The Complexity of Bariatric Patient's Pharmacotherapy: Sildenafil Biopharmaceutics and Pharmacokinetics before vs. after Gastric Sleeve/Bypass

Postbariatric altered gastrointestinal (GI) anatomy/physiology may significantly harm oral drug absorption and overall bioavailability. In this work, sildenafil, the first phosphodiesterase-5 (PDE5) inhibitor, was investigated for impaired postbariatric solubility/dissolution and absorption; this research question is of particular relevance since erectile dysfunction (ED) is associated with higher body mass index (BMI). Sildenafil solubility was determined both in vitro and ex vivo, using pre- vs. postsurgery gastric contents aspirated from patients. Dissolution tests were done in conditions mimicking the stomach before surgery, after sleeve gastrectomy (post-SG, pH 5), and after one anastomosis gastric bypass (post-OAGB, pH 7). Finally, these data were included in physiologically based pharmacokinetic (PBPK) modelling (GastroPlus®) to simulate sildenafil PK before vs. after surgery. pH-dependent solubility was demonstrated with low solubility (0.3 mg/mL) at pH 7 vs. high solubility at pH 1-5, which was also confirmed ex vivo with much lower solubility values in postbariatric gastric samples. Hampered dissolution of all sildenafil doses was obtained under post-OAGB conditions compared with complete (100%) dissolution under both presurgery and post-SG conditions. PBPK simulations revealed delayed sildenafil absorption in postbariatric patients (increased tmax) and reduced Cmax, especially in post-OAGB patients, relative to a presurgery state. Hence, the effect of bariatric surgery on sildenafil PK is unpredictable and may depend on the specific bariatric procedure. This mechanistically based analysis suggests a potentially undesirable delayed onset of action of sildenafil following gastric bypass surgery.

Selective COX-2 inhibitors after bariatric surgery: Celecoxib, etoricoxib and etodolac post-bariatric solubility/dissolution and pharmacokinetics

Anatomical/physiological gastrointestinal changes after bariatric surgery may influence the fate of orally administered drugs.Since non-selective NSAIDs are not well-tolerated post-surgery, selective cyclooxygenase-2 (COX-2) inhibitors may be important for these patients. In this work we investigated celecoxib, etoricoxib and etodolac, for impaired post-bariatric solubility/dissolution and absorption. Solubility was studied in-vitro, and ex-vivoin aspirated gastric contents from patients pre- vs. post-surgery. Dissolution was studied in conditions simulating pre- vs. post-surgery stomach. Finally, the experimental solubility data were used in physiologically-based biopharmaceutics model (PBBM) (GastroPlus®) to simulate pre- vs. post-surgery celecoxib/etoricoxib/etodolac pharmacokinetic (PK) profiles.For etoricoxib and etodolac (but not celecoxib), pH-dependent solubility was demonstrated: etoricoxib solubility decreased ∼1000-fold, and etodolac solubility increased 120-fold, as pH increased from 1 to 7, which was also confirmed ex-vivo. Hampered etoricoxib dissolution and improved etodolac dissolution post-surgery was revealed. Tablet crushing, clinically recommended after surgery, failed to improve post-bariatric dissolution. PBBM simulations revealed significantly impaired etoricoxib absorption post-surgery across all conditions; for instance, 79% lower Cmax and 53% decreased AUC was simulated post-gastric bypass procedure, after single 120 mg dose. Celecoxib and etodolac maintained unaffected absorption after bariatric surgery.This mechanistically-based analysis suggests to prefer the acidic drug etodolac or the neutral celecoxib as selective COX-2 inhibitors, over the basic drug etoricoxib, after bariatric surgery.

