Lansoprazole. A review of its pharmacodynamic and pharmacokinetic properties and its therapeutic efficacy in acid-related disorders

A novel 'peak parking' strategy for ultra-performance liquid chromatography/tandem mass spectrometric detection for enhanced performance of bioanalytical assays

Sensitive and high-throughput bioanalytical assays are of vital importance to drug discovery and development. Ultra-performance liquid chromatography (UPLC), utilizing sub-2-microm particles, greatly increases the separation throughput and efficiency, resulting in LC peaks as narrow as or less than 1 s (full width at half maxima, FWHM). This, however, could pose practical challenges for bioanalytical applications using quadrupole mass spectrometry (MS) to acquire sufficient data points to ensure accurate and reliable quantitation. Here, we present a novel 'peak parking' strategy to reduce the flow rate during UPLC peak elution, therefore extending the useful MS acquisition window. The high-throughput advantage of UPLC is maintained since no significant increase of the overall UPLC run time is needed. This strategy was demonstrated in an assay development for lansoprazole, a gastric proton-pump inhibitor, in human plasma employing liquid-liquid extraction. The method was validated from 50.0 to 50,000 pg/mL.

Safety of lansoprazole

The care with which patients are monitored during clinical trials provides an excellent database to assess the tolerability and safety of drugs. Additional information can be obtained from knowledge of the compound itself, its metabolism and its pharmacological action. Other compounds from the same class can highlight areas that need particular study. All these factors have been used to assess the safety of lansoprazole. Lansoprazole has been administered to 4749 subjects and has been well tolerated. Only 1.2% of patients have been withdrawn from trials because of suspected drug-related events but there was no pattern and no relationship to drug dosage. Diarrhoea (3.2%) and headache (4.7%) were the most commonly reported adverse events.

Acute treatment of duodenal ulcer: experience with lansoprazole

Clinical experience with lansoprazole in the acute treatment of duodenal ulcer patients has been compared with treatment using placebo, H2-antagonists or omeprazole. Among the various lansoprazole dosage regimens that have been tested, 30 mg daily for 4 weeks appears to be the optimal regimen to relieve pain rapidly and to heal ulceration in up to 90-95% of patients. Lansoprazole tolerability in the short term appears excellent, most adverse effects are trivial and not dose related. Duodenal ulcer relapse after ulcer healing with lansoprazole appears to occur at a rate similar to that observed after treatment with omeprazole or histamine H2-antagonists.

Future prospects for proton pump inhibitors

Future prospects for proton pump inhibitors depend on their efficacy and safety relative to H2-receptor antagonists, the therapeutic standard for acid peptic disorders. As safety concerns diminish, efficacy considerations become more important as these may pertain to cost effectiveness. Comparative, controlled trials show that omeprazole and lansoprazole are somewhat more effective than H2-blockers in healing duodenal and gastric ulcers, providing faster relief of symptoms. Relapse after cessation of therapy is similar between the two classes. The proton pump inhibitors are substantially more effective in healing lesions and relieving symptoms in patients with reflux oesophagitis, and are particularly effective in cases that have failed to heal after 12 weeks of treatment with H2-blockers. Relapse rates of oesophagitis are significantly less with prolonged treatment with omeprazole than ranitidine. A proton pump inhibitor combined with amoxicillin is less effective than triple therapy with antibiotics and bismuth in eradicating Helicobacter pylori infections, but is more convenient and associated with fewer side-effects. Efficacy might be improved by more optimal dosing regimens. Prospects for reversible proton pump inhibitors depend on the balance between their theoretical advantages and their acid inhibition profile which, at present, closely resembles that of H2-blockers.

Adéquation aux recommandations des prescriptions des inhibiteurs de la pompe à protons dans un service de médecine interne

INTRODUCTION

Proton pump inhibitors (PPIs) are an efficient therapy, being widely used by physicians. In 2004, cost of PPIs' therapy was as high as 748 millions of euros (for The Caisse primaire d'Assurance Maladie) in France. Although validated indications of PPIs are well known, numerous un-necessary prescriptions of PPIs are common. The aim of this prospective study was to evaluate PPIs' prescriptions of patients in a department of internal medicine.

PATIENTS AND METHODS

This is a 12-week assessment of medical charts of patients, receiving PPI therapy in patients in our department of internal medicine. Data were collected by a standardized questionnaire, with regards to: PPIs' nature and regimen, PPIs' indications as well as duration of therapy.

RESULTS

The medical charts of 729 consecutive patients, with a mean age of 67 years, were collected. Two hundred (and) twenty-four patients (30.7%) received PPI therapy; 157 of these patients were given PPI before admission in our department. Omeprazole was used in 71% of patients. Duration of PPI therapy was over one year in 45% of cases. Thirty-five per cent of family physicians' PPI prescription were validated and 23.8% of those of physicians working in the department of internal medicine. The main non-conform PPI's indications, by family physicians and internists were as follows: prevention of hemorrhagic risk of anti-platelet agent (21 vs 16.4%), anticoagulant (17.8 vs 16.4%), steroids (8.3 vs 13.4%) or non-steroid anti-inflammatory therapy without risk factor (1.9 vs 9%). Finally, in patients receiving PPI therapy before admission, this therapy was maintained in 76% of cases.

CONCLUSION

This prospective study confirms the frequent prescription of PPI therapy in a department of internal medicine (31% of patients). It also underscores the importance of PPIs' use by family physicians and physicians working in a department of internal medicine; this series further highlights the difficulties to interrupt this well tolerated therapy. To date, PPI therapy should be prescribed with a cautious consideration of cost and benefit.

Hydroxyl radical scavenging reactivity of proton pump inhibitors

In addition to the established control of acid secretion of the class of proton pump inhibitors (PPI) reactivity from the pyridyl methyl sulphinyl benzimidazole type a second independent anti-inflammatory reactivity was observed in vitro. This inhibitory reactivity was clearly noticed using three different assays where the aggressive hydroxyl radicals were successfully trapped in a concentration dependent manner. There is unequivocal evidence that the proton pump inhibitors having the sulphoxide group are able to scavenge hydroxyl radicals which are generated during a Fenton reaction. By way of contrast, the corresponding thioethers were substantially less active. No detectable effect was seen in the superoxide radical scavenging system. In conclusion, pantoprazole as well as the other proton pump inhibitors have a pronounced inhibitory reactivity towards hydroxyl radicals.

