Design of a gastroretentive mucoadhesive dosage form of furosemide for controlled release

Formulation of metoclopramide HCl gastroretentive film and in vitro- in silico prediction using Gastroplus® PBPK software

The new trends in pharmaceutical studies focus on targeting drug delivery and computer software that help in the body environment simulation, such as Gastroplus® software. The interest of this study is to prepare a gastroretentive film of metoclopramide HCl (MTC) that was followed by applying the in silico approach to estimate the in vivo prepared formulations. The films were prepared from HPMC E5 and sodium alginate polymers as primary polymers with the aid of secondary polymers. The sodium alginate high proportions films showed instant and long floating duration reaching 24 h but with variable folding endurance. Moreover, sodium alginate films with their secondary polymers carbopol and HPMC E5 slowed the release of MTC. The floating and slow-release patterns assessed the gastroretentive properties of sodium alginate films and were further examined by a mucoadhesive study that guaranteed mucosal adhesion, and the film's FESEM images showed similar top morphology, but different side view structures. Last, the pharmacokinetic profile of selected films that approached the gastroretentive properties was in silico predicted depending on in vitro release study and floating duration employing the physiological-based pharmacokinetic model in Gastroplus® software. The model determines this prediction found successfully of intravenous and immediate oral release tablets (10 and 30 mg) of MTC. The simulation showed a high amount of MTC retained for long periods in the stomach to Sod.Alginate-3, Sod.Alginate-8, and Sod.Alginate-10 films (films of secondary polymers carbopol and HPMC E5) aid in reaching the optimum site of absorption jejunum 1 due to the slow MTC release.

Gastroretentive Technologies in Tandem with Controlled-Release Strategies: A Potent Answer to Oral Drug Bioavailability and Patient Compliance Implications

There have been many efforts to improve oral drug bioavailability and therapeutic efficacy and patient compliance. A variety of controlled-release oral delivery systems have been developed to meet these needs. Gastroretentive drug delivery technologies have the potential to achieve retention of the dosage form in the upper gastrointestinal tract (GIT) that can be sufficient to ensure complete solubilisation of the drugs in the stomach fluids, followed by subsequent absorption in the stomach or proximal small intestine. This can be beneficial for drugs that have an “absorption window” or are absorbed to a different extent in various segments of the GIT. Therefore, gastroretentive technologies in tandem with controlled-release strategies could enhance both the therapeutic efficacy of many drugs and improve patient compliance through a reduction in dosing frequency. The paper reviews different gastroretentive drug delivery technologies and controlled-release strategies that can be combined and summarises examples of formulations currently in clinical development and commercially available gastroretentive controlled-release products. The different parameters that need to be considered and monitored during formulation development for these pharmaceutical applications are highlighted.

Novel Swellable/Expandable Gastroretentive Floating Films of Gliclazide Folded in Capsule Shell for the Effective Management of Diabetes Mellitus: Formulation Development, Optimization and In Vitro Evaluation

Background:

Gliclazide (GLZ) belongs to the second-generation of sulphonylureas; it is a drug of choice for the management of type II DM. It belongs to BCS Class II. The major site of drug absorption for GLZ is the stomach; it displays variation in the drug absorption rate and bioavailability due to the shorter gastric retention time. The floating mechanism gets affected when the gastric fluid level is not sufficiently higher, which ultimately obstructs the floating behavior, which is the major limitation of reported formulations. This limitation can be overcome by folding the film into the capsule shell dissolved in the gastric fluid and the film swells/expands to dimensions higher than pylorus sphincter (12mm), thus preventing its evacuation.

Objective:

The study aims to explore the floating mechanism in the design of films along with a tendency to expand by swelling and unfolding by utilizing a mixture of hydrophilic and hydrophobic polymer to achieve the controlled drug delivery and prolonged gastric retention of drug.

Methods:

The gastroretentive floating films were formulated by the solvent casting technique using 32 full factorial designs and subjected to in vitro evaluation parameters, drug-excipient compatibility, Xray diffraction and accelerated stability study.

Results:

The pre-formulation study established the purity and identification of a drug. FTIR study confirmed no drug excipient interaction. F3, F6, and F9 were optimized based on in vitro floating characteristics, swelling/expanding ability, and unfolding time. All developed formulations were unfolded within 14-22 min after capsule disintegration. The F3 was selected as the final formulation as its ability to control the release of the drug for 24 hrs followed by zero-order kinetics having super case 2 transport. XRD confirmed the amorphousness of the drug within the formulation. The stability study results revealed that the formulation was quite stable at extreme storage conditions.

