Systematic review: impaired drug absorption related to the co-administration of antisecretory therapy

Good clinical practice recommendations for proton pump inhibitor prescription and deprescription. A review by experts from the AMG

INTRODUCTION AND AIM

Proton pump inhibitors (PPIs) are widely known drugs that are used quite frequently and indicated in both the short and long terms, in numerous acid-related diseases. Our aim was to produce an expert review that establishes recommendations for the adequate prescription and deprescription of PPIs.

METHODS

A group of experts in PPI use that are members of the Asociación Mexicana de Gastroenterología (AMG), after extensively reviewing the published literature and discussing each recommendation at a face-to-face meeting, prepared the present document of good clinical practice recommendations. This document is not intended to be a clinical practice guideline or utilize the methodology said format requires.

RESULTS

Eighteen experts on PPI use developed 22 good clinical practice recommendations for prescribing short-term, long-term, and on-demand PPIs, recognizing adverse events, and lastly, deprescribing PPIs, in acid-related diseases.

CONCLUSIONS

At present, there is scientific evidence on PPI use in numerous diseases, some in the short term (4-8 weeks), others on-demand (for short periods until symptoms improve), or in the long term (without suspending). Numerous adverse effects have been attributed to PPIs, but the majority have no well-established causal association. Nevertheless, PPIs should be suspended when there is no clear indication for their use. These recommendations aim to aid general physicians and specialists, with respect to PPI prescription and deprescription.

Is use of a long-term proton pump inhibitor or histamine-2 receptor antagonist a risk factor for iron-deficiency anaemia in Taiwan? A neglected clinical drug-drug interaction

BACKGROUND

Proton pump inhibitors (PPIs) and histamine-2 receptor (H2) antagonists change the gastric pH and reduce the intestinal absorption of nonheme iron. Case reports and case-control studies have demonstrated that absorption of iron is affected by gastric acidity, but the clinical importance of these drug-drug interactions has remained uncertain.

OBJECTIVES

The present case-control study employed 2 million longitudinal claims in 2011-2018 in the Taiwan National Health Insurance Research Database to investigate the impact of PPIs/H2 antagonists on the occurrence of iron-deficiency anaemia (IDA).

METHODS

The present study retrospectively compared exposure to PPIs/H2 antagonists for 1 year among 5,326 cases with IDA and 21,304 matched controls. The postdiagnosis prescribing pattern was also calculated to understand current practice.

RESULTS

Long-term (≥2 month) use of PPIs/H2 antagonists resulted in a higher risk of developing IDA than noncontinuous use/nonuse of those drugs (adjusted odds ratio [aOR] = 2.36, 95% confidence interval [CI] = 1.94-2.86, P < 0.001). There were significant changes in the postdiagnosis prescribing patterns of PPIs/H2 antagonists. The risk of developing IDA remained significant in the female subgroup (aOR = 2.16, 95% CI = 1.73-2.70, P < 0.001) and was even more prominent in those aged ≥ 50 years (aOR = 2.68, 95% CI = 1.94-3.70, P < 0.05).

CONCLUSIONS

This study found that long-term use of PPIs/H2 antagonists increased the risk of developing IDA, and there was strong evidence of prescription pattern adjustments postdiagnosis. Physicians and pharmacists should be aware of this risk when patients are expected to take or have been taking PPIs/H2 antagonists for the long term.

Tracking the journey: Gastrointestinal transit and intraluminal pH dynamics in aging populations using wireless motility capsule

INTRODUCTION

Gastrointestinal (GI) changes may alter drug absorption, potentially impacting both efficacy and safety of oral pharmacotherapy. However, the GI physiology is rarely studied in the aging population. This study aimed to explore GI transit time and pH in geriatric inpatients and older adults, and compare these findings with those from young volunteers.

METHODS

A prospective study was performed in geriatric inpatients and community-dwelling adults aged ≥ 75 years. GI transit and intraluminal pH were assessed by using a wireless motility capsule system. Participants' data were pooled with those from a previous study in healthy young volunteers (n = 11). Multivariable linear regression models were developed to identify explanatory variables for GI transit time and pH value.

RESULTS

We recruited 30 subjects (median age 80 [interquartile range (IQR) = 77-83] years). When compared to young volunteers (median age 21 [20-33]) years), geriatric inpatients (N = 8) exhibited prolonged gastric emptying times (median = 0.63 h [IQR = 0.32-0.86 h] vs median = 2.98 h [IQR = 1.50-20.35 h], p < 0.01). Community-dwelling older adults (N = 22) did not demonstrate delayed gastric emptying (median = 0.42 h [IQR = 0.36-0.53 h]; p = 0.85. Proton pump inhibitors (PPI) use was associated with increased gastric pH (median pH = 3.75 [IQR = 1.69-4.96] vs. non-PPI median pH = 1.28[IQR = 1.01-1.70]; p < 0.01) in the pooled analysis. The total older cohort had significantly lower small intestine pH compared to young group (median pH = 6.8 vs. 7.2; p < 0.01).

CONCLUSION

Older age did not necessarily alter GI physiology with respect to gastric emptying time and luminal pH values. Only geriatric inpatients exhibited delayed gastric emptying of the motility capsule as compared to young volunteers, while community-dwelling older adults did not. Prevalent PPI use in the aging population led to higher gastric pH levels, with substantial intersubject variability.

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

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

Prediction of gastric pH-mediated drug exposure using physiologically-based pharmacokinetic modeling: A case study of itraconazole

Abnormal gastric acidity, including achlorhydria, can act as a significant source of variability in orally administered drugs especially with pH-sensitive solubility profiles, such as weak bases, potentially resulting in an undesirable therapeutic response. This study aimed to evaluate the utility of physiologically-based pharmacokinetic (PBPK) modeling in the prediction of gastric pH-mediated drug exposure by using itraconazole, a weak base, as a case. An itraconazole PBPK model was developed on the mechanistic basis of its absorption kinetics in a middle-out manner from a stepwise in vitro-in vivo extrapolation to in vivo refinement. Afterward, an independent prospective clinical study evaluating gastric pH and itraconazole pharmacokinetics (PKs) under normal gastric acidity and esomeprazole-induced gastric hypoacidity was conducted for model validation. Validation was performed by comparing the predicted data with the clinical observations, and the valid model was subsequently applied to predict PK changes under achlorhydria. The developed itraconazole PBPK model showed reasonable reproducibility for gastric pH-mediated exposure observed in the clinical investigation. Based on the model-based simulations, itraconazole exposure was expected to be decreased up to 65% under achlorhydria, and furthermore, gastric pH-mediated exposure could be mechanistically interpreted according to sequential variation in total solubility, dissolution, and absorption. This study suggested the utility of PBPK modeling in the prediction of gastric pH-mediated exposure, especially for drugs whose absorption is susceptible to gastric pH. Our findings will serve as a leading model for further mechanistic assessment of exposure depending on gastric pH for various drugs, ultimately contributing to personalized pharmacotherapy.

