A Systematic Investigation of Process Parameters for Small-Volume Aqueous Suspension Production by the Use of Focused Ultrasonication.

Aqueous suspensions containing crystalline drug in the sub-micron range is a favorable platform for long-acting injectables where particle size can be used to obtain a desired plasma-concentration profile. Stabilizers are added to the suspensions and screened extensively to define the optimal formulation composition. In the initial formulation screening the amount of drug compound can be limited, necessitating milling methods for small-volume screening predictable for scale-up. Hence, adaptive focused ultrasound was investigated as a potential milling method for rapid small-volume suspensions by identifying the critical process parameters during preparation. Suspensions containing drug compounds with different mechanical properties and thereby grindability, i.e., cinnarizine, haloperidol, and indomethacin with brittle, elastic, and plastic properties, respectively, were investigated to gain an understanding of the manufacturing with adaptive focused acoustics as well as comparison to already established milling techniques. Using a DoE-design, peak incident power was identified as the most crucial process parameter impacting the milling process for all three compounds. It was possible to decrease the sizes of drug particles to micron range after one minute of focused ultrasound exposure which was superior compared to other milling techniques (e.g., non-focused ultrasound exposure). The addition of milling beads decreased the drug particle sizes even further, thus to a lower degree than other already established milling techniques such as milling by dual centrifugation. This study thereby demonstrated that adaptive focused ultrasonication was a promising method for rapid homogenization and particle size reduction to micron range for different compounds varying in grindability without altering the crystalline structure.

Intratympanic injections of emulsion-like dispersions to augment cinnarizine amount in a healthy rabbit inner ear model.

Aim: To investigate eutectic liquid-based emulsion-like dispersions for intratympanic injections to augment cinnarizine permeability across round window membrane in a healthy rabbit inner ear model.Methods: Two-tier systematic optimization was used to get the injection formula. The drug concentrations in perilymph and plasma were analyzed via. Ultra-performance liquid chromatography-tandem mass spectrometry method after 30-, 60-, 90- and 120-min post intratympanic injection time points in rabbits.Results: A shear-thinning behavior, immediate drug release (∼98.80%, 10 min) and higher cell viability (>97.86%, 24 h) were observed in dispersions. The cinnarizine level of 8168.57 ± 1236.79 ng/ml was observed in perilymph at 30 min post intratympanic injection in rabbits.Conclusion: The emulsion-like dispersions can augment drug permeability through round window membrane.

[Box: see text].

ChlorTox scale assessment, greenness, and whiteness evaluation of selective spectrophotometric analysis of dimenhydrinate and cinnarizine.

Nausea and vomiting are considered common series side effects induced by chemotherapy treatment in cancer patients. This annoying side effect can impair the patient's compliance to cancer treatment and affect their quality of life. Dimenhydrinate and cinnarizine in combined pharmaceutical dosage form is used to control chemotherapy induced nausea and vomiting in cancer patients. For safety, selective spectrophotometric methods based on novel dual resolution strategies were introduced to estimate dimenhydrinate and cinnarizine in presence of their harmful impurities namely benzophenone and 1- (diphenylmethyl)piperazine, respectively. These methods namely, dual ratio difference (DRD), dual ratio extraction (DRE) and dual absorbance extraction coupled with dual ratio extraction (DAE-DRE) were successfully performed to simultaneously analyze the drug of interests dimenhydrinate and cinnarizine in their pure form, synthetic mixtures and in market dosage form. Linearity ranges were 6.0-60.0 µg/mL and 3.0-30.0 µg/mL for dimenhydrinate and cinnarizine, respectively with good recovery% of Mean ± SD for all the proposed methods 99.82 ± 0.48, 99.79 ± 0.40, 100.14 ± 0.82, 100.03 ± 0.69, respectively. ICH guidelines were adhered in accordance with confirming validation of the proposed methods where fulfilling results were accomplished. Various unified greenness and whiteness assessment tools, such as the chlorTox scale, greenness index via spider chart, AGREE (The Analytical Greenness Metric), green certificate, and the RGB12 algorithm were employed in this research to assess the greenness and sustainability of the introduced UV-spectrophotometric methods in comparison to the reported HPLC method. As a result, these methods hold significant potential for utilization in the quality control department of pharmaceutical companies, contributing to enhanced pharmaceutical product analysis and overall sustainability practices.

