Enhancement of carvedilol solubility by solid dispersion technique using cyclodextrins, water soluble polymers and hydroxyl acid

Supercritical fluid (SCF)-assisted preparation of cyclodextrin-based poly(pseudo)rotaxanes for transdermal purposes

This study aims to investigate the effect of the preparation of solid dispersions using supercritical CO2 (scCO2) on the physicochemical properties and the performance of supramolecular gels based on polymer-cyclodextrin (CD) interactions (named poly(pseudo)rotaxanes, PPR) envisaging a transdermal administration. Solid dispersions containing Soluplus®, the antihypertensive drug carvedilol (CAR), and CD (αCD or HPβCD) were prepared and characterized by HPLC, XRPD, FTIR, and DSC. PPRs prepared from solid dispersions (SCF gels) and the corresponding physical mixtures (PM gels) were analyzed regarding rheology, morphology, in vitro drug diffusion, and ex vivo drug skin permeation. The application of scCO2 led to the loss of the crystalline lattice of CAR while preserving its chemical identity. On the contrary, αCD crystals were still present in the SCF solid dispersions. SCF gels were more uniform than their corresponding PM, and the supercritical treatment resulted in changes in the rheological behavior, reducing the viscosity. CAR in vitro diffusion was significantly higher (p < 0.05) for the αCD-based SCF gel than its corresponding PM gel. Drug skin permeation showed a significant increase in drug flux from CD-based SCF gels (containing αCD or HPβCD) compared to corresponding PM gels. Additionally, the pretreatment of the skin with αCD exhibited increased CAR permeation, suggesting an interaction between αCD and the skin membrane. Results evidenced that SCF processing decisively modified the properties of the supramolecular gels, particularly those prepared with αCD.

Overview and thermodynamic modelling of deep eutectic solvents as co-solvents to enhance drug solubilities in water

The poor water solubility of active pharmaceutical ingredients (APIs) is a major challenge in the pharmaceutical industry. Co-solvents are sometimes added to enhance drug dissolution. A novel group of co-solvents, the Deep Eutectic Solvents (DES), have gained interest in the pharmaceutical field due to their good solvent power, biodegradability, sustainability, non-toxicity, and low cost. In this study, we first provide an overview of all the literature solubility studies involving a drug or API + water + DES, which can be a valuable list to some researchers. Then, we analyze these systems with focus on each individual drug/API and provide statistical information on each. A similar analysis is carried out with focus on the individual DESs. An investigation of the numeric values of the water-solubility enhancement by the different DESs for various drugs indicates that DESs are indeed effective co-solvents, with varying degrees of solubility enhancement, even up to 15-fold. This is strongly encouraging, indicating the need for further studies to find the most promising DESs for solubility enhancement. However, time-consuming and costly trial and error should be prevented by first screening, using theoretical-based or thermodynamic-based models. Based on this conclusion, the second part of the study is concerned with investigating and suggesting accurate thermodynamic approaches to tackle the phase equilibrium modeling of such systems. For this purpose, a large data bank was collected, consisting of 2009 solubility data of 25 different drugs/APIs mixed with water and 31 different DESs as co-solvents at various DES concentrations, over wide ranges of temperatures at atmospheric pressure. This data bank includes 107 DES + water + drug/API systems in total. The solubility data were then modeled according to the solid-liquid equilibrium framework, using the local composition activity coefficient models of NRTL, and UNIQUAC. The results showed acceptable behavior with respect to the experimental values and trends for all of the investigated systems, with AARD% values of 9.65 % and 14.08 % for the NRTL and UNIQUAC models, respectively. In general, the lower errors of NRTL, as well as its simpler calculation process and the requirement of fewer component parameters, suggest the priority of NRTL over UNIQUAC for use in this field.

Co-rotating twin screw process for continuous manufacturing of solid crystal suspension: A promising strategy to enhance the solubility, permeation and oral bioavailability of Carvedilol

Background: In the current work, co-rotating twin-screw processor (TSP) was utilized to formulate solid crystal suspension (SCS) of carvedilol (CAR) for enhancing its solubility, dissolution rate, permeation and bioavailability using mannitol as a hydrophilic carrier. Methods: In-silico molecular dynamics (MD) studies were done to simulate the interaction of CAR with mannitol at different kneading zone temperatures (KZT). Based on these studies, the optimal CAR: mannitol ratios and the kneading zone temperatures for CAR solubility enhancement were assessed. The CAR-SCS was optimized utilizing Design-of-Experiments (DoE) methodology using the Box-Behnken design. Saturation solubility studies and in vitro dissolution studies were performed for all the formulations. Physicochemical characterization was performed using differential scanning calorimetry , Fourier transform infrared spectroscopy, X-ray diffraction studies, and Raman spectroscopy analysis. Ex vivo permeation studies and in vivo pharmacokinetic studies for the CAR-SCS were performed. Stability studies were performed for the DoE-optimized CAR-SCS at accelerated stability conditions at 40 ºC/ 75% RH for three months. Results: Experimentally, the formulation with CAR: mannitol ratio of 20:80, prepared using a KZT of 120 ºC at 100 rpm screw speed showed the highest solubility enhancement accounting for 50-fold compared to the plain CAR. Physicochemical characterization confirmed the crystalline state of DoE-optimized CAR-SCS. In-vitro dissolution studies indicated a 6.03-fold and 3.40-fold enhancement in the dissolution rate of optimized CAR-SCS in pH 1.2 HCl solution and phosphate buffer pH 6.8, respectively, as compared to the pure CAR. The enhanced efficacy of the optimized CAR-SCS was indicated in the ex vivo and in vivo pharmacokinetic studies wherein the apparent permeability was enhanced 1.84-fold and bioavailability enhanced 1.50-folds compared to the plain CAR. The stability studies showed good stability concerning the drug content. Conclusions: TSP technology could be utilized to enhance the solubility, bioavailability and permeation of poor soluble CAR by preparing the SCS.