Pharmacokinetics of proton pump inhibitors in children

The use of proton pump inhibitors (PPIs) has become widespread in children and infants for the management of paediatric acid-related disease. Pharmacokinetic profiles of only omeprazole and lansoprazole have been well characterised in children over 2 years of age with acid-related diseases. Few data have been recently published regarding the pharmacokinetics of pantoprazole in children, and none are available for rabeprazole or esomeprazole. The metabolism of PPI enantiomers has never been studied in the paediatric population. A one-compartment model best describes the pharmacokinetic behaviour of omeprazole, lansoprazole and pantoprazole in children, with important interindividual variability for each pharmacokinetic parameter. Like adults, PPIs are rapidly absorbed in children following oral administration; the mean time to reach maximum plasma concentration varies from 1 to 3 hours. Since these agents are acid labile, their oral formulations consist of capsules containing enteric-coated granules. No liquid formulation is available for any of the PPIs. Thus, for those patients unable to swallow capsules, extemporaneous liquid preparations for omeprazole and lansoprazole have been reported; however, neither the absolute nor the relative bioavailabilities of these oral formulations have been studied in children. Intravenous formulations are available for omeprazole (in Europe), lansoprazole and pantoprazole. PPIs are rapidly metabolised in children, with short elimination half-lives of around 1 hour, similar to that reported for adults. All PPIs are extensively metabolised by the liver, primarily by cytochrome P450 (CYP) isoforms CYP2C19 and CYP3A4, to inactive metabolites, with little unchanged drug excreted in the urine. Similar to that seen in adults, the absolute bioavailability of omeprazole increases with repeated dosing in children; this phenomenon is thought to be due to a combination of decreased first-pass elimination and reduced systemic clearance. The apparent clearance (CL/F) of omeprazole, lansoprazole and pantoprazole appears to be faster for children than for adults. A higher metabolic capacity in children as well as differences in the extent of PPI bioavailability are most likely responsible for this finding. This may partly account for the need in children for variable and sometimes considerably greater doses of PPIs, on a per kilogram basis, than for adults to achieve similar plasma concentrations. Furthermore, no studies have been able to demonstrate a statistically significant correlation between age and pharmacokinetic parameters among children. Despite the small number of very young infants studied, there is some evidence for reduced PPI metabolism in newborns. The limited paediatric data regarding the impact of CYP2C19 genetic polymorphism on PPI metabolism are similar to those reported for adults, with poor metabolisers having 6- to 10-fold higher area under the concentration-time curve values compared with extensive metabolisers. Finally, because a pharmacokinetic/pharmacodynamic relationship exists for PPIs, the significant interindividual variability in their disposition may partly explain the wide range of therapeutic doses used in children. Further studies are needed to better define the pharmacokinetics of PPIs in children <2 years of age.

Determination of lansoprazole and two of its metabolites by liquid–liquid extraction and automated column-switching high-performance liquid chromatography: application to measuring CYP2C19 activity

A simple and sensitive column-switching high-performance liquid chromatographic (HPLC) method for the simultaneous determination of lansoprazole, a proton pump inhibitor and its major metabolites: 5-hydroxylansoprazole and lansoprazole sulfone in human plasma. The test compounds were extracted from 1 mL of plasma using diethyl ether-dichloromethane (7:3, v/v) mixture and the extract was injected into a column I (TSK-PW precolumn, 10 microm, 3.5 mm x 4.6 mm i.d.) for clean-up and column I (C(18) STR ODS-II analytical column, 5 microm, 150 mm x 4.6 mm i.d.) for separation. The peak was detected by a ultraviolet detector set at a wavelength of 285 nm, and the total time for a chromatographic separation was approximately 25 min. The method was validated for the concentration range from 3 to 5000 ng/mL. Mean recoveries were 74.0% for lansoprazole, 68.3% for 5-hydroxylansoprazole, and 79.4% for lansoprazole sulfone. Intra- and inter-day relative standard derivatives were less than 6.1 and 5.1% for lansoprazole, 5.8 and 5.8% for 5-hydroxylansoprazole, 4.4 and 5.9% for lansoprazole sulfone, respectively, at the different concentration ranges. This method is suitable for use in therapeutic drug monitoring and pharmacokinetic studies, and provides use tool for measuring CYP2C19 activity.

A Pharmacological Approach to Gastric Acid Inhibition

Proton pump inhibitors have changed our approach to gastric acid-related diseases. They are much more potent acid inhibitors than H2-antagonists and exhibit a sophisticated mechanism of action. The present review analyses the general pharmacology of proton pump inhibitors and differentiates the specific characteristics of the various compounds that belong to this family. Special emphasis has been placed in describing the clinical implications of such differences and the potential importance for adverse effects.

Stereoselective metabolism of lansoprazole by human liver cytochrome P450 enzymes

The stereoselective metabolism of lansoprazole enantiomers was evaluated by incubation of human liver microsomes and cDNA-expressed cytochrome p450 (p450) enzymes to understand and predict their stereoselective disposition in humans in vivo. The intrinsic clearances (Clint) of the formation of both hydroxy and sulfone metabolites from S-lansoprazole were 4.9- and 2.4-fold higher than those from the R-form, respectively. The sums of formation Clint of both metabolites were 13.5 and 57.3 microl/min/mg protein for R- and S-lansoprazole, respectively, suggesting that S-lansoprazole would be cleared more rapidly than the R-form. The p450 isoform selective inhibition study in liver microsomes, and the incubation study of cDNA-expressed enzymes, demonstrated that the stereoselective sulfoxidation is mediated by CYP3A4 and that the hydroxylation is mediated by CYP2C9 and CYP3A4 as well as by CYP2C19. Total Clint values of hydroxy and sulfone metabolite formation catalyzed by all these p450 enzymes were consistently higher for S-lansoprazole than for the R-form. The CYP3A4 produced the greatest difference of Clint between S- and R-enantiomers, mainly due to a difference of sulfoxidation metabolism (Clint 76.5 versus 10.8 microl/min/nmol of p450, respectively), whereas CYP2C19-catalyzed hydroxylation resulted in a minor difference of Clint between S- and R-enantiomers (179.6 versus 143.3 microl/min/nmol of p450, respectively). However, the affinity of CYP2C19 on hydroxylation was 5.7-fold higher for S-enantiomer than for the R-form (Km 2.3 versus 13.1 microM), suggesting that the role of CYP2C19 on stereoselective hydroxylation would be more prominent at concentrations around the usual therapeutic level. These findings suggest that both CYP2C19 and CYP3A4 are major enzymes contributing to the stereoselective disposition of lansoprazole, but stereoselective hydroxylation of lansoprazole enantiomers is mainly influenced by CYP2C19, especially at the usual therapeutic doses.

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.

Lansoprazole quantification in human plasma by liquid chromatography-electrospray tandem mass spectrometry

An analytical method based on liquid chromatography with positive ion electrospray ionization (ESI) coupled to tandem mass spectrometry detection was developed for the determination of lansoprazole in human plasma using omeprazole as the internal standard. The analyte and internal standard were extracted from the plasma samples by liquid-liquid extraction using diethyl-ether-dichloromethane (70:30; v/v) and chromatographed on a C(18) analytical column. The mobile phase consisted of acetonitrile-water (90:10; v/v)+10 mM formic acid. The method has a chromatographic total run time of 5 min and was linear within the range 2.5-2000 ng/ml. Detection was carried out on a Micromass triple quadrupole tandem mass spectrometer by Multiple Reaction Monitoring (MRM). The intra- and inter-run precision, calculated from quality control (QC) samples, was less than 3.4%. The accuracy as determined from QC samples was less than 9%. The method herein described was employed in a bioequivalence study of two capsule formulations of lansoprazole.

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.

Lansoprazole in children: pharmacokinetics and efficacy in reflux oesophagitis

BACKGROUND

Data on the proton pump inhibitor lansoprazole in paediatric patients are limited.

AIM

To investigate the pharmacokinetics, optimal dosage and efficacy of lansoprazole in paediatric patients.

METHODS

A 24-h gastric pH recording and a pharmacokinetic study were performed after 7 days of lansoprazole, 17 mg/m2, in 23 patients with reflux oesophagitis (median age, 3.5 years). Response was defined as pH > 3 for > 65% of the recording. The dosage was doubled in non-responders. Patients with no response on day 14 were excluded. Responders underwent endoscopy after 4 weeks on the response-inducing dosage; abnormal findings led to a repeat endoscopy after four additional weeks.

