In vitro methods can forecast the effects of intragastric residence on dosage form performance

Use of Magnetic Resonance Imaging for Visualization of Oral Dosage Forms in the Human Stomach: A Scoping Review

Oral dosage forms are the most widely and frequently used formulations to deliver active pharmaceutical ingredients (APIs), due to their ease of administration and noninvasiveness. Knowledge of intragastric release rates and gastric mixing is crucial for predicting the API release profile, especially for immediate release formulations. However, knowledge of the intragastric fate of oral dosage forms in vivo to date is limited, particularly for dosage forms administered when the stomach is in the fed state. An improved understanding of gastric food processing, dosage form location, disintegration times, and food effects is essential for greater understanding for effective API formulation design. In vitro standard and controlled modeling has played a significant role in predicting the behavior of dosage forms in vivo. However, discrepancies are reported between in vitro and in vivo disintegration times, with these discrepancies being greatest in the fed state. Studying the fate of a dosage form in vivo is a challenging process, usually requiring the use of invasive methods, such as intubation. Noninvasive, whole body imaging techniques can however provide unique insights into this process. A scoping review was performed systematically to identify and critically appraise published studies using MRI to visualize oral solid dosage forms in vivo in healthy human subjects. The review identifies that so far, an all-purpose robust contrast agent or dosage form type has not been established for dosage form visualization and disintegration studies in the gastrointestinal system. Opportunities have been identified for future studies, with particular focus on characterizing dosage form disintegration for development after the consumption food, as exemplified by the standard Food and Drug Administration (FDA) high fat meal.

Dissolution testing of modified release products with biorelevant media: An OrBiTo ring study using the USP apparatus III and IV

During the OrBiTo project, our knowledge on the gastrointestinal environment has improved substantially and biorelevant media composition have been refined. The aim of this study was to propose optimized biorelevant testing conditions for modified release products, to evaluate the reproducibility of the optimized compendial apparatus III (USP apparatus III) and compendial apparatus IV (USP apparatus IV, open-loop mode) dissolution methods and to evaluate the usefulness of these methods to forecast the direction of food effects, if any, based on the results of two «ring» studies and by using two model modified release (MR) products, Ciproxin / Cipro XR and COREG CR. Six OrBiTo partners participated in each of the ring studies. All laboratories were provided with standard protocols, pure drug substance, and dose units. For the USP apparatus III, the dissolution methods applied to Ciproxin / Cipro XR, a monolithic MR product of an active pharmaceutical ingredient (API) with moderate aqueous solubility, were robust with low intra- and inter-laboratory data variability. Data from all partners were in line on a qualitative basis with food effect data in humans. For the USP apparatus IV, the dissolution methods applied to COREG CR, a multiparticulate, pH dependent, MR product of an API with low and pH dependent solubility led to high intra- and inter- laboratory data variability. Data from all partners were in line, on a qualitative basis, with the previously observed food effects in humans.

The impact of food intake on the luminal environment and performance of oral drug products with a view to in vitro and in silico simulations: a PEARRL review

Objectives

Using the type of meal and dosing conditions suggested by regulatory agencies as a basis, this review has two specific objectives: first, to summarize our understanding on the impact of food intake on luminal environment and drug product performance and second, to summarize the usefulness and limitations of available in vitro and in silico methodologies for the evaluation of drug product performance after food intake.

Key findings

Characterization of the luminal environment and studies evaluating product performance in the lumen, under conditions suggested by regulatory agencies for simulating the fed state, are limited. Various in vitro methodologies have been proposed for evaluating drug product performance in the fed state, but systematic validation is lacking. Physiologically based pharmacokinetic (PBPK) modelling approaches require the use of in vitro biorelevant data and, to date, have been used primarily for investigating the mechanisms via which an already observed food effect is mediated.

Summary

Better understanding of the impact of changes induced by the meal administration conditions suggested by regulatory agencies on the luminal fate of the drug product is needed. Relevant information will be useful for optimizing the in vitro test methods and increasing the usefulness of PBPK modelling methodologies.