Effect of an Antacid (Aluminum Hydroxide/Magnesium Hydroxide/Simethicone) or a Proton Pump Inhibitor (Omeprazole) on the Pharmacokinetics of Tebipenem Pivoxil Hydrobromide (TBP-PI-HBr) in Healthy Adult Subjects

Tebipenem pivoxil hydrobromide (TBP-PI-HBr) is a novel oral carbapenem prodrug being developed for the treatment of serious bacterial infections. This open-label, 3-period, fixed sequence study evaluated the effect of gastric acid-reducing agents, aluminum hydroxide/magnesium hydroxide/simethicone, and omeprazole on the pharmacokinetics (PK) of tebipenem (TBP), the active moiety, following coadministration with immediate release TBP-PI-HBr during fasting. In Period 1, subjects received a single oral dose of TBP-PI-HBr 600 mg (2 × 300 mg tablets). In Period 2, subjects received a single oral dose of aluminum hydroxide 800 mg/magnesium hydroxide 800 mg/simethicone 80 mg suspension co-administered with a single dose of TBP-PI-HBr 600 mg. In Period 3, subjects received a single oral dose of omeprazole 40 mg once daily over 5 days, followed by single dose administration of TBP-PI-HBr 600 mg on day 5. In each period, whole blood samples were obtained prior to, and up to 24 h, following TBP-PI-HBr dose administration in order to characterize TBP PK. A 7-day washout was required between periods. Twenty subjects were enrolled and completed the study. Following co-administration of TBP-PI-HBr with either aluminum hydroxide/magnesium hydroxide/simethicone or omeprazole, total TBP exposure (area under the curve [AUC]) was approximately 11% (geometric mean ratio 89.2, 90% confidence interval: 83,2, 95.7) lower, and Cmax was 22% (geometric mean ratio 78.4, 90% confidence interval: 67.9, 90.6) and 43% (geometric mean ratio 56.9, 90% confidence interval: 49.2, 65.8) lower, respectively, compared to administration of TBP-PI-HBr alone. Mean TBP elimination half-life (t_1/2) was generally comparable across treatments (range: 1.0 to 1.5 h). Concomitant administration of TBP-PI-HBr with omeprazole or aluminum hydroxide/magnesium hydroxide/simethicone is not expected to impact the efficacy of TBP-PI-HBr, as there is minimal impact on TBP plasma AUC, which is the pharmacodynamic driver of efficacy. Co-administration was generally safe and well tolerated.

Advances in Oral Drug Delivery Systems: Challenges and Opportunities

The oral route is the most preferred route for systemic and local drug delivery. However, the oral drug delivery system faces the harsh physiological and physicochemical environment of the gastrointestinal tract, which limits the bioavailability and targeted design of oral drug delivery system. Innovative pharmaceutical approaches including nanoparticulate formulations, biomimetic drug formulations, and microfabricated devices have been explored to optimize drug targeting and bioavailability. In this review, the anatomical factors, biochemical factors, and physiology factors that influence delivering drug via oral route are discussed and recent advance in conventional and novel oral drug delivery approaches for improving drug bioavailability and targeting ability are highlighted. We also address the challenges and opportunities of oral drug delivery systems in future.

Appropriateness of Proton Pump Inhibitor Prescription Evaluated by Using Serological Markers

Inappropriate prescription of proton pump inhibitors (PPI) has been widely reported, often lacking initial exclusion of Helicobacter pylori (HP) infection and evaluation of gastric functional status. The aim of this study was to evaluate the utility of gastric functional tests to define the acid output, as well as HP status, in order to better direct PPI therapy prescription. Dyspeptic patients without alarm symptoms from a primary care population were evaluated. For each patient, serum Pepsinogen I (PGI) and II (PGII), gastrin 17 (G17) and anti-HP IgG antibodies (Biohit, Oyj, Finland) were determined. For each subject, data were collected regarding symptoms, past medical history of HP infection, and PPI use. Therapeutic response to PPIs was determined according to PGI and G17 values, where G17 > 7 in the presence of elevated PGI and absence of chronic atrophic gastritis (CAG) was considered an adequate response. Among 2583 dyspeptic patients, 1015/2583 (39.3%) were on PPI therapy for at least 3 months before serum sampling, and were therefore included in the study. Active HP infection and CAG were diagnosed in 206 (20.2%) and 37 (3.6%) patients, respectively. Overall, an adequate therapeutic response to PPIs was observed in 34.9%, reaching 66.7% at the highest dose. However, 41.1% and 20.4% of patients showed low (G17 1-7) or absent (G17 < 1) response to PPI, regardless of the dosage used. According to gastric functional response, most patients currently on PPI maintenance therapy lack a proper indication for continuing this medication, either because acid output is absent (as in CAG) or because gastrin levels fail to rise, indicating absence of gastric acid negative feedback. Lastly, HP eradication is warranted in all patients, and gastric function testing ensures this pathogen is sought for and adequately treated prior to initiating long-term PPI therapy.

Use of Gastrointestinal Simulator, Mass Transport Analysis, and Absorption Simulation to Investigate the Impact of pH Modifiers in Mitigating Weakly Basic Drugs' Performance Issues Related to Gastric pH: Palbociclib Case Study

It is well known that reduced gastric acidity, for example with concomitant administration of acid reducing agents, can result in variable pharmacokinetics and decreased absorption of weakly basic drugs. It is important to identify the risk of reduced and variable absorption early in development, so that product design options to address the risk can be considered. This article describes the utilization of in vitro and in silico tools to predict the effect of gastric pH, as well as the impact of adding pH modifiers, in mitigating the effect of acid reducing agents on weak base drugs' dissolution and absorption. Palbociclib, a weakly basic drug, was evaluated in low and high gastric pH conditions in a multicompartmental dissolution apparatus referred to as a gastrointestinal simulator (GIS). The GIS permits the testing of pharmaceutical products in a way that better assesses dissolution under physiologically relevant conditions of pH, buffer concentration, formulation additives, and physiological variations including GI pH, buffer concentrations, secretions, stomach emptying rate, residence time in the GI, and aqueous luminal volume. To predict drug dissolution in the GIS, a hierarchical mass transport model was used and validated using in vitro experimental data. Dissolution results were then compared to observed human clinical plasma data with and without proton pump inhibitors using a GastroPlus absorption model to predict palbociclib plasma profiles and pharmacokinetic parameters. The results showed that the in silico model successfully predicted palbociclib dissolution in the GIS under low and high gastric pH conditions with and without pH modifiers. Furthermore, the GIS data coupled with the in silico tools anticipated (1) the reduced palbociclib exposure due to proton pump inhibitor coadministration and (2) the mitigating effect of a pH-modifying agent. This study provides tools to help in the development of orally administered formulations to overcome the effect of elevated gastric pH, especially when formulating with pH modifiers.