RESULTS

Nine patients responded to 17 mg/m2 and six to 30.3 mg/m2. On day 7, time with pH > 3 was significantly correlated with the area under the plasma concentration-time curve (P=0.003). The area under the plasma concentration-time curve was significantly greater in the nine responders to 17 mg/m2 than in the 14 other patients. Pharmacokinetic parameters were similar in responders and non-responders to the higher dose. After 4 weeks, oesophagitis was healed in 80% of responders. Adverse events occurred in three patients and required treatment discontinuation in one.

CONCLUSIONS

Lansoprazole is effective and safe in children. The optimal starting dosage is 30 mg/m2 or 1.4 mg/kg.

High-performance liquid chromatographic assay for the simultaneous determination of lansoprazole enantiomers and metabolites in human liver microsomes

In this study, a simple, sensitive and enantioselective HPLC method was developed for the simultaneous determination of lansoprazole enantiomers: a proton pump inhibitor, and its major metabolites: 5-hydroxylansoprazole and lansoprazole sulfone in human liver microsomes. After extraction from the microsomal incubation mixture with a diethyl etherdichloromethane (7:3, v/v) mixture, analytes were measured by reversed-phase HPLC on a Chiralcel OD-R column. Detection was made using an ultraviolet absorbance detector set at a wavelength of 285 nm. The mobile phase consisted of a methanol-water (75:25, v/v) mixture. At a flow-rate of 0.5 ml/min, the total run time was 35 min. The limit of quantification for both lansoprazole enantiomers was 0.25 microM and for the metabolites 0.13 microM. The method is suitable for the analysis of lansoprazole enantiomers and its metabolites from human microsomal liver incubations.

Preformulation investigation of the novel proton pump inhibitor lansoprazole

Some technologically important physicochemical properties of lansoprazole were investigated. This compound is very unstable, especially in aqueous solutions with low pH. It has one acidic and two basic dissociation constants. Lansoprazole has relatively high solubility in solutions with high pH and is well partitioned from aqueous to n-octanol phase. Under conditions examined in this study, lansoprazole was not hydroscopic and did not decompose at higher relative humidities.

Differential stereoselective pharmacokinetics of pantoprazole, a proton pump inhibitor in extensive and poor metabolizers of pantoprazole--a preliminary study

Pantoprazole (PAN) is a proton pump inhibitor that is administered as a racemic mixture. The pharmacokinetics of PAN enantiomers were investigated in extensive metabolizers (EMs) and apparent poor metabolizers (PMs) of PAN who received a single, 40, 60, or 80 mg oral dose of racemic PAN as enteric-coated formulation. In the EMs, the serum concentrations of (-)-PAN were slightly higher than those of (+)-PAN at each dose level. The (+)/(-) ratios for the area under the concentration-time curve (AUC) and the half-life were 0.58-0.89 and 0.62-0.88, respectively. In the PMs, the serum concentrations and both enantiomers were much higher than those in the EMs at each dose level and significant differences in pharmacokinetics of (+)- and (-)-PAN were observed. The half-lives for (+)-PAN were 2.67-3.77 times longer than those for (-)-PAN. The AUCs for (+)-PAN were 2.65-3.45 times greater than those for (-)-PAN. Therefore, the metabolism of (+)-PAN is impaired to a greater extent than (-)-PAN in the PMs, which resulted in the stereoselective disposition of PAN in the PMs. It has been suggested that the EMs and the PMs of PAN could be differentiated by determining the (+)/(-) enantiomer ratio in serum at one time point, possibly 2-6 h after oral dosing, because the (+)/(-) enantiomer ratios in the PMs were opposite those in the EM subjects.

Stereoselective chiral inversion of pantoprazole enantiomers after separate doses to rats

(+/-)-Pantoprazole ((+/-)-PAN), (+/-)-5-(difluoromethoxy)-2-[[3.4-dimethoxy-2-pyridinyl)methyl]sul finyl]- 1H-benzimidazole) is a chiral sulfoxide that is used clinically as a racemic mixture. The disposition kinetics of (+)-PAN and (-)-PAN given separately has been studied in rats. Serum levels of (+)- and (-)-PAN and its metabolites, pantoprazole sulfone (PAN-SO2), pantoprazole sulfide (PAN-S), 4'-O-demethyl pantoprazole sulfone (DMPAN-SO2), and 4'-O-demethyl pantoprazole sulfide (DMPAN-S) were measured by HPLC. Following single intravenous or oral administration, both enantiomers were rapidly absorbed and metabolized, resulting in similar serum concentrations, suggesting that the two enantiomers have approximately the same disposition kinetics. The major metabolite of both (+)- and (-)-PAN was PAN-SO2, while DMPAN-SO2 was also detected as a minor metabolite. Serum levels of PAN-S and DMPAN-S could not be quantified after intravenous or oral administration of either enantiomer. Significant chiral inversion occurred after intravenous and oral administration of (+)-PAN. The AUCs of (-)-PAN after intravenous and oral dosing of (+)-PAN were 36.3 and 28.1%, respectively of those of total [(+) + (-)] PAN. In contrast, the serum levels of (+)-PAN were below quantitation limits after intravenous or oral administration of (-)-PAN. Therefore, chiral inversion was observed only after administration of (+)-PAN, supporting the hypothesis that stereoselective inversion from (+)-PAN to (-)-PAN occurs in rats.

Pharmacologic strategies for treating gastroesophageal reflux disease

OBJECTIVE

This paper presents a synopsis of the pathophysiology of gastroesophageal reflux disease (GERD) and the efficacy, safety, and cost of the agents commonly used in its treatment.

BACKGROUND

Symptomatic relief of GERD can be obtained with lifestyle changes (avoidance of factors that may exacerbate symptoms, such as overeating and use of alcohol and tobacco) and use of over-the-counter medications such as antacids or histamine-2 (H2)-receptor antagonists. When these measures are unsuccessful, treatment with prescription-strength medications is required to prevent complications, such as Barrett's esophagus or esophageal adenocarcinoma.

METHODS

Current guidelines for the management of GERD were identified through a MEDLINE search of the English-language literature from January 1995 through December 1999 and a search of the bibliographies of identified articles.

CONCLUSION

Patients who do not respond to initial therapy should be managed with prescription-strength H2-receptor antagonists. Endoscopy should be considered for patients with atypical or refractory symptoms. Patients with a confirmed diagnosis of refractory GERD, severe esophagitis, Barrett's esophagus, or peptic stricture should be treated with and maintained on a proton-pump inhibitor.

A prospective trial of lansoprazole triple therapy for pediatric Helicobacter pylori infection

BACKGROUND

Triple therapy with a proton-pump inhibitor and two antibiotics is widely used in the treatment of Helicobacter pylori infection in adults. Experience with such therapy in the pediatric population is limited. This was a prospective, nonrandomized, open-label trial to evaluate safety and efficacy of a combination of lansoprazole, clarithromycin, and amoxicillin in symptomatic children with H. pylori infection.