In Vitro Digestion-In Situ Absorption Setup Employing a Physiologically Relevant Value of the Membrane Surface Area/Volume Ratio for Evaluating Performance of Lipid-Based Formulations: A Comparative Study with an In Vitro Digestion-Permeation Model.

The aim of this study is to establish and test an in vitro digestion-in situ absorption model that can mimic in vivo drug flux by employing a physiologically relevant value of the membrane surface area (S)/volume (V) ratio for accurate prediction of oral drug absorption from lipid-based formulations (LBFs). Three different types of LBFs (Type IIIA-MC, Type IIIA-LC, and Type IV) loaded with cinnarizine (CNZ), a lipophilic weak base with borderline permeability, and a control suspension were prepared. Subsequently, a simultaneous in vitro digestion-permeation experiment was conducted using a side-by-side diffusion cell with a dialysis membrane having a low S/V value. During digestion, CNZ partially precipitated for Type IV, while it remained solubilized in the aqueous phase for Type IIIA-MC and Type IIIA-LC in the donor compartment. However, in vitro drug fluxes for Type IIIA-MC and Type IIIA-LC were lower than those for Type IV due to the reduced free fraction of CNZ in the donor compartment. In pharmacokinetic studies, a similar improvement in in vivo oral exposure relative to suspension was observed, regardless of the LBFs used. Consequently, a poor correlation was found between in vitro permeation and areas under the plasma concentration-time curve (AUCoral) (R2 = 0.087). A luminal concentration measurement study revealed that this discrepancy was attributed to the extremely high absorption rate of CNZ in the gastrointestinal tract compared to that across a dialysis membrane evaluated by the in vitro digestion-permeation model, i.e., the absorption of CNZ in vivo was completed regardless of the extent of the free fraction, owing to the rapid removal of CNZ from the intestine. Subsequently, we aimed to predict the oral absorption of CNZ from the same formulations using a model that demonstrated high drug flux by employing the physiologically relevant S/V value and rat jejunum segment as an absorption sink (for replicating in vivo intestinal permeability). Predigested formulations were injected into the rat intestinal loop, and AUCloop values were calculated from the plasma concentration-time profiles. A better correlation was found between AUCloop and AUCoral (R2 = 0.72), although AUCloop underestimated AUCoral for Type IV due to the precipitation of CNZ during the predigestion process. However, this result indicated the importance of mimicking the in vivo drug absorption rate in the predictive model. The method presented herein is valuable for the development of LBFs.

Absorption of cinnarizine from type II lipid-based formulations: Impact of lipid chain length, supersaturation, digestion, and precipitation inhibition.

Lipid-based formulations (LBFs) are an enabling-formulation approach for lipophilic poorly water-soluble compounds. In LBFs, drugs are commonly pre-dissolved in lipids, and/or surfactants/cosolvents, hereby avoiding the rate-limiting dissolution step. According to the Lipid formulation classification system, proposed by Pouton in 2006, in type II LBFs a surfactant with an HLB-value lower than 12 is added to the lipids. If high drug doses are required, e.g. for preclinical toxicity studies, supersaturated LBFs prepared at elevated temperatures may be a possibility to increase drug exposure. In the present study, the impact of digestion on drug absorption in rats was studied by pre-dosing of the lipase inhibitor orlistat. The lipid chain length of the type II LBFs was varied by administration of a medium-chain- (MC) and a long-chain (LC)-based formulation. Different drug doses, both non-supersaturated and supersaturated, were applied. Due to an inherent precipitation tendency of cinnarizine in supersaturated LBFs, the effect of the addition of the precipitation inhibitor Soluplus® was also investigated. The pharmacokinetic results were also evaluated by multiple linear regression. In most cases LC-based LBFs did not perform better in vivo, in terms of a higher area under the curve (AUC0-24 h) and maximal plasma concentration (Cmax), than MC-based LBFs. The administration of supersaturated LBFs resulted in increased AUC0-24 h (1.5 - 3.2-fold) and Cmax (1.1 - 2.6-fold)-values when compared to the non-supersaturated equivalents. Lipase inhibition led to a decreased drug exposure in most cases, especially for LC formulations (AUC0-24 h reduced to 47 - 67%, Cmax to 46 - 62%). The addition of Soluplus® showed a benefit to drug absorption from supersaturated type II LBFs (1.2 - 1.7-fold AUC0-24 h), due to an increased solubility of cinnarizine in the formulation. Upon dose-normalization of the pharmacokinetic parameters, no beneficial effect of Soluplus® could be demonstrated.