Conclusion:

The developed novel formulation has good potential for the effective management and treatment of diabetes mellitus.

Formulation and in vitro evaluation of self-nanoemulsifying liquisolid tablets of furosemide

Self-nanoemulsifying drug delivery systems (SNEDDS) were used to enhance the dissolution rate of furosemide as a model for class IV drugs and the system was solidified into liquisolid tablets. SNEDDS of furosemide contained 10% Castor oil, 60% Cremophor EL, and 30% PEG 400. The mean droplets size was 17.9 ± 4.5 nm. The theoretical model was used to calculate the amounts of the carrier (Avicel PH101) and coating materials (Aerosil 200) to prepare liquisolid powder. Carrier/coating materials ratio of 5/1 was used and Ludipress was added to the solid system, thus tablets with hardness of 45 ± 2 N were obtained. Liquisolid tablets showed 2-folds increase in drug release as compared to the generic tablets after 60 min in HCl 0.1 N using USP apparatus-II. Furosemide loaded SNEDDS tablets have great prospects for further in vivo studies, and the theoretical model is useful for calculating the adequate amounts of adsorbents required to solidify these systems.

BCS Class IV Oral Drugs and Absorption Windows: Regional-Dependent Intestinal Permeability of Furosemide

Biopharmaceutical classification system (BCS) class IV drugs (low-solubility low-permeability) are generally poor drug candidates, yet, ~5% of oral drugs on the market belong to this class. While solubility is often predictable, intestinal permeability is rather complicated and highly dependent on many biochemical/physiological parameters. In this work, we investigated the solubility/permeability of BCS class IV drug, furosemide, considering the complexity of the entire small intestine (SI). Furosemide solubility, physicochemical properties, and intestinal permeability were thoroughly investigated in-vitro and in-vivo throughout the SI. In addition, advanced in-silico simulations (GastroPlus^®) were used to elucidate furosemide regional-dependent absorption pattern. Metoprolol was used as the low/high permeability class boundary. Furosemide was found to be a low-solubility compound. Log D of furosemide at the three pH values 6.5, 7.0, and 7.5 (representing the conditions throughout the SI) showed a downward trend. Similarly, segmental-dependent in-vivo intestinal permeability was revealed; as the intestinal region becomes progressively distal, and the pH gradually increases, the permeability of furosemide significantly decreased. The opposite trend was evident for metoprolol. Theoretical physicochemical analysis based on ionization, pK_a, and partitioning predicted the same trend and confirmed the experimental results. Computational simulations clearly showed the effect of furosemide’s regional-dependent permeability on its absorption, as well as the critical role of the drug’s absorption window on the overall bioavailability. The data reveals the absorption window of furosemide in the proximal SI, allowing adequate absorption and consequent effect, despite its class IV characteristics. Nevertheless, this absorption window so early on in the SI rules out the suitability of controlled-release furosemide formulations, as confirmed by the in-silico results. The potential link between segmental-dependent intestinal permeability and adequate oral absorption of BCS Class IV drugs may aid to develop challenging drugs as successful oral products.

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.

Current State and Future Perspectives on Gastroretentive Drug Delivery Systems

In recent years, many attempts have been made to enhance the drug bioavailability and therapeutic effectiveness of oral dosage forms. In this context, various gastroretentive drug delivery systems (GRDDS) have been used to improve the therapeutic efficacy of drugs that have a narrow absorption window, are unstable at alkaline pH, are soluble in acidic conditions, and are active locally in the stomach. In this review, we discuss the physiological state of the stomach and various factors that affect GRDDS. Recently applied gastrointestinal technologies such as expandable, superporous hydrogel; bio/mucoadhesive, magnetic, ion-exchange resin; and low- and high-density-systems have also been examined along with their merits and demerits. The significance of in vitro and in vivo evaluation parameters of various GRDDS is summarized along with their applications. Moreover, future perspectives on this technology are discussed to minimize the gastric emptying rate in both the fasted and fed states. Overall, this review may inform and guide formulation scientists in designing the GRDDS.