Isolated Colonic Histoplasmosis in Patients Undergoing Immunomodulator Therapy: A Systematic Review

Gastrointestinal histoplasmosis remains an inconspicuous clinicopathologic entity. It is predominantly considered a protean manifestation of disseminated disease. We hereby delineate a unique case of biopsy-proven isolated colonic histoplasmosis in a patient undergoing methotrexate therapy. Furthermore, we present the first systematic review of the MEDLINE, Google Scholar, Embase, and Scopus databases regarding isolated colonic histoplasmosis in adult patients receiving immunomodulator therapy (IMT). A total of 13 case reports (level of clinical evidence: IV) were identified. The mean age was 55.6 ± 11.1 years, with 9 (69.2%) cases reported in women. Patients with subclinical disease (5, 38.5%) were often incidentally diagnosed by screening colonoscopy. Symptomatic individuals predominantly presented with diarrhea (4, 30.8%), weight loss (3, 23.1%), and/or abdominal pain (3, 23.1%). IMT was mainly administered for liver transplant (4, 30.8%), renal transplant (4, 30.8%), and ulcerative colitis (2, 15.4%). Common colonoscopy features included colonic ulcerations (7, 53.8%), polyps or pseudopolyps (3, 23.1%), and/or mass-like lesions (3, 23.1%). Diagnosis was made by histology of colonic biopsy in 11 (84.6%) and resected specimens in 2 (15.4%) patients. Treatment consisted of a combination of amphotericin B with oral itraconazole in 6 (46.2%), oral itraconazole alone in 5 (38.5%), and amphotericin B alone in 2 (15.4%) patients. Complete clinical recovery was achieved in all patients. This article illustrates that isolated colonic involvement can be the only clinical presentation of histoplasmosis. It may masquerade as other bowel disorders, presenting diagnostic and therapeutic conundrums. Gastroenterologists should rule out colonic histoplasmosis in IMT recipients who develop unexplained colitis symptoms.

In silico-assisted development of supersaturable preconcentrated isotropic mixture of atazanavir for augmenting biopharmaceutical performance in the presence of H2-receptor antagonist

The therapeutic potential of atazanavir (BCS Class II drug), a highly selective inhibitor of human immunodeficiency virus (HIV-1), has been largely limited due to its low intrinsic solubility at elevated pH resulting in low oral bioavailability. Thus, the current work describes the systematic development, optimization, and evaluation of hydroxypropyl methylcellulose acetate succinate (HPMC-AS)-based supersaturable preconcentrate isotropic mixture (SP-IM) containing long-chain triglyceride to improve intestinal lymphatic transport and augment oral bioavailability of atazanavir (ATZ). A D-optimal mixture design was employed for optimization of plain IM containing corn oil, oleic acid, Tween 80, and propylene glycol, evaluating various critical quality attributes (CQAs) like particle size, polydispersity index, self-emulsification time, % transmittance, and drug content. In silico analysis and in vitro supersaturation test facilitated the selection of HPMC-AS as a best suited polymeric precipitation inhibitor (PPI) for formulating ATZ loaded SP-IM (ATZ-SP-IM). In vitro dissolution data indicated that ATZ-SP-IM exhibits superior performance in 0.025 N HCl and pH 6.8 over pure drug. Ex vivo permeation and in vivo pharmacokinetic study of ATZ-SP-IM corroborated enhanced permeation (2.03 fold) and improved drug absorption via lymphatic transport in Wistar rats. Further, the pharmacokinetic performance of ATZ-SP-IM was not affected in presence of H₂ receptor antagonist. Therefore, the results showed that ATZ-SP-IM can significantly improve the biopharmaceutical attributes of ATZ so as to lay a foundation of further research on the new dosage form of ATZ.

Impact of gastric and bowel surgery on gastrointestinal drug delivery

General surgical procedures on the gastrointestinal tract are commonly performed worldwide. Surgical resections of the stomach, small intestine, or large intestine can have a significant impact on the anatomy and physiological environment of the gastrointestinal tract. These physiological changes can affect the effectiveness of orally administered formulations and drug absorption and, therefore, should be considered in rational drug formulation design for specific pathological conditions that are commonly associated with surgical intervention. For optimal drug delivery, it is important to understand how different surgical procedures affect the short-term and long-term functionality of the gastrointestinal tract. The significance of the surgical intervention is dependent on factors such as the specific region of resection, the degree of the resection, the adaptive and absorptive capacity of the remaining tissue, and the nature of the underlying disease. This review will focus on the common pathological conditions affecting the gastric and bowel regions that may require surgical intervention and the physiological impact of the surgery on gastrointestinal drug delivery. The pharmaceutical considerations for conventional and novel oral drug delivery approaches that may be impacted by general surgical procedures of the gastrointestinal tract will also be addressed.

Atazanavir-Concentrate Loaded Soft Gelatin Capsule for Enhanced Concentration in Plasma, Brain, Spleen, and Lymphatics

This study investigates the development of atazanavir-concentrate loaded soft gelatin capsule for achieving enhanced atazanavir (ATV) concentration in plasma, brain, spleen, and lymphatics beneficial in the significant reduction of viral load in HIV infection. For this purpose, ATV-concentrate in the presence and absence of Soluplus with corn oil, oleic acid, tween 80, and propylene glycol was developed. The developed ATV-concentrate was found to have enhanced dispersibility with no signs of precipitation after dilution with simulated G.I fluid as evident from particle size (16.49±0.32 nm) and PDI (0.217±0.02) analysis. The rheological and molecular docking studies explainedthe reduction of viscosity of SuATV-C due to the intermolecular H-bond between ATV and Soluplus that helps to retard crystallization. The shell of the soft gelatin capsule retains its integrity when subjected to a folding endurance test on a texture analyzer depicting that the concentrate did not affect the integrity of the soft gelatin capsule shell. An ex vivo and in vivo pharmacokinetic study in rats revealed that the SuATV-C soft gelatin capsule (SuATV-C SGC) indicated 2.9 fold improvement in rate and extent of permeation and absorption than that of ATV-suspension. The tissue distribution study also exhibited higher drug concentration in the brain (2.5 fold), lymph nodes (2.7 fold), and spleen (1.2 fold) administered with SuATV-C SGC, revealing the overwhelming influence of Soluplus and corn oil. In a nutshell, these studies demonstrated that SuATV-C SGC seems to have the potential to deliver an anti-retroviral drug to the viral sanctuaries for the better management of HIV.

