An Integrative Review of Micro-Credentials and Digital Badges for Pharmacy Educators

Micro-credentials (MCs) and digital badges (DBs) have gained popularity in recent years as a means to supplement traditional degrees and certifications. MCs and DBs can play a significant role in supporting student-centered learning by offering personalized and flexible learning pathways, emphasizing real-world relevance and practical skills, and fostering a culture of continuous learning and growth. However, barriers currently exist within health professions education, including pharmacy education, that could limit the full adoption and implementation of MCs and DBs. Research on the use of MCs and DBs in Doctor of Pharmacy degree programs is sparse. In this integrative review, literature on the use of MCs and DBs in health professions education is reviewed, and perspectives on the benefits, issues, and potential future uses within Doctor of Pharmacy degree programs are presented.

Determination of predictors impacting performance on the third-year pharmacy curriculum outcomes assessment at a historically Black college of pharmacy

INTRODUCTION

The Pharmacy Curriculum Outcomes Assessment (PCOA) is a standardized exam developed by the National Association of Boards of Pharmacy (NABP) in 2008 to measure the curriculum in relation to student progress. The purpose of the study was to determine the impact of pre-admissions and pharmacy school variables on third-year student PCOA performance at a Historically Black College or University (HBCU) College of Pharmacy.

METHODS

A retrospective analysis was conducted using data from three cohorts of students who took the PCOA in their third professional year from 2015 to 2017. An independent samples t-test, correlation analysis, and multivariate linear regression were conducted to determine the relationship between student characteristics and the PCOA score.

RESULTS

The mean PCOA scaled score for the third-year pharmacy students was 349.6 ± 46.20 while the mean Pharmacy College Admission Test (PCAT) percentile was 62.7 ± 14.5. Most students (67%) self-identified as Black and the majority (54.9%) were female. The PCOA scores were correlated with the PCAT percentile (P < .001) and the cumulative grade point average (GPA) through the fall semester of the third professional year (P < .001). After adjusting for other factors, the cumulative GPA through the fall semester of the third professional year (P < .001) and PCAT percentiles (P < .001) remained predictive of students PCOA scores.

CONCLUSIONS

The cumulative GPA through the third-year fall semester and PCAT percentiles are important factors in helping to predict PCOA scores among third year pharmacy students at a HBCU.

NAG-PEGylated multilamellar liposomes for BBB-GLUT transporter targeting

The primary objective of the research study is to investigate Glucose (GLUT) transporter targeting of the drug (Citalopram-Hbr) for increased permeability across the Blood-Brain Barrier (BBB). The current study reports the development, physicochemical characterization, cytotoxicity analysis and in-vitro BBB permeability assessment of the Citalopram-Hbr liposomal formulations. Rat Primary Brain Microvascular Endothelial Cells (RPBECs) were used for cytotoxicity analysis and drug permeability testing. Five N-Acetyl Glucosamine (NAG) coated PEGylated multilamellar liposomal formulations were prepared and tested. Permeability of the liposomal formulations was evaluated in RPBECs monolayer. The particle size of the formulations ranged from 13 to 4259 nm. Entrapment efficiency was 50–75%. Cytotoxicity analysis indicated viability (>90%) for all five formulations (0.3–1.25 mg/ml). Apparent drug permeability (Papp) of the formulations ranged from 5.01 × 10⁴ to 15 × 10⁴ cm/min. The study demonstrated successful preparation of NAG-coated PEGylated multilamellar liposomal formulations with high drug entrapment efficiency. Cytotoxicity data indicated that the formulations were well tolerated by the cells up to a concentration of 1.25 mg/ml. Transport study data demonstrated that RPBMECs monolayers can be employed as a robust screening tool for future drug transport studies targeting GLUT transporter on the BBB. The drug permeability values provide a promising preliminarily proof that NAG-coated liposomal formulations can be an effective tool for BBB-GLUT transporter targeting.