METHODS

Children with H. pylori gastritis diagnosed by endoscopy performed for persistent nausea, vomiting, recurrent abdominal pain, and diarrhea with consistent histology were treated with the regimen of 0.45 mg/kg per day lansoprazole divided into two doses (maximum dose, 15 mg twice daily), amoxicillin 40 mg/kg per day in two doses (maximum dose, 1.0 g twice daily), and 250 mg clarithromycin twice daily (<10 years old) or 500 mg twice daily (>10 years old) for 2 weeks. Pre- and posttreatment endoscopic biopsy specimens were graded for the severity of gastritis and H. pylori density by a blinded pathologist. A questionnaire for assessing the severity of symptoms at the time of initial and second endoscopy were completed by patient and/or parent.

RESULTS

Thirty-two children (age range, 1-25 years; mean age, 11 years; 19 females, 13 males) were treated with this regimen during an 18-month period. H. pylori organisms with varying grades of gastritis were present in tissue specimens of all patients. Only 28 children had follow-up endoscopy, which showed eradication of H. pylori in 15 (54%) children. Histologic symptoms of gastritis improved after therapy in the whole group. Overall, symptoms of vomiting, abdominal pain, diarrhea, anorexia, and halitosis significantly improved (P < 0.05). Minor adverse effects of therapy occurred in 25% of patients.

CONCLUSIONS

Symptoms, histologic, and endoscopic findings improved after triple therapy in children with H. pylori gastritis; however, eradication of bacteria was achieved in only 56% of children.

Pharmacokinetic considerations in the eradication of Helicobacter pylori

As Helicobacter pylori plays an important role in the aetiopathogenesis of peptic ulcer, therapeutic strategies aimed at maintaining long term remission have shifted from the control of intragastric pH to targeting H. pylori. According to recent international guidelines the clinical goals--rapid ulcer healing and prevention of relapse--can be best accomplished by combination therapy consisting of an antisecretory drug (proton pump inhibitor or ranitidine) and 2 antimicrobial agents (preferable amoxicillin, clarithromycin or metronidazole). When applying such multidrug regimens, possible synergy between the agents suggests that pharmacokinetic considerations might help to improve H. pylori eradication rates, which should be above 85 to 90% on an intention-to-treat basis. The present review summarises the pharmacokinetic properties and interaction potential of all drugs presently used in the various H. pylori eradication regimens, with emphasis on particular patient populations such as the elderly and those with renal impairment. The drugs considered are omeprazole, lansoprazole, pantoprazole, rabeprazole, ranitidine and ranitidine bismutrex, bismuth salts, amoxicillin, clarithromycin, azithromycin, roxithromycin, metronidazole, tinidazole and tetracycline. When addressing the clinically important questions of the efficacy, safety and costs of the recommended regimens, the impact of drug disposition on H. pylori eradication should not be neglected.

The gastric H,K-ATPase blocker lansoprazole is an inhibitor of chloride channels

1. It was postulated that swelling dependent chloride channels are involved in the proton secretion of parietal cells. Since omeprazole, lansoprazole and its acid activated sulphenamide form AG2000 are structurally related to phenol derivatives known to block swelling dependent chloride channels, we set out to test, whether these substances--which are known to block the H,K-ATPase--could also lead to an inhibition of swelling-dependent chloride channels. Swelling-dependent chloride channels--characterized in many different cell types--show highly conserved biophysical and pharmacological features, therefore we investigated the effect of omeprazole, lansoprazole and its acid activated sulphenamide form AG2000 on swelling-dependent chloride channels elicited in fibroblasts, after the reduction of the extracellular osmolarity. 2. Omeprazole, lansoprazole and its acid activated sulphenamide form AG2000 are able to block swelling-dependent chloride channels (IClswell). 3. Lansoprazole and its protonated metabolite AG2000 act on at least two different sites of the IClswell protein: on an extracellular site which seems to be in a functional proximity to the nucleotide binding site, and on an intracellular site which allows the formation of disulfide-bridges. 4. The inhibition of the proton pump and the simultaneous blocking of chloride channels by omeprazole, lansoprazole and its acid activated sulphenamide form AG2000, as described here could be an effective mode to restrict proton secretion in parietal cells.

Standard-dose lansoprazole is more effective than high-dose ranitidine in achieving endoscopic healing and symptom relief in patients with moderately severe reflux oesophagitis. The Dutch Lansoprazole Study Group

BACKGROUND

In the treatment of reflux oesophagitis, H2-receptor antagonists are still widely used in spite of the apparent higher efficacy of proton pump inhibitors. In an attempt to compensate for the lower efficacy, H2-receptor antagonists are now increasingly being used at a higher dose.

OBJECTIVE

To assess whether or not standard-dose lansoprazole (30 mg o.d.) is more effective than high-dose ranitidine (300 mg b.d.) in moderately severe reflux oesophagitis (grades II-III).

METHODS

Lansoprazole or ranitidine was given to 133 patients for 4-8 weeks in a double-blind, randomized, parallel group, multicentre trial.

RESULTS

The percentage of patients with endoscopically-verified healing was significantly higher on lansoprazole than on ranitidine both after 4 weeks (79% vs. 42%) and 8 weeks (91% vs. 66%), though smoking had a negative impact on oesophagitis healing with lansoprazole. Heartburn, retrosternal pain and belching improved significantly better with lansoprazole than with ranitidine, as did the patient-rated overall symptom severity. Relief of heartburn appeared somewhat faster with ranitidine, but was more pronounced with lansoprazole. The number of patients with adverse events was similar in both treatment groups.

CONCLUSION

Standard-dose lansoprazole is better than high-dose ranitidine in moderately severe reflux oesophagitis.

Review article: current perspectives on hypergastrinaemia and enterochromaffin-like-cell hyperplasia

Rabeprazole, a new benzimidazole proton pump inhibitor (PPI), is among a class of agents known to be very potent inhibitors of gastric acid secretion. PPIs inhibit hydrogen-potassium adenosine triphosphatase activity on the luminal surface of the parietal cell, effectively blocking the final common pathway for gastric acid secretion. Raising gastric pH stimulates the production of gastrin by G cells in the antrum of the stomach, which can lead to enterochromaffin-like (ECL)-cell hyperplasia. In the past, these changes have been viewed with concern, particularly in the light of studies in rats indicating that hypergastrinaemia and ECL-cell hyperplasia induce gastric carcinoid tumour formation. All available clinical data indicate that long-term PPI use does not lead to carcinoid tumour formation in humans. In fact, both serum gastrin elevation and ECL-cell hyperplasia are now generally viewed as normal physiological responses to gastric acid suppression. Serum gastrin concentrations, in particular, correlate well with gastric acid suppression, which has led to the use of gastrin response by some investigators as a surrogate marker of antisecretory effectiveness. Long-term tolerability data indicate that PPIs have a favourable side-effect profile. Data obtained from patients receiving acute or long-term maintenance rabeprazole therapy support this conclusion. Furthermore, neither animal nor human data obtained with rabeprazole suggest a significant risk for neoplastic changes secondary to hypergastrinaemia.

