Comprehensive quality by design approach for stable nanocrystalline drug products

Nanocrystal formulations of mebendazole employing Quality by Design and molecular level insights by atomistic simulations

OBJECTIVE

The present study investigates the production of mebendazole nanocrystal formulations by wet media milling.

SIGNIFICANCE

Nanocrystal formulations are expected to enhance the dissolution properties of mebendazole, which possesses poor solubility, highly dependent on crystal polymorphism.

METHODS

A Box-Behnken design was employed to study the effects of formulation and process variables on the nanocrystal size and ζ-potential. The optimal nanosuspensions were solidified by spay-drying and freeze-drying with and without mannitol, and the effects of the drying method on the reconstitution of the nanosuspension was studied. Additionally, their physicochemical properties were determined, while the mechanism of fracture and stabilizer adsorption were investigated by atomistic simulations.

RESULTS

Poloxamer 407 is the most suitable stabilizer, while the bead size, milling speed, and stabilizer content significantly affect the diameter. The ζ-potential is affected by the stabilizer concentration depending on bead size. Energy-vector diagrams revealed a slip plane in the lattice of form C, while molecular dynamics simulations revealed strong interactions between stabilizer and crystal surface. Both drying processes induce polymorphic transformation to form A, which, however, can be partially prevented by the addition of mannitol in freeze-drying, at the expense of suspension redispersibility. The spray-dried nanosuspensions exhibited substantially enhanced dissolution profile compared to neat mebendazole, probably due to reduction of particle size, despite transformation to the unfavorable form A.

CONCLUSIONS

Nanocrystal formulations exhibited significant dissolution enhancement, while experimental design and atomistic simulations provided useful insights into the mechanism of their formation and stability.

Evaluation of gender differences in the pharmacokinetics of oral zileuton nanocrystalline formulation using a rat model

Zileuton is a leukotriene inhibitor used to treat asthma. As a BCS class II drug it exhibits challenges with solubility which likely impact its absorption. As patient gender significantly impacts the pharmacokinetics of many drugs, this study aimed to investigate potential gender-based pharmacokinetic differences after oral zileuton administration in rats. Male and female Sprague Dawley rats received single oral gavage doses of pure zileuton as an active pharmaceutical ingredient (30 mg/kg body weight (bw)), physical mixture (PM; at 30 mg/kg bw of the formulation contains zileuton, kollidon VA64 fine, dowfax2A1 and trehalose), and nanocrystalline formulation of zileuton (NfZ; at 30 mg/kg bw of the formulation). Plasma, tissue, and urine concentrations were quantified using high performance liquid chromatography (HPLC). Noncompartmental pharmacokinetic analysis showed higher zileuton levels in the plasma of female versus male rats across all evaluated forms of zileuton (API, PM, and NfZ). Female rats demonstrated higher peak plasma concentrations (Cmax) and increased area under the plasma concentration-time curve (AUC) relative to males, regardless of formulation. These findings reveal substantial gender disparities in the pharmacokinetics of zileuton in the rat model. This study emphasizes the critical need to evaluate gender differences during preclinical drug development to enable gender-based precision dosing strategies for equivalent efficacy/safety outcomes in male and female patients. Additional studies are warranted to investigate underlying mechanisms of such pharmacokinetic gender divergences.

Tannic acid coated nanosuspension for oral delivery of chrysin intended for anti-schizophrenic effect in mice

Chrysin is a flavonoid drug with numerous therapeutic activities. It suffers from low intestinal absorption owing to its hydrophobicity. Therefore, the aim of this study is to exploit the efficient technique of nanosuspension (NSP) to formulate chrysin-NSP coated with tannic acid (TA) to improve the solubility and anti-schizophrenic activity of chrysin. A 23 full factorial design was constructed where the independent factors were type of polymer, surfactant concentration (0.5 or 1 %) and the aqueous phase volume (5 or 15 mL), while the dependent responses were the particle size (PS) of the obtained formulation as well as the % chrysin dissolved after 2 h (Q2h). The optimum formulation (NSP-4) composed of 1 % PEG 400 and 1 % Cremophor RH40 in 15 mL aqueous phase. It achieved a PS and Q2h values of 108.00 nm and 38.77 %, respectively. NSP-4 was then coated with TA (TA-coated NSP-4) for further enhancement of chrysin solubility. TA-coated NSP-4 revealed PS and zeta potential values of 150 ± 14 nm and -32.54 ± 2.45 mV, respectively. After 6 h, chrysin dissolved % were 53.97 and 80.22 for uncoated NSP-4 and TA-coated NSP-4, respectively, compared with only 9.47 for free chrysin. The developed formulations and free chrysin were assessed regarding their effect on schizophrenia induced in mice by cuprizone (CPZ). Treatment with the developed formulations and free chrysin ameliorated demyelination and behavioral deficit induced by CPZ via elevating MBP and PI3K/PKC activities as well as reducing GFAP expression levels. The developed formulations and free chrysin inhibited Galactin-3 and TGF-β expressions and stimulated GST antioxidant enzyme. Furthermore, they maintained the balances in glutamatergic and dopaminergic neurotransmission via modulation on neuregulin-1 and alleviated nuclear pyknosis and degeneration in the neurons. The order of activity was: TA-coated NSP-4 > NSP-4 > free chrysin.