Microsponge-derived mini tablets loaded with immunosuppressive agents: Pharmacokinetic investigation in human volunteers, cell viability and IVIVC correlation

Sirolimus, a potent immunosuppressant, has been demonstrated to have remarkable activity in inhibiting allograft rejection in transplantation. The objective of the study was to fabricate microsponge mini tablets with enhanced solubility and bioavailability. β-Cyclodextrin and NEOCEL C91 were selected to prepare the microsponges (SLM-M) to improve the stability and solubility of sirolimus. The current study involved the quasi emulsion-solvent diffusion technique to design sirolimus-loaded microsponges that were further compressed into mini tablets 4 mm in diameter. Solid-state characterization, dissolution at different pH values, stability, and pharmacokinetic profiles with IVIVC data were analyzed in humans. Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and X-ray diffraction (XRD) were used to characterize the formulations, and high-performance liquid chromatography (HPLC) was used to assess the drug stability of the compressed microsponge minitablets. The API changed from the crystalline state to an amorphous state, as shown by XRD and DSC. The compressed mini tablets showed a 4-fold enhancement in the drug dissolution profile. A toxicology investigation suggested that mini tablets were safe. In humans, the bioavailability of sirolimus compressed mini tablets from SLM-M was significantly improved. The results suggest that mini tablets prepared with β-cyclodextrin and NEOCEL C91 by a quasi emulsion-solvent diffusion process might be an alternative way to improve the bioavailability of sirolimus. In addition, the manufacturing process is easily scalable for the commercialization of drugs to market.

Amorphous Solid Dispersion as Drug Delivery Vehicles in Cancer

Cancer treatment has improved over the past decades, but a major challenge lies in drug formulation, specifically for oral administration. Most anticancer drugs have poor water solubility which can affect their bioavailability. This causes suboptimal pharmacokinetic performance, resulting in limited efficacy and safety when administered orally. As a result, it is essential to develop a strategy to modify the solubility of anticancer drugs in oral formulations to improve their efficacy and safety. A promising approach that can be implemented is amorphous solid dispersion (ASD) which can enhance the aqueous solubility and bioavailability of poorly water-soluble drugs. The addition of a polymer can cause stability in the formulations and maintain a high supersaturation in bulk medium. Therefore, this study aimed to summarize and elucidate the mechanisms and impact of an amorphous solid dispersion system on cancer therapy. To gather relevant information, a comprehensive search was conducted using keywords such as "anticancer drug" and "amorphous solid dispersion" in the PubMed, Scopus, and Google Scholar databases. The review provides an overview and discussion of the issues related to the ASD system used to improve the bioavailability of anticancer drugs based on molecular pharmaceutics. A thorough understanding of anticancer drugs in this system at a molecular level is imperative for the rational design of the products.

Enhanced Efficacy of Carvedilol by Utilization of Solid Dispersion and Other Novel Strategies: A Review

Carvedilol is classified as a second class drug of Biopharmaceutical classification system (BCS), and it is an excellent beta blocker and vasodilating agent. It is used in a diverse range of disease states. Despite having tremendous advantages, the drug cannot be used effectively and productively due to aquaphobicity and poor bioavailability. To overcome this limitation, numerous novel approaches and tactics have been introduced over the past few years, such as Selfmicro emulsifying drug delivery systems (SMEDDS), nanoparticles, solid dispersions and liposomal drug delivery. The present review aims to accentuate the role of solid dispersion in improving the dissolution profile and aqua solubility of carvedilol and also to emphasize other novel formulations of carvedilol proposed to prevail the limitations of carvedilol. Solid dispersion and other novel approaches were found to play a significant role in overcoming the drawbacks of carvedilol, among which solid dispersion is the most feasible and effective approach being used worldwide. Reduced particle size, more wettability, and large surface area are obtained by the implementation of solid dispersion technique, hence improving carvedilol solubility and bioavailability.

Tablet Formulations of Polymeric Electrospun Fibers for the Controlled Release of Drugs with pH-Dependent Solubility

A challenge in the pharmaceutical sector is the development of controlled release dosage forms for oral administration of poorly soluble drugs, in particular, drugs characterized by pH-dependent solubility through the gastrointestinal tract, which itself shows wide variability in terms of environmental pHs. The best approach is to increase the dissolution rate of the drugs at the different pHs and only then modify its release behavior from the pharmaceutical form. This work aims to demonstrate the ability of properly designed polymeric nanofibers in enhancing the release rate of model drugs with different pH-dependent solubility in the different physiological pHs of the gastrointestinal tract. Polymeric nanofibers loaded with meloxicam and carvedilol were prepared using the electrospinning technique and were then included in properly designed tablet formulations to obtain fast or sustained release dosage forms. The nanofibers and the tablets were characterized for their morphological, physico-chemical and dissolution properties. The tablets are able to deliver the dose according to the expected release behavior, and zero-order, first-order, Higuchi, Korsmeyer–Peppas and Hixon–Crowell kinetics models were used to analyze the prevailing release mechanism of the tablets. This study shows that the electrospun fibers can be advantageously included in oral dosage forms to improve their release performances.