A comparative study on prophylactic efficacy of cinnarizine and amitriptyline in childhood migraine: a randomized double-blind clinical trial.

BACKGROUND: Pediatric migraine prophylaxis is indicated when headaches are frequent and/or disabling. We aimed to conduct a study to compare the efficacy of cinnarizine and amitriptyline in pediatric migraine prophylaxis. METHODS: In a randomized, double-blind trial, patients aged 4-17 years with migraine who were eligible for prophylaxis enrolled. The primary outcome was a reduction response rate of ≥50% with p < 0.005 with respect to headache characteristics. The secondary outcome was migraine disability assessment. We evaluated patients every four weeks for three months: T1: week 4, T2: week 8 and T3: week 12. The safety profile was also assessed. RESULTS: Thirty patients were randomly assigned to each group. However, 43 patients completed the trial. Headache frequency decreased in amitriptyline group more effectively in T1 (p = 0.004). Amitriptyline was more successful in reducing the headache duration in all three periods (p < 0.005). There was no significant difference in severity improvement and reducing disability score between the two groups (p > 0.005). No serious adverse events were observed. CONCLUSIONS: Both medications are effective in ameliorating migraine headaches and related disabilities. However, amitriptyline appears be a preferable option over cinnarizine, given its faster onset of action, efficacy in reducing headache duration and longer-lasting effects.Trial Registration: The study was registered with the Iranian Registry of Clinical Trials (IRCT) under the code IRCT-20191112045413N1.

Development of lipid-based SEDDS using digestion products of long-chain triglyceride for high drug solubility: Formulation and dispersion testing.

A self-emulsifying drug delivery system (SEDDS) containing long chain lipid digestion products (LDP) and surfactants was developed to increase solubility of two model weakly basic drugs, cinnarizine and ritonavir, in the formulation. A 1:1.2 w/w mixture of glyceryl monooleate (Capmul GMO-50; Abitec) and oleic acid was used as the digestion product, and a 1:1 w/w mixture of Tween 80 and Cremophor EL was the surfactant used. The ratio between LDP and surfactant was 1:1 w/w. Since the commercially available Capmul GMO-50 is not pure monoglyceride and contained di-and-triglycerides, the digestion product used would provide 1:2 stoichiometric molar ratio of monoglyceride and fatty acid after complete digestion in gastrointestinal fluid. Both cinnarizine and ritonavir had much higher solubility in oleic acid (536 and 72 mg/g, respectively) than that in glyceryl monooleate and glyceryl trioleate. Therefore, by incorporating oleic acid in place of glyceryl trioleate in the formulation, the solubility of cinnarizine and ritonavir could be increased by 5-fold and 3.5-fold, respectively, as compared to a formulation without the fatty acid. The formulation dispersed readily in aqueous media, and adding 3 mM sodium taurocholate, which is generally present in GI fluid, remarkably improved the dispersibility of SEDDS and reduced particle size of dispersions. Thus, the use of digestion products of long-chain triglycerides as components of SEDDS can enhance the drug loading of weakly basic compounds and increase dispersibility in GI fluids.

Digestion is a critical element for absorption of cinnarizine from supersaturated lipid-based type I formulations.