Evaluation of mucosal immune profile associated with Zileuton nanocrystal-formulated BCS-II drug upon oral administration in Sprague Dawley rats

Nanocrystal drug formulation involves several critical manufacturing procedures that result in complex structures to improve drug solubility, dissolution, bioavailability, and consequently the efficacy of poorly soluble Biopharmaceutics Classification System (BCS) II and IV drugs. Nanocrystal formulation of an already approved oral drug may need additional immunotoxic assessment due to changes in the physical properties of the active pharmaceutical ingredient (API). In this study, we selected Zileuton, an FDA-approved drug that belongs to BCS-II for nanocrystal formulation. To evaluate the efficacy and mucosal immune profile of the nanocrystal drug, 10-week-old rats were dosed using capsules containing either API alone or nanocrystal formulated Zileuton (NDZ), or with a physical mixture (PM) using flexible oral gavage syringes. Control groups consisted of untreated, or placebo treated animals. Test formulations were administrated to rats at a dose of 30 mg/kg body weight (bw) once a day for 15 days. The rats treated with NDZ or PM had approximately 4.0 times lower (7.5 mg/kg bw) API when compared to the micron sized API treated rats. At the end of treatment, mucosal (intestinal tissue) and circulating cytokines were measured. The immunological response revealed that NDZ decreased several proinflammatory cytokines in the ileal mucosa (Interleukin-18, Tumor necrosis Factor-α and RANTES [regulated upon activation, normal T cell expressed and secreted]). A similar pattern in the cytokine profile was also observed for the micron sized API and PM treated rats. The cytokine production revealed that there was a significant increase in the production of IL-1β and IL-10 in the females in all experimental groups. Additionally, NDZ showed an immunosuppressive effect on proinflammatory cytokines both locally and systemically, which was similar to the response in micron sized API treated rats. These findings indicate that NDZ significantly decreased several proinflammatory cytokines and it displays less immunotoxicity, probably due to the nanocrystal formulation. Thus, the nanocrystal formulation is more suitable for oral drug delivery, as it exhibited better efficacy, safety, and reduced toxicity.

Optimizing adjuvant inhaled chemotherapy: Synergistic enhancement in paclitaxel cytotoxicity by flubendazole nanocrystals in a cycle model approach

Lung cancer is the leading cause of cancer-related death. In addition to new innovative approaches, practical strategies that improve the efficacy of already available drugs are urgently needed. In this study, an inhalable dry powder formulation is used to repurpose flubendazole, a poorly soluble anthelmintic drug with potential against a variety of cancer lineages. Flubendazole nanocrystals were obtained through nanoprecipitation, and dry powder was produced by spray drying. Through fractional factorial design, the spray drying parameters were optimized and the impact of formulation on aerolization properties was clarified. The loading limitations were clarified through response surface methodology, and a 15% flubendazole loading was feasible through the addition of 20% L-leucine, leading to a flubendazole particle size of 388.6 nm, median mass aerodynamic diameter of 2.9 μm, 50.3% FPF, emitted dose of 83.2% and triple the initial solubility. Although the cytotoxicity of this formulation in A549 cells was limited, the formulation showed a synergistic effect when associated with paclitaxel, leading to a surprising 1000-fold reduction in the IC50. Compared to 3 cycles of paclitaxel alone, a 3-cycle model combined treatment increased the threshold of cytotoxicity by 25% for the same dose. Our study suggests, for the first time, that orally inhaled flubendazole nanocrystals show high potential as adjuvants to increase cytotoxic agents' potency and reduce adverse effects.

