Changes In Gastric pH Research Articles

Synthesis and Physicochemical Stability of a Copaiba Balsam Oil (Copaifera sp.) Nanoemulsion and Prospecting of Toxicological Effects on the Nematode Caenorhabditis elegans.

Nanoemulsions are dispersions of oil-in-water (O/W) and water-in-oil (W/O) immiscible liquids. Thus, our main goal was to formulate a nanoemulsion with low surfactant concentrations and outstanding stability using Copaiba balsam oil (Copaifera sp.). The high-energy cavitation homogenization with low Tween 80 levels was employed. Then, electrophoretic and physical mobility properties were assessed, in addition to a one- and two-year physicochemical characterization studies assessment. Copaiba balsam oil and nanoemulsions obtained caryophyllene as a major constituent. The nanoemulsions stored at 4 ± 2 °C exhibited better physical stability. Two years after formulation, the nanoemulsion showed a reduction in the particle size. The size underwent changes in gastric, intestinal, and blood pH, and the PdI was not changed. In FTIR, characteristic bands of sesquiterpenes and overlapping bands were detected. When subjected to freezing and heating cycles, nanoemulsions did not show macroscopic changes in higher concentrations. Nanoemulsions subjected to centrifuge force by 1000 rpm do not show macroscopic instability and phase inversion or destabilization characteristics when diluted. Therefore, the nanoemulsion showed stability for long-term storage. The nematode Caenorhabditis elegans was used to assess the potential toxicity of nanoemulsions. The nanoemulsion did not cause toxicity in the animal model, except in the highest concentration tested, which decreased the defecation cycle interval and body length. The toxicity and stability outcomes reinforce the nanoemulsions' potential for future studies to explore pharmacological mechanisms in superior experimental designs.

Evaluation of Gastric pH and Gastrin Concentrations in Horses Subjected to General Inhalation Anesthesia in Dorsal Recumbency.

The prevalence of gastric disorders in high-performance horses, especially gastric ulceration, ranges from 50 to 90%. These pathological conditions have negative impacts on athletic performance and health. This study was designed to evaluate changes in gastric pH during a 24 h period and to compare gastrin concentrations at different time points in horses undergoing general inhalation anesthesia and dorsal recumbency. Twenty-two mixed-breed mares weighing 400 ± 50 kg and aged 8 ± 2 years were used. Of these, eight were fasted for 8 h and submitted to 90 min of general inhalation anesthesia in dorsal recumbency. Gastric juice samples were collected prior to anesthesia (T0), and then at 15 min intervals during anesthesia (T15-T90). After recovery from anesthesia (45 ± 1 min), samples were collected every hour for 24 h (T1 to T24) for gastric juice pH measurement. During this period, mares had free access to Bermuda grass hay and water and were fed a commercial concentrate twice (T4 and T16). In a second group (control), four non-anesthetized mares were submitted to 8 h of fasting followed by nasogastric intubation. Gastric juice samples were then collected at T0, T15, T30, T45, T60, T75, and T90. During this period, mares did not receive food or water. After 45 min, mares had free access to Bermuda grass hay and water, and gastric juice samples were collected every hour for four hours (T1 to T4). In a third group comprising ten non-fasted, non-anesthetized mares with free access to Bermuda grass hay and water, gastric juice samples were collected 30 min after concentrate intake (T0). In anesthetized mares, blood gastrin levels were measured prior to anesthesia (8 h fasting; baseline), during recovery from anesthesia, and 4 months after the anesthetic procedure, 90 min after the morning meal. Mean values of gastric juice pH remained acidic during general anesthesia. Mean pH values were within the physiological range (4.52 ± 1.69) and did not differ significantly between time points (T15-T90; p > 0.05). After recovery from anesthesia, mean gastric pH values increased and remained in the alkaline range throughout the 24 h period of evaluation. Significant differences were observed between T0 (4.88 ± 2.38), T5 (7.08 ± 0.89), T8 (7.43 ± 0.22), T9 (7.28 ± 0.36), T11 (7.26 ± 0.71), T13 (6.74 ± 0.90), and T17 (6.94 ± 1.04) (p < 0.05). The mean gastric juice pH ranged from weakly acidic to neutral or weakly alkaline in all groups, regardless of food and water intake (i.e., in the fasted, non-fasted, and fed states). Mean gastric pH measured in the control group did not differ from values measured during the 24 h post-anesthesia period or in the non-fasted group. Gastrin concentrations increased significantly during the post-anesthetic period compared to baseline (20.15 ± 7.65 pg/mL and 15.15 ± 3.82 pg/mL respectively; p < 0.05). General inhalation anesthesia and dorsal recumbency did not affect gastric juice pH, which remained acidic and within the physiological range. Gastric juice pH was weakly alkaline after recovery from anesthesia and in the fasted and fed states. Serum gastrin levels increased in response to general inhalation anesthesia in dorsal recumbency and were not influenced by fasting. Preventive pharmacological measures are not required in horses submitted to general anesthesia and dorsal recumbency.