Enabling formulations, such as lipid-based formulations (LBFs), are means to deliver challenging-to-formulate, poorly soluble drugs. LBFs may be composed of lipids, surfactants and/or cosolvents and can be classified depending on the proportions of the components and the hydrophilicity of the surfactant according to the Lipid Formulations Classification System, ranging from type I (very lipophilic) to type IV (hydrophilic). In cases where drug solubility in LBFs does not suffice, e.g. for preclinical toxicity studies, supersaturated LBFs can be used in order to increase the drug load. However, the effect of digestion on drug absorption from supersaturated type I formulations (consisting exclusively of lipids) still remains relatively unexplored and unclear. In the present study, the impact of lipid digestion on absorption of cinnarizine-loaded supersaturated lipid-based formulations of type I was investigated in rats by pre-dosing of the lipase inhibitor orlistat. The lipid chain length and the drug dose were varied by testing medium-chain triglycerides (MCT) and long-chain triglycerides (LCT), both supersaturated and non-supersaturated. Due to the physical instability of supersaturated formulations of cinnarizine, i.e. a potential of precipitation of cinnarizine, the impact of the addition of the amphiphilic polymer Soluplus®, as a potential precipitation inhibitor, was also investigated. The supersaturated systems resulted in a 2.3 - 3.3-fold higher Area Under the Curve (AUC0-24 h, not dose-normalized) and 1.4 - 2.2-fold higher maximum plasma concentration (Cmax, not dose-normalized) than non-supersaturated formulations (statistically significant with p = 0.05), whereas the addition of Soluplus® did not reveal any benefit. Results indicated that lipase inhibition affected the in vivo performance of LBFs: Co-administration of the lipase inhibitor significantly reduced Cmax and AUC0-24 h (both to 33-39 %, not dose-normalized) for the LCT formulations and, though not significant, a similar trend was observed for the AUC0-24 h of the MCT formulations (to 53-87 %), suggesting a higher dependency on lipolysis for LCT. Also, tmax tended to decrease to 20-60 % when compared to the animals not dosed with orlistat but lacking statistical significance. Without lipase inhibition, the LCT in general lead to better absorption of cinnarizine as compared to MCT, with 1.2-1.7-fold higher AUC0-24 h and 1.4-1.8-fold higher Cmax, but without showing statistical significance. Overall, the study revealed that lipolysis plays a major role in drug absorption from supersaturated lipid-based formulations type I.

Is roller milling - the low energy wet bead media milling - a reproducible and robust milling method for formulation investigation of aqueous suspensions?

Long-acting injectables have shown to offer a prolonged release of a drug compound up to several months, providing the opportunity to increase patient compliance for treatment of long-term and chronic conditions. Different formulation technologies have already been utilized for long-acting injectables, and especially aqueous suspensions with crystalline drug particles in the sub-micron range have sparked an interest for future development of long-acting injectables. Wet bead milling is a common top-down process used to prepare nano- and microsuspensions of crystalline drug particles with the addition of surfactants in the dispersion medium, which are working as stabilizers to prevent agglomeration or crystal growth that ultimately may influence the physical stability of nano- and microsuspensions. To examine the reproducibility of the suspensions manufactured and the behavior of their physical stability, i.e., changes in particle sizes over time, low-energy roller mill was utilized for the manufacturing of nano- and microsuspensions in the present study. Investigated formulation parameters was stabilizer type and concentration and milling parameters varied in bead size and duration of milling. The obtained results demonstrated that the physical stability of suspensions containing the two model compounds, cinnarizine and indomethacin, was highly affected by the constitution of surfactant and processing. Various size classes were obtained and accompanied by high variations between the individual samples that indicated uneven and unpredictable milling by the low-energy roller mill, limiting the possibility to prepare reproducible and physical stable suspensions. Short-term stability studies revealed clear tendencies towards reversed Ostwald ripening of suspensions stabilized with poloxamer 188 that contained cinnarizine as the drug compound, and to a smaller extent suspensions containing indomethacin. Furthermore, X-ray Powder Diffraction confirmed no alteration of the drug compounds crystal structure after roller milling for multiple days.

Uncertainty in surface wind speed projections over the Iberian Peninsula: CMIP6 GCMs versus a WRF-RCM.

This study assessed the projected near-surface wind speed (SWS) changes and variability over the Iberian Peninsula for the 21st century. Here, we compared Coupled Model Intercomparison Project Phase 6 global climate models (GCMs) with a higher spatial resolution regional climate model (RCM; ∼20 km), known as WRF-CESM2, which was created by a dynamic downscaling of the Community Earth System Model version 2 (CESM2) using the Weather Research and Forecasting (WRF) model. Our analysis found that the GCMs tended to overestimate observed SWS for 1985-2014, while the higher spatial resolution of the WRF-CESM2 did not improve the accuracy and underestimated the SWS magnitude. GCMs project a decline of SWS under high shared socioeconomic pathways (SSPs) greenhouse concentrations, such as SSP370 and SSP585, while an interdecadal oscillation appears in SSP126 and SSP245 for the end of the century. The WRF-CESM2 under SSP585 predicts the opposite increasing SWS. Our results suggest that 21st-century projections of SWS are uncertain even for regionalized products and should be taken with caution.