Pharmaceutical characterization of novel tenofovir liposomal formulations for enhanced oral drug delivery: in vitro pharmaceutics and Caco-2 permeability investigations

Tenofovir, currently marketed as the prodrug tenofovir disoproxil fumarate, is used clinically to treat patients with HIV/AIDS. The oral bioavailability of tenofovir is relatively low, limiting its clinical effectiveness. Encapsulation of tenofovir within modified long-circulating liposomes would deliver this hydrophilic anti-HIV drug to the reticuloendothelial system for better therapeutic efficacy. The objectives of the current study were to prepare and pharmaceutically characterize model liposomal tenofovir formulations in an attempt to improve their bioavailability. The entrapment process was performed using film hydration method, and the formulations were characterized in terms of encapsulation efficiency and Caco-2 permeability. An efficient reverse-phase high-performance liquid chromatography method was developed and validated for tenofovir quantitation in both in vitro liposomal formulations and Caco-2 permeability samples. Separation was achieved isocratically on a Waters Symmetry C8 column using 10 mM Na₂PO₄/acetonitrile pH 7.4 (95:5 v/v). The flow rate was 1 mL/min with a 12 min elution time. Injection volume was 10 µL with ultraviolet detection at 270 nm. The method was validated according to United States Pharmacopeial Convention category I requirements. The obtained result showed that tenofovir encapsulation within the prepared liposomes was dependent on the employed amount of the positive charge-imparting agent. The obtained results indicated that calibration curves were linear with r² > 0.9995 over the analytical range of 1–10 µg/mL. Inter- and intraday accuracy and precision values ranged from 95% to 101% and 0.3% to 2.6%, respectively. The method was determined to be specific and robust. Regarding the potential of the prepared vectors to potentiate tenofovir permeability through the Caco-2 model, a 10-fold increase in tenofovir apparent permeability was observed compared to its oral solution. In conclusion, this novel and validated method was successfully applied to characterize both in vitro encapsulation efficiency and Caco-2 permeability transport for the pharmaceutical assessment of novel tenofovir formulations.

QbD approach to investigate product and process variabilities for brain targeting liposomes

Efficacy of central nervous system-acting medications is limited by its localization and ability to cross the blood-brain barrier (BBB); therefore, the crux is in designing delivery systems targeted to cross the BBB. Toward this objective, this study proposed pegylated and glycosylated citalopram hydrobromide (Cit-HBr) liposomes as a delivery approach for brain targeting. The multicomponent liposomes were evaluated for drug encapsulation, vesicular size, size distribution, conductivity and drug release characteristics. Moreover, the interaction among the employed components was evaluated by Fourier transform infrared, differential scanning calorimetric and X-ray diffraction analysis. Through a systematic screening design of formulation and process variables in the optimization phase, an improvement of Cit-HBr loading, fine vesicular size with narrow size distribution, greater stability and sustained release features were achieved. The compatibility studies unveiled a significant interaction between Cit-HBr and dicetyl phosphate to control drug encapsulation and release properties. The optimization process showed a minimal range of design space to achieve the preset desirability; more precisely dicetyl phosphate, polyethylene glycol, N-acetyl glucosamine and freeze-thaw cycles of 3%, 5%, 4% and 2 cycles, respectively, were used. Using brain endothelial cell models, the optimized formulations showed an acceptable cell viability with preserved monolayer integrity and an enhanced flux and permeability. Thus, this study has proposed an optimized pegylated and glycosylated vector that is a promising step for brain targeting.

Abstract P6-07-02: Pharmacoeconomic evaluation of denosumab for the treatment of bone metastases in patients with advanced breast cancer in Canada

Background: Skeletal-related events (SREs) occur in 80% of patients with advanced breast cancer (BC) and bone metastases. SREs are costly and can be painful and debilitating, impacting patients’ quality of life and morbidity. While intravenous bisphosphonates such as pamidronate (PAM) and zoledronic acid (ZA) have demonstrated clinical benefit in reducing SREs, skeletal metastases remain a problem as treatments that are more efficacious, well tolerated, more convenient and less costly to administer are needed. Denosumab (XGEVA™) is a novel subcutaneous human monoclonal antibody therapy that significantly reduces the risk of developing SREs in patients with bone metastases from BC.