In Vitro and In Vivo Evaluation of Inhalable Ciprofloxacin Sustained Release Formulations

Respiratory antibiotics delivery has been appreciated for its high local concentration at the infection sites. Certain formulation strategies are required to improve pulmonary drug exposure and to achieve effective antimicrobial activity, especially for highly permeable antibiotics. This study aimed to investigate lung exposure to various inhalable ciprofloxacin (CIP) formulations with different drug release rates in a rat model. Four formulations were prepared, i.e., CIP-loaded PLGA micro-particles (CHPM), CIP microcrystalline dry powder (CMDP), CIP nanocrystalline dry powder (CNDP), and CIP spray-dried powder (CHDP), which served as a reference. The physicochemical properties, drug dissolution rate, and aerosolization performance of these powders were characterized in vitro. Pharmacokinetic profiles were evaluated in rats. All formulations were suitable for inhalation (mass median aerodynamic diameter < 5 µm). CIP in CHPM and CHDP was amorphous, whereas the drug in CMDP and CNDP remained predominantly crystalline. CHDP exhibited the fastest drug release rate, while CMDP and CNDP exhibited much slower drug release. In addition, CMDP and CNDP exhibited significantly higher in vivo lung exposure to CIP compared with CHDP and CHPM. This study suggests that lung exposure to inhaled drugs with high permeability is governed by drug release rate, implying that lung exposure of inhaled antibiotics could be improved by a sustained-release formulation strategy.

Antiallergic Treatment of Bariatric Patients: Potentially Hampered Solubility/Dissolution and Bioavailability of Loratadine, but Not Desloratadine, Post-Bariatric Surgery

Gastrointestinal anatomical/physiological changes after bariatric surgery influence variables affecting the fate of drugs after ingestion, and medication management of these patients requires a thorough and complex mechanistic analysis. The aim of this research was to study whether loratadine/desloratadine antiallergic treatment of bariatric patients is at risk of being ineffective due to impaired solubility/dissolution. The pH-dependent solubility of loratadine/desloratadine was studied in vitro, as well as ex vivo, in gastric content aspirated from patients before versus after bariatric surgery. Then, a biorelevant dissolution method was developed to simulate the gastric conditions after sleeve gastrectomy (SG) or one-anastomosis gastric bypass (OAGB), accounting for key variables (intragastric volume, pH, and contractility), and the dissolution of loratadine/desloratadine was studied pre- versus post-surgery. Dissolution was also studied after tablet crushing or syrup ingestion, as these actions are recommended after bariatric surgery. Finally, these experimental data were implemented in a newly developed physiologically based pharmacokinetic (PBPK) model to simulate loratadine/desloratadine PK profiles pre- versus post-surgery. For both drugs, pH-dependent solubility was demonstrated, with decreased solubility at higher pH; over the pH range 1-7, loratadine solubility decreased ∼2000-fold, and desloratadine decreased ∼120-fold. Ex vivo solubility in aspirated human gastric fluid pre- versus post-surgery was in good agreement with these in vitro results and revealed that while desloratadine solubility still allows complete dissolution post-surgery, loratadine solubility post-surgery is much lower than the threshold required for the complete dissolution of the drug dose. Indeed, severely hampered loratadine dissolution was revealed, dropping from 100% pre-surgery to only 3 and 1% post-SG and post-OAGB, respectively. Tablet crushing did not increase loratadine dissolution in any post-bariatric condition, nor did loratadine syrup in post-OAGB (pH 7) media, while in post-laparoscopic SG conditions (pH 5), the syrup provided partial improvement of up to 40% dissolution. Desloratadine exhibited quick and complete dissolution across all pre-/post-surgery conditions. PBPK simulations revealed pronounced impaired absorption of loratadine post-surgery, with 84-88% decreased C_max, 28-36% decreased F_a, and 24-31% decreased overall bioavailability, depending on the type of bariatric procedure. Desloratadine absorption remained unchanged post-surgery. We propose that desloratadine should be preferred over loratadine in bariatric patients, and as loratadine is an over-the-counter medication, antiallergic therapy after bariatric surgery requires special attention by patients and clinicians alike. This mechanistic approach that reveals potential post-surgery complexity, and at the same time provides adequate substitutions, may contribute to better pharmacotherapy and overall patient care after bariatric surgery.