An Enthalpy-Balance Model for Timewise Evolution of Temperature during Wet Stirred Media Milling of Drug Suspensions

PURPOSE

Nanosuspensions have been used for enhancing the bioavailability of poorly soluble drugs. This study explores the temperature evolution during their preparation in a wet stirred media mill using a coupled experimental-enthalpy balance approach.

METHODS

Milling was performed at three levels of stirrer speed, bead loading, and bead sizes. Temperatures were recorded over time, then simulated using an enthalpy balance model by fitting the fraction of power converted to heat ξ. Moreover, initial and final power, ξ, and temperature profiles at 5 different test runs were predicted by power-law (PL) and machine learning (ML) approaches.

RESULTS

Heat generation was higher at the higher stirrer speed and bead loading/size, which was explained by the higher power consumption. Despite its simplicity with a single fitting parameter ξ, the enthalpy balance model fitted the temperature evolution well with root mean squared error (RMSE) of 0.40-2.34°C. PL and ML approaches provided decent predictions of the temperature profiles in the test runs, with RMSE of 0.93-4.17 and 1.00-2.17°C, respectively.

CONCLUSIONS

We established the impact of milling parameters on heat generation-power and demonstrated the simulation-prediction capability of an enthalpy balance model when coupled to the PL-ML approaches.

Analysis of heat generation during the production of drug nanosuspensions in a wet stirred media mill

Although heat is generated during the wet stirred media milling of drug suspensions, leading to notable temperature rise, a comprehensive analysis of heat generation does not exist. Hence, we investigated the impact of stirrer speed, bead loading, and bead size at three levels on the evolution of suspension temperature at the mill outlet during the milling of fenofibrate. The particle sizes and viscosities of the milled suspensions and power were measured. Our results suggest that stirrer speed had the most significant impact on the temperature increase, followed by bead loading and bead size. Both the time when the temperature reached 22 °C and the temperature at 5 min of milling were strongly correlated with the power. Assessing the impacts of the process parameters on the temperature rise, cycle time, power, and median particle size holistically, an optimal milling process was identified: 3000 rpm with 50% loading of 200 or 400 µm beads. A power number correlation was established to calculate power at any milling condition which determines the heat generation rate. Overall, this study indicated the importance of developing a good understanding of heat generation during nanomilling for development of a robust milling process especially for thermally labile drugs.

Oral Formulation Based on Irbesartan Nanocrystals Improve Drug Solubility, Absorbability, and Efficacy

We previously reported that the bioavailability (BA) of irbesartan (IRB), a BSC class II drug, was improved by preparing nanocrystalline suspensions. However, nanocrystalline suspensions have chemical and physical instabilities and must be converted into tablets through drying approaches in order to overcome such instabilities. In this study, we attempted to design a molded tablet based on nanocrystalline IRB suspensions (IRB-NP tablet) and investigated the effects of this IRB-NP tablet on blood pressure (BP) in a stroke-prone spontaneously hypertensive (SHR-SP) rat. The IRB-NP tablet (with a hardness of 42.6 N) was developed by combining various additives (methylcellulose, 2-hydroxypropyl-β-cyclodextrin HPβCD, D-mannitol, polyvinylpyrrolidone, and gum arabic) followed by bead-milling and freeze-drying treatments. The mean particle size in the redispersions of the IRB-NP tablet was approximately 118 nm. The solubility and intestinal absorption of IRB in the IRB-NP tablet were significantly enhanced in comparison with the microcrystalline IRB tablet (IRB-MP tablet), and both solubility and clathrin-dependent endocytosis helped improve the low BA of the IRB. In addition, the BP-reducing effect of the IRB-NP tablet was significantly higher than that of the IRB-MP tablet. These results provide useful information for the preservation of nanocrystalline suspensions of BCS class II drugs, such as IRB.