Enzymatic activity in the presence of surfactants commonly used in dissolution media, Part 1: Pepsin

The United States Pharmacopeia (USP) General Chapters Dissolution 〈711〉 and Disintegration and Dissolution of Dietary Supplements 〈2040〉 allows the use of enzymes in dissolution media when gelatin capsules do not conform to dissolution specifications due to cross linking. Possible interactions between enzymes and surfactants when used together in dissolution media could result in loss of the enzymatic activity. Pepsin is an enzyme commonly used in dissolution media, and in this work, the activity of pepsin was determined in the presence of different surfactants as usually found in case of dissolution tests of certain gelatin capsule formulations. Pepsin enzymatic activity was determined according to the Ninth Edition of the Food Chemicals Codex (FCC) 9 method, in dissolution conditions: simulated gastric fluid, 37 °C and 50 rpm. Sodium dodecyl sulfate (SDS), cetyltrimethyl ammonium bromide (CTAB), polysorbate 80 (Tween 80) and octoxynol 9 (Triton X100) in concentrations above and below their critical micellar concentrations were selected. Results showed a significant reduction in the activity of pepsin at all the concentrations of SDS assayed. On the contrary, CTAB, Tween 80, and Triton X100 did not alter the enzymatic activity at of pepsin any of the concentration assayed. This data demonstrates a rational selection of the surfactant to be used when pepsin is required in dissolution test.

Enzymes in the dissolution testing of gelatin capsules

Gelatin capsules are a widely used dosage form both for pharmaceutical drug products as well as dietary supplements. Gelatin in the presence of certain compounds, mainly aldehydes, or in high humidity and high temperature conditions can cross-link. Cross-linking involves covalent bonding of the amine group of a lysine side chain of one gelatin molecule to a similar amine group on another molecule. The covalent bonding is, for practical purposes, irreversible. Cross-linking results in the formation of a pellicle on the internal or external surface of the gelatin capsule shell that prevents the capsule fill from being released. In vitro dissolution testing of cross-linked gelatin capsules can result in slower release of the drug or no release at all. The data obtained by the Gelatin Capsule Working Group, created in the early 90s to investigate noncompliance of gelatin capsules, was used to establish the type and amounts of enzymes that can be added to the dissolution medium in the case of test failure to the presence of cross-linking in the gelatin. The two-tier dissolution testing was included in the US Pharmacopeia and it recommends the addition of pepsin (pH below 6.8) or pancreatin (pH above 6.8) to the medium depending on its pH. Pepsin shows good protease activity up to pH 4 and pancreatin above pH 6 leaving a gap where neither one has good activity. Possible proteolytic enzymes that could be used for the pH range 4-6.8 could be papain or bromelain.

Feasibility of capsule endoscopy for direct imaging of drug delivery systems in the fasted upper-gastrointestinal tract

PURPOSE

To develop a minimally-invasive method for direct visualization of drug delivery systems in the human stomach and to compare the obtained results with an established in vitro model. The method should provide the capsule rupture, dispersion characteristics, and knowledge regarding the surrounding physiological environment in the stomach.

METHODS

A capsule endoscopic method was developed. The disintegration time, dispersion characteristics and the impact of the physiological environment on different lipid based delivery systems in different gelatin capsules in the fasted stomach of nine healthy volunteers were visualized. Biorelevant dissolution studies using a USP II apparatus and a droplet size analysis of the released SNEDDS were performed.

RESULTS

Visualization of the behavior of both hard and soft gelatin capsules formulations was possible. The disintegration and dispersion of EP oil in a soft capsule and SNEDDS in a hard shell capsule were visualized. The in vitro release rates were different from the in vivo release rates of the soft capsule due to volume, fluid composition and motility differences but not for the hard capsule containing SNEDDS.