Application of text-mining techniques for extraction and analysis of paracetamol and ibuprofen marketed products' qualitative composition

Text mining (TM) applications in the field of biomedicine are gaining great interest. TM tools can facilitate formulation development by analyzing textual information from patent databases, scientific articles, summary of products characteristics, etc. The aim of this study was to utilize TM tools to perform qualitative analysis of paracetamol (PAR) and ibuprofen (IBU) formulations, in terms of identifying and evaluating the presence of excipients specific to the active pharmaceutical ingredient (API) and/or dosage form. A total of 152 products were analyzed. Web-scraping was used to retrieve the data, and Python-based open-source software Orange 3.31.1 was used for TM and statistical analysis (ANOVA) of the obtained results. The majority of marketed products for both APIs were tablets. The predominant excipients in all tablet formulations were povidone, starch, microcrystalline cellulose and hypromellose. Povidone, stearic acid, potassium sorbate, maize starch and pregelatinized starch occurred more frequently in PAR tablets. On the other hand, titanium dioxide, lactose, shellac, sucrose and ammonium hydroxide were specific to IBU tablets. PAR oral suspensions more frequently contained dispersible cellulose; liquid sorbitol; methyl and propyl parahydroxybenzoate, glycerol and acesulfame potassium. Specific excipients in other PAR dosage forms, such as effervescent tablets, hard capsules, oral powders, solutions and suspensions, as well as IBU gels and soft capsules, were also evaluated.

Liquisolid systems: Evaluation of the influence of formulation variables on the optimum liquid load

Liquisolid systems represent an emerging approach in the preparation of solid dosage forms with liquid lipophilic drug or poorly water-soluble drug solution/suspension in suitable liquid vehicle. This study addresses the lack of data regarding the compaction behavior of liquisolid systems, with the aim to investigate the influence of liquid load, carrier to coating ratio, carrier type (microcrystalline cellulose vs. spray dried calcium hydrogen phosphate, anhydrous (Fujicalin®)) on flowability and compaction properties of liquisolid systems and to determine the optimum liquid loads. Liquisolid admixtures with Fujicalin® showed notably better flowability than those with microcrystalline cellulose. An increase in carrier to coating ratio led to enhanced flowability of the admixtures. Compacts with Fujicalin® had good mechanical properties up to 24.7% liquid, while those with microcrystalline cellulose had acceptable mechanical strength up to 16.2% liquid. Liquisolid systems with Fujicalin® showed similar tabletability profiles as those with microcrystalline cellulose, despite having higher liquid content. The ejection stress values indicated that the addition of lubricant might be needed in the case of liquisolid systems with Fujicalin®. Superior properties of Fujicalin® as a carrier for liquisolid tablets were revealed, and dynamic compaction analysis was found to be a valuable tool for the assessment of compaction behavior of liquisolid systems.

How to choose an appropriate drug dosage form for the treatment of respiratory infections in children: Facts and tips

The treatment of respiratory infections in children requires special attention, since the paediatric population has rather specific characteristics and consists of heterogenous subgroups. In this context, the choice of a suitable drug dosage form is of particular importance, depending on the active substance properties, along with the age and general condition of a paediatric patient. The most commonly used pharmaceutical products for respiratory infections in children include oral, parenteral and inhalation dosage forms, although a large number of drugs are not available in a suitable dosage form and/or strength for paediatric age, leading to the frequent use of unauthorized drugs (i.e., unlicensed use). Other important issues that should be considered when choosing the appropriate paediatric dosage form and/or compounding procedure are related to the careful considerations of the pharmaceutical product composition (safety of excipients) and the choice of administration/dosing device in relation to a child's age. This paper provides an overview of paediatric dosage forms used in the treatment of respiratory infections in children, their benefits and limitations. The review includes examples of various pharmaceutical products, along with the considerations regarding administration/dosing devices. Specific characteristics of paediatric populations affecting the decision on the choice of age-appropriate paediatric formulation are also addressed.

The evaluation of the effect of different superdisintegrants on the drug release from FDM 3D printed tablets through different applied strategies: In vitro-in silico assessment

Paracetamol-loaded tablets were printed by fused deposition modelling technique, using polyvinyl alcohol as a backbone polymer and Affinisol™ HPMC as a plasticizer in all formulations. Four different strategies were applied in order to accelerate the drug release from the tablets. First, different release enhancers were added: sodium starch glycolate, croscarmellose sodium, Kollidon CL and mannitol. Kollidon CL and mannitol showed the greatest influence on the drug dissolution rate. The second strategy included lowering the infill density, which did not make any significant changes in dissolution profiles, according to the calculated similarity factor. Then the best two release enhancers from the first strategy were combined (Kollidon CL and mannitol) and this proved to be the most effective in the drug release acceleration. The fourth strategy, increasing the percentage of the release enhancers in formulation, revealed the importance of their concentration limits. In summary, the drug release accelerated from 58% released after 5 h to reaching the plateau within 2 h. In silico physiologically-based biopharmaceutics modelling showed that formulations with mannitol and Kollidon CL, especially the formulation containing a combination of these release enhancers, can provide relatively fast drug release and extent of drug absorption that complies with an immediate release tablet.