The Effect of Surfactant Type and Concentration on Physicochemical Properties of Carvedilol Solid Dispersions Prepared by Wet Milling Method

The present study mainly aimed to prepare solid dispersions (SDs) of a poorly water-soluble compound, carvedilol (CA), in the presence of pluronic F68 (F68) and myrj 52 by wet milling technique in order to enhance drug dissolution. The process enabled the preparation of SDs without using any toxic organic solvents. SDs with different CA: surfactant ratios were prepared by wet milling followed by freeze-drying method and evaluated for their particle size and dissolution. They were also characterized based on/using X-ray diffraction (XRD), differential scanning calorimetry (DSC), fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), and saturated solubility. The effect of cryoprotectant type on the dissolution and particle size of SDs was also investigated. Wet milling process resulted in the reduced particle size depending on the type of surfactant. The significant drug dissolution and saturated solubility enhancement were recorded for milled SD formulations. In this regard, Myrj had a greater impact compared to F68. Dissolution efficiencies (DE₃₀) obtained for the myrj-included SDs were up to 8.2-fold higher than that of untreated CA. The type of cryoprotectant was also found to affect the drug dissolution. According to the results, partial amorphization occurred in wet-milled samples, as confirmed by XRD and DSC analysis. It was concluded that using an appropriate surfactant along with wet-milling method may have been an effective approach for improving the dissolution rate of CA, a poorly soluble compound.

Preparation and Characterization of a Novel Mucoadhesive Carvedilol Nanosponge: A Promising Platform for Buccal Anti-Hypertensive Delivery

Carvedilol (CRV) is a non-selective third generation beta-blocker used to treat hypertension, congestive heart failure and angina pectoris. Oral administration of CRV showed poor bioavailability (25%), which might be ascribed to its extensive first-pass metabolism. Buccal delivery is known to boost drugs bioavailability. The aim of this study is to investigate the efficacy of bilosomes-based mucoadhesive carvedilol nanosponge for enhancing the oral bioavailability of CRV. The bilosomes were prepared, optimized and characterized for particle size, surface morphology, encapsulation efficiency and ex-vivo permeation studies. Then, the optimized formula was incorporated into a carboxymethyl cellulose/hydroxypropyl cellulose (CMC/HPC) composite mixture to obtain buccal nanosponge enriched with CRV bilosomes. The optimized bilosome formula (BLS9), showing minimum vesicle size, maximum entrapment, and highest cumulative in vitro release, exhibited a spherical shape with 217.2 nm in diameter, 87.13% entrapment efficiency, and sustained drug release for up to 24 h. In addition, ex-vivo drug permeation across sheep buccal mucosa revealed enhanced drug permeation with bilosomal formulations, compared to aqueous drug suspension. Consecutively, BLS9 was incorporated in a CMC/HPC gel and lyophilized for 24 h to obtain bilosomal nanosponge to enhance CRV buccal delivery. Morphological analysis of the prepared nanosponge revealed improved swelling with a porosity of 67.58%. The in vivo assessment of rats indicated that CRV-loaded nanosponge efficiently enhanced systolic/diastolic blood pressure, decreased elevated oxidative stress, improved lipid profile and exhibited a potent cardio-protective effect. Collectively, bilosomal nanosponge might represent a plausible nanovehicle for buccal delivery of CRV for effective management of hypertension.

Mixed micelles formulation for carvedilol delivery: In-vitro characterization and in-vivo evaluation

Carvedilol (CAR) is a widely studied, beta and alpha-1 blocker, antihypertensive drug due to its poor water solubility and low oral bioavailability (25-35%). The aim of this work is to improve poor water solubility and the pharmacokinetic parameters of carvedilol by using an optimized and self-assembly prepared micelle formulation. Optimized micelle formulation composed of Pluronic® F127, D-α-tocopheryl polyethylene glycol 1000 succinate, L-cysteine HCl in a ratio of 4:3:3. Micellar size, polydispersity index, zeta potential, morphology, critical micelle concentration, thermal behaviors, in-vitro dissolution of micelles and pharmacokinetic parameters in rats were characterized in this study. Carvedilol aqueous solubility increased (up to 271-fold) as a result of its encapsulation within a mixed micelle formulation. The measured micellar sizes of blank and carvedilol loaded mixed micelles are lower than 30 nm with size distributions of 26.69 ± 2.93 nm and 24.16 ± 4.89 nm, respectively. Transmission electron microscopy revealed that the micelles were spherically shaped. There is a significant enhancement of carvedilol dissolution compared to commercially available tablet formulation (f2 < 50). The in-vivo test demonstrated that the t_1/2 and AUC_0-∞ values of micelles were approximately 10.89- and 2.65-fold greater than that of the commercial tablets, respectively. Based on our study, bring such applications into being may provide effective new drugs for treatment armamentarium of cardiovascular diseases and hypertension in near future.

