and intragastric pH in Chinese subjects with gastro-oesophageal reflux disease

BACKGROUND

Previous studies have suggested that the acid secretory capacity of the Chinese population is lower than that of the Western population.

AIM

To compare the effect of lansoprazole 30 mg and 15 mg once daily on the 24-h oesophageal and intragastric pH profiles in Chinese patients with gastro-oesophageal reflux disease.

METHODS

Forty-four patients (male to female ratio, 27 : 17; mean age, 53 years; 55% with oesophagitis) with gastro-oesophageal reflux disease were randomized to receive lansoprazole 30 mg or 15 mg once daily for 4 weeks. Measurement of the 24-h oesophageal and intragastric pH, gastro-oesophageal reflux disease symptoms and quality of life was performed at baseline and during the last week of each dosing period.

RESULTS

Lansoprazole 30 mg maintained an intragastric pH > 4 for 10.5 h vs. 9.6 h for lansoprazole 15 mg (P = 0.44). The percentage total time at oesophageal pH < 4 was similar for lansoprazole 30 mg and 15 mg (2.0% vs. 2.3%, P = 0.30). The proportion of patients with complete cure of heartburn and acid regurgitation and the quality of life assessment were similar for lansoprazole 30 mg and 15 mg. Both dosages of lansoprazole were well tolerated and the compliance was 100% in both groups.

CONCLUSION

Lansoprazole dosages of 30 mg and 15 mg once daily provide a satisfactory decrease for oesophageal acid exposure and are equally effective for the treatment of gastro-oesophageal reflux disease in the Chinese population.

Esomeprazole 20mg Provides More Effective Intragastric Acid Control than Maintenance-Dose Rabeprazole, Lansoprazole or Pantoprazole in Healthy Volunteers

OBJECTIVE

A high proportion of patients with gastro-oesophageal reflux disease experience recurrence of symptoms within a year of initial treatment. The key to preventing relapse is an effective maintenance therapy that maintains intragastric pH >4. This study was conducted to compare the effects on intragastric pH of maintenance doses of four proton pump inhibitors: esomeprazole 20mg, lanso-prazole 15mg, rabeprazole 10mg and pantoprazole 20mg.

STUDY PARTICIPANTS AND METHODS

Three standardised, randomised, two-way crossover studies were performed in a total of 108 Helicobacter pylori-negative healthy subjects. Intragastric pH was monitored on day 5 of once-daily oral dosing. The percentage of time of a 24-hour period with intragastric pH >4 and 24-hour median pH were measured on day 5.

RESULTS

The mean percentage of time with intragastric pH >4 on day 5 was significantly longer following esomeprazole 20mg compared with either lansoprazole 15mg (esomeprazole 50.4% vs lansoprazole 43.0%, p = 0.026), rabeprazole 10mg (esomeprazole 59.8% vs rabeprazole 51.7%, p = 0.011) or pantoprazole 20mg (esomeprazole 59.6% vs pantoprazole 39.5%, p < 0.0001).

CONCLUSIONS

Maintenance dose esomeprazole 20mg provided greater acid control and maintained intragastric pH >4 for a longer period of time than maintenance dose lansoprazole 15mg, rabeprazole 10mg and pantoprazole 20mg in healthy subjects.

Lansoprazole: in the management of gastroesophageal reflux disease in children

Lansoprazole, a proton pump inhibitor, inactivates the H(+)/K(+)-ATPase pump in parietal cells, thereby suppressing basal and stimulated gastric acid secretion and increasing intragastric pH. After 8-12 weeks' treatment with lansoprazole, all children (n = 27) with esophagitis at baseline were healed (confirmed by endoscopy) and 76% of 62 evaluable children experienced improvements in overall gastroesophageal reflux disease (GERD) symptoms. In this noncomparative trial, 66 children (aged 1-11 years) with GERD with or without esophagitis received oral lansoprazole 15 or 30 mg once daily dependent on their weight. The drug is generally well tolerated in children with GERD. In the largest study, the most common treatment-related adverse events occurring during therapy were constipation and headache.