Continuous Synthesis of Cinnarizine Salt with Malic Acid by Applying Green Chemistry Using Water-Assisted Twin Screw Extrusion.

Organic solvent-free process or green chemistry is needed for manufacturing pharmaceutical salts to avoid various environmental, safety, and manufacturing cost issues involved. In this study, a cinnarizine (CNZ) salt with malic acid at a 1:1 molar ratio was successfully prepared by twin screw extrusion (TSE) with water assistance. The feasibility of salt formation was first evaluated by screening several carboxylic acids by neat grinding (NG) and liquid-assisted grinding (LAG) using a mortar and pestle, which indicated that malic acid and succinic acid could form salts with CNZ. Further studies on salt formation were conducted using malic acid. The examination by hot-stage microscopy revealed that the addition of water could facilitate the formation and crystallization of CNZ-malic acid salt even though CNZ is poorly water-soluble. The feasibility of salt formation was confirmed by determining the pH-solubility relationship between CNZ and malic acid, where a pHmax of 2.7 and a salt solubility of 2.47 mg/mL were observed. Authentic salt crystals were prepared by solution crystallization from organic solvents for examining crystal properties and structure by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, solid-state 13C and 15N nuclear magnetic resonance (NMR), and single-crystal X-ray diffraction (SXD). These techniques also established that a salt, and not a cocrystal, was indeed formed. The CNZ salt crystals were then prepared by TSE of a 1:1 CNZ-malic acid mixture, where the addition of small amounts of water resulted in a complete conversion of the mixture into the salt form. The salts prepared by solvent crystallization and water-assisted TSE had identical properties, and their moisture sorption profiles were also similar, indicating that TSE is a viable method for salt preparation by green chemistry. Since TSE can be conducted in a continuous manner, the results of the present investigation, if combined with other continuous processes, suggest the possibility of continuous manufacturing of drug products from the synthesis of active pharmaceutical ingredients (APIs) to the production of final dosage forms.

Spectrofluorometric determination of orphenadrine, dimenhydrinate, and cinnarizine using direct and synchronous techniques with greenness assessment.

Orphenadrine (ORP), dimenhydrinate (DMN), and cinnarizine (CNN) were investigated using green-sensitive spectrofluorometric methods. Method, I used for determination of DMN in 0.1 M hydrochloric acid (HCl) and 1.0% sodium dodecyl sulphate (SDS) at 286 nm after λex 222 nm, while for determination of ORP in 1.0% w/v SDS involves measuring the fluorescence at 285 nm after λex 220 nm. For DMN and ORP, the detection and quantitation limits were 2.99 and 4.71 and 9.08 and 14.29 ng/mL, respectively. The ranges of DMN and ORP were 0.10-1.0 and 0.04-0.5 µg/mL, respectively, in micellar aqueous solution. Method II, the derivative intensities of DMN and CNN were measured at a fixed of different wavelength between the excitation and the emission wavelengths (Δλ) = 60 nm at 282 and 322 nm, at the zero crossing of each other, respectively. The detection and quantitation limits for DMN and CNN were 1.77 and 0.88 ng/mL and 5.36 and 2.65 ng/mL, correspondingly, through the entire range of 0.1-1.0 µg/mL for DMN and CNN. The linearity was perfectly determined through the higher values of the correlation coefficient ranging from 0.9997 to 0.9999 for both direct and synchronous methods. The precision of the proposed methods was also confirmed via the lower values of the standard deviation which ranged from 0.39 to 1.11. The technique was expanded to analyze this mixture in combined tablets and laboratory-prepared mixtures. The method validation was done depending on the international conference on harmonization (ICH) recommendations. An analysis of the statistical data revealed a high agreement between the proposed data and the comparison methodology. Three different assessment methods demonstrated the greenness of the technique.

Anticholinergic Versus Antihistaminic Treatment for Simulator Sickness Prevention.

