Drug interactions with proton pump inhibitors

A Systematic Review of Gastric Acid-Reducing Agent-Mediated Drug-Drug Interactions with Orally Administered Medications

BACKGROUND AND OBJECTIVE

Several review articles have been published discussing gastric acid-related drug-drug interactions (DDIs) mediated by coadministration of antacids, histamine H₂ receptor antagonists, or proton pump inhibitors, but are not sufficiently comprehensive in capturing all documented DDIs with acid-reducing agents (ARAs) and tend to focus on gastric pH-dependent DDIs and/or basic drugs. Subsequently, several new drugs have been approved, and new information is available in the literature. The objective of this systematic review is to comprehensively identify oral medications that have clinically meaningful DDIs, including loss of efficacy or adverse effects, with gastric ARAs, and categorize these medications according to mechanism of interaction.

METHODS

An indepth search of clinical data in the PDR3D: Reed Tech Navigator™ for Drug Labels, University of Washington Drug-Drug Interaction Database, DailyMed, Drugs@FDA.gov, and UpToDate^®/Lexicomp^® Drug and Drug Interaction screening tool was conducted from 1 June to 1 August 2018. The PDR3D, University of Washington Drug-Drug Interaction Database, and DailyMed were searched with terms associated with gastric acid and ARAs. Conflicting findings were further investigated using the UpToDate^®/Lexicomp^® screening tool. Clinical relevance was assessed on whether an intervention was needed, and prescribing information and/or literature supporting the DDI.

RESULTS

Through the search strategy, 121 medications were found to clinically meaningfully interact with ARAs. For 38 medications the mechanism of interaction with ARAs was identified as gastric pH dependent, and for 83 medications the interaction was found to be not gastric pH mediated, with mechanisms involving metabolic enzymes, transporters, chelation, and urine alkalization. Additionally, 109 medications were studied and did not have a clinically meaningful interaction with ARAs.

CONCLUSION

This review may provide a resource to healthcare professionals in aiding the care of patients by increasing awareness of interactions with ARAs and may also identify and potentially aid in avoiding clinically relevant DDIs and preventing risk of treatment failure and/or adverse effects. Advances in non-clinical predictions of gastric pH-mediated DDIs may guide the need for a future clinical evaluation.

Association of Gastric Acid Suppression and Sorafenib Efficacy in Advanced Hepatocellular Carcinoma

BACKGROUND

Recent studies have revealed that coadministration of gastric acid suppressants reduces the efficacy of the tyrosine kinase inhibitors erlotinib and sunitinib in patients with non-small cell lung cancer and renal cell carcinoma, respectively. The authors have therefore assessed if the concurrent use of gastric acid suppressants and sorafenib impairs outcomes in patients with advanced hepatocellular carcinoma (HCC).

METHODS

A retrospective analysis was conducted on all patients treated with sorafenib for advanced HCC at a single tertiary referral unit in the United Kingdom, between January 2008 and January 2014. A multivariate Cox proportional hazard model was used to assess the effect of the concomitant use of gastric acid suppression and sorafenib on progression-free survival (PFS) and overall survival (OS).

RESULTS

Data were collected from 197 patients, of which 182 could be assessed for this study; 77 (42%) were on concurrent gastric acid suppression therapy. After adjusting for imbalances between the groups, a Cox regression analysis gave an adjusted hazard ratio for the concurrent acid suppression group compared with the no acid suppression group of 5.4 (95% confidence interval, 3.6-7.9) for PFS and 1.85 (95% confidence interval, 1.3-2.6) for OS.

CONCLUSIONS

This single-center experience shows that patients with advanced HCC taking sorafenib and concomitant gastric acid suppression therapy have significantly inferior PFS and OS. This is the first time that this negative interaction has been reported and further prospective validation is warranted.

Pharmacokinetic interactions between ilaprazole and clarithromycin following ilaprazole, clarithromycin and amoxicillin triple therapy

AIM

To investigate the drug interactions between ilaprazole, a new proton pump inhibitor, and clarithromycin following ilaprazole, clarithromycin and amoxicillin combination therapy.

METHODS

Twelve healthy Chinese volunteers were recruited in a randomized, open-label, 3-period crossover study. All subjects were administered ilaprazole (5 mg), clarithromycin (500 mg) or a triple therapy, including ilaprazole (5 mg), clarithromycin (500 mg) and amoxicillin (1 g), twice daily for 6 consecutive days. On the 7th day, the drugs were given once, and blood samples were collected and analyzed using a well-validated HPLC/MS/MS method.