Objective: The objective of this project is to estimate the incremental cost-effectiveness of denosumab relative to ZA and PAM in the treatment of advanced BC patients with bone metastases.

Methods: A lifetime Markov model with four-week cycle lengths was developed with three health states: on treatment; off treatment; and death. The model included the risk of an SRE for patients on and off treatment and adverse events during treatment. Efficacy was measured as reduction in SREs. Head-to-head efficacy data, transition probabilities, and risk of adverse events were obtained from the clinical trial of denosumab versus ZA. (Stopeck AT et al JCO 2010) Efficacy data compared to PAM was determined from a published network meta-analysis. (Ford JA et al Eur J Cancer 2012) The baseline SRE risk was derived from clinical trial data due to the absence of real-world Canadian data. Analyses were conducted from the Canadian healthcare system perspective and reported in 2011 $CAD. Resource use was determined from a Canadian retrospective chart review of oncology patients with SREs. Costs were based on the published literature, the Ontario Case Costing Initiative, and input from a physician panel. Utility inputs were based on a time trade-off study. (Matza LS et al. Eur J Health Econ 2013) Bisphosphonate administration costs were derived from a published time and motion study. (Dranitsaris G et al. J Oncol Pharm Pract 2001) Outcomes were measured as both SREs avoided and quality-adjusted life years (QALYs) gained. Dominance was assessed or incremental cost-effectiveness ratios calculated per SRE avoided and per QALY gained, for denosumab compared to ZA and PAM. Future costs and QALYs were discounted at 5% per annum. Sensitivity analyses were conducted to test the robustness of the results.

Results: Denosumab was dominant and resulted in $5,733 in cost savings compared to ZA and $2,566 in cost savings compared to PAM based on a probabilistic analysis. Cost savings was driven by differences in drug administration costs and reduction in SREs. SREs avoided were 0.27 and 0.57 compared to ZA and PAM respectively. Denosumab resulted in 0.012 QALYs gained and 0.025 QALYs gained per patient compared to ZA and PAM, respectively. Sensitivity analyses showed the results were robust but most sensitive to drug administration costs and the relative risk of SREs.

Conclusion: Compared to both ZA and PAM, denosumab is more efficacious and offers better value for money (i.e. dominant) in Canada for managing SREs in patients with advanced BC and bone metastases.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-07-02.

Ion-pair chromatography for simultaneous analysis of ethionamide and pyrazinamide from their porous microparticles

Ethionamide (ETA) and pyrazinamide (PZA) are considered the drugs of choice for the treatment of multidrug-resistant tuberculosis. Current methods available in the literature for simultaneous determination of ETA and PZA have low sensitivity or involve column modifications with lipophilic cations. The aim of this study was to develop a simple and validated reversed-phase ion-pair HPLC method for simultaneous determination of ETA and PZA for the characterization of polymeric-based porous inhalable microparticles in in vitro and spiked human serum samples. Chromatographic separation was achieved on a Phenomenex C18 column (250 mm × 4.6 mm) using a Shimadzu LC 10 series HPLC. The mobile phase consisted of A: 0.01% trifluoroacetic acid in distilled water and B: ACN/MeOH at 1:1 v/v. Gradient elution was run at a flow rate of 1.5 mL/min and a fixed UV wavelength of 280 nm. The validation characteristics included accuracy, precision, linearity, analytical range, and specificity. Calibration curves at seven levels for ETA and PZA were linear in the analytical range of 0.1-3.0 μg/mL with correlation coefficient of r (2) > 0.999. Accuracy for both ETA and PZA ranged from 94 to 106% at all quality control (QC) standards. The method was precise with relative standard deviation less than 2% at all QC levels. Limits of quantitation for ETA and PZA were 50 and 70 ng/mL, respectively. There was no interference from either the polymeric matrix ions or the biological matrix in the analysis of ETA and PZA.