Mucoadhesive buccal tablets with propranolol hydrochloride: Formulation development and in vivo performances in experimental essential hypertension

The objective of this study was to formulate extended-release mucoadhesive buccal tablets of propranolol hydrochloride in order to provide a prolonged absorption of propranolol hydrochloride from the buccal mucosa and to reduce presystemic metabolism and thus provide a better therapeutic effect. Besides, the aim was to perform comparative in vivo pharmacokinetic and hemodynamic studies of the developed extended-release (ER) propranolol hydrochloride 10 mg mucoadhesive buccal tablets and commercial immediate-release (IR) propranolol hydrochloride 10 mg tablets in spontaneously hypertensive rats. Formulation with 15% polyethylene oxide showed the highest degree of propranolol hydrochloride permeation, satisfactory mucoadhesiveness, and extended-release of propranolol hydrochloride, thus it was selected for further in vivo study. The pharmacokinetic study in rats showed the superiority of ER mucoadhesive buccal tablets over IR tablets in terms of propranolol hydrochloride absorption extent (AUC values: 70.32 ± 19.56 versus 31.69 ± 6.97 µg·h/mL), although lower maximum plasma propranolol hydrochloride concentration (C_max) was achieved. However, no statistically significant difference was observed in C_max between these treatments. The hemodynamic study showed that ER mucoadhesive buccal tablets provide a more pronounced decrease primarily in heart rate, but also in systolic and diastolic arterial pressure, as well as a longer heart rate reduction compared to IR tablets.

Mucoadhesive Gelatin Buccal Films with Propranolol Hydrochloride: Evaluation of Mechanical, Mucoadhesive, and Biopharmaceutical Properties

This study processes and characterizes propranolol hydrochloride/gelatin mucoadhesive buccal films. Two types of gelatin are used: Gelatin from porcine skin, type A (GA), and gelatin from bovine skin (GB). The influence of gelatin type on mechanical, mucoadhesive, and biopharmaceutical characteristics of buccal films is evaluated. Fourier-Transfer infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) analysis show that GA with propranolol hydrochloride (PRH) in the film (GAP) formed a physical mixture, whereas GB with PRH (GBP) form a compound-complex. Results of mechanical testing (tensile test, hardness) revealed that GAP films exhibit higher elastic modulus, tensile strength, and hardness. A mucoahesion test shows that GBP has higher adhesion strength, while GAP shows higher work of adhesion. Both in vitro release study and in silico simulation indicated that processed films can provide effective drug transport through the buccal mucosa. In silico simulation shows improved bioavailability from buccal films, in comparison to the immediate-release tablets-indicating that the therapeutic drug dose can be markedly reduced.

In vitro - in vivo - in silico approach in the development of inhaled drug products: Nanocrystal-based formulations with budesonide as a model drug

This study aims to understand the absorption patterns of three different kinds of inhaled formulations via in silico modeling using budesonide (BUD) as a model drug. The formulations investigated in this study are: (i) commercially available micronized BUD mixed with lactose (BUD-PT), (ii) BUD nanocrystal suspension (BUD-NC), (iii) BUD nanocrystals embedded hyaluronic acid microparticles (BUD-NEM). The deposition patterns of the three inhaled formulations in the rats’ lungs were determined in vivo and in silico predicted, which were used as inputs in GastroPlus™ software to predict drug absorption following aerosolization of the tested formulations. BUD pharmacokinetics, estimated based on intravenous data in rats, was used to establish a drug-specific in silico absorption model. The BUD-specific in silico model revealed that drug pulmonary solubility and absorption rate constant were the key factors affecting pulmonary absorption of BUD-NC and BUD-NEM, respectively. In the case of BUD-PT, the in silico model revealed significant gastrointestinal absorption of BUD, which could be overlooked by traditional in vivo experimental observation. This study demonstrated that in vitro-in vivo-in silico approach was able to identify the key factors that influence the absorption of different inhaled formulations, which may facilitate the development of orally inhaled formulations with different drug release/absorption rates.