Gastroprotective Effect of Quercus infectoria Olivier Galls on Ethanol-Induced Gastritis in Rats.

One of the common inflammatory disorders that substantially affects the stomach and its mucosa is gastritis. It can be induced by non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, alcohol, Helicobacter pylori infection, and stress. These factors affect cellular regeneration, mucus production, and bicarbonate secretion, resulting finally in inflammation and ulceration. Ethanol-induced gastritis is one of the commonly used models for studying the pathology of gastritis and investigating the effect of drugs in managing the disease. Several drugs, such as proton pump inhibitors (PPIs), are available to control and correct the pathological signs of gastritis; however, the side effects of such drugs represent an obstacle to their applications in many cases. Quercus infectoria(QI) Olivier galls are formed as a pathological response to wasp insults to the tree. They are rich in several bioactive molecules, e.g., gallotannins that have been shown to be effective in several inflammatory conditions due to their antioxidant and anti-inflammatory potentials. In this study, we aimed to evaluate the therapeutic potential of QI gall extract (QIGE) in treating ethanol-induced gastritis in rats. To test this, 20 adult male Swiss rats were divided into four groups: healthy control, ethanol-treated (80% in water, 5 ml/kg, per oral gavage), ethanol + omeprazole (20 mg/kg, per oral gavage), and ethanol + QIGE (300 mg/kg, per oral gavage). QIGE was administered for seven days before ethanol administration, which took place three hours after the last QIGE dose. Three hours after ethanol intake, animals were euthanized, gastric content was collected, and stomach tissue was examined for macroscopic changes and then fixed to be further utilized for histological assessment by hematoxylin and eosin (H&E), periodic acid-Schiff (PAS), and Masson's trichrome staining. Ethanol treatment significantly decreased gastric pH and increased gastric acidity compared to healthy control. It also induced clear morphological and histological damage and ulceration, depleted mucus on the gastric epithelium, and induced edema and collagen deposition in gastric submucosa. The QIGE treatment ameliorated the changes in gastric pH and total acidity. It also protected stomach tissue from ethanol-induced ulceration, histopathological changes, edema, and collagen deposition. The protective effects of QIGE were comparable to those of omeprazole. In conclusion, QI gall extract possesses a promising gastroprotective effect against ethanol-induced gastritis.

Ipomoea carnea mitigates ethanol-induced ulcers in irradiated rats via Nrf2/HO−1 pathway: an in vivo and in silico study

The aim of this study was to investigate the potential of Ipomoea carnea flower methanolic extract (ICME) as a natural gastroprotective therapy against ethanol-induced gastric ulcers, particularly in individuals exposed to ionizing radiation (IR). The study focused on the Nrf2/HO−1 signaling pathway, which plays a crucial role in protecting the gastrointestinal mucosa from oxidative stress and inflammation. Male Wistar rats were divided into nine groups, the control group received distilled water orally for one week, while other groups were treated with ethanol to induce stomach ulcers, IR exposure, omeprazole, and different doses of ICME in combination with ethanol and/or IR. The study conducted comprehensive analyses, including LC-HRESI-MS/MS, to characterize the phenolic contents of ICME. Additionally, the Nrf2/HO−1 pathway, oxidative stress parameters, gastric pH, and histopathological changes were examined. The results showed that rats treated with IR and/or ethanol exhibited histopathological alterations, increased lipid peroxidation, decreased antioxidant enzyme activity, and reduced expression levels of Nrf2 and HO−1. However, pretreatment with ICME significantly improved these parameters. Phytochemical analysis identified 39 compounds in ICME, with flavonoids, hydroxybenzoic acids, and fatty acids as the predominant compounds. Virtual screening and molecular dynamics simulations suggested that ICME may protect against gastric ulceration by inhibiting oxidative stress and inflammatory mediators. In conclusion, this study demonstrates the potential of ICME as a natural gastroprotective therapy for preventing gastric ulcers. These findings contribute to the development of novel interventions for gastrointestinal disorders using natural plant extracts particularly in individuals with a history of radiation exposure.