Lansoprazole versus omeprazole for duodenal ulcer healing and prevention of relapse: a randomized, multicenter, double-masked trial

The aim of this randomized, multicenter, double-masked, parallel-group study was to compare the efficacy of lansoprazole with that of omeprazole monotherapy in duodenal ulcer healing and prevention of relapse. A total of 251 patients with duodenal ulcer were treated with either lansoprazole 30 mg/d (n = 167) or omeprazole 40 mg/d (n = 84). Patients with healed ulcers were then randomly allocated to 12 months of maintenance therapy with lansoprazole 15 mg/d (n = 74), lansoprazole 30 mg/d (n = 71), or omeprazole 20 mg/d (n = 73). Healing rates at 4 weeks (intent-to-treat analysis) were 93.9% (95% confidence interval [CI], 90.2% to 97.6%) with lansoprazole and 97.5% (95% CI, 93.7% to 100%) with omeprazole; there were no significant differences between groups. Endoscopic relapse rates after 6 months were 4.5% (95% CI, 0% to 10.6%) with lansoprazole 15 mg, 0% with lansoprazole 30 mg, and 6.3% (95% CI, 1.5% to 12.5%) with omeprazole 20 mg, compared with 3.3% (95% CI, 0% to 8.2%), 0%, and 3.5% (95% CI, 0% to 8.8%), respectively, at 12 months. Again, there were no significant differences between groups. The incidence of adverse events during acute treatment was 6.0% and 7.1% in the lansoprazole and omeprazole groups, respectively; during maintenance therapy, the incidences were 12.2% (lansoprazole 15 mg), 5.6% (lansoprazole 30 mg), and 11.0% (omeprazole 20 mg). Within treatment groups, pain was significantly ameliorated after the acute phase but not after maintenance therapy (P < 0.05); no differences were observed between groups. Gastrin values increased significantly after acute therapy (P < 0.05), persisted at these increased levels during maintenance therapy, and returned to normal after 6-month follow-up. Both lansoprazole and omeprazole were highly effective and well tolerated in the treatment of duodenal ulcer; relapse rates were similar for all doses studied. Thus no additional benefit is to be gained from using a proton-pump inhibitor at a dose > 15 mg lansoprazole to prevent relapse.

Determination of Lansoprazole in pharmaceutical dosage forms by two different spectroscopic methods

Two different ultraviolet (UV) spectroscopic methods were developed for determination of Lansoprazole in pharmaceutical dosage forms. The solutions of the standard and the sample were prepared in 0.1 M NaOH and phosphate buffer pH 6.6. Both UV spectrophotometric and derivative spectroscopic techniques were applied. Second-order derivative spectra were generated between 200 and 400 nm at N = 9, deltalambda = 31.5. The linear range for the UV spectrophotometric method was 3.0-25.0 microg ml(-1) and that for the derivative spectroscopic method was 0.5-25.0 microg ml(-1). The developed methods were applied to three different pharmaceutical preparations. The percentage recovery was 100.2%.

Effect of lansoprazole on human leukocyte function

Recent findings on the capacity of omeprazole to influence various leukocyte functions, in vitro, raises the question on the potential use of protonic pump inhibitors, commonly used in the treatment of acid-secretion-related disorders, as immunomodulators. The aim of this study was to evaluate the in vitro effect of lansoprazole on human natural killer (NK) cell cytotoxix activity, chemotaxis and superoxide anion (O2*-) generation exerted by polymorphonucleated cells (PMNs). NK cytotoxicity activity was assessed by a 51Cr release assay, PMN chemotaxis was determined by an under agarose method and O2*- generation was analyzed on the basis of reduced cytochrome C. Incubation times with lansoprazole was 30 min for PMNs and 1-4.5 hours for NK cells, respectively. Lansoprazole induced significant dose dependent inhibition of NK cell activity and PMN functions at concentrations ranging from 100 to 1,000 microM. This study demonstrate that lansoprazole, like omeprazole, inhibits several leukocyte functions, in vitro, then suggesting that protonic pump inhibitors are able to provoke these effects, at least at certain doses.

Helicobacter pylori infection, chronic gastritis, and proton pump inhibitors

The proton pump inhibitors (PPIs) omeprazole, lansoprazole, and pantoprazole are widely used as antisecretory drugs and, in association with antibiotics, for the treatment of Helicobacter pylori infections. PPIs possess antibacterial activity against H. pylori in vitro, and may also exert an anti-inflammatory effect by interfering with the cellular immune response to infection. Their antimicrobial activity is selective for H. pylori. Lansoprazole is the most effective, although its bactericidal activity is similar to that of omeprazole. Pantoprazole is the least effective. The mechanisms that account for the antibacterial effects of PPIs may depend on a structural similarity of PPIs to antibiotics which are active against H. pylori, on the inhibition of bacterial urease exerted by PPIs, or on the possible interaction of PPIs with bacterial ATPases that regulate the transmembrane ion flux. Recent studies have shown that PPIs have anti-inflammatory actions and can interfere with the host-bacteria interactions. Lansoprazole can bind to polymorphonuclear leukocytes that infiltrate the gastric mucosa colonized by H. pylori and can thus inhibit the oxidative burst of activated inflammatory cells. In an in vivo study, lansoprazole reduced the degree of activity of histologic gastritis independently of the presence of H. pylori. In another study, omeprazole was capable of inhibiting the cytotoxic activity of NK T cells. Investigation of PPI interactions with H. pylori activities and the cellular immune response to the infection may help us to understand the pathogenic mechanisms of H. pylori-associated diseases and enable clinicians to better treat them.

Effect of rabeprazole (E3810), a novel proton pump inhibitor, on intragastric pH in healthy volunteers

In this study, we examined the effect of rabeprazole (E3810), a novel proton pump inhibitor, on gastric acidity under physiological conditions in healthy volunteers using 24-hour intragastric pH monitoring. Twenty-four-hour intragastric pH monitoring was performed three times to seven subjects randomly assigned in a cross over fashion to one of the following groups; without drug administration (basal), and with 10 mg or 20 mg of rabeprazole for four days. The median pH for 24 hours was 2.15 in the basal study, while the corresponding median pH were 5.05 and 5.90 after treatment with 10 mg and 20 mg of rabeprazole, respectively. Significant differences in the median pH were observed between the basal study and that after administration of the 10 mg and 20 mg doses of rabeprazole. The cumulative percentage of pH readings above the threshold pH 4 value, was 34.1% in the basal study, and 72.6% and 78.3% after treatment with 10 mg and 20 mg doses of rabeprazole, respectively. This result indicates that the efficacy of rabeprazole allows for substantial control of gastric acidity with once-daily dosing, and that both the 10 mg and 20 mg doses result in potent inhibition of gastric acid secretion.

An ascending single-dose safety and tolerance study of an oral formulation of rabeprazole (E3810)

BACKGROUND

Proton pump inhibitors such as omeprazole produce a long-lasting inhibition of gastric acid secretion associated with significant increases in plasma gastrin. Rabeprazole (E3810) is a new substituted benzimidazole H+,K+ ATPase inhibitor. It acts as an irreversible, non-competitive inhibitor of the H+,K+ ATPase and preliminary studies demonstrate that rabeprazole produces a potent and long-lasting inhibition of gastric acid secretion and a low level of hypergastrinaemia.

AIM

This randomized, double-blind, placebo-controlled study was performed to further examine the effects of different single doses of rabeprazole on gastric acid secretion and serum gastrin.

METHODS

In this study, four groups of 10 healthy, non-smoking Helicobacter pylori-negative men (mean age 22.5 +/- 3.9 years) received single oral doses of 10, 20, 30 and 40 mg of rabeprazole. Two of the 10 volunteers in each group received placebo as part of the double-blind study design. All volunteers who entered into the study had a normal gastric acid secretory capacity as evaluated by pentagastrin challenge. Prior to administration of the first dose of test drug, volunteers underwent an inpatient 24-h measurement of baseline intragastric pH. One week later, volunteers received the test drug and again underwent an inpatient 24-h measurement of intragastric pH. During both periods, plasma samples were collected at specified intervals over 48 h and were sent for analysis of rabeprazole and gastrin levels.