Gastroesophageal reflux in children: pathogenesis, prevalence, diagnosis, and role of proton pump inhibitors in treatment

A substantial percentage of infants, children and adolescents experience gastroesophageal reflux disease (GERD) and its accompanying symptoms, as well as disease complications. The diagnosis of GERD in children is made based upon the child's history, and data derived primarily from pH monitoring tests and endoscopy. In those children with confirmed reflux disease, the options for management parallel those recommended in adult patients, with the first step consisting of lifestyle changes. Surgical procedures may also be performed; however, these are rarely recommended prior to an adequate course of pharmacologic therapy, and appropriate case selection is important. Among the current pharmacotherapeutic options available in the US, the prokinetic agents and the acid-inhibitory agents (histamine-2 receptor antagonists, proton pump inhibitors) are the most widely used. The clinical utility of the prokinetic agents has been limited by the recent withdrawal of cisapride from the US marketplace and the potential for irreversible central nervous system complications with metoclopramide. Numerous clinical studies performed in adults, and several studies involving children, have demonstrated that the proton pump inhibitors are more effective than the histamine-2 receptor antagonists in the relief of GERD symptoms and healing of erosive esophagitis. In children, omeprazole and lansoprazole may be administered as the intact oral capsule, or in those who are unable or unwilling to swallow, the granule contents of the capsule may be mixed with soft foods (e.g. apple sauce) or fruit drinks/liquid dietary supplements prior to oral administration with no detrimental effects on pharmacokinetics, bioavailability, or pharmacodynamics. Studies performed with omeprazole and lansoprazole in children have shown pharmacokinetic parameters that closely resemble those observed in adults. In over a decade of use in adults, the proton pump inhibitor class of agents has been found to have a good safety profile. Studies involving children have also shown these agents to be well tolerated. In numerous drug-drug interaction studies performed with these two proton pump inhibitors, relatively few clinically significant interactions have been observed.

Comparative pharmacokinetics and safety of lansoprazole oral capsules and orally disintegrating tablets in healthy subjects

BACKGROUND

Many individuals with acid-related gastrointestinal disorders have difficulty in swallowing oral agents.

AIM

To compare the bio-availability of a single dose of lansoprazole orally disintegrating tablet with that of an intact capsule.

METHODS

One hundred and twenty healthy subjects participated in two prospective, Phase I, open-label, two-period cross-over studies to receive lansoprazole, 15 mg or 30 mg. Within each study, subjects were randomized into two parallel cohorts consisting of 30 subjects per regimen, dispensed in opposing sequence over two periods separated by a 7-day washout period. Blood samples were collected on day 1 of both periods to determine the pharmacokinetic parameters.

RESULTS

Tmax occurred at 1.8 and 2.0 h with the 15-mg and 30-mg tablets, respectively. Dose proportional increases in Cmax, AUCt and AUC infinity were observed in the 15-mg and 30-mg groups. The terminal elimination half-lives (t1/2) were identical in both dose groups (1.18 h). Lansoprazole administered as the orally disintegrating tablet was bio-equivalent to the intact capsule formulation with respect to Cmax, AUCt and AUC infinity.

CONCLUSIONS

Lansoprazole orally disintegrating tablets, 15 mg and 30 mg, are bio-equivalent to the respective dose administered as the intact capsule. This novel dosage formulation represents an option for patients who have difficulty in swallowing oral agents.