The emerging role of physiologically-based pharmacokinetic/biopharmaceutics modeling in formulation development

Computer-based (in silico) modeling & simulation tools have been embraced in different fields of pharmaceutics for a variety of applications. Among these, physiologically-based pharmacokinetic/biopharmaceutics modeling (PBPK/PBBM) emerged as a particularly useful tool in formulation development. PBPK/PBBM facilitated strategies have been increasingly evaluated over the past few years, as demonstrated by several reports from the pharmaceutical industry, and a number of research and review papers on this subject. Also, the leading regulatory authorities have recently issued guidance on the use of PBPK modeling in formulation design. In silico PBPK models can comprise different dosing routes (oral, intraoral, parenteral, inhalation, ocular, dermal etc.), although the majority of published examples refer to modeling of oral drugs performance. In order to facilitate the use of PBPK modeling tools, a couple of companies have launched commercially available software such as GastroPlus™, Simcyp™ PBPK Simulator and PK-Sim®. This paper highlights various application fields of PBPK/PBBM modeling, along with the basic principles, advantages and limitations of this approach, and provides relevant examples to demonstrate the practical utility of modeling & simulation tools in different stages of formulation development.

Multiparticulate oral formulations as a viable strategy for precise drug dosing in pediatrics: Propranolol case study

The development of solid dosage forms that are both convenient for administration and allow precise drug dosing for pediatric patients is one of the great challenges in contemporary pharmaceutical technology. The presented study has utilized propranolol hydrochloride, as one of the most frequently prescribed drugs that require manipulation of the conventional dosage forms to be administered to children. Multiparticulate oral formulations, powderand granulefilled capsules, as well as mini tablets, were prepared and characterized in terms of their mass and content uniformity and compared to conventional marketed tablets split into halves and quarters. The obtained results have demonstrated the superiority of the multiparticulate formulations, in terms of their average mass and drug content uniformity. It has also been demonstrated that, due to improved flowability, granule-filled capsules are more conveniently compounded and provide higher content uniformity compared to powder-filled capsules. The presented compounding method could be easily employed in community pharmacy settings. Mini tablets with high and uniform content of propranolol hydrochloride have been successfully prepared, thereby presenting a viable strategy for efficient drug dose adjustment.

Assessment of hot-melt coating methods for multiparticulate substrates: Mortar-coating vs. pan-coating

Hot-melt coating (HMC) is an alternative, solvent-free coating method generally used to modify substrate release rate and/or mask its unpleasant taste. The aim of this study was to assess two HMC methods (pan-coating and mortar-coating) by assaying functional properties of the coated material. The selected substrates included highly soluble sodium chloride (model substance) and caffeine (bitter drug), and the coating agent was glycerol distearate without/with the addition of liquid paraffin. Experiments with sodium chloride revealed that pan-coating yielded particles of more regular shape, while mortar-coating yielded samples of more uniform coating layer. The flowability of the coated material depended on the particle size. Sustained sodium chloride release was achieved for all mortar-coated and some pan-coated samples. The analysis of the results indicated mortar-coating as a preferable HMC method for caffeine coating. The resulting caffeine yield in the coated samples was high (99%), the material showed satisfactory mechanical properties and drug release from the coated particles was sustained. Overall, the obtained results suggest that both pan-and mortar-coating can be used to sustain the release of drugs with unpleasant taste, but mortar-coating can be considered as a more simple and practical method that can be potentially used in compounding pharmacies.