Precision Medicine in Autoimmune Thyroiditis and Hypothyroidism

Autoimmune thyroid diseases (AITD) are T-cell-mediated organ specific autoimmune disorders, deriving from an altered response of the immune system that leads to the immune attack to the thyroid. Hashimoto’s thyroiditis (HT) and Graves’ disease (GD) are the two principal AITD clinical presentations. Hypothyroidism and thyrotoxicosis are, respectively, the clinical hallmarks of HT and GD. Patients with autoimmune thyroiditis are treated daily with synthetic L-thyroxine (L-T4) at the dose of 1.5–1.7 μg/kg. Various L-T4 formulations are commercially available (tablet, liquid solution, or soft gel capsule). L-T4 in tablets is generally prescribed to treat hypothyroidism, whereas the liquid formulation, or soft gel capsules, can be administered in hypothyroid patients in case of malabsorption or in patients in therapy with drugs interfering with L-T4 absorption. Furthermore, myoinositol has a crucial role in thyroid autoimmunity and function. Clinical studies reported a significant decline in TSH and antithyroid autoantibodies levels after treatment with myoinositol + selenium in patients with subclinical hypothyroidism and autoimmune thyroiditis. Moreover, thyroidectomy can be rarely recommended in patients with autoimmune thyroiditis, with cosmetic reasons for a goiter, or with important signs or symptoms of local compression, or nodular disease with a “suspicious” cytology for malignancy. Furthermore, a recent randomized trial suggested that total thyroidectomy can improve quality of life and fatigue, while medical therapy did not. In this review, we overview currently available evidence in personalized medicine in patients with autoimmune thyroiditis and hypothyroidism. Further research is needed in larger population to investigate the effect of these new treatments on quality of life.

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.

Zinc Poisoning - Symptoms, Causes, Treatments

Zinc poisoning has been reported from many parts of the world. It is one of the global health problems that affect many organs, if exposed by inhalation of zinc vapors or by consumption of contaminated food and water. Long term exposure to zinc compounds from different sources such as air, water, soil, and food, lead to toxic effects on body systems, especially digestive, respiratory, and nerve systems, and also causes cancer. Zinc levels can be determined in blood, urine, hair, and nails. Patients with zinc toxicity need chelating agents, other pharmacological treatment, protective lung ventilation, extracorporeal membrane oxygenation (ECMO), and supportive care.

Utilizing Tiny-TIM to Assess the Effect of Acid-Reducing Agents on the Absorption of Orally Administered Drugs

Acid-reducing agents (ARAs) are the most commonly used medicines to treat patients with gastric acid-related disorders. ARA administration results in an elevation of intragastric pH and eases symptoms such as acid reflux. However, this effect could also lead to a reduction in the absorption of some co-administered oral medications (i.e. weakly basic drugs) by decreasing their gastric solubility. This in turn can result in a significant reduction of the efficacy of the co-administered oral medications. In order to address this problem, substantial efforts in translational modeling and the development of predictive in-vitro assays to better forecast the effect of ARA on oral absorption are conducted in the pharmaceutical industry. Despite these efforts, it remains challenging to predict the impact of ARAs on co-administered drugs. In this study, we evaluated the utility of Triskelion's Gastro-Intestinal Model (Tiny-TIM) in predicting ARA effect on twelve model drugs whose in-vivo data are available. The Tiny-TIM prediction of the ARA effect matched the observed effect of ARA co-administration in humans for the 12 model compounds. In summary, Tiny-TIM is a very reliable and promising GI model to successfully predict the nature of DDI when ARAs are co-administered with the drug of interest.

The Stability of TSH, and Thyroid Hormones, in Patients Treated With Tablet, or Liquid Levo-Thyroxine

Approximately, 5% of the population is affected by hypothyroidism, mainly women and persons aged more than 60 years. After the diagnosis of hypothyroidism the usual therapy is tablet levothyroxine (L-T4), with a monitoring of the thyroid-stimulating hormone (TSH) level in primary hypothyroidism every 6-8 weeks and L-T4 is adjusted as necessary to reach an euthyroid state. Once TSH is stabilized in the normal range, it is recommended to conduct annual testing in the treated subjects to warrant suitable replacement. More recently advances regarding L-T4 treatment are the introduction of new oral formulations: the liquid solution, and soft gel capsule. The soft gel capsule permits a quick dissolution in the acid gastric pH. The liquid preparation does not require an acid gastric environment. Many pharmacokinetic studies demonstrated a more rapid absorption for the liquid L-T4, or capsule, than with tablet. Many studies have shown that the liquid, or capsule, formulations can overcome the interaction with foods, drugs or malabsorptive conditions, that are able to impair the tablet L-T4 absorption. Lately studies have suggested that liquid L-T4 can permit to maintain more efficiently normal TSH levels in hypothyroid patients in the long-term follow-up, than tablet L-T4, both in patients with malabsorptive states, and in those without malabsorption. Further large, prospective, longitudinal studies are needed to evaluate the stability of TSH, in hypothyroid patients treated with different L-T4 formulations.

L-T4 Therapy in Enteric Malabsorptive Disorders

Levothyroxine (L-T4) absorption can be impaired by various causes: a) L-T4 ingestion during breakfast, or with food; b) conditions of reduced gastric acidity; c) intestinal procedures and diseases such as bariatric surgery, lactose intolerance (LI), celiac disease (CD), inflammatory bowel disease; d) drugs that alter L-T4 absorption, increasing the gastric pH, or preventing the dissolution of tablets. The development of new oral formulations, i.e. the liquid preparation and the soft gel capsule, represents the most recent advance regarding L-T4 therapy. Treating hypothyroidism with L-T4 tablets can lead to an improper control of thyroid-stimulating hormone (TSH) in ~10%-15% of patients. The improperly elevated TSH is usually managed by increasing the L-T4 daily dose, and revaluating TSH upon 2-6 months. The increase of the L-T4 dosage may cause iatrogenic hyperthyroidism, especially when the underlying disorders are cured. Liquid L-T4 can be administered in patients unable to swallow capsules or tablets, and this is one of its major benefits. Liquid L-T4 can: 1- overcome food and beverages interference; 2- bypass the malabsorption associated with an increased gastric pH; 3- circumvent the issue of malabsorption in patients who underwent bariatric surgery; 4-maintain TSH values under control better than L-T4 tablets in hypothyroid patients with typical or atypical CD, or in patients with LI. Few clinical studies evaluated soft gel L-T4 with encouraging findings in patients with gastric- or coffee-related malabsorption, or hypothyroid patients without malabsorption. Additional research is necessary to investigate liquid L-T4, or soft gel capsule, in other conditions of altered L-T4 absorption.