Effects of Formulation and Manufacturing Process on Drug Release from Solid Self-emulsifying Drug Delivery Systems Prepared by High Shear Mixing

This study sought to investigate the influence of formulation and process factors of the high shear mixing (HSM) on the properties of solid self-emulsifying drug delivery systems (S-SEDDS) containing the model drug carvedilol (CAR). Firstly, liquid SEDDS (L-SEDDS) were prepared by mixing castor oil with different proportions of surfactant (Solutol or Kolliphor RH40) and cosolvent (Transcutol or PEG400). A miscible L-SEDDS with high drug solubility (124.3 mg/g) was selected and gave rise to 10% (m/m) CAR loaded-emulsion with reduced particle size. Then, a factorial experimental design involving five component's concentration and two process factors was used to study the solidification of the selected L-SEDDS by HSM. CAR content, diffractometric profile, and in vitro dissolution were determined. Morphological and flow analyses were also performed. Porous and spherical particles with mean sizes ranging from 160 to 210 µm were obtained. Particle size was not affected by any formulation factor studied. Powder flowability, in turn, was influenced by L-SEDDS and crospovidone concentration. CAR in vitro dissolution from S-SEDDS was significantly increased compared to the drug as supplied and was equal (pH 1.2) or lower (pH 6.8) than that determined for L-SEDDS. Colloidal silicon dioxide decreased drug dissolution, whereas an increase in water-soluble diluent lactose and L-SEDDS concentration increased CAR dissolution. The proper selection of liquid and solid constituents proved to be crucial to developing an S-SEDDS by HSM. Indeed, the results obtained here using experimental design contribute to the production of S-SEDDS using an industrially viable process.

Cyclodextrin Multicomponent Complexes: Pharmaceutical Applications

Cyclodextrins (CDs) are naturally available water-soluble cyclic oligosaccharides widely used as carriers in the pharmaceutical industry for their ability to modulate several properties of drugs through the formation of drug-CD complexes. The addition of an auxiliary substance when forming multicomponent complexes is an adequate strategy to enhance complexation efficiency and to facilitate the therapeutic applicability of different drugs. This review discusses multicomponent complexation using amino acids; organic acids and bases; and water-soluble polymers as auxiliary excipients. Special attention is given to improved properties by including information on the solubility, dissolution, permeation, stability and bioavailability of several relevant drugs. In addition, the use of multicomponent CD complexes to enhance therapeutic drug effects is summarized.

The effect of drug loading on the properties of abiraterone-hydroxypropyl beta cyclodextrin solid dispersions processed by solvent free KinetiSol® technology

Abiraterone is a poorly water-soluble drug used in the treatment of prostate cancer. In our previous study, we reported that KinetiSol® processed solid dispersions (KSDs) based on hydroxypropyl β-cyclodextrin (HPBCD) showed improved dissolution and pharmacokinetics of abiraterone. However, the nature of abiraterone-HPBCD interaction within the KSDs or the effect of drug loading on the physicochemical properties and in vivo performance of HPBCD-based KSDs remain largely unknown. We hypothesize that KinetiSol technology can prepare abiraterone-HPBCD complexes within KSDs and that increasing the drug loading beyond an optimal point reduces the in vitro and in vivo performance of these KSDs. To confirm our hypothesis, we developed KSDs with 10-50% w/w drug loading and analyzed them using X-ray diffractometry and modulated differential scanning calorimetry. We found that KSDs containing 10-30% drug were amorphous. Interestingly, two-dimensional solid-state nuclear magnetic resonance and Raman spectroscopy indicated that the abiraterone-HPBCD complexes were formed. At elevated temperatures, the 10% and 20% drug-loaded KSDs were physically stable, while the 30% drug-loaded KSD showed recrystallization of abiraterone. In vitro dissolution and in vivo pharmacokinetic performances improved as the drug loading decreased; we attribute this to increased noncovalent interactions between abiraterone and HPBCD at lower drug loadings. Overall, the 10% drug loaded KSD showed a dissolution enhancement of 15.7-fold compared to crystalline abiraterone, and bioavailability enhancement of 3.9-fold compared to the commercial abiraterone acetate tablet Zytiga®. This study is first to confirm that KinetiSol, a high-energy, solvent-free technology, is capable of forming abiraterone-HPBCD complexes. Furthermore, in terms of in vitro and in vivo performance, a 10% drug load is optimal.

Solubility enhancement of carvedilol using drug–drug cocrystallization with hydrochlorothiazide

Background

Increasing hydrophilicity of poorly water-soluble drugs is a major challenge in drug discovery and development. Cocrystallization is one of the techniques to enhance the hydrophilicity of such drugs. Carvedilol (CAR), a nonselective beta/alpha1 blocker, used in the treatment of mild to moderate congestive heart failure and hypertension, is classified under BCS class II with poor aqueous solubility and high permeability. Present work is an attempt to improve the solubility of CAR by preparing cocrystals using hydrochlorothiazide (HCT), a diuretic drug, as coformer. CAR-HCT (2:0.5) cocrystals were prepared by slurry conversion method and were characterized by DSC, PXRD, FTIR, Raman, and SEM analysis. The solubility, stability, and dissolution (in vitro) studies were conducted for the cocrystals.

Results

The formation of CAR-HCT cocrystals was confirmed based on melting point, DSC thermograms, PXRD data, FTIR and Raman spectra, and finally by SEM micrographs. The solubility of the prepared cocrystals was significantly enhanced (7.3 times), and the dissolution (in vitro) was improved by 2.7 times as compared to pure drug CAR. Further, these cocrystals were also found to be stable for 3 months (90 days).