Lansoprazole: an update of its place in the management of acid-related disorders

Lansoprazole is an inhibitor of gastric acid secretion and also exhibits antibacterial activity against Helicobacter pylori in vitro. Current therapy for peptic ulcer disease focuses on the eradication of H. pylori infection with maintenance therapy indicated in those patients who are not cured of H. pylori and those with ulcers resistant to healing. Lansoprazole 30 mg combined with amoxicillin 1g, clarithromycin 250 or 500mg, or metronidazole 400 mg twice daily was associated with eradication rates ranging from 71 to 94%, and ulcer healing rates were generally >80% in well designed studies. In addition, it was as effective as omeprazole- or rabeprazole-based regimens which included these antimicrobial agents. Maintenance therapy with lansoprazole 30 mg/day was significantly more effective than either placebo or ranitidine in preventing ulcer relapse. Importantly, preliminary data suggest that lansoprazole-based eradication therapy is effective in children and the elderly. In the short-term treatment of patients with gastro-oesophageal reflux disease (GORD), lansoprazole 15, 30 or 60 mg/day was significantly more effective than placebo, ranitidine 300 mg/day or cisapride 40 mg/day and similar in efficacy to pantoprazole 40 mg/day in terms of healing of oesophagitis. Lansoprazole 30 mg/day, omeprazole 20 mg/day and pantoprazole 40 mg/day all provided similar symptom relief in these patients. In patients with healed oesophagitis. 12-month maintenance therapy with lansoprazole 15 or 30 mg/day prevented recurrence and was similar to or more effective than omeprazole 10 or 20 mg/day. Available data in patients with NSAID-related disorders or acid-related dyspepsia suggest that lansoprazole is effective in these patients in terms of the prevention of NSAID-related gastrointestinal complications, ulcer healing and symptom relief. Meta-analytic data and postmarketing surveillance in >30,000 patients indicate that lansoprazole is well tolerated both as monotherapy and in combination with antimicrobial agents. After lansoprazole monotherapy commonly reported adverse events included dose-dependent diarrhoea, nausea/vomiting, headache and abdominal pain. After short-term treatment in patients with peptic ulcer, GORD, dyspepsia and gastritis the incidence of adverse events associated with lansoprazole was generally < or = 5%. Similar adverse events were seen in long-term trials, although the incidence was generally higher (< or = 10%). When lansoprazole was administered in combination with amoxicillin, clarithromycin or metronidazole adverse events included diarrhoea, headache and taste disturbance. In conclusion, lansoprazole-based triple therapy is an effective treatment option for the eradication of H. pylori infection in patients with peptic ulcer disease. Preliminary data suggest it may have an important role in the management of this infection in children and the elderly. In the short-term management of GORD, lansoprazole monotherapy offers a more effective alternative to histamine H2-receptor antagonists and initial data indicate that it is an effective short-term treatment option in children and adolescents. In adults lansoprazole maintenance therapy is also an established treatment option for the long-term management of this chronic disease. Lansoprazole has a role in the treatment and prevention of NSAID-related ulcers and the treatment of acid-related dyspepsia; however, further studies are needed to confirm its place in these indications. Lansoprazole has emerged as a useful and well tolerated treatment option in the management of acid-related disorders.

Acid suppression in healthy subjects following lansoprazole or pantoprazole

AIM

To compare the effect of lansoprazole, 30 mg once daily, with that of pantoprazole, 40 mg once daily, for the inhibition of gastric acid secretion.

METHODS

Two randomized, single-blind, two-way, crossover studies were conducted in 74 healthy male volunteers. Lansoprazole, 30 mg, or pantoprazole, 40 mg, was administered once daily for five consecutive days with at least a 2-week washout period between regimens. Ambulatory 24-h intragastric pH was recorded at baseline and on days 1 and 5 of each crossover treatment period.

RESULTS

On day 1 in both studies, lansoprazole, 30 mg, produced significantly higher mean 24-h intragastric pH values when compared to pantoprazole, 40 mg (3.78 vs. 3.08, P < 0.001, and 3.97 vs. 3.20, P < 0.001, in the first and second studies, respectively). In both studies, lansoprazole, 30 mg, produced significantly greater proportions of time that the intragastric pH was above 3, 4 and 5 when compared with pantoprazole, 40 mg (P < 0.005 in all comparisons). By treatment day 5 in the first study, lansoprazole, 30 mg, continued to produce a higher mean 24-h intragastric pH (4.15 vs. 3.91, P=0.014) and a significantly greater percentage of time that the intragastric pH was above 4 (63% vs. 56%, P=0.017) and 5 (41% vs. 30%, P < 0.001) when compared with pantoprazole, 40 mg. In the second study, the effects on intragastric pH were comparable between the two treatment groups. Headache was the most commonly reported adverse experience (nine lansoprazole-treated subjects, seven in the first study and two in the second study; six pantoprazole-treated subjects, five in the first study and one in the second study).

CONCLUSIONS

Lansoprazole, 30 mg once daily, produces a faster onset and greater degree of acid inhibition than pantoprazole, 40 mg once daily. The implications for these differences on symptom relief and healing of erosive oesophagitis should be explored.