Cyclodextrin complexes: Perspective from drug delivery and formulation

Cyclodextrins (CDs) have been widely investigated as a unique pharmaceutical excipient for past few decades and is still explored for new applications. They are highly versatile oligosaccharides which possess multifunctional characteristics, and are mainly used to improve the physicochemical stability, solubility, dissolution rate, and bioavailability of drugs. Stability constant, factors affecting complexation, techniques to enhance complexation efficiency, the preparation methods for molecular inclusion complexes and release of guest molecules are discussed in brief. In addition, different CD derivatives and their pharmacokinetics are elaborated. Further, the significance of CD complex in aqueous solubility, dissolution and bioavailability, stability, and taste masking is explained. The recent advancement of CDs in developing various drug delivery systems is enlightened. Indeed, the potential of CDs by means of inclusion complex formation have widen the applicability of these materials in various drug delivery systems including ocular, osmotic, mucoadhesive, transdermal, nasal, and targeted delivery systems. Feasibility studies have been performed on the benefit of these cyclic oligomers as nanocarriers, a strategy that can modify the drugs with improved physicochemical properties. Studies also demonstrated the feasibility of CDs to self-assemble in the form of stable nanoaggregates, which may extend the scope of CDs in drug delivery to the continually expanding list of new drug entities.

Implementation of Quality by Design for Formulation of Rebamipide Gastro-retentive Tablet

The purpose of the present study was to develop a rebamipide (RBM) gastro-retentive (GR) tablet by implementing quality by design (QbD). RBM GR tablets were prepared using a sublimation method. Quality target product profile (QTPP) and critical quality attributes (CQAs) of the RBM GR tablets were defined according to the preliminary studies. Factors affecting the CQAs were prioritized using failure mode and effects analysis (FMEA). Design space and optimum formulation were established through a mixture design. The validity of the design space was confirmed using runs within the area. The QTPP of the RBM GR tablets was the orally administered GR tablet containing 300 mg of RBM taken once daily. Based on the QTPP, dissolution rate, tablet friability, and floating property were chosen as CQAs. According to the risk assessment, the amount of sustained-release agent, sublimating material, and diluent showed high-risk priority number (RPN) values above 40. Based on the RPN, these factors were further investigated using mixture design methodology. Design space of formulations was depicted as an overlaid contour plot and the optimum formulation to satisfy the desired responses was obtained by determining the expected value of each response. The similarity factor (f2) of the release profile between predicted response and experimental response was 89.463, suggesting that two release profiles are similar. The validity of the design space was also confirmed. Consequently, we were able to develop the RBM GR tablets by implementing the QbD concept. These results provide useful information for development of tablet formulations using the QbD.

Fabrication and statistical optimization of a polysaccharide-based sublingual film of buprenorphine hydrochloride for breakthrough pain management: in vitro and in vivo performance

A typical breakthrough pain episode is severe, categorized by a fast onset, typically reaches peak intensity instantly, and lasts for an average duration of about 30 min. The research work includes the use of opioid for the treatment of breakthrough pain with special emphasis on the development of rapidly dissolving sublingual film formulation of buprenorphine hydrochloride (BPH). BPH is an opioid analgesic with low oral bioavailability due to less absorption and first-pass metabolism. The clear and transparent sublingual films were prepared using a film-forming polymer (pullulan) with a plasticizer (PEG 400). The formulation was optimized statistically using 3(2) randomized full factorial design. The optimized film formulation showed desired mechanical properties (tensile strength of 25 N/m(2)) and a minimum disintegration time of 16 s. Differential scanning calorimetry and X-ray diffraction studies confirmed the uniform distribution of the drug in polymeric matrices. Morphological study showed the absence of drug crystals on polymeric surface. The relative bioavailability of the film formulation was increased by 10 % with respect to tablet formulation due to rapid T max (0.08 h for film while 0.15 h for tablet), which was confirmed by in vivo studies performed on rabbits. The present technology could be a promising alternative to conventional drug delivery systems and traditional routes of administration for breakthrough pain management.

Transmission FTIR derivative spectroscopy for estimation of furosemide in raw material and tablet dosage form

A Fourier transform infrared derivative spectroscopy (FTIR-DS) method has been developed for determining furosemide (FUR) in pharmaceutical solid dosage form. The method involves the extraction of FUR from tablets with N,N-dimethylformamide by sonication and direct measurement in liquid phase mode using a reduced path length cell. In general, the spectra were measured in transmission mode and the equipment was configured to collect a spectrum at 4 cm⁻¹ resolution and a 13 s collection time (10 scans co-added). The spectra were collected between 1400 cm⁻¹ and 450 cm⁻¹. Derivative spectroscopy was used for data processing and quantitative measurement using the peak area of the second order spectrum of the major spectral band found at 1165 cm⁻¹ (SO₂ stretching of FUR) with baseline correction. The method fulfilled most validation requirements in the 2 mg/mL and 20 mg/mL range, with a 0.9998 coefficient of determination obtained by simple calibration model, and a general coefficient of variation <2%. The mean recovery for the proposed assay method resulted within the (100±3)% over the 80%–120% range of the target concentration. The results agree with a pharmacopoeial method and, therefore, could be considered interchangeable.