Pectin microparticles for peptide delivery: Optimization of spray drying processing

Spray-dried pectin microparticles can potentially improve the oral bioavailability of peptides by virtue of their mucoadhesion. However, developing such formulations with desirable quality attributes is challenging due to the sensitivity of microparticle critical quality attributes towards changes in spray drying processing parameters. In this study, a central composite design approach was applied to investigate the influence of input temperature, aspirator rate, feed flow rate, polymer concentration and polymer feed weight on the yield and particle size of pectin microparticles prepared via spray drying. A mathematical model for the prediction of yield was statistically significant with good predictability. A maximum yield of 72.2% was achieved through optimizing the spray drying conditions. The particle size remained in a relatively narrow range (D50, 2.16-3.67 μm), and therefore was considered independent of the factors investigated. The model for yield prediction was further validated using octreotide acetate as a representative peptide. The presence of octreotide acetate in the pectin microparticles increased their surface roughness and decreased their melting enthalpy. In addition, it was determined that pectin with a high degree of esterification (72%, AU201) resulted in faster drug release compared to pectin with a lower degree of esterification (62%, CU401). Interestingly, the degree of esterification did not impact microparticle particle size, morphology or thermal properties. This study demonstrates the importance of DoE in optimization of the spray drying process for the development of pectin-based peptide microparticles. This is the first report using spray-dried pectin-based microparticles for octreotide delivery. The yield prediction model achieved using a central composite design may also be helpful for formulation development of similar drug products.

Development of agomelatine nanocomposite formulations by wet media milling

Nanocrystal formulations of the BCS class II agomelatine, were developed by wet media milling. The most suitable stabilizer was identified and effects of process and formulation variables on the nanocrystal size and ζ-potential were evaluated employing a Box-Behnken experimental design. The optimized nanosuspensions were dried and subsequently evaluated for redispersibility and physicochemical properties. Computational simulation of solid state properties was applied to rationalize crystal fracture. It was found that low viscosity hydroxypropylcellulose with sodium dodecyl sulfate is the most suitable stabilizer. Stabilizer concentration exerts a statistically significant effect on particle size, which depends on the mill's rotation speed. The milling process induces a polymorphic transition to form II, which could affect size reduction kinetics. The solidified nanosuspensions' redispersibility is deteriorating progressively with storage time, with only minor differences between drying methods, retaining enhanced dissolution rate. Crystal lattice simulations suggest high mechanical anisotropy of form I crystals, which could be an additional reason for fast particle size reduction prior to the polymorphic transformation. Wet media milling, combined with a suitable drying method, can be an efficient technique for the production of stable nanocrystals of agomelatine. Particle informatics methods can enhance our understanding of the mechanisms responsible for agomelatine's nanocomminution.

Progress in the development of stabilization strategies for nanocrystal preparations

In recent years, nanocrystal technology has been extensively investigated. Due to the submicron particle size and unique physicochemical properties of nanocrystals, they overcome the problems of low drug solubility and poor bioavailability. Although the structures of nanocrystals are simple, the further development of these materials is hindered by their stability. Drug nanocrystals with particle sizes of 1∼1000 nm usually require the addition of stabilizers such as polymers or surfactants to enhance their stability. The stability of nanocrystal suspensions and the redispersibility of solid nanocrystal drugs are the key factors for the large-scale production of nanocrystal preparations. In this paper, the factors that affect the stability of drug nanocrystal preparations are discussed, and related methods for solving the stability problem are put forward.

Development and Evaluation of Tannic Acid-Coated Nanosuspension for Enhancing Oral Bioavailability of Curcumin

Curcumin (CUR) has been used in the treatment of various diseases such as cough, fever, skin disease, and infection because of various biological benefits such as anti-inflammatory, antiviral, antibacterial, and antitumor activity. However, CUR is a BCS class 4 group and has a limitation of low bioavailability due to low solubility and permeability. Therefore, the purpose of this study is to prepare a nanosuspension (NSP) loaded with CUR (CUR-NSP) using a statistical design approach to improve the oral bioavailability of CUR, and then to develop CUR-NSP coated with tannic acid to increase the mucoadhesion in the GI tract. Firstly, the optimized CUR-NSP, composed of sodium dodecyl sulfate (SDS) and polyvinylpyrrolidone/vinyl acetate (PVP/VA), was modified with tannic acid (TA). The particle size and polydispersity index of the formulation measured by laser scattering analyzer were 127.7 ± 1.3 nm and 0.227 ± 0.010, respectively. In addition, the precipitation in distilled water (DW) was 1.52 ± 0.58%. Using a differential scanning calorimeter and X-ray diffraction analysis, the stable amorphous form of CUR was confirmed in the formulation, and it was confirmed that CUR-NSP formulation was coated with TA through a Fourier transform-infrared spectroscopy. In the mucoadhesion assay using the turbidity, it was confirmed that TA-CUR-NSP had higher affinity for mucus than CUR-NSP under all pH conditions. This means that the absorption of CUR can be improved by increasing the retention time in the GI tract of the formulation. In addition, the drug release profile showed more than 80% release, and in the cellular uptake study, the absorption of the formulation (TA-CUR-NSP) containing TA acting as an inhibitor of P-gp was increased by 1.6-fold. In the evaluation of antioxidant activity, the SOD activity of TA-CUR-NSP was remarkably high due to TA, which improves cellular uptake and has antioxidant activity. In the pharmacokinetic evaluation, the maximum drug plasma concentration of the TA-coated NSP formulation was 7.2-fold higher than that of the pure drug. In all experiments, it was confirmed that the TA-CUR-NSP is a promising approach to overcome the low oral bioavailability of CUR.