CONCLUSIONS

A minimally-invasive capsule endoscopic method was developed for direct visualizing of drug delivery systems in the human stomach and maybe later, in the duodenum.

Biorelevant in-vitro performance testing of orally administered dosage forms

Objectives

This review focuses on the evolution and current status of biorelevant media and hydrodynamics, and discusses the usefulness of biorelevant performance testing in the evaluation of specific dosage form related lumenal processes.

Key findings

During the last 15 years our knowledge of the gastrointestinal environment (including the lower gut) has improved dramatically and biorelevant media composition and, to a lesser extent, biorelevant hydrodynamics, have been refined. Biorelevant dissolution/release testing is useful for the evaluation of formulation and food effects on plasma levels after administration of immediate release dosage forms containing low solubility compounds and after administration of extended release products. Lumenal disintegration times of immediate release dosage forms and the bile acid sequestering activity of resins in the lumen can also be successfully forecasted with biorelevant in vitro testing.

Summary

Biorelevant in-vitro performance testing is an important tool for evaluating intralumenal dosage form performance. Since the formulation of new active pharmaceutical ingredients for oral delivery is more challenging than ever before, efforts to improve the predictability of biorelevant tests are expected to continue.

Predicting the human in vivo performance of different oral capsule shell types using a novel in vitro dynamic gastric model

The disintegration of a capsule shell may determine the onset of drug dissolution from capsule formulations. In this study, the release of a rapidly dissolving model drug (paracetamol), from two hydroxypropyl methylcellulose capsules containing either carageenan (HPMC-C) or gellan gum (HPMC-G) and one hard gelatin (HG) capsule, were investigated using a conventional in vitro model, the USP dissolution apparatus I, and a novel in vitro model of the human gastric compartment, the dynamic gastric model (DGM). The results obtained in vitro were compared with in vivo gamma scintigraphy human data and in vivo gastric emptying profiles available in the literature. The drug release from HPMC-G capsules, observed with the USP dissolution apparatus I, was delayed with respect to the other two capsules, while the results obtained from the DGM in the fasted state were closer together, which was in agreement with data from the in vivo studies. In the fasted state, the capsule rupture times obtained from the DGM were similar to those observed by gamma scintigraphy in vivo studies. In the fed state, the 'apparent' rupture times observed with the DGM were delayed compared to fasted, and were even longer than those observed by scintigraphy in vivo for HPMC-G and HG capsules. However, these discrepancies can reasonably be explained by considering the impact of food upon dispersion of the capsule contents and the sampling from the DGM, when compared to the human scintigraphy experiments.

Mechanistic study of the azithromycin dosage-form-dependent food effect

PURPOSE

Azithromycin capsules are known to exhibit a negative food effect, manifest as a decrease in azithromycin bioavailability in the fed state. Azithromycin tablets are known to be bioequivalent to capsules in the fasted state, but do not exhibit a food effect. In the present study, the involvement of gastric degradation of azithromycin to des-cladinose azithromycin (DCA) has been investigated as a possible mechanism for the observed capsule food effect.

METHODS

Healthy volunteers were dosed with azithromycin tablets and capsules, fasted and fed, in a four-way randomized crossover study. Serum levels of DCA were measured as a function of time post-dose. Natural log-transformed PK parameters were statistically analyzed using an ANOVA model appropriate for the study design.

RESULTS

When capsules were dosed to fed subjects, the systemic AUC for DCA was 243% of the value observed after fasted-state dosing, and the DCA C(max) was 270% of the value observed after fasted-state dosing. When azithromycin tablets were dosed in the fasted and fed states, there was no significant difference in systemic DCA.

CONCLUSION

Gastric degradation of azithromycin to DCA is the likely mechanism for the observed negative food effect observed for azithromycin capsules. This effect is not observed for tablets. These observations suggest that azithromycin capsules exhibit slow and/or delayed disintegration in the fed stomach, resulting in extended gastric residence and degradation of a portion of the gastrically retained azithromycin.