Physiologically Based Pharmacokinetic/Pharmacodynamic Modeling to Support Waivers of In Vivo Clinical Studies: Current Status, Challenges, and Opportunities

Physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) modeling has been extensively applied to quantitatively translate in vitro data, predict the in vivo performance, and ultimately support waivers of in vivo clinical studies. In the area of biopharmaceutics and within the context of model-informed drug discovery and development (MID3), there is a rapidly growing interest in applying verified and validated mechanistic PBPK models to waive in vivo clinical studies. However, the regulatory acceptance of PBPK analyses for biopharmaceutics and oral drug absorption applications, which is also referred to variously as "PBPK absorption modeling" [Zhang et al. CPT: Pharmacometrics Syst. Pharmacol. 2017, 6, 492], "physiologically based absorption modeling", or "physiologically based biopharmaceutics modeling" (PBBM), remains rather low [Kesisoglou et al. J. Pharm. Sci. 2016, 105, 2723] [Heimbach et al. AAPS J. 2019, 21, 29]. Despite considerable progress in the understanding of gastrointestinal (GI) physiology, in vitro biopharmaceutic and in silico tools, PBPK models for oral absorption often suffer from an incomplete understanding of the physiology, overparameterization, and insufficient model validation and/or platform verification, all of which can represent limitations to their translatability and predictive performance. The complex interactions of drug substances and (bioenabling) formulations with the highly dynamic and heterogeneous environment of the GI tract in different age, ethnic, and genetic groups as well as disease states have not been yet fully elucidated, and they deserve further research. Along with advancements in the understanding of GI physiology and refinement of current or development of fully mechanistic in silico tools, we strongly believe that harmonization, interdisciplinary interaction, and enhancement of the translational link between in vitro, in silico, and in vivo will determine the future of PBBM. This Perspective provides an overview of the current status of PBBM, reflects on challenges and knowledge gaps, and discusses future opportunities around PBPK/PD models for oral absorption of small and large molecules to waive in vivo clinical studies.

Potential proton pump inhibitor-related adverse effects

Proton pump inhibitors (PPIs) are one of the most common medications taken by patients worldwide. PPIs are used to treat acid-related disorders, including gastroesophageal reflux disease, peptic ulcer disease, Helicobacter pylori infection, and nonsteroidal anti-inflammatory drug/stress ulceration. For some of these diseases, long-term treatment is necessary. With such prolonged use, concern and investigation into potential adverse effects has increased. In addition, data are available regarding potential anticancer effects of PPIs, especially regarding solid tumors. The aim of this review is to assess the literature on PPIs with regard to common concerns, such as drug-drug interactions, the intestinal microbiome, dementia and central nervous system disease, and osteoporosis, as well as to highlight potential negative and positive impacts of the drug in cancer.

Advances in Oral Drug Delivery for Regional Targeting in the Gastrointestinal Tract - Influence of Physiological, Pathophysiological and Pharmaceutical Factors

The oral route is by far the most common route of drug administration in the gastrointestinal tract and can be used for both systemic drug delivery and for treating local gastrointestinal diseases. It is the most preferred route by patients, due to its advantages, such as ease of use, non-invasiveness, and convenience for self-administration. Formulations can also be designed to enhance drug delivery to specific regions in the upper or lower gastrointestinal tract. Despite the clear advantages offered by the oral route, drug delivery can be challenging as the human gastrointestinal tract is complex and displays a number of physiological barriers that affect drug delivery. Among these challenges are poor drug stability, poor drug solubility, and low drug permeability across the mucosal barriers. Attempts to overcome these issues have focused on improved understanding of the physiology of the gastrointestinal tract in both healthy and diseased states. Innovative pharmaceutical approaches have also been explored to improve regional drug targeting in the gastrointestinal tract, including nanoparticulate formulations. This review will discuss the physiological, pathophysiological, and pharmaceutical considerations influencing drug delivery for the oral route of administration, as well as the conventional and novel drug delivery approaches. The translational challenges and development aspects of novel formulations will also be addressed.

A phase I study of the effect of repeated oral doses of pantoprazole on the pharmacokinetics of a single dose of fedratinib in healthy male subjects

PURPOSE

Fedratinib, an oral, selective Janus kinase 2 inhibitor with activity against both wild-type and mutant Janus kinase 2, has pH-dependent solubility, with free solubility at pH 1. Concomitant administration of drugs that reduce gastric acid secretion, such as pantoprazole, may decrease the absorption of fedratinib and affect patient outcomes. The aim of this study was to evaluate the impact of 7-day repeated 40-mg doses of pantoprazole on the pharmacokinetic (PK) properties of a single 500-mg dose of fedratinib in healthy male subjects.

METHODS

In this phase I, single-center, open-label, two-period, two-treatment, fixed-sequence crossover study, healthy male subjects were administered a single dose of fedratinib 500 mg on day 1 in Period 1, followed by pantoprazole 40 mg daily for 7 days (day 1 to day 7) and a single dose of fedratinib 500 mg on day 7 in Period 2. After the discontinuation of nine subjects due to vomiting, the protocol was amended to provide ondansetron as antiemetic prophylaxis to an additional ten enrolled subjects.

RESULTS

Twenty-six subjects were included. Repeated doses of pantoprazole 40 mg resulted in clinically insignificant increases in fedratinib exposure. Maximum plasma concentration increased by 1.09-fold and area under the plasma concentration-time curve from time 0 to infinity increased by 1.15-fold. All treatment-emergent adverse events were mild or moderate, except for one instance of neutropenia, which was considered unrelated to study intervention.

CONCLUSION

Coadministration with pantoprazole did not have clinically meaningful effects on fedratinib PK. No new or unexpected safety signals were observed with fedratinib.

Nutrigenomics-Associated Impacts of Nutrients on Genes and Enzymes With Special Consideration of Aromatase