Nanocrystalline Suspensions of Irbesartan Enhance Oral Bioavailability by Improving Drug Solubility and Leading Endocytosis Uptake into the Intestine

We attempted to design irbesartan nanocrystalline (IRB-NC) suspensions by the bead mill method, and we evaluated the bioavailability (BA) in the oral administration of the nanocrystalline drug. The mean particle size of the IRB-NC suspensions was approximately 140 nm, and the crystalline structure of irbesartan in these suspensions was different using the bead mill method. The aggregation and degradation of irbesartan were not observed for one month, and the solubility increased. Moreover, the inclusion complex formation of IRB-NC suspensions with 2-hydroxypropyl-β-cyclodextrin was higher than that in traditional IRB powder (IRB-P). In addition, the intestinal absorption of IRB-NC suspensions was higher than that of IRB-P suspensions, and the reducing effect on blood pressure in spontaneously hypertensive SHR-SP rats orally administered IRB-NC suspensions was significantly higher than in those administered IRB-P suspensions. On the other hand, the intestinal penetration of IRB-NC suspensions was attenuated by the inhibitors of clathrin-dependent endocytosis (CME). In conclusion, we improved the low oral BA of irbesartan by preparing IRB-NC suspensions and showed that both the solubility and CME are related to the enhanced intestinal absorption of IRB-NC suspensions, resulting in an increase in their antihypertensive effect. These findings provide significant information for the development of oral nanomedicines.

Use of Bead Mixtures as a Novel Process Optimization Approach to Nanomilling of Drug Suspensions

PURPOSE

We aimed to evaluate the feasibility of cross-linked polystyrene (CPS)-yttrium-stabilized zirconia (YSZ) bead mixtures as a novel optimization approach for fast, effective production of drug nanosuspensions during wet stirred media milling (WSMM).

METHODS

Aqueous suspensions of 10% fenofibrate (FNB, drug), 7.5% HPC-L, and 0.05% SDS were wet-milled at 3000-4000 rpm and 35%-50% volumetric loading of CPS:YSZ bead mixtures (CPS:YSZ 0:1-1:0 v:v). Laser diffraction, SEM, viscometry, DSC, and XRPD were used for characterization. An n^th-order model described the breakage kinetics, while a microhydrodynamic model allowed us to gain insights into the impact of bead materials.

RESULTS

CPS beads achieved the lowest specific power consumption, whereas YSZ beads led to the fastest breakage. Breakage followed second-order kinetics. Optimum conditions were identified as 3000 rpm and 50% loading of 0.5:0.5 v/v CPS:YSZ mixture from energy-cycle time-heat dissipation perspectives. The microhydrodynamic model suggests that YSZ beads experienced more energetic/forceful collisions with smaller contact area as compared with CPS beads owing to the higher density-elastic modulus of the former.

CONCLUSIONS

We demonstrated the feasibility of CPS-YSZ bead mixtures and rationalized its optimal use in WSMM through their modulation of breakage kinetics, energy utilization, and heat dissipation.