Flight simulators have an essential role in aircrew training. Occasionally, symptoms of motion sickness, defined as simulator sickness, develop during these sessions. Preventive methods for motion sickness have been investigated thoroughly; however, only a few studies have examined preventive treatments for simulator sickness. The aim of this study was to examine the efficacy of scopolamine (an anticholinergic drug) compared with cinnarizine (an antihistaminic drug) for helicopter simulator sickness prevention. A validated simulator sickness questionnaire (SSQ) score was used to determine the severity of simulator sickness symptoms in this study. Preliminary SSQ scores and SSQ scores after each sortie were calculated. Each participant was given scopolamine, cinnarizine, or a placebo in a double-blind randomized manner before the first sortie of each training day. Forty-one helicopter pilots participated in the trial. The average age was 30.5 ± 7.1 years. SSQ values significantly improved from an average of 73.30 in the preliminary SSQ questionnaire to an average of 30.92 after 2 hours following the administration of cinnarizine (P = .012, 95%CI 8.071-76.703). Scopolamine was found to be less effective than both cinnarizine and the placebo in the alleviation of simulator sickness symptoms. This study is the first to compare scopolamine with cinnarizine for simulator sickness prevention. Based on the results of this study, we recommend the use of cinnarizine over scopolamine for simulator sickness prevention.

Environmentally sustainable DRS-FTIR probe assisted by chemometric tools for quality control analysis of cinnarizine and piracetam having diverged concentration ranges: Validation, greenness, and whiteness studies.

A novel diffuse reflectance fourier transform infrared spectroscopic method accompanied by chemometrics was optimized to fulfill the white analytical chemistry and green analytical chemistry principles for the quantification of cinnarizine and piracetam for the first time without any prior separation in their challenging pharmaceutical preparation, which has a pretty substantial difference in the concentration of cinnarizine/piracetam (1:16). Furthermore, the suggested method was used for cinnarizine/piracetam dissolution testing as an effective alternative to traditional methods. For the cinnarizine/piracetam dissolution tests, we used a dissolution vessel with 900 mL of phosphate buffer pH 2.5 at 37 °C ± 0.5 °C, then the sampling was carried out by frequent withdrawal of 20 µl samples from the dissolution vessel at a one-minute interval, over one hour, then representative fourier transform infrared spectra were recorded. To create a partial-least-squares regression model, a fractional factorial design with 5 different levels and 2 factors was used. This led to the creation of 25 mixtures, 15 as a calibration set and 10 as a validation set, with varying concentration ranges: 1-75 and 16-1000 µg/mL for cinnarizine/piracetam, respectively. Upon optimization of the partial-least-squares regression model, in terms of latent variables and spectral region, root mean square error of cross-validation of 0.477 and 0.270, for cinnarizine/piracetam respectively, were obtained. The optimized partial-least-squares regression model was further validated, providing good results in terms of recovery% (around 98 to 102 %), root mean square error of prediction (0.436 and 3.329), relative root mean square error of prediction (1.210 and 1.245), bias-corrected mean square error of prediction (0.059 and 0.081), and limit of detection (0.125 and 2.786) for cinnarizine/piracetam respectively. Ultimately, the developed method was assessed for whiteness, greenness, and sustainability using five assessment tools. the developed method achieved a greener national environmental method index and complementary green analytical procedure index quadrants with higher eco-scale assessment scores (91), analytical greenness metric scores (0.87), and red-greenblue 12 algorithm scores (89.7) than the reported methods, showing high practical and environmental acceptance for quality control of cinnarizine/piracetam.

[Formulation Studies and Application of Their Experimental Techniques to Drug Discoveries].

In my first experience as a researcher, I isolated and performed structural predictions of the novel compounds, cis- and trans-palythenic acids, from Noctiluca milialis. I then worked for a pharmaceutical company in a research laboratory of pharmaceutics. I examined an inclusion complex of cinnarizine with ß-cyclodextrin, and found that the inclusion complex did not improve the oral bioavailability of cinnarizine. However, the bioavailability of the inclusion complex after its oral administration was improved by a competing agent. This was the first study to show the potential of a competing agent to improve bioavailability. I subsequently joined a laboratory performing drug discovery research and used experimental techniques from pre-formulation studies. A screening system of solubility for drug design and discovery was constructed to increase the solubilities of compounds synthesized in the laboratory. This screening system contributed to the discovery of a phosphodiesterase type 5 inhibitor with sufficient solubility. As a visiting lecturer at a university, I prepared amoxicillin intragastric buoyant sustained-release tablets for the eradication of Helicobacter pylori and applied cinnarizine as a competing agent. I established a laboratory of pharmaceutics at a university in Tochigi. To develop an enema with fluticasone propionate for ulcerative colitis, I investigated its physicochemical properties and methods to improve its solubility. After moving to another university in Kagawa, I developed a method to reduce the amount of drugs remaining on the surfaces of a pestle and mortar following the grinding of tablets, and new cleaning agents for an automatic dividing packaging machine were discovered.