Conclusion

It may be inferred that the drug–drug (CAR-HCT) cocrystallization enhances the solubility and dissolution rate of carvedilol significantly. Further, by combining HCT as coformer could well be beneficial pharmacologically too.

Impact of drying on dissolution behavior of carvedilol-loaded sustained release solid dispersion: development and characterization

Purpose

The present study aimed to develop carvedilol (CAR)-loaded (25% w/w) sustained release solid dispersion (SRSD), for enhanced dissolution and to explore the applicability of different industrially accessible drying techniques.

Methods

SRSD-CAR containing different ratios of polymers were prepared and physicochemically characterized. Dissolution study was carried out in both sink and supersaturated conditions to identify the possible enhancement in dissolution behavior.

Results

Based on the solubility study, Kolliphor® P188 and Eudragit® RSPO (50:25, % w/w) ratio exhibited the highest solubility among the samples and was chosen as the optimal composition of SRSD-CAR for further characterization. The crystallinity assessments of the optimized formulation indicated amorphization of CAR in the formulation, bring about improved solubility of CAR. The infrared spectroscopic study revealed minor transitions; demonstrating the absence of significant interactions between drug and carrier. Furthermore, the SRSD-CAR exhibited immediate formation of nano particles when dispersed in water. Dissolution study revealed significant improvement in dissolution behavior, with a release of CAR in a gradual manner compared to crystalline CAR. From the dissolution kinetics analysis, the Korsmeyer Peppas model fit the best and diffusion was predominant in release of CAR. The drug release pattern showed insignificant differences between the SRSD-CAR formulations prepared by rotary vacuum drying and freeze drying.

Conclusion

From these experimental findings, SRSD approach might be a favorable dosage option for CAR, offering improved biopharmaceutical properties.

Amorphous solid dispersions: An update for preparation, characterization, mechanism on bioavailability, stability, regulatory considerations and marketed products

Amorphous solid dispersions (ASDs) are being employed frequently to improve bioavailability of poorly soluble molecules by enhancing the rate and extant of dissolution in drug product development process. These systems comprise of an amorphous active pharmaceutical ingredient stabilized by a polymer matrix to provide enhanced stability. This review discussed the methodologies of preparation and characterization of ASDs with an emphasis on understanding and predicting stability. Rational selection of polymers, preparation techniques with its advantages and disadvantages and characterization of polymeric amorphous solid dispersions have discussed. Stability aspects have been described as per ICH guidelines which intend to depend on selection of polymers and preparation methods of ASD. The mechanism involved on improvement of bioavailability also considered. Regulatory importance of ASD and current evolving details of QBD approach were reviewed. Amorphous products and particularly ASDs are currently most emerging area in the pharmaceutical field. This strategic approach presents huge impact and advantageous features concerning the overall improvement of drug product performance in clinical settings which ultimately lead to drug product approval by leading regulatory agencies into the market.

Piperine fast disintegrating tablets comprising sustained-release matrix pellets with enhanced bioavailability: formulation, in vitro and in vivo evaluation

Piperine (Pip) has been widely studied for its multiple activities such as antidepressant, anti-epileptic, and so forth. However, the poor water solubility coupled with low bioavailability may inevitably hinder the application of Pip in the clinical setting. In this study, a formulation strategy was proposed to spontaneously resolve the low bioavailability and dose dividing issue of Pip. The matrix pellets (Pip-SR-pellets) consisting of Pip solid dispersion (Pip-SD) and hydroxypropylmethyl cellulose-K100 were developed to achieve an increased and sustained release profile in vitro. The Pip-SR-pellets were compacted into fast disintegrating tablets (FDTs) with a blend of excipients comprising lactose, MCC, LS-HPC, and CMS-Na. The Pip-SD was characterized by solubility study and XRD. The evaluation of the cross-sectional morphology of the Pip-FDTs via scanning electron microscope proved that Pip-SR-pellets maintained its structural integrity during compression and were uniformly distributed in the Pip-FDTs. The release profile of Pip-SR-pellets was highly consistent with the Pip-FDTs. In vivo pharmacokinetics study demonstrated that the relative bioavailability of Pip-SR-pellets was approximately 2.70-fold higher than that of the pure drug, and 1.62-fold compared with that of Pip-SD. This work therefore showed a potential industrialized method could be applied to formulate poorly water-soluble drug that has dose-dividing requirement.

An overview of techniques for multifold enhancement in solubility of poorly soluble drugs

Poor water solubility of newly discovered compounds has become the most common challenge in the drug development process. Indeed, poor solubility is considered as the root cause of failure of drug during drug development phases. Moreover, it has also been reported to be the main reason for bioavailability issues such as poor, inconsistent, incomplete and highly variable bioavailability of the marketed products. As per an estimate, approximately 90% of drug molecules suffer with poor water solubility at early stage and approximately 40% of the marketed drugs have bioavailability problems mainly due to poor water solubility. Solubility enhancement of the newly discovered compounds is primary research area for the pharmaceutical industries and research institutions. The conventional techniques to improve aqueous solubility of drugs employ salt formation, prodrug formation, co-crystallization, complexation, amorphous solid dispersion and use of co-solvent, surfactants or hydrotropic agents. Current advancement in the science and technology has enabled the use of relatively new techniques under the umbrella of nanotechnology. These include the development of nanocrystals, nanosuspensions, nanoemulsions, microemulsions, liposomes and nanoparticles to enhance the solubility. This review focuses on the conventional and current approaches of multifold enhancement in the solubility of poorly soluble marketed drugs, including newly discovered compounds.