RESULTS

Following the triple therapy, the peak concentration (C(max)) and the area under the concentration-time curve from 0 h to 12 h (AUC(0→12)) of ilaprazole were significantly decreased, as compared with the single medication group (C(max):1025.0±319.6 vs 1452.3±324.6 ng/mL; AUC(0→12): 9777.7±3789.8 vs 11363.1±3442.0 ng·h/mL). Similar changes were found for ilaprazole sulfone (C(max): 5.9±0.5 vs 9.3±1.7 ng/mL; AUC(0→12): 201.4±32.1 vs 277.1±66.2 ng·h/mL). The triple therapy significantly elevated the C(max) of clarithromycin (3161.5±702.2 vs 2541.9±476.2 ng/mL).

CONCLUSION

The H pylori eradication therapy with clarithromycin, amoxicillin and ilaprazole may cause pharmacokinetic interactions that decrease the amount of ilaprazole and its metabolites and elevate that of clarithromycin.

Safety of the long-term use of proton pump inhibitors

The proton pump inhibitors (PPIs) as a class are remarkably safe and effective for persons with peptic ulcer disorders. Serious adverse events are extremely rare for PPIs, with case reports of interstitial nephritis with omeprazole, hepatitis with omeprazole and lansoprazole, and disputed visual disturbances with pantoprazole and omeprazole. PPI use is associated with the development of fundic gland polyps (FGP); stopping PPIs is associated with regression of FGP. In the absence of Helicobacter pylori infection, the long-term use of PPIs has not been convincingly proven to cause or be associated with the progression of pre-existing chronic gastritis or gastric atrophy or intestinal metaplasia. Mild/modest hypergastrinemia is a physiological response to the reduction in gastric acid secretion due to any cause. The long-term use of PPIs has not been convincingly proven to cause enterochromaffin-like cell hyperplasia or carcinoid tumors. PPIs increase the risk of community acquired pneumonia, but not of hospital acquired (nosocomial) pneumonia. There is no data to support particular care in prescribing PPI therapy due to concerns about risk of hip fracture with the long-term use of PPIs. Long-term use of PPIs does not lead to vitamin B12 deficiencies, except possibly in the elderly, or in persons with Zollinger-Ellison Syndrome who are on high doses of PPI for prolonged periods of time. There is no convincingly proven data that PPIs increase the risk of Clostridium difficile-associated diarrhea in persons in the community. The discontinuation of PPIs may result in rebound symptoms requiring further and even continuous PPI use for suppression of symptoms. As with all medications, the key is to use PPIs only when clearly indicated, and to reassess continued use so that long-term therapy is used judiciously. Thus, in summary, the PPIs are a safe class of medications to use long-term in persons in whom there is a clear need for the maintenance of extensive acid inhibition.

Role of cytochrome P450 in drug interactions

Drug-drug interactions have become an important issue in health care. It is now realized that many drug-drug interactions can be explained by alterations in the metabolic enzymes that are present in the liver and other extra-hepatic tissues. Many of the major pharmacokinetic interactions between drugs are due to hepatic cytochrome P450 (P450 or CYP) enzymes being affected by previous administration of other drugs. After coadministration, some drugs act as potent enzyme inducers, whereas others are inhibitors. However, reports of enzyme inhibition are very much more common. Understanding these mechanisms of enzyme inhibition or induction is extremely important in order to give appropriate multiple-drug therapies. In future, it may help to identify individuals at greatest risk of drug interactions and adverse events.

A summary of Food and Drug Administration-reported adverse events and drug interactions occurring during therapy with omeprazole, lansoprazole and pantoprazole

BACKGROUND

Pantoprazole is claimed to have a lower potential for drug interaction than other proton pump inhibitors.

AIM

To estimate the frequency of adverse events and drug interactions reported to the Food and Drug Administration in patients receiving omeprazole, lansoprazole or pantoprazole.

METHODS

The study involved a search of the Food and Drug Administration's database for adverse events and drug interactions with omeprazole, lansoprazole or pantoprazole as primary or secondary suspect drug. An estimate of the amount of drug dispensed during the adverse event collection period (from US drug launch) was obtained from the International Medical Statistics health database.

RESULTS

Of the suspected drug interactions recorded, vitamin K antagonist interactions, although rare, were the most common. The frequency of vitamin K antagonist interactions was 0.09 per million packages for omeprazole and 0.11 per million packages for lansoprazole and pantoprazole. Interactions with benzodiazepines or phenytoin were even rarer, being reported in less than 10 patients on each proton pump inhibitor.