Interactions are occurring in the course of liberation, absorption, distribution, metabolism, and excretion of active ingredients, or at the target receptors. They are causing therapy failures and undesirable events. Forty-seven of fifty-seven human hepatic isoenzymes are specific and relevant in hormone and vitamin metabolism and biosynthesis. Aromatase (syn. CYP19A1) is one of the specific CYP450 isoenzymes so far not elucidated in detail. As aromatase-inhibiting phytochemicals are currently recommended for breast cancer prevention and as add-on accompanying aromatase-inhibitor pharmacotherapy, it was the aim of this literature review to assess whether a common interpretation on genetic and -omics basis could be found. Articles retrieved showed that traditional antioxidation diet is one of the most approved explanations of inhibition of aromatase by phytonutrients of flavonoid derivatives. Flavonoids compete for the oxygen provided by the heme moiety of aromatase in the course of aromatase-catalyzed conversion of steroid precursors to estrogens. Flavonoids are therefore promoted for breast cancer prevention. A further explanation of flavonoids' mechanism of action proposed was related to enzymatic histone deacetylation. By keeping DNA-structure wide through a high acetylation degree, acetylated histones favor transcription and replication. This mechanism corresponds to a procedure of switching genes on. Inhibiting acetylation and therefore switching genes off might be an important regulation of repressing cancer genes. Aromatase expression depends on the genotype and phenotype of a person. Aromatase itself depends on the expression of the heme moiety encoded in the genotype. Biosynthesis of porphyrins in turn depends on the substrates succinate and glycine, as well as on a series of further enzymes, with ALA synthetase as the rate-limiting step. The effect of the heme moiety as prosthetic group of aromatase further depends on the absorption of iron as a function of pH and redox state. To assess the function of aromatase precisely, multiple underlying biochemical pathways need to be evaluated. As a conclusion, the genetic regulation of metabolism is a complex procedure affecting multiple pathways. To understand a metabolic step, multiple underlying individually performing reactions need to be considered if personalized (nutritional) medicine should bring an advantage for a patient. Nutrition sciences need to consider the genome of an individual to truly find answers to nutrition-derived non-communicable diseases. With current GWAS (genome-wide association study) approaches, inherited errors of metabolism are identified and ideally treated effectively. It is much more difficult to get a precise genetic profile for non-communicable diseases stemming from multifactorial causes. Polygenic risks evaluation is feasible but diagnostic tools are not yet available in a desired extent. Neither flavonoid researchers nor providers of genetic testing kits are going into the details needed for a truly personalized nutritional medicine. The next step with profiling the exome and then the whole genome is on the threshold of becoming routine diagnosis and of bringing the desired details.

Effects of medicines used to treat gastrointestinal diseases on the pharmacokinetics of coadministered drugs: a PEARRL Review

OBJECTIVES

Drugs used to treat gastrointestinal diseases (GI drugs) are widely used either as prescription or over-the-counter (OTC) medications and belong to both the 10 most prescribed and 10 most sold OTC medications worldwide. The objective of this review article is to discuss the most frequent interactions between GI and other drugs, including identification of the mechanisms behind these interactions, where possible.

KEY FINDINGS

Current clinical practice shows that in many cases, these drugs are administered concomitantly with other drug products. Due to their metabolic properties and mechanisms of action, the drugs used to treat gastrointestinal diseases can change the pharmacokinetics of some coadministered drugs. In certain cases, these interactions can lead to failure of treatment or to the occurrence of serious adverse events. The mechanism of interaction depends highly on drug properties and differs among therapeutic categories. Understanding these interactions is essential to providing recommendations for optimal drug therapy.

SUMMARY

Interactions with GI drugs are numerous and can be highly significant clinically in some cases. While alterations in bioavailability due to changes in solubility, dissolution rate, GI transit and metabolic interactions can be (for the most part) easily identified, interactions that are mediated through other mechanisms, such as permeability or microbiota, are less well-understood. Future work should focus on characterising these aspects.

Pharmacokinetic Interaction Study Between Saxagliptin and Omeprazole, Famotidine, or Magnesium and Aluminum Hydroxides Plus Simethicone in Healthy Subjects: An Open-Label Randomized Crossover Study

Saxagliptin is an orally administered, highly potent, and selective dipeptidyl peptidase-4 inhibitor for the management of type 2 diabetes mellitus. This study was conducted to determine the effect of magnesium and aluminum hydroxides plus simethicone, famotidine, and omeprazole on the pharmacokinetics of saxagliptin and its active metabolite, 5-hydroxy saxagliptin. This was an open-label, randomized, 5-treatment, 5-period, 3-way crossover study in 15 healthy subjects. Mean C_max of saxagliptin was 26% lower, but AUC was almost unchanged when saxagliptin was coadministered with Maalox Max. Mean C_max was 14% higher, but AUC was almost unchanged when saxagliptin was coadministered with famotidine. Changes in pharmacokinetics of 5-hydroxy saxagliptin generally paralleled the changes in saxagliptin. These pharmacokinetic changes were unlikely to be clinically meaningful. Coadministration of omeprazole did not affect saxagliptin C_max or AUC. Saxagliptin in combination with these medicines resulted in no unexpected safety or tolerability findings in these healthy subjects. No dose adjustment of saxagliptin or separation in the time of saxagliptin dosing is necessary with medicines that raise gastric pH when coadministered with saxagliptin.

Using pH Gradient Dissolution with In-Situ Flux Measurement to Evaluate Bioavailability and DDI for Formulated Poorly Soluble Drug Products

This study described a pH-gradient dissolution method combined with flux measurements as an in vitro tool for assessing the risk of bioavailability reduction due to drug-drug interactions (DDI) caused by acid reducing agents (ARAs). The device incorporates absorption chambers into USP II dissolution vessels, with fiber optic UV-probes monitoring concentration in situ. Dosage forms of Genentech BCS class II drugs, GDC-0810, GDC-0941, and compound A, were tested by starting the dissolution in either pH 1.6 or pH 4.0 media then converting to FaSSIF after 30 min. GDC-0810 showed no significant difference in flux between the two conversion experiments. A supersaturation phase was observed for GDC-0941 in the pH 1.6 experiments after media conversion to FaSSIF; however, it did not appear to occur in the pH 4.0 experiment due to low drug solubility at pH 4.0, resulting in a 95% decrease in flux compared to pH 1.6 experiment. The extent of flux reduction and the total accumulated API mass in the absorption chamber agreed well with the 89% reduction in mean Cmax and the 82% reduction in mean AUC from dog PK study between animals treated with pentagastrin and famotidine. Testing of the compound A optimized formulation tablets showed a 25% reduction in flux and in vitro absorbed amount by changing pH 1.6 to 4.0, correlating well with the AUC decrease in clinical studies. Good correlation between in vitro data and in vivo PK data demonstrated the applicability of the method for formulators to develop drug products mitigating DDI from ARAs.

Interindividual and intraindividual variability of fasted state gastric fluid volume and gastric emptying of water

The amount and composition of gastrointestinal media are crucial parameters in oral drug delivery. In fasted state, variable residual gastric volumes and gastric emptying behavior often cause variable drug release and absorption from oral drug products. Unfortunately, interindividual and intraindividual variability of the gastric conditions in fasted state are currently insufficiently mapped. In this work, datasets from 5 MRI studies with 16 treatments in total were pooled. The interindividual and intraindividual variability of residual gastric volumes after 10 h overnight fasting and the subsequent emptying of 240 mL of water were compared in healthy human subjects under conditions mimicking clinical studies. This work shows that even under standardized clinical conditions, residual gastric volumes and water emptying are highly variable. Interestingly, interindividual and intraindividual variabilities of both parameters were comparable, suggesting that the variability within the studies was mainly resulting from intraindividual day-to-day variations. The mean resting volumes in all conducted investigations amounted to 25 ± 18 mL (n = 120). Furthermore, 85 ± 13% (n = 22) of initially available gastric volume (resting volume plus 240 mL) was emptied after 30 min. The findings of this work will hopefully contribute to a better comprehension of the variability of oral drug release and absorption.