Analytical Quality by Design-Driven RP-HPLC Method Conditions to Concomitantly Determine Cinnarizine and Morin Hydrate in Combined Drug Solution and Dual Drug-Loaded Formulations.

BACKGROUND: The replacement of traditional oils with a camphor and menthol-based eutectic mixture is done to prepare oil-less emulsion-like dispersions for co-delivery of cinnarizine (CNZ) and morin hydrate (MH) for managing Meniére's disease (MD). Since two drugs are loaded into the dispersions, the development of a suitable reverse phase-high performance liquid chromatography (RP-HPLC) method for their simultaneous analysis becomes inevitable. OBJECTIVE: By applying the analytical quality by design (AQbD) approach, the RP-HPLC method conditions were optimized for the concomitant determination of two drugs. METHODS: The systematic AQbD started with identifying critical method attributes (CMA) through an Ishikawa fishbone diagram, risk estimation matrix, and risk priority number-based failure mode effect analysis followed by screening using fractional factorial design and optimization by face-centered central composite design. The concomitant determination of two drugs by the optimized RP-HPLC method condition was substantiated via specificity checking using combined drug solution, drug entrapment efficiency, and in vitro release of the two drugs from emulsion-like dispersions. RESULTS: The AQbD optimized RP-HPLC method conditions revealed the retention time for CNZ and MH at 5.017 and 5.323, respectively. The studied validation parameters were found within the ICH-prescribed limits. Exposing the individual drug solutions to acidic and basic hydrolytic conditions yielded extra chromatographic peaks for MH, probably due to the degradation of MH. The DEE % values of 87.40 ± 4.70 and 74.79 ± 2.94, respectively, were noticed for CNZ and MH in emulsion-like dispersions. More than 98% CNZ and MH release was occurred from emulsion-like dispersions within 30 min post-dissolution in artificial perilymph. CONCLUSIONS: Overall, the AQbD approach could be helpful for systematic optimization of RP-HPLC method conditions to estimate concomitantly other therapeutic moieties. HIGHLIGHTS: The proposed article shows the successful application of AQbD for the optimization of RP-HPLC method conditions to concomitantly estimate CNZ and MH in combined drug solution and dual-drug-loaded emulsion-like dispersions.

A Combined In-Vitro and GastroPlus® Modeling to Study the Effect of Intestinal Precipitation on Cinnarizine Plasma Profile in a Fasted State.

Poorly water-soluble weak base molecules such as cinnarizine often exhibit pH-dependent solubility within the gastrointestinal tract. This means that their solubility can be influenced by the pH of the surrounding environment, and this can affect their oral absorption. The differential pH solubility between the fasted-state stomach and intestine is an important consideration when studying the oral absorption of cinnarizine. Cinnarizine has moderate permeability and is known to exhibit supersaturation and precipitation in fasted-state simulated intestinal fluid (FaSSIF), which can significantly impact its oral absorption. The present work is aimed at studying the precipitation behavior of cinnarizine in FaSSIF using biorelevant in vitro tools and GastroPlus® modeling, to identify the factors contributing to the observed variability in clinical plasma profiles. The study found that cinnarizine demonstrated variable precipitation rates under different bile salt concentrations, which could impact the concentration of the drug available for absorption. The results also showed that a precipitation-integrated modeling approach accurately predicted the mean plasma profiles from the clinical studies. The study concluded that intestinal precipitation may be one of the factors contributing to the observed variability in Cmax but not the AUC of cinnarizine. The study further suggests that the integration of experimental precipitation results representing a wider range of FaSSIF conditions would increase the probability of predicting some of the observed variability in clinical results. This is important for biopharmaceutics scientists, as it can help them evaluate the risk of in vivo precipitation impacting drug and/or drug product performance.

The effect of anionic Eudragit polymers on drug supersaturation and in vitro permeation improvement.