CONCLUSION

The frequency of reported drug interactions was low for omeprazole, lansoprazole and pantoprazole and vitamin K antagonist interactions were by far the most common. These potentially important drug interactions, although rare, were no less frequent on pantoprazole than on omeprazole or lansoprazole, suggesting a class effect.

Pharmacogenetics of the proton pump inhibitors: a systematic review

Cytochrome P450 (CYP) 2C19 mediates the major metabolic transformations of the proton pump inhibitors (PPIs) omeprazole, pantoprazole, lansoprazole, esomeprazole, and rabeprazole. Genetic polymorphism of CYP2C19 can lead to significant phenotypic variation in the activity of this isoenzyme and thus in the metabolism of PPIs. We systematically reviewed the pharmacogenetic studies of PPIs with respect to the effects of CYP2C19 polymorphism on the clinical outcomes of PPI therapy. We searched MEDLINE (January 1966-August 2002) and EMBASE (January 1988-August 2002) for English-language articles on the pharmacogenetics of PPIs; the search was supplemented by a bibliographic review of all relevant articles. Seventeen pertinent citations were identified, and the quality (level) of evidence for each was categorized according to the rating scale of the United States Preventive Services Task Force. We found that the relationship between CYP2C19 genetic polymorphism and clinical outcomes after PPI therapy has not yet been clearly delineated. Virtually all pharmacogenetic studies of PPIs have been performed in Japanese men; thus, the clinical relevance of CYP2C19 genetic polymorphism in non-Asian patients and women is unknown. Differences among dual- and triple-therapy drug regimens make it difficult to compare H. pylori eradication studies and assess their applicability to current practice patterns. Drug adherence, a pivotal factor in the success of eradication therapy, was addressed in only four trials. Future directions for research include performing more studies with larger sample sizes, particularly in non-Asian populations and women; measuring plasma PPI concentrations to directly correlate H. pylori infection and ulcer cure rates with plasma drug availability; expanding the study population to patients with gastroesophageal reflux disease; and exploring the influence of CYP3A4 in the success or failure of PPI therapy. Although CYP2C19 genotyping is currently only a research instrument, it may be a valuable clinical tool in select patients to ensure optimal PPI therapy.

Pharmacology for the gastrointestinal tract

A variety of drugs are used in the neonatal nursery for the management of feeding intolerance, gastroesophageal reflux, and acid-related disease. Although the pharmacokinetics of some of these drugs have been described in infants and older children, further data are needed, particularly for preterm infants. No data are available characterizing the disposition of the proton pump inhibitors, which will likely be used in infants with refractory, acid-related disease. Further data are also needed to characterize fully the pharmacodynamics, or efficacy, of many of the commonly used drugs.

Effects of CYP2C19 gene polymorphism on cure rates for Helicobacter pylori infection by triple therapy with proton pump inhibitor (omeprazole or rabeprazole), amoxycillin and clarithromycin in Japan

BACKGROUND

Omeprazole is mainly metabolized by cytochrome P450 2C19 (CYP2C19) in the liver. Rabeprazole, on the other hand, is mainly metabolized to thioether-rabeprazole via a non-enzymatic pathway and partially metabolized to demethylated-rabeprazole by CYP2C19 in liver CYP2C19 status may affect cure rate for Helicobacter pylori infection with proton pump inhibitor triple therapy.

AIM

To investigate whether genetic polymorphism of CYP2C19 and selected proton pump inhibitors (omeprazole or rabeprazole) were associated with cure rate for Helicobacter pylori infection using triple therapy with omeprazole or rabeprazole, amoxicillin, and clarithromycin.

METHODS

A total of 170 Helicobacter pylori-positive patients with chronic gastritis were randomized to receive one of the following Helicobacter pylori eradication regimens; OAC (omeprazole 20 mg bd, amoxycillin 750 mg bd and clarithromycin 400 mg bd for 1 week) and RAC (rabeprazole 20 mg bd, amoxycillin 750 mg bd and clarithromycin 400 mg bd for 1 week). The CYP2C19 genotype; wild-type or two mutant genes (ml in exon 5 and m2 in exon 4), or both, were identified by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

In DAC regimen, cure rate (per protocol analysis) was 73.3% in homozygous extensive metabolizers, 86.1% in heterozygous extensive metabolizers, and 85.0% in poor metabolizers. In RAC regimen, the cure rate was 81.0% in homozygous extensive metabolizers, 82.9% in heterozygous extensive metabolizers, and 87.5% in poor metabolizers. Cure rate was not significantly different between the CYP2C19 genotypes in both regimens.