Exploring Differences in Pharmacometrics of Rabeprazole between Genders via Population Pharmacokinetic-Pharmacodynamic Modeling.

Rabeprazole is a proton pump inhibitor that inhibits gastric acid production and increases gastric pH; it is widely used clinically as a treatment option for gastritis and gastric ulcers. However, information on the inter-individual variability of rabeprazole pharmacometrics, which is a key element in establishing its scientific clinical use, is still lacking. Particularly, the differences in pharmacokinetics between genders and the degree of variation in pharmacodynamics have not been clearly identified. Thus, the main purpose of this study was to explore any differences in rabeprazole pharmacokinetics between genders and to quantitatively predict and compare the effects of any differences in pharmacokinetics between genders on known pharmacodynamics using population pharmacokinetic-pharmacodynamic modeling. To compare pharmacokinetics and modeling data between genders, bioequivalence results were used simultaneously on healthy Korean men and women using the physiological and biochemical parameters derived from each individual. Pharmacodynamic modeling was performed based on the data of previously reported gastric pH changes in response to rabeprazole plasma concentrations, which was co-linked to the central compartmental bioavailable concentration in the population pharmacokinetic model. There was no significant difference in the level of rabeprazole exposure and elimination of plasma between genders following oral administration of 10 mg enteric-coated rabeprazole tablets; however, there was a clear delay in absorption in women compared to men. Additionally, a comparison of pharmacokinetic parameters normalized to body weight between genders showed that the maximum plasma concentrations were significantly higher in women than in men, again suggesting gender differences in rabeprazole absorption. The population pharmacokinetic profiles for rabeprazole were described using a three-sequential multi-absorption with lag time (Tlag) two-compartment model, whereas body surface area and gender were explored as effective covariates for absorption rate constant and Tlag, respectively. The effect of increased gastric pH due to plasma exposure to rabeprazole was explained using the Sigmoid Emax model, with the baseline as a direct response. The significantly longer rabeprazole Tlag in females delayed the onset of an effect by an average of 1.58 times (2.02-3.20 h), yet the overall and maximum effects did not cause a significant difference within 15%. In the relative comparison of the overall efficacy of rabeprazole enteric-coated tablet administration between genders, it was predicted based on the model that males would have higher efficacy. This study will be very useful in broadening the perspective of interpreting drug diversity between individuals and narrowing the gap in knowledge related to scientific precision medicine by presenting new information on gender differences in rabeprazole pharmacometrics that had not been previously identified.

Atractylenolide III ameliorated reflux esophagitis via PI3K/AKT/NF-κB/iNOS pathway in rats

Reflux esophagitis (RE), an esophageal inflammation caused by reflux of gastric contents, often damages the lower esophagus, seriously affecting the quality of life of patients. This study aims to investigate the therapeutic effects and underlying molecular mechanisms of atractylenolide III (ATL III) on RE model rats. In this research, the RE rat model is established sequentially following hemipyloric ligation, cardia transection, and hydrochloric acid perfusion. Further, the RE-induced rats are intragastrically administrated with ATL III (0.6, 1.2, and 2.4 mg/kg/D) for 28 days to evaluate ATL III therapeutic effects. To study the molecular mechanism, RE rats are treated with a phosphoinositide-3 kinase (PI3K) agonist (740 Y–P) combined with ATL III. The histopathological changes in the esophagus are eventually observed by hematoxylin & eosin (H&E) staining. In addition to changes in gastric pH and levels of reactive oxygen species (ROS), enzyme-linked immunosorbent assay (ELISA) and Western blot analyses are used to detect the expression levels of tumor necrosis factor-α (TNF-α, mmol/L), interleukin (IL)-8, IL-6, IL-1β in the esophageal tissues. As a result, the lesions in the esophageal tissues of RE rats are alleviated, decreasing the macroscopic observation scores of the esophageal mucosa after ATL III treatment,. The experimental results indicated significantly increased pH value of the gastric contents and reduced ROS, thiobarbituric acid reactants (TBARS), TNF-α, IL-8, IL-6, and IL-1β levels, as well as expression levels of p-PI3K, p-AKT, iNOS, and nuclear NF-κB proteins in esophageal tissues. In conclusion, the study indicated that ATL III could efficiently treat RE in rats by inhibiting oxidative stress and inflammatory damage through the PI3K/AKT/NF-κB/iNOS pathway.