RESULTS

Administration of rabeprazole resulted in a dose-dependent increase in the duration and extent of intragastric pH elevation. The response among all volunteers receiving drug was significantly different from placebo, with greater acid inhibition occurring in the 30 and 40 mg groups. In addition, there was also a dose-related increase in plasma gastrin. The pharmacokinetics of rabeprazole were similar to those of other proton pump inhibitors with a t1/2 of between 0.7 and 1.0 h. There were no clinically significant effects on patient laboratory tests or serious adverse events.

CONCLUSIONS

The results of this study suggest that rabeprazole is as potent as omeprazole and lansoprazole in inhibiting gastric acid secretion.

Lansoprazole and secnidazole with clarithromycin, amoxycillin or pefloxacin in the eradication of Helicobacter pylori in a developing country

BACKGROUND

A number of triple drug regimens using proton pump inhibitors and two antibiotics have been evaluated in the West and reported to achieve Helicobacter pylori eradication rates of over 90%. In developing countries however, these combinations have neither been well evaluated, nor the optimum treatment for H. pylori infection well defined.

AIM

To compare the combination of a proton pump inhibitor with a nitroimidazole and another antibiotic in eradicating H. pylori infection and healing duodenal ulcer.

METHODS

Sixty consecutive patients with active duodenal ulcer who were positive for H. pylori (by rapid urease test and 14C-urea breath test) were randomized into three treatments groups: (1) LAS (n=21): lansoprazole 30 mg o.m., amoxycillin 500 mg q.d.s. and secnidazole 2 g on alternate days for 2 weeks; (2) LCS (n=18): lansoprazole 30 mg o.m., clarithromycin 500 mg b.d. and secnidazole 2 g on alternate days for 1 week; (3) LPS (n=21): lansoprazole 30 mg o.m., pefloxacin 400 mg o.m. and secnidazole 2 g on alternate days for 2 weeks. Urease and breath tests were performed at 0, 6 and 12 weeks to check for H. pylori eradication.

RESULTS

Intention-to-treat eradication rates were as follows: LAS 86%, LCS 83%, LPS 71%; the overall ulcer healing rate was 90% at 6 weeks.

CONCLUSIONS

High H. pylori eradication rates were achieved using the amoxycillin- and clarithromycin-based therapies. Fewer side-effects, better compliance and low cost favoured the amoxycillin-based therapy.

A placebo-controlled dose-ranging study of lansoprazole in the management of reflux esophagitis

OBJECTIVE

We compared the efficacy of three different doses of the proton pump inhibitor lansoprazole in the management of reflux esophagitis.

METHODS

Two hundred ninety-two patients with endoscopically confirmed reflux esophagitis were enrolled in a double-blind, multicenter study and were randomized to lansoprazole 15, 30, or 60 mg or placebo administered once daily for 8 wk.

RESULTS

Healing rates after 4 wk of lansoprazole 15, 30, and 60 mg/d were 67.6%, 81.3%, and 80.6%, respectively. These were all significantly superior (p < 0.001) to placebo, which produced endoscopic healing in only 32.8% of the patients after 4 wk. The 4-wk healing rates with lansoprazole 30 or 60 mg were significantly higher than that with lansoprazole 15 mg (p < 0.05), confirming a dose-response effect. Cumulative healing rates after 8 wk of treatment were 52.5% with placebo and 90.0%, 95.4%, and 94.4% with lansoprazole 15, 30, and 60 mg, respectively (p < 0.001 for all doses of lansoprazole vs placebo). Lansoprazole was also significantly superior to placebo in relieving symptoms in patients with reflux esophagitis. Lansoprazole was well tolerated, and no serious treatment-related adverse events were encountered. Up to 3 months after discontinuation of treatment, all lansoprazole-treated groups had more patients free of endoscopic evidence of esophagitis than the group treated with placebo.

CONCLUSIONS

Lansoprazole was safe and effective for the treatment of reflux esophagitis in this trial. This study indicates that the optimum daily dose of lansoprazole for reflux esophagitis is 30 mg.

Comparative pharmacokinetic/pharmacodynamic analysis of proton pump inhibitors omeprazole, lansoprazole and pantoprazole, in humans

The relationship between plasma concentrations and inhibitory effects on gastric acid secretion by proton pump inhibitors (PPIs) omeprazole (OPZ), lansoprazole (LPZ) and pantoprazole (PPZ), was analyzed using a pharmacokinetic/pharmacodynamic (PK/PD) model in humans. The estimated values of apparent reaction rate constant of PPI and H+,K+-ATPase (K) were 1.34 +/- 0.17 (microM(-1) x h(-1)), 0.339 +/- 0.002 and 0.134 +/- 0.006 for OPZ, LPZ and PPZ, respectively. The estimated values of apparent turn-over rate constant of H+,K+-ATPase (k) were 0.0252 +/- 0.0019 (h(-1)), 0.0537 +/- 0.0006 and 0.0151 +/- 0.0002 for OPZ, LPZ and PPZ, respectively. The apparent dissociation constants of the H+,K+-ATPase-PPI complex (k/K x fp) corrected with plasma free fraction (fp) were about 1 nM for OPZ and LPZ and 2.3 nM for PPZ. Therefore, the potency of the inhibitory effect of PPZ on acid secretion may be slightly weaker than that of OPZ or LPZ. The apparent half lives (ln2/k) of the inhibitory effect on acid secretion were 12.9 h for LPZ, < 27.5 h for OPZ, and < 45.9 h for PPZ, the recovery rate of the inhibitory effect of PPZ on acid secretion was slowest among these PPIs. In conclusion, the relationship between plasma concentrations and inhibitory effects of PPIs on gastric acid secretion could be analyzed by the PK/PD model.

Lansoprazole. An update of its pharmacological properties and clinical efficacy in the management of acid-related disorders

Lansoprazole is a proton pump inhibitor that reduces gastric acid secretion. It has proved effective in combination regimens for the eradication of Helicobacter pylori and as monotherapy to heal and relieve symptoms of gastric or duodenal ulcers and gastro-oesophageal reflux. After initial healing, it may be used to prevent recurrence of oesophageal erosions or peptic ulcers in patients in whom H. pylori is not the major cause of ulceration and to reduce basal acid output in patients with Zollinger-Ellison syndrome. Usual dosages are 15 to 60 mg/day, although dosages of < or = 180 mg/day have been used in patients with hypersecretory states. In patients with duodenal or gastric ulcer, short term lansoprazole monotherapy was similar to omeprazole and superior to histamine H2 receptor antagonists in achieving healing rates > 90%. Lansoprazole was as effective a component of H. pylori eradication regimens as omeprazole, tripotassium dicitrato bismuthate (colloidal bismuth subcitrate) or ranitidine. Lansoprazole was superior to ranitidine in symptom relief and healing of gastro-oesophageal reflux disease and tended to relieve symptoms more rapidly than omeprazole, although initial healing was similar. As maintenance treatment, lansoprazole was similar to omeprazole and superior to ranitidine in relieving symptoms and preventing relapse. Lansoprazole was also superior to ranitidine in healing and relieving symptoms of oesophageal erosions associated with Barrett's oesophagus; healing was maintained for a mean of 2.9 years in > or = 70% of patients. Lansoprazole was also superior to ranitidine in prophylaxis of redilatation of oesophageal strictures. After > or = 4 years of use in patients with Zollinger-Ellison syndrome, lansoprazole 60 to 180 mg/day effectively controlled basal acid output. Dosages may be reduced in some patients once healing and symptom relief has been achieved. Preliminary studies of lansoprazole in patients at risk of aspiration pneumonia or stress ulcers show promise. Although studies show lansoprazole is potentially effective in treating gastrointestinal bleeding, future studies should assess patients' H. pylori status. Lansoprazole has been well tolerated in clinical trials, with headache, diarrhoea, dizziness and nausea appearing to be the most common adverse effects. Tolerability of lansoprazole does not deteriorate with age and the drug is well tolerated in long term use (< or = 4 years) in patients with Zollinger-Ellison syndrome or reflux disease. Thus, lansoprazole is an important alternative to omeprazole and H2 receptor antagonists in acid-related disorders. In addition to its efficacy in healing or maintenance treatment, it may provide more effective symptom relief than other comparator agents.