CONCLUSION

Triple therapy with proton pump inhibitor (omeprazole or rabeprazole), amoxycillin, and clarithromycin is sufficiently effective in cure of Helicobacter pylori infection regardless of CYP2C19 status.

Proton pump inhibitors and their drug interactions: an evidence-based approach

The proton pump inhibitors (PPIs) are the most effective antisecretory agents used to treat acid-related disorders. As such, they are frequently prescribed for patients who are concurrently using other medications. PPIs may interact with other drugs through numerous mechanisms. The most important include competitive inhibition of hepatic cytochrome P (CYP) 450 enzymes involved in drug metabolism, and alteration of the absorption of other drugs via changes in gastric pH levels. Poor metabolizers, who lack CYP2C19, may be particularly predisposed to drug interactions. Although the potential for drug interactions is high, few clinically significant interactions have been reported for the PPIs. Nevertheless, caution is indicated when certain drugs are co-prescribed with these agents. The incidence of clinically significant drug interactions increases proportionately with the number of drugs taken and with the age of the patient. The drug interaction with the greatest clinical importance is the reduction in benzodiazepine clearance by omeprazole.

Pantoprazole: a new proton pump inhibitor

OBJECTIVE

This paper reviews the pharmacology, clinical efficacy, and tolerability of pantoprazole in comparison with those of other available proton pump inhibitors (PPIs).

METHODS

Relevant English-language research and review articles were identified by database searches of MEDLINE, International Pharmaceutical Abstracts, and UnCover, and by examining the reference lists of the articles so identified. In selecting data for inclusion, the author gave preference to full-length articles published in peer-reviewed journals.

RESULTS

Like other PPIs, pantoprazole exerts its pharmacodynamic actions by binding to the proton pump (H+,K+ -adenosine triphosphatase) in the parietal cells, but, compared with other PPIs, its binding may be more specific for the proton pump. Pantoprazole is well absorbed when administered as an enteric-coated, delayed-release tablet, with an oral bioavailability of approximately 77%. It is hepatically metabolized via cytochrome P2C19 to hydroxypantoprazole, an inactive metabolite that subsequently undergoes sulfate conjugation. The elimination half-life ranges from 0.9 to 1.9 hours and is independent of dose. Pantoprazole has similar efficacy to other PPIs in the healing of gastric and duodenal ulcers, as well as erosive esophagitis, and as part of triple-drug regimens for the eradication of Helicobacter pylori from the gastric mucosa. It is well tolerated, with the most common adverse effects being headache, diarrhea, flatulence, and abdominal pain. In clinical studies, it has been shown to have no interactions with various other agents, including carbamazepine, cisapride, cyclosporine, digoxin, phenytoin, theophylline, and warfarin.

CONCLUSIONS

Pantoprazole appears to be as effective as other PPIs. Its low potential for drug interactions may give it an advantage in patients taking other drugs.

Selection of drugs to treat gastro-oesophageal reflux disease: the role of drug interactions

Gastro-oesophageal reflux disease is probably the most common acid-peptic disease in Western countries, and the successful treatment of mild to moderate disease with pharmacotherapy has become commonplace. A large number of effective drugs are now available, and so the decision-making process for physicians increasingly relies on considerations other than pure efficacy. Cost, adverse effects and drug interactions have therefore become important, particularly in the most vulnerable patients - children, the elderly and patients who are ill and are taking medications that may influence the efficacy of antireflux therapy. Important drug interactions with antacids include the prevention of the absorption of antibacterials such as tetracycline, azithromycin and quinolones. H2 antagonists, proton pump inhibitors and prokinetic agents undergo metabolism by the cytochrome P450 (CYP) system present in the liver and gastrointestinal tract. Cimetidine is an inhibitor of CYP3A and it may cause significant interactions with drugs of narrow therapeutic range and low bioavailability that are metabolised by these enzymes. The gastroparietal proton pump inhibitors lansoprazole, omeprazole and pantoprazole are all primarily metabolised by a genetically polymorphic enzyme, CYP2C19, that is absent from approximately 3% of Caucasians and 20% of Asians. These drugs may also interact with CYP3A, but to a lesser extent. Interactions with prokinetic agents carry the greatest potential for harm. Metoclopramide is a dopamine antagonist that may cause extrapyramidal effects when administered alone at high concentrations, or when coadministered with antipsychotic agents such as haloperidol or phenothiazines. Cisapride is clearly able to prolong the electrocardiographic QT interval and cause lethal ventricular arrhythmias when its metabolism is slowed by interaction with inhibitors of CYP3A, such as erythromycin, ketoconazole or itraconazole.