Gastric pH changes during post‐operative ileus in horses

Gastric pH changes during post‐operative ileus in horses

Physiologically based pharmacokinetic modeling to assess the drug-drug interactions of anaprazole with clarithromycin and amoxicillin in patients undergoing eradication therapy of H. pylori infection

ObjectiveThis study aimed to assess the pharmacokinetic (PK) interactions of anaprazole, clarithromycin, and amoxicillin using physiologically based pharmacokinetic (PBPK) models. MethodsThe PBPK models for anaprazole, clarithromycin, and amoxicillin were constructed using the GastroPlus™ software (Version 9.7) based on the physicochemical data and PK parameters obtained from literature, then were optimized and validated in healthy subjects to predict the plasma concentration-time profiles of these three drugs and assess the predictive performance of each model. According to the analysis of the properties of each drug, the developed and validated models were applied to evaluate potential drug-drug interactions (DDIs) of anaprazole, clarithromycin, and amoxicillin. ResultsThe developed PBPK models properly described the pharmacokinetics of anaprazole, clarithromycin, and amoxicillin well, and all predicted PK parameters (Cmax,ss, AUC0-τ,ss) ratios were within 2.0-fold of the observed values. Furthermore, the application of these models to predict the anaprazole-clarithromycin and anaprazole-amoxicillin DDIs demonstrates their good performance, with the predicted DDI Cmax,ss ratios and DDI AUC0-τ,ss ratios within 1.25-fold of the observed values, and all predicted DDI Cmax,ss, and AUC0-τ,ss ratios within 2.0-fold. The simulated results show no need to adjust the dosage when co-administered with anaprazole in patients undergoing eradication therapy of H. pylori infection since the dose remained in the therapeutic range. ConclusionThe whole-body PBPK models of anaprazole, clarithromycin, and amoxicillin were built and qualified, which can predict DDIs that are mediated by gastric pH change and inhibition of metabolic enzymes, providing a mechanistic understanding of the DDIs observed in the clinic of clarithromycin, amoxicillin with anaprazole.

Description of Gastric Acidity (pH) with Simple Method in Lipopolysaccharide Induced Mice

The gastrointestinal acidity/pH can considerably influence the stability and absorption of oral medications. As a result, understanding the circumstances for drug delivery requires knowledge of gastrointestinal pH. Mice injected with lipopolysaccharide (LPS) are used in the most well-studied animal models of sepsis. However, information on gastrointestinal pH in sepsis mice is still insufficient. This study was conducted to identify gastric pH values in mice induced by lipopolysaccharide. The LPS was injected intraperitoneally as well as 0.9% NaCl as control groups. Treated groups (LPS) consisted of four groups and the control group (0.9% NaCl) consisted of four groups. Ten mice were used in each group. Gastric pH measurement was conducted using pH meter Lutron PH-201. Based on this study, the factors that influenced gastric pH in sepsis animal models were the LPS doses and the time after LPS injection. The results of gastric pH measurement in sepsis mice did not show a decrease in the pH compared to the normal conditions. The dose of LPS significantly influences the gastric pH change.

Fe-Doped Carbon Dots as NIR-II Fluorescence Probe for In Vivo Gastric Imaging and pH Detection.