Preparation and physicochemical characterization of binary and ternary ground mixtures of carvedilol with PVP and SLS aimed to improve the drug dissolution

The objective of the present study was to enhance the dissolution rate of carvedilol (CA), a poorly water-soluble antihypertensive drug, using a co-grinding method in the presence of polyvinylpyrrolidone (PVP) and sodium lauryl sulfate (SLS). Various ratios of CA:PVP:SLS were ground by a planetary ball mill. They were studied in terms of dissolution, solubility, and particle size. The solid state and morphology of the intact drug and prepared samples were also characterized using differential scanning calorimetry (DSC), infrared spectroscopy (IR), X-ray diffraction (XRD), and scanning electron microscope (SEM). According to the results, co-grinding in the presence of PVP and SLS significantly increased CA dissolution rate. DE₆₀ (dissolution efficiency) obtained for the best ternary ground mixture (89.31%) was 3.4 and 4.5 times higher than that of the related physical mixture (PM) and the intact drug, respectively. Further, the solubility of this formulation was about 10 times higher compared to that of the intact CA. A direct correlation was also observed between the chamber rotation speed of the planetary mill within the range of 100-400 rpm and CA dissolution rate. Finally, DSC, IR, and XRD analysis ruled out any polymorphic changes and chemical interactions during the grinding process.

Preparation, characterization and ex vivo-in vivo assessment of candesartan cilexetil nanocrystals via solid dispersion technique using an alkaline esterase activator carrier

The objective of this study was to improve candesartan cilexetil (CC) efficacy by formulating nanocrystals via solid dispersion (SD) technique using tromethamine (Tris). SD was prepared by solvent evaporation at different drug carrier ratios, evaluated for particle size, vitro dissolution studies, TEM, FTIR, and X-ray powder diffraction. Ex vivo, in vivo pharmacokinetic parameters were conducted on selected formulae compared to drug suspension and marketed product. Size analysis demonstrated formation of particles in the nanorange lower than 300 nm. A burst drug release followed by an improved dissolution was observed indicating instant formation of nanocrystals along with amorphization as confirmed by X-ray diffraction. FTIR studies suggested the absence of chemical interaction between Tris and CC. TEM revealed formation of irregular oval nanoparticles. SD-1:5 has higher apparent permeability coefficient compared to CC suspension. Furthermore, the pharmacokinetic results proved the ability of the formed nanoparticles to enhance the efficacy of CC compared to drug suspension and marketed product. In conclusion, using of Tris as alkaline esterase activator carrier could be a promising tool to bypass the controversial effect of esterase enzymes that may be a source for inter-individual variations affecting ester prodrug candidates' efficacy.

Synthon hierarchy in theobromine cocrystals with hydroxybenzoic acids as coformers

Cocrystals, solids composed of molecular and/or ionic compounds connected by noncovalent interactions, are objects of interest in crystal engineering. Theobromine, as an active pharmaceutical ingredient, was used in cocrystallization with dihydroxybenzoic acids.

Amorphous solid dispersions of carvedilol along with pH-modifiers improved pharmacokinetic properties under hypochlorhydoria

Carvedilol (CAR) belongs to biopharmaceutics classification system class-II drugs, with poor aqueous solubility and pH-dependent solubility. The present study aimed to develop a novel amorphous solid dispersion (ASD) of CAR with acidic counter ions for pH modifications in microenvironment to improve the pharmacokinetic properties under hypochlorhydric conditions. CAR-ASD was prepared by freeze-drying in combination with counter ions and hydroxypropyl cellulose, and their physicochemical properties including dissolution behavior, storage stability, and photostability were characterized. Pharmacokinetic studies were carried out after oral administration of CAR samples in both normal and omeprazole-treated (30 mg/kg, p.o.) rats as a hypochlorhydria model. Among the tested six counter ions, citric acid (CA) was found to be a preferable pH-modifier of CAR with respect to the dissolution profile and photostability (both potency and colorimetric evaluation). In CAR-ASD formulation with 50% loading of CA (CAR-ASD/CA50), amorphization of CAR was observed during the preparation process. After the oral administration of crystalline CAR in rats under hypochlorhydric condition, there was a 34.4% reduction in the systemic exposure of CAR compared with that in normal rats. However, orally-dosed CAR-ASD/CA50 resulted in limited alterations of pharmacokinetic behavior between normal and omeprazole-treated rats. From these findings, addition of CA as pH-modifier in CAR-ASD might provide consistent pharmacokinetic behavior of CAR even under hypochlorhydric conditions.

Cyclodextrin-based poly(pseudo)rotaxanes for transdermal delivery of carvedilol

This work aimed to design supramolecular gels combining Soluplus or Solutol and alfa- and hydroxypropyl-β-cyclodextrin (α-CD, HPβ-CD) for carvedilol (CAR) transdermal delivery. Poly(pseudo)rotaxane formation (appearance, SEM, ¹H NMR), drug solubilization, rheological properties and in vitro release were investigated. CAR-CD complexes were prepared in situ or by spray drying. For Solutol, poly(pseudo)rotaxanes were formed immediately after mixing with α-CD and did not influence CAR solubility. Differently, Soluplus poly(pseudo)rotaxanes took 24-48 h to be formed and CAR solubility decreased compared to Soluplus micelles. Soluplus 20% + α-CD (5-10%) showed higher G' and G'' but also faster CAR release than Solutol poly(pseudo)rotaxanes, which is explained by the different location of PEG chains in the two amphiphilic polymers. Faster drug release was achieved incorporating HPβ-CD or CAR-HPβ-CD spray-dried complexes. The results evidenced the versatility of the formulations in terms of rheological behavior and drug release patterns, which can be adjusted for CAR transdermal delivery.