Physicochemical characterization of complex drug substances: evaluation of structural similarities and differences of protamine sulfate from various sources

The purpose of this study was to characterize and evaluate differences of protamine sulfate, a highly basic peptide drug, obtained from five different sources, using orthogonal thermal and spectroscopic analytical methods. Thermogravimetric analysis and modulated differential scanning calorimetry showed that all five protamine sulfate samples had different moisture contents and glass transition and melting temperatures when temperature was modulated from 25 to 270°C. Protamine sulfate from source III had the highest residual moisture content (4.7 ± 0.2%) at 105°C, resulting in the lowest glass transition (109.7°C) and melting (184.2°C) temperatures compared with the other four sources. By Fourier-transform infrared (FTIR) spectroscopy, the five sources of protamine sulfate had indistinguishable spectra, and the spectra were consistent with a predominantly random coil conformation in solution and a minor population in a β-sheet conformation (~12%). Circular dichroism spectropolarimetry confirmed the FTIR results with prominent minima at 206 nm observed for all five sources. Finally, proton ((1)H) nuclear magnetic resonance spectroscopy showed that all five protamine sulfate sources had identical spectra with backbone amide chemical shifts between 8.20 and 8.80 ppm, consistent with proteins with predominantly random coil conformation. In conclusion, thermal analyses showed differences in the thermal behavior of the five sources of protamine sulfate, while spectroscopic analyses showed the samples had a predominantly random coil conformation with a small amount of β-sheet present.

Evaluation of anticancer drug-loaded nanoparticle characteristics by nondestructive methodologies

The purpose of this study was to utilize near-infrared (NIR) spectroscopy and near-infrared chemical imaging (NIR-CI) as non-invasive techniques to evaluate the drug loading in letrozole-loaded PLGA nanoparticle formulations prepared by the emulsification-solvent evaporation method. A Plackett-Burman design was applied to evaluate the main effects of amount of drug (X(1)), amount of polymer (X(2)), stirring rate (X(3)), emulsifier concentration (X(4)), organic to aqueous phase volume ratio (X(5)), type of organic solvent (X(6)), and homogenization time (X(7)) on drug entrapment efficiency. The influence of three different spectral pretreatment methods (multiplicative scatter correction, standard normal variate, and Savitzky-Golay second derivative transformation with third-order polynomial) and two different regression methods (PLS regression and principal component regression (PCR)) on model prediction ability were compared. PLS of spectra that were pretreated with Savitzky-Golay second derivative transformation provided better model prediction than PCR as it revealed better linear correlation (correlation coefficient of 0.991) for both calibration and prediction models. Relatively low values of root mean square errors of calibration (RMSEC = 0.748) and prediction (RMSEP = 0.786) and low standard errors of calibration (SEC = 0.758) and prediction (SEP = 0.589) suggested good predictability for estimation of the loading of letrozole in PLGA nanoparticles. NIR-CI analysis also revealed mutual homogenous distribution of both polymer and drug and was capable of clearly distinguishing the 12 formulations both quantitatively and qualitatively. In conclusion, NIR and NIR-CI could be potentially used to characterize anticancer drug-loaded nanoparticulate matrix.

Enhanced Dissolution and Oral Bioavailability of Piroxicam Formulations: Modulating Effect of Phospholipids

Several biologically relevant phospholipids were assessed as potential carriers/additives for rapidly dissolving solid formulations of piroxicam (Biopharmaceutics Classification System Class II drug). On the basis of in vitro dissolution studies, dimyristoylphosphatidylglycerol (DMPG) was ranked as the first potent dissolution rate enhancer for the model drug. Subsequently, the solid dispersions of varying piroxicam/DMPG ratios were prepared and further investigated. Within the concentration range studied (6.4-16.7 wt %), the dissolution rate of piroxicam from the solid dispersions appeared to increase as a function of the carrier weight fraction, whereas the cumulative drug concentration was not significantly affected by piroxicam/DMPG ratio, presumably due to a unique phase behavior of the aqueous dispersions of this carrier phospholipid. Solid state analysis of DMPG-based formulations reveled that they are two-component systems, with a less thermodynamically stable form of piroxicam (Form II) being dispersed within the carrier. Finally, oral bioavailability of piroxicam from the DMPG-based formulations in rats was found to be superior to that of the control, as indicated by the bioavailability parameters, c_max and especially T_max (53 µg/mL within 2 h vs. 39 µg/mL within 5.5 h, respectively). Hence, DMPG was regarded as the most promising carrier phospholipid for enhancing oral bioavailability of piroxicam and potentially other Class II drugs.

Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products

A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (L-T(4)) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250 mm × 3.9 mm) using a 0.01 M phosphate buffer (pH 3.0)-methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 μL and the column temperature was maintained at 28°C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r(2)>0.99) over the analytical range of 0.08-0.8 μg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for L-T(4) over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets.

Tablet splitting of a narrow therapeutic index drug: a case with levothyroxine sodium

Levothyroxine is a narrow therapeutic index, and to avoid adverse effect associated with under or excessive dosage, the dose response is carefully titrated. The tablets are marketed with a score providing an option to split. However, there are no systematic studies evaluating the effect of splitting on dose accuracy, and current study was undertaken to evaluate effects of splitting and potential causes for uniformity failures by measuring assay and content uniformity in whole and split tablets. Stability was evaluated by assaying drug for a period of 8 weeks. Effect of formulation factors on splittability was evaluated by a systematic investigation of formulation factors by preparing levothyroxine tablets in house by varying the type of excipients (binder, diluent, disintegrant, glidant) or by varying the processing factors (granulating liquid, mixing type, compression pressure). The tablets were analyzed using novel analytical tool such as near infrared chemical imaging to visualize the distribution of levothyroxine. Assay was not significantly different for whole versus split tablets irrespective of method of splitting (hand or splitter), and splitting also had no measurable impact on the stability. Split tablets either by hand or splitter showed higher rate of content uniformity failures as compared to whole tablets. Tablet splitter produced more fragmentation and, hence, more content uniformity and friability failures. Chemical imaging data revealed that the distribution of levothyroxine was heterogeneous and was dependent on type of binder and the process used in the manufacture of tablets. Splitting such tablets could prove detrimental if sub- or super-potency becomes an issue.

Influence of formulation and processing factors on stability of levothyroxine sodium pentahydrate

Stability of formulations over shelf-life is critical for having a quality product. Choice of excipients, manufacturing process, storage conditions, and packaging can either mitigate or enhance the degradation of the active pharmaceutical ingredient (API), affecting potency and/or stability. The purpose was to investigate the influence of processing and formulation factors on stability of levothyroxine (API). The API was stored at long-term (25 degrees C/60%RH), accelerated (40 degrees C/75%RH), and low-humidity (25 degrees C/0%RH and 40 degrees C/0%RH) conditions for 28 days. Effect of moisture loss was evaluated by drying it (room temperature, N(2)) and placed at 25 degrees C/0%RH and 40 degrees C/0%RH. The API was incubated with various excipients (based on package insert of marketed tablets) in either 1:1, 1:10, or 1:100 ratios with 5% moisture at 60 degrees C. Commonly used ratios for excipients were used. The equilibrium sorption data was collected on the API and excipients. The API was stable in solid state for the study duration under all conditions for both forms (potency between 90% and 110%). Excipients effect on stability varied and crospovidone, povidone, and sodium laurel sulfate (SLS) caused significant API degradation where deiodination and deamination occurred. Moisture sorption values were different across excipients. Crospovidone and povidone were hygroscopic whereas SLS showed deliquescence at high RH. The transient formulation procedures where temperature might go up or humidity might go down would not have major impact on the API stability. Excipients influence stability and if possible, those three should either be avoided or used in minimum quantity which could provide more stable tablet formulations with minimum potency loss throughout its shelf-life.

