Formulation and evaluation of gastroretentive floating drug delivery system of dipyridamole

Polymeric Excipients in the Technology of Floating Drug Delivery Systems

The combination of targeted transport and improvement of the release profile of the active pharmaceutical ingredient (API) is a current trend in the development of oral medicinal products (MP). A well-known way to implement this concept is to obtain floating gastroretentive delivery systems that provide a long stay of the dosage form (DF) on the surface of the stomach contents. The nomenclature of excipients (Es) of a polymeric nature used in the technology of obtaining floating drug delivery systems (FDDS) is discussed. Based on the data presented in research papers, the most widely used groups of polymers, their properties, and their purpose in various technological approaches to achieving buoyancy have been determined. In addition, ways to modify the release of APIs in these systems and the Es used for this are described. The current trends in the use of polymers in the technology of floating dosage forms (FDF) and generalized conclusions about the prospects of this direction are outlined.

Optimized copolymeric microstructured platforms for smart controlled delivery of an anticoagulant drug: Preparation, in vitro assessment and crossover study in healthy adult human volunteers

In the present study, novel micro-structured copolymeric carriers were developed based on the grafting technology where acrylamide was chemically crosslinked with different types of Eudragits® (NE30D, L100, RL30D, or RS30D) based on a 4¹*2¹ factorial design. The designed systems efficiently engulfed the anticoagulant drug dipyridamole (DIP), within their formed entangled mesh of crosslinked polymeric network. An optimized formulation, ECOP4 with a desirability-value of 0.706, (in which DIP is engulfed within a copolymeric network of acrylamide and Eudragit® RS30D) showed high engulfment capacity (97.13 ± 1.34%) and controlled DIP release over 8 h. FTIR studies revealed absence of interactions between DIP and the formed copolymer. ECOP4 was further inserted within an easily-administered safe raft forming system composed of a mixture of LM-pectin and gellan gum. A pharmacokinetic study was performed using human volunteers to determine DIP concentration in their plasma after administering the designed formulation using the high-performance liquid chromatography (HPLC) method. A crossover design was adopted comparing the designed formulation with Persantin® 25 mg tablets as a reference standard. Superior results were obtained for the optimized formulation regarding the measured pharmacokinetic parameters (AUC_0-24h, C_max, and T_max) with a 2.31 fold increase in relative bioavailability, which reveals the usefulness of the designed grafted dipyridamole formulation in site-specific delivery system.

Recombinant organophosphorus hydrolase (OPH) expression in E. coli for the effective detection of organophosphate pesticides

Accumulation and exposure of organophosphate pesticides are of great concern today owing to their abundant usage and potential health hazards. Harmful effects of organophosphate pesticide exposure and limitations of the available treatment methods necessitate the development of reliable, selective, cost-effective, and sensitive methods of detection. We developed a novel biosensor based on the enzymatic action of recombinant organophosphorus hydrolase (OPH) expressed in E. coli. We report the development of colorimetric biosensors made of His-Nus-OPH as well as His-Nus-OPH loaded alginate microspheres. The colorimetric detection method developed using solution-phase and alginate-encapsulated His-Nus-OPH exhibited detection limits of 0.045 and 0.039 mM, respectively, for ethyl paraoxon, and 0.101 and 0.049 mM, respectively, for methyl parathion. Additionally, fluorescence measurement using pH-sensitive fluorescein isothiocyanate (FITC) was used to sense the quantity of organophosphorus pesticides. The fluorometric detection method using solution-phase His-Nus-OPH, with ethyl paraoxon and methyl parathion as the substrate, reveals the lower limit of detection as 0.014 mM and 0.044 mM, respectively. Our results demonstrate the viability of His-Nus-OPH for OP detection with good sensitivity, LOD, and linear range. We report the first use of N-terminal His-NusA-tagged OPH, which enhances solubility significantly and presents a significant advance for the scientific community.

Highlighting the impact of chitosan on the development of gastroretentive drug delivery systems

The development of gastroretentive systems have been growing lately due to the high demand for carriers that increase drug bioavailability and therapeutic effectiveness after oral administration. Most of systems reported up to now are based on chitosan (CS) due to its peculiar properties, such as cationic nature, biodegradability, biocompatibility and important mucoadhesiveness, which make CS a promising biopolymer to design effective gastroretentive systems. In light of this, we reported in this review the CS versatility to fabricate different types of nano- and microstructured gastroretentive systems. For a better understanding of the gastric retention mechanisms, we highlighted expandable, density-based, magnetic, mucoadhesive and superporous systems. The biological and chemical properties of CS, anatomophysiological aspects related to gastrointestinal tract (GIT) and some applications of these systems are also described here. Overall, this review may assist researchers to explore new strategies to design safe and efficient gastroretentive systems in order to popularize them in the treatment of diseases and clinical practices.