Mechanistic Modeling of Wet Stirred Media Milling for Production of Drug Nanosuspensions

Drug nanocrystals have been used for a wide range of drug delivery platforms in the pharmaceutical industry, especially for bioavailability enhancement of poorly water-soluble drugs. Wet stirred media milling (WSMM) is the most widely used process for producing dense, stable suspensions of drug nanoparticles, also referred to as nanosuspensions. Despite a plethora of review papers on the production and applications of drug nanosuspensions, modeling of WSMM has not been thoroughly covered in any review paper before. The aim of this review paper is to briefly expose the pharmaceutical scientists and engineers to various modeling approaches, mostly mechanistic, including computational fluid dynamics (CFD), discrete element method (DEM), population balance modeling (PBM), coupled methods, the stress intensity-number model (SI-SN model), and the microhydrodynamic (MHD) model with a main focus on the MHD model for studying the WSMM process. A total of 71 studies, 30 on drugs and 41 on other materials, were reviewed. Analysis of the pharmaceutics literature reveals that WSMM modeling is largely based on empirical, statistically based modeling approaches, and mechanistic modeling could help pharmaceutical engineers develop a fundamental process understanding. After a review of the salient features and various pros-cons of each modeling approach, recent advances in microhydrodynamic modeling and process insights gained therefrom were highlighted. The SI-SN and MHD models were analyzed and critiqued objectively. Finally, the review points out potential research directions such as more mechanistic and accurate CFD-DEM-PBM simulations and the coupling of the MHD-PBM models with the CFD.

Quality by design thinking in the development of long-acting injectable PLGA/PLA-based microspheres for peptide and protein drug delivery

Adopting the Quality by Design (QbD) approach in the drug development process has transformed from "nice-to-do" into a crucial and required part of the development, ensuring the quality of pharmaceutical products throughout their whole life cycles. This review is discussing the implementation of the QbD thinking into the production of long-acting injectable (LAI) PLGA/PLA-based microspheres for the therapeutic peptide and protein drug delivery. Various key elements of the QbD approaches are initially elaborated using Bydureon®, a commercial product of LAI PLGA/PLA-based microspheres, as a classical example. Subsequently, the factors influencing the release patterns and the stability of the peptide and protein drugs are discussed. This is followed by a summary of the state-of-the-art of manufacturing LAI PLGA/PLA-based microspheres and the related critical process parameters (CPPs). Finally, a landscape of generic product development of LAI PLGA/PLA-based microspheres is reviewed including some major challenges in the field.

Interpreting In Vitro Release Performance from Long-Acting Parenteral Nanosuspensions Using USP-4 Dissolution and Spectroscopic Techniques

Injectable sustained release dosage forms have emerged as desirable therapeutic routes for patients that require life-long treatments. The prevalence of drug molecules with low aqueous solubility and bioavailability has added momentum toward the development of suspension-based long-acting parenteral (LAP) formulations; the previously undesirable physicochemical properties of Biopharmaceutics Classification System (BCS) Class II/IV compounds are best suited for extended release applications. Effective in vitro release (IVR) testing of crystalline suspensions affirms product quality during early-stage development and provides connections with in vivo performance. However, before in vitro-in vivo correlations (IVIVCs) can be established, it is necessary to evaluate formulation attributes that directly affect IVR properties. In this work, a series of crystalline LAP nanosuspensions were formulated with different stabilizing polymers and applied to a continuous flow-through (USP-4) dissolution method. This technique confirmed the role of salt effects on the stability of polymer-coated nanoparticles through the detection of disparate active pharmaceutical ingredient (API) release profiles. The polymer stabilizers with extended hydrophilic chains exhibited elevated intrapolymer activity from the loss of hydrogen-bond cushioning in dissolution media with heightened ionic strength, confirmed through one-dimensional (1D) ¹H NMR and two-dimensional nuclear Overhauser effect spectroscopy (2D NOESY) experiments. Thus, steric repulsion within the affected nanosuspensions was limited and release rates decreased. Additionally, the strength of interaction between hydrophobic polymer components and the API crystalline surface contributed to suspension dissolution properties, confirmed through solution- and solid-state spectroscopic analyses. This study provides a unique perspective on the dynamic interface between the crystalline drug and aqueous microenvironment during dissolution.