Coprescribing proton-pump inhibitors with nonsteroidal anti-inflammatory drugs: risks versus benefits

Nonsteroidal anti-inflammatory drugs (NSAIDs) are often coadministered with proton-pump inhibitors (PPIs) to reduce NSAID-induced gastrointestinal (GI) adverse events. This coadministration is generally regarded as safe, and is included in many of the guidelines on NSAID prescription. However, recent evidence indicates that the GI risks associated with NSAIDs can be potentiated when they are combined with PPIs. This review discusses the GI effects and complications of NSAIDs and how PPIs may potentiate these effects, options for prevention of GI side effects, and appropriate use of PPIs in combination with NSAIDs.

Proton-pump inhibitors: understanding the complications and risks

Proton-pump inhibitors (PPIs) are the most effective therapy for the full spectrum of gastric-acid-related diseases. However, in the past decade, a steadily increasing list of complications following long-term use of PPIs has been reported. Their potent acid-suppressive action induces several structural and functional changes within the gastric mucosa, including fundic gland polyps, enterochromaffin-like cell hyperplasia and hypergastrinaemia, which can be exaggerated in the presence of Helicobacter pylori infection. As discussed in this Review, most associations of PPIs with severe adverse events are not based on sufficient evidence because of confounding factors and a lack of plausible mechanisms. Thus, a causal relationship remains unproven in most associations, and further studies are needed. Awareness of PPI-associated risks should not lead to anxiety in patients but rather should induce the physician to consider the appropriate dosing and duration of PPI therapy, including long-term monitoring strategies in selected groups of patients because of their individual comorbidities and risk factors.

Peritoneal dialysis: The unique features by compartmental delivery of renal replacement therapy

Despite decades of research, the clinical efficacy of peritoneal dialysis (PD) remains enigmatic. We may wonder why the modality fail in some patients but perhaps the more proper question would be, why it works in so many? We know that the contribution of residual renal function (RRF), more so than in hemodialysis, is critically important to the well-being of many of the patients. Unique features of the modality include the relatively low volume of dialysate fluid needed to provide effective uremic control and the disproportionate tendency for both hypokalemia and hypoalbuminemia, when compared to hemodialysis. It is currently believed that most uremic toxins are generated on the interface of human and bacterial structures in the gastrointestinal tract, the intestinal biota. PD offers disproportionate removal of these toxins upon "first-pass", i.e., via PD fluid exchanges before reaching the systemic circulation beyond the gastrointestinal compartment. Studies examining the net removal gradient of protein-bound uremic toxins during PD are scarce, whereas RRF receives considerably more attention without effective interventions being developed to preserve it. We propose an alternative view on PD, emphasizing the modality's compartmental nature, both for its benefits and the limitations.

Proton Pump Inhibitors in Gastroesophageal Reflux Disease: Friend or Foe

PURPOSE OF REVIEW

Proton pump inhibitor (PPI) use in gastroesophageal reflux disease (GERD) has been redefined, in light of recent advances highlighting GERD phenotypes that respond to PPIs, and fresh revelations of potential risks of long-term PPI therapy.

RECENT FINDINGS

Erosive esophagitis predicts excellent response to PPI therapy, but non-erosive reflux disease (NERD) with abnormal reflux parameters on ambulatory reflux monitoring also demonstrates a similar response. In contrast, response is suboptimal in the absence of abnormal reflux parameters. In this setting, if an alternate appropriate indication for PPI therapy does not coexist, risks may outweigh benefits of PPI therapy. Adverse events from long-term PPI therapy continue to be reported, most based on association rather than cause-and-effect. Appropriate indications need to be established before embarking on long-term PPI therapy. Future research will define true risks of long-term PPI therapy, and develop alternate management options for acid peptic diseases.

Tablet and oral liquid L-thyroxine formulation in the treatment of naïve hypothyroid patients with Helicobacter pylori infection

To compare the clinical efficacy of tablet and oral liquid L-thyroxine (LT4) formulation in naïve hypothyroid subjects with Helicobacter pylori infection. Forty-seven adult naïve hypothyroid subjects with dyspeptic symptoms were investigated with upper endoscopy and divided into: 28 patients with Helicobacter pylori infection (Group A); 15 patients without gastric alterations (group B); 4 patients with autoimmune gastritis were excluded from the study. Subjects were randomly treated with a same dose of LT4 tablet (TAB) or oral liquid formulation (SOL), for 9 months on group A and 6 months on group B. Helicobacter pylori infection was eradicated after 3 months of LT4 treatment. On group A, after 3 months (before Helicobacter pylori eradication), subjects treated with SOL showed a greater thyroid-stimulating hormone reduction (ΔTSH_3-0: TAB = -4.1 ± 4.6 mU/L; SOL = -7.7 ± 2.5 mU/L; p = 0.029) and a greater homogeneity in the thyroid-stimulating hormone values (TSH_3mo: TAB = 5.7 ± 4.9 mU/L; SOL = 4.1 ± 2.0 mU/L; p = 0.025), compared to LT4 tablet. At 9 months (after 6 months of Helicobacter pylori eradication) mean thyroid-stimulating hormone values were lower in subjects treated with LT4 tablet (TSH_9mo: TAB = 1.8 ± 1.2 mU/L; SOL = 3.2 ± 1.7 mU/L; p = 0.006). On group B no difference were observed, at each time point, in the mean thyroid-stimulating hormone values and thyroid-stimulating hormone variations between two LT4 formulations. LT4 liquid formulation may produce a better clinical response compared to the tablet formulation in hypothyroid subjects with Helicobacter pylori infection.