Different types, applications and limits of enabling excipients of pharmaceutical dosage forms

Along with the development of novel drug delivery systems the material science is also advancing. Conventional and novel synthetic or natural excipients provide opportunities to design dosage forms of the required features including their bioavailability. Emerging trends in the design and development of drug products indicate an increasing need for the functionality-related characterization of excipients. The purpose of this review is to provide an overview of different types of excipients in relation to their application possibilities in various dosage forms with special focus on the enabling excipients. The study also summarizes the applied excipient systems of research formulations and dosage forms available on the market.

Antioxidant MMCC ameliorates catch-up growth related metabolic dysfunction

Postnatal catch-up growth may be related to reduce mitochondrial content and oxidation capacity in skeletal muscle. The aim of this study is to explore the effect and mechanism of antioxidant MitoQuinone mesylate beta cyclodextrin complex (MMCC) ameliorates catch-up growth related metabolic disorders. Catch-up growth mice were created by restricting maternal food intake during the last week of gestation and providing high fat diet after weaning. Low birthweight mice and normal birthweight controls were randomly subjected to normal fat diet, high fat diet and high fat diet with MMCC drinking from the 4th week. MMCC treatment for 21 weeks slowed down the catch up growth and ameliorated catch-up growth related obesity, glucose intolerance and insulin resistance. MMCC administration significantly inhibited the peroxidation of the membrane lipid and up-regulated the antioxidant enzymes Catalase and MnSOD. In addition, MMCC treatment effectively enhanced mitochondrial functions in skeletal muscle through the up-regulation of the ATP generation, and the promotion of mitochondrial replication and remodeling. To conclude, this study demonstrates that antioxidant MMCC effectively ameliorates catch-up growth related metabolic dysfunctions by increasing mitochondrial functions in skeletal muscle.

Dual Activity of Hydroxypropyl-β-Cyclodextrin and Water-Soluble Carriers on the Solubility of Carvedilol

Carvedilol (CAR) is a non-selective α and β blocker categorized as class II drug with low water solubility. Several recent studies have investigated ways to overcome this problem. The aim of the present study was to combine two of these methods: the inclusion complex using hydroxypropyl-β-cyclodextrin (HPβCD) with solid dispersion using two carriers: Poloxamer 188 (PLX) and Polyvinylpyrrolidone K-30 (PVP) to enhance the solubility, bioavailability, and the stability of CAR. Kneading method was used to prepare CAR-HPβCD inclusion complex (KD). The action of different carriers separately and in combination on Carvedilol solubility was investigated in three series. CAR-carrier and KD-carrier solid dispersions were prepared by solvent evaporation method. In vitro dissolution test was conducted in three different media: double-distilled water (DDW), simulative gastric fluid (SGF), and PBS pH 6.8 (PBS). The interactions between CAR, HPβCD, and different carriers were explored by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffractometry (XRD), and differential scanning colorimetry (DSC). The results showed higher solubility of CAR in KD-PVP solid dispersions up to 70, 25, and 22 fold compared to pure CAR in DDW, SGF, and PBS, respectively. DSC and XRD analyses indicated an improved degree of transformation of CAR in KD-PVP solid dispersion from crystalline to amorphous state. This study provides a new successful combination of two polymers with the dual action of HPβCD and PLX/PVP on water solubility and bioavailability of CAR.

Development of carvedilol-cyclodextrin inclusion complexes using fluid-bed granulation: a novel solid-state complexation alternative with technological advantages

Objectives

This study sought to evaluate the achievement of carvedilol (CARV) inclusion complexes with modified cyclodextrins (HPβCD and HPγCD) using fluid-bed granulation (FB).

Methods

The solid complexes were produced using FB and spray drying (SD) and were characterised by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction, SEM, flowability and particle size analyses and in vitro dissolution.

Key findings

The DSC, FTIR and powder X-ray diffraction findings suggested successful CARV inclusion in the modified β- and γ-cyclodextrins, which was more evident in acidic media. The CARV dissolution rate was ~7-fold higher for complexes with both cyclodextrins prepared using SD than for raw CARV. Complexes prepared with HPβCD using FB also resulted in a significant improvement in dissolution rate (~5-fold) and presented superior flowability and larger particle size.

Conclusions

The findings suggested that FB is the best alternative for large-scale production of solid dosage forms containing CARV. Additionally, the results suggest that HPγCD could be considered as another option for CARV complexation because of its excellent performance in inclusion complex formation in the solid state.