Development of solid lipid microparticles by melt-emulsification/spray-drying processes as carriers for pulmonary drug delivery

The aim of this study was to optimize the parameters of the complex melt-emulsification process coupled with the spray-drying, in order to maintain the balance between solid lipid microparticles (SLMs) powders aerodynamic performance and salbutamol sulfate release rate. Quality target product profile was identified and risk management and principal component analysis were used to guide formulation development. Obtained dry powders for inhalation (DPIs) were evaluated in terms of SLMs size distribution, morphology, true density, drug content, solid state characterization studies, in vitro aerosol performance and in vitro drug release. SLMs micrographs indicated spherical, porous particles. Selected powders showed satisfactory aerosol performance with a mean mass aerodynamic diameter of around 3 μm and acceptable fine particle fraction (FPF). Addition of trehalose positively affected SLMs aerodynamic properties. The results of in vitro dissolution testing indicated that salbutamol sulfate release from the tested SLMs formulations was modified, in comparison to the raw drug release. In conclusion, SLMs in a form of DPIs were successfully developed and numerous factors that affects SLMs properties were identified in this study. Further research is required for full understanding of each factor's influence on SLMs properties and optimization of DPIs with maximized FPFs.

Paracetamol extended release FDM 3D printlets: Evaluation of formulation variables on printability and drug release

Paracetamol printlets were prepared via hot-melt extrusion process and fused deposition modelling, using two types of backbone polymers. Polycaprolactone (PCL) and Polyethylene oxides (PEO) 100 K and 200 K were used, while Arabic gum was used as a plasticizer to facilitate the material flow and Gelucire® 44/14 as an enhancer of drug release. Different drug/polymer ratios were prepared. Extrusion temperature was adjusted according to the mixture/polymer types. It was possible to produce filaments with maximum of 60% w/w of drug. Mechanical properties of filaments were evaluated using three-point bend test, while obtained parameters were modelled using decision tree as a data mining method. Correlation between maximum displacement, maximum force and printability was obtained with accuracy of 84.85% and can be a useful tool for predicting printability of filaments. This study briefly demonstrated that backbone polymer in formulation plays crucial role in obtaining FDM printlets with desired properties. PEO-based filaments were more prone to be clogged in printcore, but their printlets showed much faster drug release. Drug release from all printlets was prolonged: from 50% in 8 h (PCL), to complete release in 4 h (PEO). Paracetamol release kinetics was guided by anomalous transport, attributed to the diffusion and erosion process.

An Investigation into the Influence of Process Parameters and Formulation Variables on Compaction Properties of Liquisolid Systems

Liquisolid technology, as a promising approach for bioavailability enhancement, has received increasing attention in recent years. However, literature reports addressing the challenges for its industrial application, particularly those related to compaction behavior of liquisolid systems, are scarce. The aim of this study was to investigate the influence of process parameters and formulation variables on the flowability, wetting, and compaction properties of the liquisolid systems prepared in a fluid bed processor. The experiments with microcrystalline cellulose, as a carrier, were performed according to 2³ full factorial design. The effects of liquid content, spray air pressure, and liquid feed rate on the properties of liquisolid systems were investigated. Liquisolid admixtures with microcrystalline cellulose were compared with those prepared with novel carriers, Fujicalin^® and Neusilin^® US2. "Out-die" Heckel, modified Walker, and Kuentz-Leuenberger models were used to analyze the compressibility of liquisolid admixtures. The results obtained showed that an increase in liquid content (in the range of 10 to 15%) led to a decrease in flowability of liquisolid admixtures with microcrystalline cellulose, as well as more pronounced influence of spraying conditions. On the other hand, higher liquid content led to higher compressibility. Fujicalin^® and Neusilin^® US2 liquisolid admixtures were found to have superior flowability and compressibility in comparison with those with microcrystalline cellulose, despite the considerably higher liquid load (50-55% liquid content in Neusilin^® US2 compacts). Acceptable compactibility of the investigated liquisolid systems was observed. The fluid bed processor was shown to be suitable equipment for production of liquisolid systems, but with careful adjustment of process parameters.

Biopharmaceutical characterization of rebamipide: The role of mucus binding in regional-dependent intestinal permeability