A comparison of simplified lansoprazole suspension administered nasogastrically and pantoprazole administered intravenously: effects on 24-h intragastric pH

AIM

To compare the 24-h intragastric pH effects of simplified lansoprazole suspension, 30 mg, administered nasogastrically, with pantoprazole, 40 mg, administered intravenously.

METHODS

Thirty-six healthy adults were enrolled and given simplified lansoprazole suspension, 30 mg (nasogastrically), or pantoprazole, 40 mg (intravenously), once daily for five consecutive days in a cross-over fashion. Intragastric pH was monitored at baseline and on Days 1 and 5 of each treatment period. The pharmacokinetic parameters of lansoprazole and pantoprazole were also determined on Days 1 and 5.

RESULTS

No statistically significant changes in pharmacokinetic parameters occurred between Days 1 and 5 with either regimen, except for pantoprazole Cmax. On Days 1 and 5, significantly higher mean 24-h intragastric pH values were observed with 30 mg simplified lansoprazole suspension compared with 40 mg intravenous pantoprazole (Day 1, 3.13 vs. 2.67; Day 5, 3.95 vs. 3.61, respectively; P < 0.05). Additionally, 30 mg simplified lansoprazole suspension produced significantly (P < 0.05) higher percentages of time intragastric pH was above 3, 4, 5 or 6 as compared with 40 mg intravenous pantoprazole throughout Days 1 and 5.

CONCLUSIONS

A 30 mg dose of simplified lansoprazole suspension administered nasogastrically was consistently more effective at controlling intragastric pH than pantoprazole, 40 mg, administered intravenously.

Review article: role of proton pump inhibitors in non-H. pylori-related ulcers

The proportion of ulcers that are not associated with Helicobacter pylori infection is increasing, especially in the United States and Australia. The alarming increase in this type of ulcer warrants an analysis of the diagnostic and treatment approaches to H. pylori-negative ulcers, which was the aim of this study. The medical literature was reviewed to gather information about the prevalence, aetiology, and treatment of H. pylori-negative ulcers. The reports indicated that up to 52% of duodenal ulcers and 47% of gastric ulcers are not caused by H. pylori infection. The cause of H. pylori-negative ulceration appears to be multifactorial. Contributing factors include covert non-steroidal anti-inflammatory drug use, false-negative H. pylori tests, genetic predisposition, and in rare cases, Crohn's disease or Zollinger-Ellison syndrome. H. pylori-negative ulcers tend to be associated with hypersecretion and can have serious clinical sequelae. H. pylori-negative ulcers are often refractory to treatment, possibly because they lack the beneficial effect of H. pylori infection on antisecretory therapy. Proton pump inhibitors (PPIs) appear to effectively treat both H. pylori-positive and H. pylori-negative ulcers. We conclude that H. pylori-negative ulcers are becoming more prevalent in the United States and Australia. These ulcers may have an aggressive clinical course and can be refractory to treatment. PPI therapy is indicated for treating and preventing H. pylori-negative peptic ulcers.

Effects on 24-hour intragastric pH: a comparison of lansoprazole administered nasogastrically in apple juice and pantoprazole administered intravenously

OBJECTIVE

To compare the 24-h intragastric pH effects of lansoprazole, 30 mg administered nasogastrically, with pantoprazole, 40 mg administered i.v.

METHODS

Healthy adults were enrolled in an open label, two-way crossover, single-center study. Thirty milligrams of lansoprazole (administered nasogastrically in apple juice) or pantoprazole (i.v.) were administered once daily at 8:00 AM for 5 consecutive days with at least a 2-wk washout period between the regimens. Ambulatory 24-h intragastric pH was monitored at baseline and on days 1 and 5 of each treatment period. Blood specimens were collected on days I and 5 for pharmacokinetic parameter determinations.