Cyclodextrin-based telmisartan ophthalmic suspension: Formulation development for water-insoluble drugs

In this study, cyclodextrin-based aqueous eye drop suspension of the water insoluble drug telmisartan was developed. Formation of a drug/γ-cyclodextrin complex was enabled by preventing formation of a poorly water-soluble zwitterion using a volatile base that was removed upon drying of the complex powder. Hydroxypropyl methylcellulose was shown to have the overall best effect, stabilizing the complexes without hampering the drug release from the formulation. Two strategies for preparing cyclodextrin-based aqueous eye drop suspensions of telmisartan were investigated, one where hydroxypropyl methylcellulose was added to the medium during preparation of the drug/γ-cyclodextrin complex powder (ternary complex) and the other where hydroxypropyl methylcellulose was added to the complex powder after preparation of the complex (binary complex). The complexation was characterized by DSC, FT-IR and (1)H NMR and the eye drop suspensions formed were examined regarding their stability and in vitro mucoadhesion property. The ternary complex exhibited inferior mucoadhesive property compared to the binary complex. However, the ternary complex was more stable as no notable change in particle size and particle size distribution was observed during storage at 4°C over 6 months (p<0.05) with the mean particle size determined between 2.0 and 2.5μm.

pH-Dependent Solubility and Dissolution Behavior of Carvedilol--Case Example of a Weakly Basic BCS Class II Drug

The objective of this study was to investigate the pH-dependent solubility and dissolution of weakly basic Biopharmaceutical Classification Systems (BCS) class II drugs, characterized by low solubility and high permeability, using carvedilol, a weak base with a pK a value of 7.8, as a model drug. A series of solubility and in vitro dissolution studies was carried out using media that simulate the gastric and intestinal fluids and cover the physiological pH range of the GI from 1.2 to 7.8. The effect of ionic strength, buffer capacity, and buffer species of the dissolution media on the solubility and dissolution behavior of carvedilol was also investigated. The study revealed that carvedilol exhibited a typical weak base pH-dependent solubility profile with a high solubility at low pH (545.1-2591.4 μg/mL within the pH range 1.2-5.0) and low solubility at high pH (5.8-51.9 μg/mL within the pH range 6.5-7.8). The dissolution behavior of carvedilol was consistent with the solubility results, where carvedilol release was complete (95.8-98.2% released within 60 min) in media simulating the gastric fluid (pH 1.2-5.0) and relatively low (15.9-86.2% released within 240 min) in media simulating the intestinal fluid (pH 6.5-7.8). It was found that the buffer species of the dissolution media may influence the solubility and consequently the percentage of carvedilol released by forming carvedilol salts of varying solubilities. Carvedilol solubility and dissolution decreased with increasing ionic strength, while lowering the buffer capacity resulted in a decrease in carvedilol solubility and dissolution rate.

Novel Gefitinib Formulation with Improved Oral Bioavailability in Treatment of A431 Skin Carcinoma

PURPOSE

Oral administration of anticancer agents presents a series of advantages for patients. However, most of the anticancer drugs have poor water solubility leading to low bioavailability.

METHODS

Controlled released spray dried matrix system of Gefitinib with hydroxypropyl β-cyclodextrin, chitosan, hydroxy propyl methyl cellulose, vitamin E TPGS, succinic acid were used for the design of formulations to improve the oral absorption of Gefitinib. Spray drying with a customized spray gun which allows simultaneous/pulsatile flow of two different liquid systems through single nozzle was used to prepare Gefitinib spray dried formulations (Gef-SD). Formulation was characterized by in vitro drug release and Caco-2 permeability studies. Pharmacokinetic studies were performed in Sprague Dawley rats. Efficacy of Gef-SD was carried out in A431 xenografts models in nude mice.

RESULTS

In Gef-SD group 9.14-fold increase in the AUC was observed compared to free Gef. Improved pharmacokinetic profile of Gef-SD translated into increase (1.75 fold compared to Gef free drug) in anticancer effects. Animal survival was significantly increased in Gef formulation treated groups, with superior reduction in the tumor size (1.48-fold) and volumes (1.75-fold) and also increase in the anticancer effects (TUNEL positive apoptotic cells) was observed in Gef-SD treated groups. Further, western blot, immunohistochemical and proteomics analysis demonstrated the increased pharmacodynamic effects of Gef-SD formulations in A431 xenograft tumor models.

CONCLUSION

Our studies suggested that Gefitinib can be successfully incorporated into control release microparticles based oral formulation with enhanced pharmacokinetic and pharmacodynamic activity. This study demonstrates the novel application of Gef in A431 tumor models.

Development of oral dispersible tablets containing prednisolone nanoparticles for the management of pediatric asthma

The purpose of the present study was to develop oral dispersible tablets containing prednisolone (PDS)-loaded chitosan nanoparticles using microcrystalline cellulose (MCC 101), lactose, and croscarmellose sodium (CCS). The PDS-loaded chitosan nanoparticles were formulated by ionotropic external gelation technique in order to enhance the solubility of PDS in salivary pH. Prepared nanoparticles were used for the development of oral fast disintegrating tablets by direct compression method. The prepared tablets were evaluated for disintegration time (DT), in vitro drug release (DR), thickness, weight variation, drug content uniformity, friability, and hardness. The effect of concentrations of the dependent variables (MCC, lactose, CCS) on DT and in vitro DR was studied. Fast disintegrating tablets of PDS can be prepared by using MCC, CCS, and lactose with enhanced solubility of PDS. The minimum DT was found to be 15 seconds, and the maximum DR within 30 minutes was 98.50%. All independent variables selected for the study were statistically significant. Oral fast disintegrating tablets containing PDS nanoparticles could be the better choice for the pediatric patients that would result in better patient compliance. From this study, it can be concluded that fast disintegrating tablets could be a potential drug delivery technology for the management of asthma in pediatrics.