Understanding the quality of protein loaded PLGA nanoparticles variability by Plackett-Burman design

The aim of this investigation was to screen and understand the product variability due to important factors affecting the characteristics CyA-PLGA nanoparticles prepared by O/W emulsification-solvent evaporation method. Independent variables studied were cyclosporine A (CyA) (X(1)), PLGA (X(2)), and emulsifier concentration namely SLS (X(3)), stirring rate (X(4)), type of organic solvent employed (chloroform or dichloromethane, X(5)) and organic to aqueous phase ratio (X(6)). The nanoparticles properties considered were encapsulation efficiency (Y(1)), mean particle size (Y(2)), zeta potential (Y(3)), burst effect (Y(4)) and dissolution efficiency (Y(5)). The statistical analysis of the results allowed determining the most influent factors. The nanoparticles were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The factors combination showed variability of entrapment efficiency (Y(1)), mean particle size (Y(2)) and zeta potential (Y(3)) from 10.17% to 93.01%, 41.60 to 372.80 nm and 29.60 to 34.90 mV, respectively. Initially, nanoparticles showed burst effect followed by sustained release during the 7-day in vitro release study period. The dissolution efficiency (Y(5)) varied from 52.67% to 84.11%. The nanoparticles revealed Higuchi release pattern and release occurred by coupling of diffusion and erosion. In conclusion, this study revealed the potential of QbD in understanding the effect of formulation and process variables on the characteristics on CyA-PLGA nanoparticles.

Spectral and spatial characterization of protein loaded PLGA nanoparticles

The objective of this study was to evaluate near infrared (NIR) spectroscopy and imaging as approaches to assess drug contents in poly(dl-lactide-co-glycolide) (PLGA) based nanoparticles of a model protein, cyclosporine A (CyA). A 6-factors 12-runs designed set of experiments with Plackett-Burman (PB) screening was applied in order to examine the effects of drug loading (X(1)), polymer loading (X(2)), emulsifier concentration (X(3)), stirring rate (X(4)), type of organic solvent (X(5)), and ratio of organic to aqueous phases' volumes (X(6)), on drug entrapment efficiency (EFF). After omitting the factors with nonsignificant influences on EFF, a reduced mathematical relationship, EFF = 48.34 + 7.3X(1) - 29.95X(3), was obtained to explain the effect of the significant factors on EFF. Using two different sets for calibration and validation, the developed NIR calibration model was able to assess CyA contents within the 12 PB formulations. NIR spectral imaging was capable of clearly distinguishing the 12 formulations, both qualitatively and quantitatively. A good correlation with a coefficient of 0.9727 was obtained for constructing a quantile-quantile plot for the actual drug loading percentage and the % standard deviation obtained for the drug loading prediction using the hyperspectral images.

Effects of hydroxyurea and L-arginine on the production of nitric oxide metabolites in cultures of normal and sickle erythrocytes

Previous in vitro studies suggest that erythrocytes may be a source of nitric oxide (NO) produced by nitric oxide synthase (NOS) or by oxyhemoglobin-mediated oxidation of hydroxyurea (HU). This study was performed to determine the roles of HU and NOS in the production of NO by normal and sickle erythrocytes. Red blood cells (RBCs) from normal adult hemoglobin (HbAA) and homozygous sickle cell subjects (HbSS) were incubated with PBS containing 0.2 mM hydrogen peroxide (control) for 2 h at 37 degrees C in the presence and absence of l-arginine, the substrate for NOS, and with l-arginine plus HU in the presence and absence of l-NMMA, a specific inhibitor of NOS. The nitrate and nitrite metabolites of NO, expressed as [NOx], were measured. [NOx] in the HbAA and HbSS RBC cultures was not significantly different in the presence and absence of 1.0 mM l-arginine (p>0.1). [NOx] in the HbAA and HbSS cultures treated with a clinically relevant dose of HU (1.0 mM) plus 1.0 mM l-arginine was significantly greater than that in controls incubated with PBS and with l-arginine p < 0.01. However, [NOx] in the HbAA and HbSS cultures treated with 50 microg/ml l-NMMA was not significantly different than that in the cultures treated with HU plus l-arginine in the absence of l-NMMA. These findings suggest that NOx production by erythrocytes may be increased by treatment with HU and may not be decreased by inhibiting NOS. Therefore, we conclude that a therapeutic dose of HU may increase the plasma concentration of NO by a mechanism that does not require erythrocytes NOS activity.