In this study, we aimed to elucidate biopharmaceutical characteristics of the anti-ulcer drug rebamipide, with special emphasis on the influence of gastrointestinal (GI) mucus on rebamipide segmental-dependent permeability and absorption. Experimental studies and physiologically-based pharmacokinetic (GastroPlus^TM) simulations were used to elucidate segmental-dependent absorption and pharmacokinetic (PK) profile, accounting for various drug properties, including solubility/dissolution limitations, regional-dependent drug affinity to mucus and membrane permeability, as well as physiological factors such as regional-pH differences along the intestine, thickness and types of mucus, transit time and surface areas. Low permeability and extensive binding to GI mucus were the key modeling features, and accounting for these resulted in good fitting between the predicted and in-vivo PK profiles, validating the ability of the model to pinpoint the underlying mechanisms of rebamipide limited oral bioavailability. Furthermore, the simulations indicated regional-dependent intestinal permeability of rebamipide, with absorption rank order of jejunum>ileum>duodenum>colon, mainly attributable to segmental mucus differences. Food effect simulations indicated somewhat decreased rebamipide absorption in the fed state, in corroboration with previous reports. Since this anti-ulcer drug is currently examined for additional indications, this work provides important input for future development of rebamipide.

Hydrophilic excipients in digital light processing (DLP) printing of sustained release tablets: Impact on internal structure and drug dissolution rate

Three-dimensional (3D) printing enables the production of different objects adjusted for the specific application, which has particular importance of providing personalized therapy, whereby the challenge is to apply pharmaceutical materials into 3D printing technology. In this study, effect of poly(ethylene glycol) 400 (PEG 400), sodium chloride (NaCl), and mannitol, as hydrophilic excipients, was investigated in order to overcome very slow and incomplete drug release from tablets (printlets) fabricated by photopolymerization using digital light processing (DLP) technology. Paracetamol (acetaminophen) was used as a model drug, while polyethylene glycol diacrylate (PEGDA) was used as a photopolymer and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide as a photoinitiator in photoreactive mixtures. Most of printlet formulations exhibit sustained release over 8 h, wherein drug release kinetics is the best described with Korsmeyer-Peppas kinetics. Variation in the content of photopolymer and excipients had an influence on the dissolution rate, mechanical characteristics, and internal structure of the investigated samples. The addition of hydrophilic polymers increased drug release rate, while PEGDA had the greatest influence on the tensile strength of printlets. The results indicate the possibility of implementation of traditional excipients into different formulations for photopolymerization based 3D printing for the production of small batches of tablets with tailored drug release.

In vitro/in silico approach in the development of simvastatin-loaded self-microemulsifying drug delivery systems

OBJECTIVE

The aims of this study were to formulate simvastatin (SV)-loaded self-microemulsifying drug delivery systems (SMEDDS), and explore the potential of these drug delivery systems to improve SV solubility, and also to identify the optimal place in the gastrointestinal (GI) tract for the release of SV using coupled in vitro/in silico approach.

SIGNIFICANCE

In comparison to other published results, this study considered the extensive pre-systemic clearance of SV, which could significantly decrease its systemic and hepatic bioavailability if SV is delivered into the small intestine.

METHODS

SV-loaded SMEDDS were formulated using various proportions of oils (PEG 300 oleic glycerides, propylene glycol monocaprylate, propylene glycol monolaurate), surfactant (PEG 400 caprylic/capric glycerides) and cosurfactant (polysorbate 80) and subjected to characterization, and physiologically-based pharmacokinetic (PBPK) modeling.

RESULTS

According to the in vitro results, the selected SMEDDS consisted of 10.0% PEG 300 oleic glycerides, 67.5% PEG 400 caprylic/capric glycerides, and 22.5% polysorbate 80. The use of acid-resistant capsules filled with SV-loaded SMEDDS was found helpful in protecting the drug against early degradation in proximal parts of the GI tract, however, in silico simulations indicated that pH-controlled drug release system that dissolve in the distal parts of the intestine might further improve SV bioavailability (up to 7.20%).

CONCLUSION

The obtained results suggested that combined strategy for the improvement of SV bioavailability should comprise solubility enhancement and delayed drug release. The developed SV-specific PBPK model could potentially be used to assess the influence of formulation factors on drug absorption and disposition when developing SV oral dosage forms.