Carbon dots (CDs) with excellent cytocompatibility, tunable optical properties, and simple synthesis routes are highly desirable for use in optical bioimaging. However, the majority of existing CDs are triggered by ultraviolet/blue light, presenting emissions in the visible/first near-infrared (NIR-I) regions, which do not allow deep tissue penetration. Emerging research into CDs with NIR-II emission in the red region has generated limited designs with poor quantum yield, restricting their in vivo imaging applications due to low penetration depth. Developing novel CDs with NIR-II emissions and high quantum yield has significant and far-reaching applications in bioimaging and photodynamic therapy. Here, it is developed for the first time Fe-doped CDs (Fe-CDs) exhibiting the excellent linear relationship between 900-1200nm fluorescence-emission and pH values, and high quantum yield (QY-1.27%), which can be used as effective probes for in vivo NIR-II bioimaging. These findings demonstrate reliable imaging accuracy in tissue as deep as 4 mm, reflecting real-time pH changes comparable to a standard pH electrode. As an important example application, the Fe-CDs probe can non-invasively monitor in vivo gastric pH changes during the digestion process in mice, illustrating its potential applications in aiding imaging-guided diagnosis of gastric diseases or therapeutic delivery.

Intra- and inter-subject variability in gastric pH following a low-fat, low-calorie meal

Food can alter drug bioavailability through gastric pH changes. Time spent at gastric pH ranges is reported here, including variability data following ingestion of a light, mixed, 260 kcal meal. pH data was obtained for 20 healthy subjects undergoing SmartPill™ wireless motility capsule investigations on three separate visits. Gastric phase pH was sorted into pH < 2, 2–3, 3–4, 4–5 and > 5. All visits and all subjects were pooled to determine median time (25-75th percentiles) in minutes. Gastric emptying time was 176 (137–205) min with the majority of time, 111 (67 – 163), spent at pH < 2. Times spent at pH 2–3 and 3–4 were similar: 17 (5.7 – 35.6) and 18 (7.2–29.3). Time spent at pH 4–5 was 9 (1.3–20.6) and at pH > 5 was 0.7 (0–4.4). Intra-subject variability as determined by robust coefficient of variation (RCV)% was 30 % for pH < 2, 57 % for pH 2–3, 71 % for pH 3–4, 106 % for pH 4–5 and 144 % for pH > 5. Inter-subject variability RCV% was 49 % for pH < 2, 89 % for pH 2–3, 54 % for pH 3–4, 97 % for pH 4–5 and 148 % for pH > 5. Inter-subject variability can be up to approximately twofold higher than intra-subject variability at the lower pH ranges.

Integration of a Physiologically Based Pharmacokinetic and Pharmacodynamic Model for Tegoprazan and Its Metabolite: Application for Predicting Food Effect and Intragastric pH Alterations.

A physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) model for tegoprazan and its major metabolite M1 was developed to predict PK and PD profiles under various scenarios. The PBPK model for tegoprazan and M1 was developed and predicted using the SimCYP® simulator and verified using clinical study data obtained after a single administration of tegoprazan. The established PBPK/PD model was used to predict PK profiles after repeated administrations of tegoprazan, postprandial PK profiles, and intragastric pH changes. The predicted tegoprazan and M1 concentration–time profiles fit the observed profiles well. The arithmetic mean ratios (95% confidence intervals) of the predicted to observed values for the area under the curve (AUC0–24 h), maximum plasma drug concentration (Cmax), and clearance (CL) for tegoprazan and M1 were within a 30% interval. Delayed time of maximum concentration (Tmax) and decreased Cmax were predicted in the postprandial PK profiles compared with the fasted state. This PBPK/PD model may be used to predict PK profiles after repeated tegoprazan administrations and to predict differences in physiological factors in the gastrointestinal tract or changes in gastric acid pH after tegoprazan administration.

Physiologically Based Absorption Modelling to Explore the Formulation and Gastric pH Changes on the Pharmacokinetics of Acalabrutinib.