Efficacy of lansoprazole against peptic ulcers induced by non-steroidal anti-inflammatory drugs: endoscopic evaluation of ulcer healing

Beyond the obvious step of limiting use of non-steroidal anti-inflammatory drugs (NSAIDs), the treatment of ulcers induced by NSAIDs remains controversial. We evaluated the efficacy of the proton-pump inhibitor lansoprazole on NSAID-induced ulcers. Ulcers were endoscopically diagnosed in 47 NSAID users. These patients received 30 mg/day lansoprazole, orally, for 6 or 8 weeks (6 weeks for duodenal ulcers and 8 weeks for other ulcers). Ulcer healing was assessed using an established classification system. The presence of immunoglobulin G antibody against Helicobacter pylori was also evaluated. The antibody was present in the sera of 51% of patients (24/47). Most of the ulcers reached scarring stages S1 (healing) or S2 (good healing), and the S2 healing rate was 35%. Two H. pylori seropositive patients did not reach these stages; their ulcers were improved by H. pylori eradication therapy, followed, in one case, by medication with misoprostol. Lansoprazole seemed to be useful for most patients with NSAID-induced ulcers, but a few needed additional treatments.

High-performance thin-layer chromatographic method for the detection and determination of lansoprazole in human plasma and its use in pharmacokinetic studies

A rapid and sensitive high-performance thin-layer chromatography (HPTLC) method has been developed for the measurement of lansoprazole in human plasma and its use for pharmacokinetic study has been evaluated. Detection and quantitation were performed without using an internal standard. A single stage extraction procedure was followed for extracting lansoprazole from plasma and a known amount of the extract was spotted on precoated silica gel 60 F254 plates using a Camag Linomat IV autosampler. Lansoprazole was quantified using a Camag TLC Scanner 3. The recovery study of authentic analytes added to plasma at 0.05 to 0.25 microg/ml was 95.37+/-2.15% and the lowest amount of lansoprazole that could be detected was 20 ng/ml plasma. The method provides a direct estimate of the amount of lansoprazole present in plasma. The method was used for the determination of plasma levels as well as pharmacokinetic parameters of lansoprazole after oral administration of two marketed preparations to healthy volunteers.

Metabolic disposition of lansoprazole in relation to the S-mephenytoin 4'-hydroxylation phenotype status

OBJECTIVE

To assess the possible involvement of CYP2C19 in the metabolism of lansoprazole in vivo.

METHODS

Sixteen male Korean subjects, who had been phenotyped as extensive metabolizers and poor metabolizers of S-mephenytoin 4'-hydroxylation polymorphism (n = 8 each) with racemic mephenytoin with use of the 8-hour urine analysis of 4'-hydroxymephenytoin, took an oral dose of 30 mg lansoprazole, and blood samples were collected up to 48 hours after dosing. Lansoprazole and its metabolites were measured by high-performance liquid chromatography with ultraviolet detection.

RESULTS

The mean lansoprazole area under the concentration-time curve (AUC), elimination half-life (t1/2), and apparent oral clearance (CLoral) were significantly (p < 0.001) greater, longer, and lower, respectively, in the poor metabolizer than in the extensive metabolizer group. The mean values for the AUC of hydroxylansoprazole and AUC ratio of hydroxylansoprazole to lansoprazole were significantly (p < 0.01 to p < 0.001) less in the poor metabolizer than in the extensive metabolizer group, whereas those for the AUC of lansoprazole sulfone and ratio of lansoprazole sulfone to lansoprazole were greater (p < 0.001) in the former than in the latter group. In addition, the log10 4'-hydroxymephenytoin excreted in urine correlated significantly (p < 0.01) with the CLoral of lansoprazole.

CONCLUSIONS

These results suggest that the hydroxylation of lansoprazole cosegregates with the genetically determined S-mephenytoin 4'-hydroxylation (CYP2C19) polymorphism in the Korean subjects.

Lansoprazole pharmacokinetics in subjects with various degrees of kidney function

The pharmacokinetics of lansoprazole, a new benzimidazole proton pump inhibitor, was evaluated after multiple-dose oral administration to 20 subjects with various degrees of kidney function. Multiple blood samples were obtained after doses 1 and 7 of the once-daily seven-dose regimen, and plasma concentrations of lansoprazole and five metabolites were quantitated with use of HPLC. The free fraction of lansoprazole increased as kidney function declined. A significant, although weak, relationship existed between creatinine clearance (CLCR) and area under the plasma concentration versus time curve (AUC) and terminal disposition half-life (t1/2), calculated with total concentration data. Those individuals with lower CLCR values also had lower total AUC and t1/2 values. However, there was no statistically significant relationship between CLCR and peak plasma concentration or AUC, calculated with unbound concentration data. No adjustment of lansoprazole dose is recommended on the basis of impaired kidney function.

The effects of oral doses of lansoprazole and omeprazole on gastric pH

We compared gastric pH values after therapeutic doses of lansoprazole and omeprazole in 17 healthy adult men. The pharmacokinetics of the two drugs were studied. A three-way crossover design compared the effects on gastric pH of 15 and 30 mg lansoprazole and 20 mg omeprazole--each given once daily for 5 days. Ambulatory 24-h intragastric pH levels were measured before dosing, after the first and fifth doses in each period, and 15 days after each dosing period. A positive relationship between the lansoprazole or omeprazole area under the curve (AUCs) and the 24-h mean pH values was found for each regimen. No differences in maximum concentration (Cmax) and AUC were noted from day 1 to day 5 for the two lansoprazole doses. With omeprazole, both Cmax and AUC levels were greater on day 5 than on day 1. All three regimens increased 24-h mean gastric pH, although 30 mg lansoprazole had the most significant effect. The percentage of time that gastric pH was >3, >4, and >5 was also significantly higher with 30 mg lansoprazole. All three regimens were associated with reversible elevations of serum gastrin, which more than doubled at some points. No clinically significant adverse events were documented.