Assessing the risk of alcohol-induced dose dumping from sustained-release oral dosage forms: in vitro-in silico approach

Consumption of alcoholic beverages with sustained-release oral dosage forms may pose a risk to patients due to potential alcohol-induced dose dumping (ADD). Regulatory guidances recommend in vitro dissolution testing to identify the risk of ADD, but the question remains whether currently proposed test conditions can be considered biopredictive. The purpose of this study was to evaluate different dissolution setups to assess ADD, and the potential of combined in vitro-in silico approach to predict drug absorption after concomitant alcohol intake for hydrophilic and lipophilic sustained-release tablets containing ibuprofen or diclofenac sodium. According to the obtained results, the impact of ethanol was predominantly governed by the influence on matrix integrity, with the increase in drug solubility being less significant. Hydrophilic matrix tablets were less susceptible to ADD than lipophilic matrices, although the conclusion on formulation ethanol-vulnerability depended on the employed experimental conditions. In silico predictions indicated that the observed changes in drug dissolution would not result in plasma concentrations beyond therapeutic window, but sustained-release characteristics of the formulations might be lost. Overall, the study demonstrated that in vitro-in silico approach may provide insight into the effect of ADD on drug clinical performance, and serve as a tool for ADD risk assessment.

An in vitro--in silico--in vivo approach in biopharmaceutical drug characterization: metformin hydrochloride IR tablets

The integrated in vitro--in silico--in vivo approach has emerged into a biopharmaceutical toolkit that could accelerate drug development and improve drug product clinical performance in patients. In the present study, the influence of physiologically based media and dynamic dissolution testing on drug release from two metformin hydrochloride immediate release products with proven bioequivalence was tested. Metformin-specific physiologically based pharmacokinetic (PBPK) model was developed based on a range of literature or in silico predicted data using gastrointestinal simulation technology implemented in the Simcyp software package. Various approaches were employed in order to estimate the human effective permeability which was used as input for metformin plasma profile simulation. Influence of the rate and extent of metformin dissolution on drug absorption was evaluated. Both convolution and deconvolution approaches were used in order to establish a correlation between the in vitro and in vivo data. The results obtained indicate that physiologically based dissolution media and glass bead dissolution device exhibit certain advantages over the compendial dissolution apparatus and simple buffers which tended to be over-discriminative. Gastrointestinal simulation technology implemented in the Simcyp Simulator was successfully used in developing drug-specific PBPK model for metformin. Simulations indicate that in vitro dissolution kinetics has no significant effect on metformin absorption, if more than 65% of drug is released in 1 hour. Level A in vitro-in vivo correlation was obtained using both convolution and deconvolution approaches.

In vitro-in vivo-in silico approach in biopharmaceutical characterization of ibuprofen IR and SR tablets

Within the last decades, physiologically based pharmacokinetic models have emerged into a biopharmaceutical toolkit that has been proven useful in understanding how physicochemical, formulation and physiological factors affect oral drug absorption. The purpose of this study was to develop a drug specific physiologically based pharmacokinetic model that will allow mechanistic interpretation of oral absorption from dosage forms exhibiting different in vitro and different in vivo performance (i.e. immediate release and sustained release tablets) and identification of bioperformance dissolution testing. Ibuprofen was chosen to be used for the "proof of concept" considering it is well characterised and the necessary physicochemical, biopharmaceutical and pharmacokinetic properties for model development could be found in the literature. Gastrointestinal simulation technology implemented in Simcyp® was successful in estimating ibuprofen oral absorption. The developed model exhibited good generalisation ability for the dosage forms studied. The obtained results indicate that the model was sensitive to input kinetics represented by the in vitro drug release profiles obtained under various dissolution conditions. According to the obtained results, reciprocating cylinder apparatus with biorepresentative change in media pH might be considered as bioperformance dissolution in the case of the two ibuprofen SR products studied. These results further justify the use of integrated in vitro-in vivo-in silico approach in estimating bioperformance of oral solid dosage forms.

Improvement of trospium-specific absorption models for fasted and fed states in humans

The purpose of this study was to mechanistically interpret the oral absorption pattern of trospium in fasted and fed states by means of gastrointestinal simulation technology. A drug absorption model was built on the basis of experimental data. According to the generated model, low permeability across the intestinal epithelium, delayed gastric emptying time and a prolonged residence time in the small intestine are the key factors governing trospium absorption in the fasted state. Furthermore, in silico modelling provided a plausible explanation of the pronounced reduction in the oral bioavailability of trospium when administered with food. The simulation results support the decreased dissolution in viscous medium, and the reduced drug permeability in the fed state as the predominant mechanisms for the food effect on trospium absorption.