RESULTS

Thirty-three adults completed both crossover periods, with the exception of one patient with a zero lansoprazole plasma concentration on day 1 of period 2. Lansoprazole, 30 mg per nasogastric tube, produced significantly higher mean 24-h intragastric pH values relative to pantoprazole, 40 mg i.v., on both day 1 (3.05 vs 2.76, p < 0.002) and day 5 (3.65 vs 3.45, p = 0.024). Lansoprazole sustained the intragastric pH above 3 (days 1 and 5), 4, and 5 (day 1) significantly longer relative to pantoprazole. Lansoprazole's time to the maximum observed concentration and area under the plasma concentration-time curve over the 24-h time interval increased significantly from day I to day 5 (1.7 h vs 2.0 h and 1865 ng x h/ml vs 2091 ng x h/ml, respectively), and a significant increase in half-life relative to day 1 (0.96 h) was observed on day 5 (1.03 h) during pantoprazole treatment.

CONCLUSION

Lansoprazole, 30 mg administered nasogastrically, effectively controls intragastric pH and is an alternative to i.v. pantoprazole in patients who are unable to swallow solid dosage formulations.

Omeprazole 40 mg once a day is equally effective as lansoprazole 30 mg twice a day in symptom control of patients with gastro-oesophageal reflux disease (GERD) who are resistant to conventional-dose lansoprazole therapy-a prospective, randomized, multi-centre study

BACKGROUND

Comparative studies of omeprazole and lansoprazole are scarce and even scarcer are comparisons of higher doses. Most of the comparative studies have assessed the effect of the two proton pump inhibitors (PPIs) on gastric acid secretion or gastric pH. Few studies have compared clinical end-points such as oesophageal healing and symptom control.

AIM

To determine the clinical efficacy of omeprazole 40 mg daily as compared to lansoprazole 30 mg twice a day in symptom control of patients with severe symptomatic GERD.

METHODS

Ninety-six patients who failed a standard dose of lansoprazole (30 mg once daily), were enrolled in a prospective fashion from three VA medical centres and were randomized to receive 6 weeks of either omeprazole 40 mg daily or lansoprazole 30 mg twice daily. Patients reported daily on symptom severity and frequency, antacid consumption and side-effects.

RESULTS

Forty-six patients received omeprazole and 44 lansoprazole. Although not statistically significant, there was a consistent trend of better symptom control in the omeprazole group for daytime and night-time heartburn and acid regurgitation. There was no statistical difference between the two groups in mean antacid consumption overall and at the end of each of the 6 weeks of the study. In addition, there was no significant difference in the overall frequency of side-effects between the two groups nor for each individual side-effect.

CONCLUSION

Omeprazole 40 mg once daily is equally effective and tolerated as lansoprazole 30 mg twice daily in symptom control of patients with GERD.

Review article: comparison of the pharmacokinetics, acid suppression and efficacy of proton pump inhibitors

Proton pump inhibitors have dramatically influenced the management of acid-peptic disorders in recent years. They all have a broadly similar mechanism of action and are extensively metabolized in the liver via cytochromes P450 2C19 and 3A4. There is some variation in their potential for drug interactions due to differences in enzyme inhibition. Relatively few serious adverse effects have been reported for the proton pump inhibitors. Comparative studies of acid suppression suggest that lansoprazole and pantoprazole have a potency similar to that of omeprazole on a mg for mg basis; however, rabeprazole may have a greater potency than omeprazole. Lansoprazole and rabeprazole display a more rapid onset of maximal acid suppression than the other proton pump inhibitors. Comparative studies using proton pump inhibitors for the treatment of reflux oesophagitis, duodenal ulcer healing and Helicobacter pylori eradication show little overall difference in outcome between the proton pump inhibitors when used in their standard doses. Lansoprazole and rabeprazole provide earlier and better symptom relief than the other proton pump inhibitors in some studies of peptic ulcer treatment. The few studies of gastric ulcer treatment suggest that there is an advantage in using the proton pump inhibitors that have a higher standard daily dose.

Esomeprazole provides improved acid control vs. omeprazole In patients with symptoms of gastro-oesophageal reflux disease

BACKGROUND

Esomeprazole (Nexium) is a new proton pump inhibitor for the treatment of acid-related diseases.

METHODS

In this double-blind crossover study, 38 patients with gastro-oesophageal reflux disease (GERD) symptoms were randomized to esomeprazole 40 and 20 mg and omeprazole 20 mg once daily for 5 days. On day 5 of each dosing period, 24-h intragastric pH and pharmacokinetic variables were measured.