Gastroretentive bilayer film for sustained release of atorvastatin calcium and immediate release of amlodipine besylate: pharmaceutical, pharmacokinetic evaluation, and IVIVC

The present study was aimed to optimize capsulated unfolding type gastroretentive bilayer film constituting immediate release (IR) layer of amlodipine besylate and sustained release (SR) layer of atorvastatin calcium. A three-factor, three-level Box-Behnken-design was used to optimize bilayer film with dual-release characteristics. The selected independent variables were HPMC-K3, Eudragit RSPO, and Carbopol 934P and the responses were floating duration, swelling index, and in vitro release from SR layer in 8 h. The films were also assessed for pharmacotechnical characteristics, release kinetics, DSC, FTIR, and SEM. The pharmacokinetics of the drugs from the optimized formulation was compared with the marketed formulation in rabbits. The capsulated accordion film unfolded and provided SR of atorvastatin for 8 h (96.76% ± 0.71) and IR of amlodipine within 25 min (98.07% ± 0.62) for the optimized formulation (F14). The swelling index and floating duration for the optimized formulation were 140.48 ± 0.57 and 8.53 ± 0.10 h, respectively. Results of pharmacokinetics showed that faster absorption of amlodipine and improved bioavailability (2.16-fold) of atorvastatin in blood was made available through bilayer film. In vitro-in vivo correlation was established using numerical deconvolution method. It can be concluded that the capsulated gastroretentive system provided site specific simultaneous SR of antihyperlidemic drug and IR of antihypertensive drug as single pill that has therapeutic potential to manage cardiovascular risk.

Preparation and evaluation of gastro-floating hollow adhesive microspheres of carbomer/ethyl cellulose encapsulating dipyridamole

Gastro-floating hollow adhesive microspheres of Carbomer/ethyl cellulose encapsulating dipyridamole were fabricated and evaluated in vitro and in vivo.

Preparation and investigation of novel gastro-floating tablets with 3D extrusion-based printing

Three dimensional (3D) extrusion-based printing is a paste-based rapid prototyping process, which is capable of building complex 3D structures. The aim of this study was to explore the feasibility of 3D extrusion-based printing as a pharmaceutical manufacture technique for the fabrication of gastro-floating tablets. Novel low-density lattice internal structure gastro-floating tablets of dipyridamole were developed to prolong the gastric residence time in order to improve drug release rate and consequently, improve bioavailability and therapeutic efficacy. Excipients commonly employed in the pharmaceutical study could be efficiently applied in the room temperature 3D extrusion-based printing process. The tablets were designed with three kinds of infill percentage and prepared by hydroxypropyl methylcellulose (HPMC K4M) and hydroxypropyl methylcellulose (HPMC E15) as hydrophilic matrices and microcrystalline cellulose (MCC PH101) as extrusion molding agent. In vitro evaluation of the 3D printed gastro-floating tablets was performed by determining mechanical properties, content uniformity, and weight variation. Furthermore, re-floating ability, floating duration time, and drug release behavior were also evaluated. Dissolution profiles revealed the relationship between infill percentage and drug release behavior. The results of this study revealed the potential of 3D extrusion-based printing to fabricate gastro-floating tablets with more than 8h floating process with traditional pharmaceutical excipients and lattice internal structure design.

Preparation and evaluation of floating tablets of pregabalin

Floating tablets of pregabalin were prepared using different concentrations of the gums (xanthan gum and guar gum), Carbopol 974P NF and HPMC K100. Optimized formulations were studied for physical tests, floating time, swelling behavior, in vitro release studies and stability studies. In vitro drug release was higher for tablet batches containing guar and xanthan gum as compared to the batches containing Carbopol 974P NF. Tablet batches were subjected to stability studies and evaluated by different parameters (drug release, drug content, FTIR and DSC studies). The optimized tablet batch was selected for in vivo pharmacodynamic studies (PTZ induced seizures). The results obtained showed that the onset of jerks and clonus were delayed and extensor phase was abolished with time in treated groups. A significant difference (p > 0.05) was observed in control and treated group behavior indicating an excellent activity of the formulation for a longer period (>12 h).

Preparation and pharmacokinetics study on gastro-floating sustained-release tablets of troxipide

The purpose of this research aimed at preparing gastro-floating sustained-release tablets of troxipide and a further study on in vitro release and in vivo bioavailability. Under the circumstances of direct powder compression, the floating tablets were successfully prepared with HPMC as main matrix material, Carbopol as assistant matrix material, octadecanol as floating agent and sodium bicarbonate as foaming agent to float by gas-forming. The floating time and accumulative release amount as evaluation indexes were utilized to perform pre-experiment screening and single-factor test, respectively, while central composite design response surface method was applied for formulation optimization, followed by in vivo pharmacokinetic study in beagles after oral administration for floating tablets and commercial tablets used as the control. The results indicated that the floating sustained-release tablets held a better capability for floating and drug release and more satisfactory pharmacokinetic parameters, such as a lower Cmax, a prolonged Tmax, but an equivalent bioavailability calculated by AUC0-24 compared to commercial tablets. So a conclusion was finally drawn that the floating sustained-release tablets possessing a good release property could be suitable for demands of design.