Lansoprazole and amoxycillin: observations on the treatment of Helicobacter pylori infection

Symptomatic patients (n = 101) with Helicobacter pylori infection were enrolled into a double-blind, double-dummy study to assess the efficacy of lansoprazole plus amoxycillin in the treatment of H. pylori infection. Patients were randomized to either lansoprazole 30 mg once daily (days 0-28) together with placebo (matched to amoxycillin) three times a day (days 0-14) followed by either placebo or amoxycillin 500 mg three times daily (days 15-28). Biopsy specimens for culture and histology were collected on days 0 and 56 or upon symptomatic relapse. Blood for serology was collected at days 0, 56 and 168. A [14C]-urea breath test was performed on day 168. Eighty-one (80.2%) patients completed the 56 day assessment. Of patients treated with lansoprazole plus amoxycillin, 35.1% (13/37) were cured of infection as assessed at day 56 (26.5% on an intention-to-treat basis), compared with 4.8% (2/42) of the placebo group (4% on an intention-to-treat basis). Recrudescence/re-infection occurred in one patient upon re-evaluation at day 168. Analysis of prognostic factors indicated that smoking and alcohol intake had little impact on the treatment outcome. Inflammation (both acute and chronic) improved in patients treated with lansoprazole plus amoxycillin. The relatively low efficacy of the treatment may relate to a single daily dose of lansoprazole (30 mg) being prescribed, treatment with amoxycillin being commenced 2 weeks after the initiation of lansoprazole or accurate assessment of treatment efficacy (both antral and body biopsy specimens taken).

A risk-benefit assessment of drugs used in the eradication of Helicobacter pylori infection

Helicobacter pylori is the cause of chronic active gastritis and predisposes to peptic ulcer disease (PUD). Furthermore, H. pylori is linked to the pathogenesis of gastric lymphoma and gastric cancer. However, treatment of this infection has proven difficult. In the last decade, many antimicrobial compounds have been studied extensively as monotherapy as well as in combination with bismuth or acid-suppressive drugs. The individual drugs and the most important eradication regimens are discussed with special regard to their risks. In the past, highly complex multidrug regimens, fear of adverse effects and frequent eradication failures have hampered the broad acceptance of H. pylori-eradication therapies. Recently, new 1-week, low-dose combination regimens of 2 antibacterials with a proton pump inhibitor have consistently achieved eradication rates of 90% and more with an acceptably low rate of adverse effects. One week's standard triple therapy [tripotassium dicitrato bismuthate (or bismuth salicylate plus metronidazole plus tetracycline or amoxicillin) has been shown to be highly effective and tolerated better in combination with a proton pump inhibitor. This regimen is, however, more complex and has more adverse effects. Therefore, it is not recommended as first-line therapy. Equipped with these therapies physicians can now be strongly encouraged to use H. pylori eradication as the therapy of choice for patients with PUD and even extend this treatment to other H. pylori-associated disease conditions.

A comparison of lansoprazole, omeprazole, and ranitidine for reducing preoperative gastric secretion in adult patients undergoing elective surgery

Acid aspiration syndrome of induction of anesthesia is a life-threatening complication whose severity is affected by both pH and volume of the aspirated gastric juice. We compared the effects of two proton pump inhibitors (PPIs), lansoprazole and omeprazole, and an H2 blocker, ranitidine, on gastric secretion in a prospective, randomized, double-blind fashion in 200 adult patients of ASA physical status I undergoing elective surgery. The patients were divided into eight groups (n = 25 each) according to their premedication. The patients received lansoprazole-lansoprazole (Group L-L), lansoprazole-placebo (Group L-P), placebo-lansoprazole (Group P-L), omeprazole-omeprazole (Group O-O), omeprazole-placebo (Group O-P), placebo-omeprazole (Group P-O), placebo-ranitidine (Group P-R), or placebo-placebo (Group P-P), as the first and second medications. The dose of the study drug was 30 mg for lansoprazole, 150 mg for ranitidine, and 80 mg for omeprazole. The first medication was administered orally at 9:00 PM on the night before surgery and the second at 5:30 AM in the morning on the day of the surgery. Each patient fasted overnight and took the drug with 20 mL of water. After tracheal intubation, gastric fluid was aspirated via an orogastric tube and the volume and pH of the aspirate were measured. The pH of the aspirated gastric fluid was higher in Groups P-R, L-L, P-L, O-O, and O-P than in Group P-P (P < 0.05). The volume of the gastric contents was similar in Groups P-0 and P-P, and the other groups had smaller gastric volume than Group P-P (P < 0.05). Gastric fluid from patients in Group P-R was the least acidic (pH 6.1 +/- 1.2) and had the least volume (0.09 +/- 0.06 mL/kg). Group L-L was comparable with Group P-R in both pH and volume, whereas Groups P-L and O-O were similar to Group P-R only in volume. The proportion of patients at risk according to the traditional criteria (pH < 2.5 and volume 0.4 mL/kg) was significantly lower in Groups L-L (0%), P-L (4%), O-O (4%), and P-R (0%) than in Group P-P (48%) (P < 0.05). We concluded that two consecutive doses of lansoprazole or a morning dose of ranitidine seemed to be the most effective preanesthetic medication for reducing gastric acidity and volume.

A prospective study of the effectiveness of low dose omeprazole as initial therapy in Zollinger-Ellison syndrome

BACKGROUND

The proton pump inhibitors (omeprazole and lansoprazole) are the drugs of choice for the medical management of gastric acid hypersecretion in Zollinger-Ellison syndrome (ZES). These drugs are safe for long-term therapy but are acid-labile and high doses are expensive. The recommended starting dose of omeprazole is 60 mg/day. However, it has been shown in recent studies that the maintenance dose of omeprazole could be safely reduced to 20 mg once or twice a day in more than two-thirds of patients with ZES. The purpose of this study is to determine if an initial starting dose of omeprazole 20 mg/day is safe and effective in patients with ZES.

METHODS

Forty-nine consecutive patients with ZES being treated with ranitidine for at least 2 weeks were admitted to the NIH. Omeprazole 20 mg was started on day 1 of the admission and ranitidine discontinued 4 h after the first dose. Gastric acid output was measured for 1 h prior to the next omeprazole dose on day 2, then on day 3 if the value was > 10 mmol/h on the previous day. If acid-peptic symptoms developed or the gastric acid output remained > 10 mmol/h on day 3, the patient was considered to have failed omeprazole 20 mg/day initial therapy and the dose titrated daily to achieve adequate control of acid-peptic symptoms and gastric secretion.

RESULTS

In 33 of the 49 patients (68%) omeprazole 20 mg/day was successful as initial therapy. Sixteen patients (32%) failed this initial omeprazole dose (eight patients owing to persistent peptic symptoms and eight patients owing to inadequate acid control). The final daily omeprazole dose required in these patients was 40 mg in eight patients (16%), 60 mg in one patient (2%) and 80 mg in seven patients (14%). Basal acid output (BAO) was the only clinical or laboratory feature that was significantly different between the two groups in which low dose initial omeprazole therapy was or was not successful; all patients with basal acid output < 20 mmol/h had a successful outcome.

CONCLUSIONS

Because of the need to rapidly control gastric acid hypersecretion owing to the high risk of complications from peptic ulcer disease, patients with ZES should continue to be started on omeprazole 60 mg/day and the dose adjusted by acute titration methods as is currently recommended. After a maintenance dose is established, attempts should be undertaken to reduce the dose to 20 mg/ day once or twice a day. Only the minority of patients with ZES in whom basal acid output is known to be < 20 mmol/h (20% of patients) should be started on a low initial omeprazole dose.