RESULTS

Thirty-six patients aged 29-58 (mean 45) years completed the study. Esomeprazole 40 and 20 mg maintained intragastric pH > 4 for (mean) 16.8 and 12.7 h, respectively, vs. 10.5 h for omeprazole 20 mg (P < 0.001 and P < 0. 01). Twenty-four-hour median intragastric pH was significantly higher with esomeprazole 40 mg (4.9) and 20 mg (4.1) than with omeprazole 20 mg (3.6) (P < 0.001 and P < 0.01). Area under the plasma concentration-time curve (AUC) was 80% higher for esomeprazole 20 mg vs. omeprazole, while that for esomeprazole 40 mg was more than five times higher (each P < 0.0001). Interpatient variability in intragastric pH and AUC was less with esomeprazole than with omeprazole. Esomeprazole was well tolerated and there were no safety concerns.

CONCLUSIONS

Esomeprazole provides more effective acid control than omeprazole, with reduced interpatient variability, thereby offering the potential for improved efficacy in acid-related diseases.

Clinical and fiscal impact of lansoprazole intolerance in veterans with gastro-oesophageal reflux disease

BACKGROUND

Omeprazole was replaced by lansoprazole as the only proton pump inhibitor on the Veterans Affairs (VA) formulary in February 1997. We aimed to assess the clinical and fiscal impact of this conversion at two VA hospitals.

METHODS

We identified lansoprazole intolerant patients using pharmacy databases. We reviewed medical records to obtain data regarding reasons for lansoprazole intolerance. The costs of the formulary change and the savings to the VA were calculated.

RESULTS

A total of 3833 patients required long-term proton pump inhibitor therapy; 2224 (58%) were started on lansoprazole and 1479 (39%) were converted from omeprazole to lansoprazole. The remaining 130 (3.4%) patients were never converted from omeprazole to lansoprazole. Of the 3833 patients, 325 (8.5%) currently receive omeprazole therapy; of these, 195 out of 3703 (5.3%) patients are true lansoprazole failures; 172 of these 195 patients completed the study. Most (87%) of the lansoprazole intolerant patients received prior omeprazole. Discontinuation of lansoprazole was due to poor symptom control in 69% and/or side-effects (22%) including diarrhoea (10%), abdominal pain (5%), or hives (1%). The 1-year cost of managing lansoprazole failure in 195 patients was $61 690. However, the savings to the VA during the same time period, which totalled $321 360, more than offset the costs associated with the conversion.

CONCLUSIONS

Lansoprazole intolerance requiring omeprazole conversion occurred in 5% of veterans on proton pump inhibitor therapy for chronic gastro-oesophageal reflux disease (GERD) symptoms and in 10% of patients with prior omeprazole success. The VA realized substantial cost savings in association with the formulary change.

Twenty-four-hour intragastric pH: tolerance within 5 days of continuous ranitidine administration

OBJECTIVE

To investigate further the phenomenon of pharmacological tolerance to H2-receptor antagonists, we undertook a study of the antisecretory effect of ranitidine with continuous daily administration.

METHODS

A total of 28 healthy male volunteers were given ranitidine 150 mg q.i.d. for 5 days. Twenty-four-hour intragastric pH monitoring was performed predosing and on days 1 and 5 of ranitidine administration. Serial blood samples were collected on days 1 and 5 of ranitidine administration for pharmacokinetics.

RESULTS

Mean 24-h intragastric pH was 2.62 predosing, 4.22 on day 1 of ranitidine administration and 3.28 on day 5 (p = 0.001, ranitidine day 1 vs. day 5). Intragastric pH was >3, 4, and 5 for 69.9%, 54.3%, and 35.9%, respectively, on day 1 of ranitidine administration and was 45.8%, 30.1%, and 20.8% on day 5 (p<0.005 for each comparison). Subjects' Helicobacter pylori status did not affect the antisecretory effect of ranitidine. There was no alteration in ranitidine pharmacokinetics to account for its reduced antisecretory effect.

CONCLUSION

This study has demonstrated a statistically significant reduction in the antisecretory effect of ranitidine within 5 days of continuous administration which is not explained by altered ranitidine pharmacokinetics. This is further evidence for the development of a form of pharmacological tolerance to an H2-receptor antagonist within a few days of continuous daily dosing.