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.

Clinically significant pharmacokinetic drug interactions with benzodiazepines

The reports of interactions between benzodiazepines (BZPs) and other drugs (e.g., antidepressants, selective serotonin reuptake inhibitors, antiulcer drugs, antiepileptic drugs, macrolide antibiotics) during their combined use are reviewed. In general, metabolism of BZPs is delayed when combined with a number of other drugs but some reports have suggested otherwise. In recent years, the cytochrome P450 (P450 or CYP) isoenzyme that catalyses the metabolism of BZPs has also been identified. BZPs are mainly catalysed by CYP3A4. When published reports are studied, it appears necessary to be exceptionally careful about interactions mainly between BZPs and selective serotonin reuptake inhibitors, cimetidine, antiepileptic drugs, macrolide antibiotics and antimycotics. More information is necessary to identify individuals at greatest risk of drug interactions and adverse events.

Clinically important pharmacokinetic drug-drug interactions: role of cytochrome P450 enzymes

Drug-drug interactions have become an important issue in health care. It is now realized that many drug-drug interactions can be explained by alterations in the metabolic enzymes that are present in the liver and other extra-hepatic tissues and many of the major pharmacokinetic interactions between drugs are due to hepatic cytochrome P450 (P450 or CYP) enzymes being affected by previous administration of other drugs. After coadministration, some drugs act as potent enzyme inducers, whereas others are inhibitors. However, reports of enzyme inhibition are very much more common. Understanding these mechanisms of enzyme inhibition or induction is extremely important in order to give appropriate multiple-drug therapies. In the future, it may help to identify individuals at greatest risk of drug interactions and adverse events.

Omeprazole. A review of its use in Helicobacter pylori infection, gastro-oesophageal reflux disease and peptic ulcers induced by nonsteroidal anti-inflammatory drugs

Omeprazole is a well studied proton pump inhibitor that reduces gastric acid secretion. This review examines its use in Helicobacter pylori infection, gastro-oesophageal reflux disease (GORD) with or without oesophagitis and gastrointestinal damage caused by nonsteroidal anti-inflammatory drugs (NSAIDs). Optimal omeprazole regimens for anti-H. pylori therapy are those that administer the drug at a dosage of 40 mg/day (in 1 or 2 divided doses) for 7, 10 or 14 days in combination with 2 antibacterial agents. As a component of 3-drug regimens in direct comparative studies, omeprazole was at least as effective as lansoprazole, pantoprazole, bismuth compounds and ranitidine. However, a meta-analysis suggests that triple therapies with omeprazole are more effective than comparable regimens containing ranitidine, lansoprazole or bismuth. Omeprazole also appears to be successful in triple therapy regimens used in children with H. pylori infection. In patients with acute GORD with oesophagitis, omeprazole is at least as effective as lansoprazole or pantoprazole in promoting healing, and superior to ranitidine, cimetidine or cisapride in oesophagitis healing and symptom relief. Omeprazole was similar to lansoprazole and superior to ranitidine in preventing oesophagitis relapse in patients with all grades of oesophagitis, but may be superior to lansoprazole or pantoprazole in patients with more severe disease. More patients with symptomatic GORD without oesophagitis experienced symptom relief after short term treatment with omeprazole than with ranitidine, cisapride or placebo, and symptoms were more readily prevented by omeprazole than by cimetidine or placebo. Omeprazole was effective in healing and relieving symptoms of reflux oesophagitis in children with oesophagitis refractory to histamine H2 receptor antagonists. Omeprazole is superior to placebo in preventing NSAID-induced gastrointestinal damage in patients who must continue to take NSAIDs. It is also similar to misoprostol and superior to ranitidine in its ability to heal NSAID-induced peptic ulcers and erosions, and superior to misoprostol, ranitidine or placebo in its ability to prevent relapse. In long and short term studies, omeprazole was well tolerated, with diarrhoea, headache, dizziness, flatulence, abdominal pain and constipation being the most commonly reported adverse events. Usual omeprazole dosages, alone or combined with other agents, are 10 to 40 mg/day for adults and 10 to 20 mg/day for children.

CONCLUSIONS

Omeprazole is a well studied and well tolerated agent effective in adults or children as a component in regimens aimed at eradicating H. pylori infections or as monotherapy in the treatment and prophylaxis of GORD with or without oesophagitis or NSAID-induced gastrointestinal damage.