Acalabrutinib, a selective Bruton's tyrosine kinase inhibitor, is a biopharmaceutics classification system class II drug. The aim of this study was to develop a physiologically based pharmacokinetic (PBPK) model to mechanistically describe absorption of immediate release capsule formulation of acalabrutinib in humans. Integration of in vitro biorelevant measurements, dissolution studies and in silico modelling provided clinically relevant inputs for the mechanistic absorption PBPK model. The batch specific dissolution data were integrated in two ways, by fitting a diffusion layer model scalar to the drug product dissolution with integration of drug substance laser diffraction particle size data, or by fitting a product particle size distribution to the dissolution data. The latter method proved more robust and biopredictive. In both cases, the drug surface solubility was well predicted by the Simcyp simulator. The model using the product particle size distribution (P-PSD) for each clinical batch adequately captured the PK profiles of acalabrutinib and its active metabolite. Average fold errors were 0.89 for both Cmax and AUC, suggesting good agreement between predicted and observed PK values. The model also accurately predicted pH-dependent drug-drug interactions between omeprazole and acalabrutinib, which was similar across all clinical formulations. The model predicted acalabrutinib geometric mean AUC ratios (with omeprazole vs acalabrutinib alone) were 0.51 and 0.68 for 2 batches of formulations, which are close to observed values of 0.43 and 0.51~0.63, respectively. The mechanistic absorption PBPK model could be potentially used for future applications such as optimizing formulations or predicting the PK for different batches of the drug product.

Relationship between proton-pump inhibitor use and spontaneous bacterial peritonitis in cirrhotic patients with ascites

Objective The aim of this study was to assess the occurrence of spontaneous bacterial peritonitis in cirrhotic patients with ascites and is relationship to proton-pump inhibitor (PPI) use. Background Gastric acid plays an important role in resisting intestinal pathogens. Changes in gastric pH induced by antacids may damage the gastric protective barrier. Patients and methods This prospective cohort study was conducted on 100 patients of 18 years old or more, both sexes with liver cirrhosis and ascites. Patients were divided into two groups (50 patients in each); group (PPI use positive) with a history of PPIs use in the last 15 days at a dose of more than 20 mg and group (PPI use negative) without a history of PPI use. Results White blood cells in the blood and in the ascitic fluid showed significant increase in the PPI group than in the second group. Cultures of ascitic fluid were positive in 28 (56%) patients with PPI use, and 15 patients in the negative PPI use group and comparison showed significant increase in the positive PPI use group. The hazardous ratio of developing positive cultures in the PPI group is 1.687 times than the second group (95% confidence interval: 1.1–2.502). Conclusion The use of PPIs in cirrhotic patients who have ascites has a risk for developing spontaneous bacterial peritonitis; therefore, it is recommended to avoid their use in this category of patients.

Comprehensive PBPK model to predict drug interaction potential of Zanubrutinib as a victim or perpetrator.

A physiologically based pharmacokinetic (PBPK) model was developed to evaluate and predict (1) the effect of concomitant cytochrome P450 3A (CYP3A) inhibitors or inducers on the exposures of zanubrutinib, (2) the effect of zanubrutinib on the exposures of CYP3A4, CYP2C8, and CYP2B6 substrates, and (3) the impact of gastric pH changes on the pharmacokinetics of zanubrutinib. The model was developed based on physicochemical and in vitro parameters, as well as clinical data, including pharmacokinetic data in patients with B‐cell malignancies and in healthy volunteers from two clinical drug‐drug interaction (DDI) studies of zanubrutinib as a victim of CYP modulators (itraconazole, rifampicin) or a perpetrator (midazolam). This PBPK model was successfully validated to describe the observed plasma concentrations and clinical DDIs of zanubrutinib. Model predictions were generally within 1.5‐fold of the observed clinical data. The PBPK model was used to predict untested clinical scenarios; these simulations indicated that strong, moderate, and mild CYP3A inhibitors may increase zanubrutinib exposures by approximately four‐fold, two‐ to three‐fold, and <1.5‐fold, respectively. Strong and moderate CYP3A inducers may decrease zanubrutinib exposures by two‐ to three‐fold or greater. The PBPK simulations showed that clinically relevant concentrations of zanubrutinib, as a DDI perpetrator, would have no or limited impact on the enzyme activity of CYP2B6 and CYP2C8. Simulations indicated that zanubrutinib exposures are not impacted by acid‐reducing agents. Development of a PBPK model for zanubrutinib as a DDI victim and perpetrator in parallel can increase confidence in PBPK models supporting zanubrutinib label dose recommendations.