OBJECTIVES: In the present study, Cinnarizine was selected as a weakly basic drug with poor aqueous solubility to investigate the supersaturation maintaining the ability of different types of anionic Eudragit polymers (Eudragits L100-55, L100 and S100). Furthermore, the interplay between polymer-mediated supersaturation maintenance and in vitro permeation enhancement was studied. METHODS: The effect of Eudragit polymers on the pH-induced supersaturation of Cinnarizine was examined under different pHs (6.4, 6.8, and 7.8). Moreover, the effect of Eudragit polymers on the permeation of Cinnarizine through the Caco-2 membrane was investigated. RESULTS: The aggregate size of Eudragit polymers in solution was determined and it was found that the size of polymer aggregate was bigger when lower pH or more hydrophobic polymer was used, which corresponded strongly with improved drug supersaturation. Based on the findings, hydrophobic Cinnarizine-polymer interactions seemed to be essential in determining the impact of Eudragit polymers on maintaining the Cinnarizine supersaturation. The permeation study demonstrated that the rate of drug permeation through the Caco-2 membrane increased in the presence of Eudragit polymers, but their effect on maintaining supersaturation was more significant than their effect on the drug permeation rate. Moreover, the highest level of Cinnarizine supersaturation observed in a non-permeation condition did not correlate with the optimal absorption in a permeation condition. CONCLUSION: This study revealed that the integration of permeation and supersaturation assays is needed to reliably predict the impact of supersaturation maintenance by polymers on the absorption of poorly soluble drugs.

Insight into the mechanism behind oral bioavailability-enhancement by nanosuspensions through combined dissolution/permeation studies.

As numerous new drug candidates are poorly water soluble, enabling formulations are needed to increase their bioavailability for oral administration. Nanoparticles are a conceptually simple, yet resource consuming strategy for increasing drug dissolution rate, as predicting in vivo oral absorption using in vitro dissolution remains difficult. The objective of this study was to obtain insight into nanoparticle characteristics and performance utilizing an in vitro combined dissolution/permeation setup. Two examples of poorly soluble drugs were examined (cinnarizine and fenofibrate). Nanosuspensions were produced by top-down wet bead milling using dual asymmetric centrifugation, obtaining particle diameters of approx. 300 nm. DSC and XRPD studies indicated that nanocrystals of both drugs were present with retained crystallinity, however with some disturbances. Equilibrium solubility studies showed no significant increase in drug solubility over the nanoparticles, as compared to the raw APIs. Combined dissolution/permeation experiments revealed significantly increased dissolution rates for both compounds compared to the raw APIs. However, there were substantial differences between the dissolution curves of the nanoparticles as fenofibrate exhibited supersaturation followed by precipitation, whereas cinnarizine did not exhibit any supersaturation, but instead a shift towards faster dissolution rate. Permeation rates were found significantly increased for both nanosuspensions when compared to the raw APIs, indicating a direct implication that formulation strategies are needed, be it stabilization of supersaturation by precipitation inhibition and/or dissolution rate enhancement. This study indicates that in vitro dissolution/permeation studies can be employed to better understand the oral absorption enhancement of nanocrystal formulations.

A sensitive LC-MS/MS method for the determination of potential genotoxic impurities in Cinnarizine.

A highly sensitive LC-MS/MS method for the trace level determination of genotoxic impurities, Cinnamyl chloride and Benzhydryl chloride, in Cinnarizine drug substance was developed and validated. Chromatographic separation was successfully achieved on Atlantis d C18 column with dimensions 150× 4.6mm and particle size: 5µm. 0.1% Trifluoroacetic acid in water and 100% acetonitrile was used as mobile phases with gradient mode of elution at 1.0mL/min flow rate. Mass spectroscopic detection was carried out with selective ion monitoring (SIM) technique in positive mode at m/z 117 and 167 for Cinnamyl chloride and Benzhydryl chloride respectively. Developed method was proven to be selective, sensitive, and precise for the quantification of potential genotoxic impurities in Cinnarizine by validating as per the regulatory guidelines. The LOD and LOQ values observed for Cinnamyl chloride were 0.49 and 1.47ppm and for Benzhydryl chloride 0.55 and 1.67ppm respectively. Precision of the method at LOQ level was shown with good % RSD of 4.21. Method was proven linear from LOQ to 150% level with a correlation of 0.996 and accurate with a range of recovery from 86.4 to 100.8%. This highly sensitive method can be used to control both the genotoxic impurities in Cinnarizine drug substance by LC-MS/MS.