Development and evaluation of TPGS/PVA-based nanosuspension for enhancing dissolution and oral bioavailability of ticagrelor

In this study, we developed ticagrelor-dispersed nanosuspension (TCG-NSP) to enhance the dissolution and oral bioavailability of ticagrelor (TCG) through a statistical design approach. TCG, a reversible P2Y₁₂ receptor antagonist, is classified as a biopharmaceutics classification system (BCS) class IV drug with low solubility and permeability, resulting in low oral bioavailability. Nanosuspension (NSP) is an efficient pharmaceutical technique for overcoming the disadvantages. First, we optimized TCG-NSP consisting of D-α-Tocopherol polyethylene glycol 1000 succinate (TPGS) and polyvinyl alcohol (PVA), which exhibited homogeneously dispersed TCG particle (233 nm) and low precipitation (3%). Characterization studies demonstrated that TCG-NSP provided amorphous TCG particles and supersaturation effect, resulting in higher dissolution than a commercial product. In addition, everted gut sac and pharmacokinetic studies confirmed that TCG-NSP improved the gastrointestinal permeation of TCG by 2.8-fold compared to commercial product, thereby enhancing the oral bioavailability (2.2-fold). These results suggested that TCG-NSP could be successfully used as an efficient pharmaceutical formulation to achieve the enhanced dissolution and oral bioavailability of TCG.

Role of wetting agents and disintegrants in development of danazol nanocrystalline tablets

Poor wetting and/or particle aggregation are the shortcomings of the dried nanocrystalline suspensions, which subsequently might hinder the superior dissolution performance of the nano-crystalline suspensions. The objective of this study was to evaluate the effect of wetting agents and disintegrants on the dissolution performance of dried nanocrystals of an active pharmaceutical ingredient (API) with poor wetting property. Danazol, a BCS Class II compound with high LogP and low polar surface area, was chosen as a model compound for this study. Danazol nanocrystalline suspension was prepared by wet-media milling and converted into powder via spray granulation either with mannitol or microcrystalline cellulose as carriers at a drug: carrier ratio of 1:9 w/w. Danazol nanocrystalline suspension showed a superior dissolution performance compared to an un-milled danazol suspension. Dried danazol nanocrystals suffered from poor wetting leading to hindered dissolution performance i.e. ~ 40% and ~ 15% drug dissolution within 15 min for the mannitol and microcrystalline cellulose-based granules, respectively. Addition of a lipophilic surfactant (i.e. docusate sodium) at a surfactant: drug ratio of 0.015: 1 w/w during granulation helped in retaining the superior drug dissolution rates i.e. more than 80% drug dissolution within 15 min for mannitol-based granules by enhancing the wettability of dried danazol nanocrystals when compared to a hydrophilic surfactant (i.e. poloxamer 188) or disintegrant (i.e. sodium starch glycolate or croscarmellose sodium). The fast-dissolving mannitol-based granules containing danazol nanocrystals and docusate sodium were compressed into a tablet dosage form. The tablets containing danazol nanocrystals with docusate sodium showed a superior dissolution performance compared to a tablet containing un-milled danazol with docusate sodium.

Formation of ciprofloxacin nanocrystals within liposomes by spray drying for controlled release via inhalation

The present study was conducted to harness spray drying technology as a novel method of producing Ciprofloxacin nanocrystals inside liposomes (CNL) for inhalation delivery. Liposomal ciprofloxacin dispersions were spray dried with sucrose as a lyoprotectant in different mass ratios (0.5:1, 1:1 and 2:1 sucrose to lipids), along with 2% w/w magnesium stearate and 5% w/w isoleucine as aerosolization enhancers. Spray drying conditions were: inlet air temperature 50 °C, outlet air temperature 33-35 °C, atomizer rate 742 L/h and aspirator 35 m³/h. After spray drying, the formation of ciprofloxacin nanocrystals inside the liposomes was confirmed by cryo- transmission electron microscopy. The physiochemical characteristics of the spray dried powder (particle size, morphology, crystallinity, moisture content, drug encapsulation efficiency (EE), in vitro aerosolization performance and drug release) were determined. The EE of the liposomes was found to vary between 44 and 87% w/w as the sucrose content was increased from 25 to 57% w/w. The powders contained partially crystalline particles with a volume median diameter of ~1 µm. The powders had low water content (~2% wt.) and were stable at high relative humidity. Aerosol delivery using the Osmohaler® inhaler at a flow rate of 100 L/min produced an aerosol fine particle fraction (% wt. <5 µm) of 58-64%. The formulation with the highest sucrose content (2:1 w/w sucrose to lipid) demonstrated extended ciprofloxacin release from liposomes (80% released within 7 h) in comparison to the original liquid formulation (80% released within 2 h). In conclusion, a stable and inhalable CNL powder with controlled drug release was successfully prepared by spray drying.