Gastric pH and volume change in emergency and elective cesarean section: A randomized trial

Context: Pregnancy is a condition when a woman suffers numerous changes in the body. These changes can be physical and physiological. There are numerous factors which affect the volume and gastric pH of a pregnant lady. A lady has to bear a number of changes during pregnancy, mainly in her first trimester and after pregnancy. Vomiting is a normal symptom of pregnancy which effects a lady in her first trimester. This badly affects the gastric content and increase in pH as well as volume. In cesarian cases also the digestion is badly affected and anesthesia also plays a major role in distortion of proper gastric functions. Aim: To compare the gastric pH of the fluid in elective cesarean v/s emergency sections. Setting and Design: This study is a cross-sectional survey performed in Lahore from September 2009 to June 2010. Material and Methods: A total number of 150(n= 150) patients were studied and divided into two groups. These patient were with elevated caesarian section and emergency caesarian section. Statical analysis: The results were statistically significant. (p-value < 0> Result: Patients in emergency cesarean section group had a lower value of gastric pH ranging from (2.16 + 0.64) and higher value of, the volume of gastric acidic (26.33 + 10.59) as compared to that in elective cesarean section group (4.56 + 1.28 and 11.65 + 4.37 respectively). Conclusion: The study concluded that in emergency and elective caesarian section the level of gastric volume was significantly high whereas the level of gastric pH was low. Keywords: Gastric pH, Emergency cesareans section gastric fluid volume, Elective cesarean section.

Evaluating the impact of acid-reducing agents on drug absorption using biorelevant in vitro tools and PBPK modeling - case example dipyridamole

BackgroundIn vitro and in silico methods have become an essential tool in assessing metabolic drug-drug interactions (DDI) and avoiding reduced efficacy and increased side-effects. Another important type of DDI is the impact of acid-reducing agent (ARA) co-therapy on drug pharmacokinetics due to changes in gastric pH, especially for poorly soluble weakly basic drugs. MethodsOne-stage, two-stage and transfer dissolution experiments with dipyridamole tablets using novel biorelevant media representing the ARA effect were conducted and the results were coupled with a PBPK model. Clinical pharmacokinetic data were compared with the simulations from the PBPK model and with output from TIM-1 experiments, an evolved in vitro system which aims to simulate the physiology in the upper GI tract. ResultsTwo-stage and transfer experiments confirmed that these in vitro set-ups tend to overestimate the extent of dipyridamole precipitation occurring in the intestines in vivo. Consequently, data from one-stage dissolution testing under elevated gastric pH conditions were used as an input for PBPK modeling of the ARA/dipyridamole interaction. Using media representing the ARA effect in conjunction with the PBPK model, the ARA effect observed in vivo was successfully bracketed. As an alternative, the TIM-1 system with gastric pH values adjusted to simulate ARA pre-treatment can be used to forecast the ARA effect on dipyridamole pharmacokinetics. ConclusionDrug-drug interactions of dipyridamole with ARA were simulated well with a combination of dissolution experiments using biorelevant media representing the gastric environment after an ARA treatment together with the PBPK model. Adjustment of the TIM-1 model to reflect ARA-related changes in gastric pH was also successful in forecasting the interaction. Further testing of both approaches for predicting ARA-related DDIs using a wider range of drugs should be conducted to verify their utility for this purpose.

Physiologically Based Pharmacokinetic Modeling Approach to Identify the Drug–Drug Interaction Mechanism of Nifedipine and a Proton Pump Inhibitor, Omeprazole