The Safety of Appropriate Use of Over-the-Counter Proton Pump Inhibitors: An Evidence-Based Review and Delphi Consensus

The availability of over-the-counter (OTC) proton pump inhibitors (PPIs) for the short-term (2 weeks) management of frequent heartburn (≥2 days/week) has increased markedly, yet evidence-based recommendations have not been developed. A panel of nine international experts in gastroesophageal reflux disease developed consensus statements regarding the risks and benefits of OTC PPIs using a modified Delphi process. Consensus (based on ≥80% approval) was reached through multiple rounds of remote voting and a final round of live voting. To identify relevant data, the available literature was searched and summarized. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system terminology was used to rate the quality of evidence and strength of recommendations; consensus was based on ≥2/3 agreement. After 4 rounds of review, consensus was achieved for 18 statements. Notably, the available data did not directly reflect OTC use, but instead, prescription use; therefore, extrapolations to the OTC setting were often necessary. This limitation is regrettable, but it justifies performing this exercise to provide evidence-based expert opinion on a widely used class of drugs. The panel determined that using OTC PPIs according to label instructions is unlikely to mask the symptoms of esophageal or gastric cancer or adversely impact the natural history of related precursor conditions. OTC PPIs are not expected to substantially affect micronutrient absorption or bone mineral density or cause community-acquired pneumonia, Clostridium difficile infection, or cardiovascular adverse events. However, OTC PPI use may be associated with slightly increased risks for infectious diarrhea, certain idiosyncratic reactions, and cirrhosis-related spontaneous bacterial peritonitis. The available evidence does not suggest that OTC PPI use consistent with label instructions is associated with substantial health risks. To minimize potential risks, healthcare professionals and consumers must actively participate in decision making when managing reflux-related symptoms in the self-care setting.

Gastric Mixing During Food Digestion: Mechanisms and Applications

Gastric mixing is a complex process that is governed by meal properties, such as food buffering capacity, physical properties, and the rate of breakdown as well as physiological factors, such as the rate of gastric secretions, gastric emptying, and gastric motility. Gastric mixing processes have been studied through the use of experimental and computational methods. Gastric mixing impacts the intragastric pH distribution and residence time in the stomach for ingested materials. Development of a fundamental understanding of the advective and diffusion processes and their roles in gastric mixing will be important in furthering our understanding of food breakdown, microbial survival, and drug dissolution during gastric digestion.

Oral Contraceptives after Bariatric Surgery

OBJECTIVE

Bariatric surgery offers a highly effective mode of treatment for obese patients. Some procedures such as bypass cause an alteration in normal gastrointestinal tract with possible consequences for the uptake of orally administered drugs.

METHODS

We assessed the literature to ascertain whether the use of oral drugs and especially oral contraceptives is effective and adequate after bariatric surgery.

RESULTS

The bioavailability of drugs could be affected by the solubility and pH of the modified medium after bariatric surgery and by the loss of gastrointestinal transporters. Bariatric surgery could potentially result in a transient change in the absorption of drugs such as analgesics, antibiotics, antiarrhythmics, anticoagulants, psychotropic, and oral contraceptive drugs. Effective contraception is especially critical in the postoperative period, and implants might be representing a safe contraceptive method in women undergoing bariatric surgery.

CONCLUSION

Each drug will have to be evaluated with respect to its site of absorption and its mechanism of absorption, with special attention on parameters influencing the effectiveness of the absorption processes.

Persisting Hypocalcemia After Surgical Parathyroidectomy: The Differential Effectiveness of Calcium Citrate Versus Calcium Carbonate With Acid Suppression

The effectiveness of oral calcium (Ca) may be contingent on a patient׳s factors beyond compliance, such as proton-pump inhibitor use and the choice of calcium supplements. A 32-year-old Hispanic male with end-stage renal disease on peritoneal dialysis underwent successful surgical parathyroidectomy (intact parathyroid hormone level: 2,328pg/mL; postsurgical: 287-69pg/mL [normal: 8.5-72.5]). His postoperative course was complicated by severe and recurrent hypocalcemia as outpatient and he needed repeated admissions for intravenous Ca gluconate. Initially, severe hypocalcemia (corrected Ca: 4.8-5.6mg/dL; nadir ionized Ca: 0.57-0.69mmol/L) was attributed solely to medical noncompliance with oral Ca carbonate (3750mg, 3×/day between meals) and calcitriol (2-4mcg/day). Recognizing coexisting treatment with proton-pump inhibitor, oral Ca supplement was changed to calcium citrate (2,850mg, 3×/day) with prompt resolution of hypocalcemia (corrected Ca: 8.1-8.3mg/dL). This current case and the included literature review emphasize the disproportionate effectiveness of Ca citrate in subjects with achlorhydria.

Effective and safe proton pump inhibitor therapy in acid-related diseases - A position paper addressing benefits and potential harms of acid suppression

BACKGROUND

The introduction of proton pump inhibitors (PPIs) into clinical practice has revolutionized the management of acid-related diseases. Studies in primary care and emergency settings suggest that PPIs are frequently prescribed for inappropriate indications or for indications where their use offers little benefit. Inappropriate PPI use is a matter of great concern, especially in the elderly, who are often affected by multiple comorbidities and are taking multiple medications, and are thus at an increased risk of long-term PPI-related adverse outcomes as well as drug-to-drug interactions. Herein, we aim to review the current literature on PPI use and develop a position paper addressing the benefits and potential harms of acid suppression with the purpose of providing evidence-based guidelines on the appropriate use of these medications.

METHODS

The topics, identified by a Scientific Committee, were assigned to experts selected by three Italian Scientific Societies, who independently performed a systematic search of the relevant literature using Medline/PubMed, Embase, and the Cochrane databases. Search outputs were distilled, paying more attention to systematic reviews and meta-analyses (where available) representing the best evidence. The draft prepared on each topic was circulated amongst all the members of the Scientific Committee. Each expert then provided her/his input to the writing, suggesting changes and the inclusion of new material and/or additional relevant references. The global recommendations were then thoroughly discussed in a specific meeting, refined with regard to both content and wording, and approved to obtain a summary of current evidence.

RESULTS

Twenty-five years after their introduction into clinical practice, PPIs remain the mainstay of the treatment of acid-related diseases, where their use in gastroesophageal reflux disease, eosinophilic esophagitis, Helicobacter pylori infection, peptic ulcer disease and bleeding as well as, and Zollinger-Ellison syndrome is appropriate. Prevention of gastroduodenal mucosal lesions (and symptoms) in patients taking non-steroidal anti-inflammatory drugs (NSAIDs) or antiplatelet therapies and carrying gastrointestinal risk factors also represents an appropriate indication. On the contrary, steroid use does not need any gastroprotection, unless combined with NSAID therapy. In dyspeptic patients with persisting symptoms, despite successful H. pylori eradication, short-term PPI treatment could be attempted. Finally, addition of PPIs to pancreatic enzyme replacement therapy in patients with refractory steatorrhea may be worthwhile.

CONCLUSIONS

Overall, PPIs are irreplaceable drugs in the management of acid-related diseases. However, PPI treatment, as any kind of drug therapy, is not without risk of adverse effects. The overall benefits of therapy and improvement in quality of life significantly outweigh potential harms in most patients, but those without clear clinical indication are only exposed to the risks of PPI prescription. Adhering with evidence-based guidelines represents the only rational approach to effective and safe PPI therapy. Please see related Commentary: doi: 10.1186/s12916-016-0724-1 .