Proton pump inhibitors (PPIs) can affect the intragastric release of other drugs from their dosage forms by elevating the gastric pH. They may also influence drug absorption and metabolism by interacting with P-glycoprotein or with the cytochrome P450 (CYP) enzyme system. Nifedipine is a Biopharmaceutics Classification System (BCS) class II drug with low solubility across physiologic pH and high permeability. Previous studies have demonstrated that drug-drug interaction (DDI) existed between omeprazole and nifedipine with significantly increased systemic exposure of nifedipine in subjects after pre-treatment for 7days with omeprazole compared to the subjects without omeprazole treatment. It was shown that omeprazole not only induced an increase in intragastric pH, but also inhibited the CYP3A4 activity, while CYP3A4-mediated oxidation is the main metabolic pathway of nifedipine. The purpose of this study is to apply a physiologically based pharmacokinetic (PBPK) modeling approach to investigate the DDI mechanism for an immediate release formulation of nifedipine with omeprazole. A previously published model for omeprazole was modified to integrate metabolites and to update CYP inhibition based on the most updated published in vitro data. We simulated the nifedipine pharmacokinetics in healthy subjects with or without the multiple-dose pretreatment of omeprazole (20mg) following oral administrations of immediate-release (IR) (10mg) nifedipine. Nifedipine solubility at different pHs was used to simulate the nifedipine pharmacokinetics for both clinical arms. Multiple sensitivity analyses were performed to understand the impact of gastric pH and the CYP3A4-mediated gut and liver first pass metabolism on the overall nifedipine pharmacokinetics. The developed PBPK model properly described the pharmacokinetics of nifedipine and predicted the inhibitory effect of multiple-dose omeprazole on CYP3A4 activity. With the incorporation of the physiologic effect of omeprazole on both gastric pH and CYP3A4 to the PBPK model, the verified PBPK model allows evaluating the impact of the increase in gastric pH and/or CYP3A4 inhibition. The simulated results show that the nifedipine metabolic inhibition by omeprazole may play an important role in the DDI between nifedipine and omeprazole for IR nifedipine formulation. The developed full PBPK model with the capability to simulate DDI by considering gastric pH change and metabolic inhibition provides a mechanistic understanding of the observed DDI of nifedipine with a PPI, omeprazole.

Physiologically Based Absorption Modelling to Explore the Impact of Food and Gastric pH Changes on the Pharmacokinetics of Entrectinib

Entrectinib is a potent and selective tyrosine kinase inhibitor (TKI) of TRKA/B/C, ROS1, and ALK with both systemic and CNS activities, which has recently received FDA approval for ROS1 fusion-positive non-small cell lung cancer and NTRK fusion-positive solid tumors. This paper describes the application of aphysiologically based biophamaceutics modeling (PBBM) during clinical development to understand the impact of food and gastric pH changes on absorption of this lipophilic, basic, molecule with reasonable permeability but strongly pH-dependent solubility. GastroPlus™ was used to develop a physiologically based pharmacokinetics (PBPK) model integrating in vitro and in silico data and dissolution studies and in silico modelling in DDDPlus™ were used to understand the role of self-buffering and acidulant on formulation performance. Models were verified by comparison of simulated pharmacokinetics for acidulant and non-acidulant containing formulations to clinical data from a food effect study and relative bioavailability studies with and without the gastric acid-reducing agent lansoprazole. A negligible food effect and minor pH-dependent drug-drug interaction for the market formulation were predicted based on biorelevant in vitro measurements, dissolution studies, and in silico modelling and were confirmed in clinical studies. These outcomes were explained as due to the acidulant counteracting entrectinib self-buffering and greatly reducing the effect of gastric pH changes. Finally, sensitivity analyses with the verified model were applied to support drug product quality. PBBM has great potential to streamline late-stage drug development and may have impact on regulatory questions.

The comparison of gastric ph after premedication using ranitidine, antacids, and ranitidine-antacids combination in cesarean section

Background: Pregnant women are at high risk of experiencing gastric fluid aspiration, which is known as Mendelson's syndrome. The possibility of aspiration increases in an emergency condition. Low pH and high volume of aspirate increase the severity of aspiration. Ranitidine and antacids can increase gastric pH. This study aimed to compare gastric pH after receiving ranitidine, antacids, and ranitidine-antacids combination as premedication in patients undergoing an emergency cesarean section (C-section). Patients and Methods: This study is a true-experimental design on 27 participants who underwent a C-section at Dr. Saiful Anwar Hospital. The R group received ranitidine 50 mg, the A group received 10 ml of antacids, and the C group received the combination of both. The measurement of gastric pH was carried out on 0, 5, 15, 30, 45, and 60 min after premedication. The data were analyzed using the one-way ANOVA test. Results: The average change in gastric pH is better seen in the antacids group. The gastric pH increases from 3.19 ± 1.04 to 4.64 ± 1.20 at 60 min after premedication (P > 0.05). Ranitidine administration showed better results at 5, 15, and 30 min after premedication (P > 0.05). The combination of ranitidine and antacids showed better results at 45 and 60 min after premedication (P > 0.05). Conclusion: There is no significant difference in gastric pH after receiving premedication in patients undergoing a C-section. However, all groups show an increase in gastric pH after receiving premedication. The administration of ranitidine and antacids combination is not better than a single dose of ranitidine or antacids.