Quality by design: Understanding the formulation variables of a cyclosporine A self-nanoemulsified drug delivery systems by Box–Behnken design and desirability function

Quality by design (QBD) refers to the achievement of certain predictable quality with desired and predetermined specifications. A very useful component of the QBD is the understanding of factors and their interaction effects by a desired set of experiments. The present project deals with a case study to understand the effect of formulation variables of nanoemulsified particles of a model drug, cyclosporine A (CyA). A three-factor, three-level design of experiment (DOE) with response surface methodology (RSM) was run to evaluate the main and interaction effect of several independent formulation variables that included amounts of Emulphor El-620 (X(1)), Capmul MCM-C8 (X(2)) and 20% (w/w) CyA in sweet orange oil (X(3)). The dependent variables included nanodroplets size (Y(1)), nanoemulsions turbidity (Y(2)), amounts released after 5 and 10min (Y(3), Y(4)), emulsification rate (Y(5)) and lag time (Y(6)). A desirability function was used to minimize lag time and to maximize the other dependent variables. A mathematical relationship, Y(5)=9.09-0.37X(1)+0.37X(2)-0.45X(3)+0.732X(1)X(2)-0.62X(1)X(3)+0.3X(2)X(3)+0.02X(1)(2)-0.28X(2)(2)+0.471X(3)(2) (r(2)=0.92), was obtained to explain the effect of all factors and their colinearities on the emulsification rate. The optimized nanodroplets were predicted to yield Y(1), Y(2), Y(3), Y(4), Y(5) and Y(6) values of 42.1nm, 50.6NTU, 56.7, 107.2, 9.3%/min and 3.5min, respectively, when X(1), X(2), and X(3) values were 36.4, 70 and 10mg, respectively. A new batch was prepared with these levels of the independent variables to yield Y(1)-Y(6) values that were remarkably close to the predicted values. In conclusion, this investigation demonstrated the potential of QBD in understanding the effect of the formulation variables on the quality of CyA self-nanoemulsified formulations.

Formulation of anastrozole microparticles as biodegradable anticancer drug carriers

The purpose of this study was to develop poly(d,l-lactic-co-glycolic acid) (PLGA)-based anastrozole microparticles for treatment of breast cancer. An emulsion/extraction method was used to prepare anastrozole sustained-release PLGA-based biodegradable microspheres. Gas chromatography with mass spectroscopy detection was used for the quantitation of the drug throughout the studies. Microparticles were formulated and characterized in terms of encapsulation efficiency, particle size distribution, surface morphology, and drug release profile. Preparative variables such as concentrations of stabilizer, drug-polymer ratio, polymer viscosity, stirring rate, and ratio of internal to external phases were found to be important factors for the preparation of anastrozole-loaded PLGA microparticles. Fourier transform infrared with attenuated total reflectance (FTIR-ATR) analysis and differential scanning calorimetry (DSC) were employed to determine any interactions between drug and polymer. An attempt was made to fit the data to various dissolution kinetics models for multiparticulate systems, including the zero order, first order, square root of time kinetics, and biphasic models. The FTIR-ATR studies revealed no chemical interaction between the drug and the polymer. DSC results indicated that the anastrozole trapped in the microspheres existed in an amorphous or disordered-crystalline status in the polymer matrix. The highest correlation coefficients were obtained for the Higuchi model, suggesting a diffusion mechanism for the drug release. The results demonstrated that anastrozole microparticles with PLGA could be an alternative delivery method for the long-term treatment of breast cancer.

Controlled release tacrine delivery system for the treatment of Alzheimer's disease

Alzheimer's disease is a neurodegenerative condition that affects approximately 5 million people and is the fourth leading cause of death in America. Tacrine is one of the three drugs approved by the FDA for the treatment of Alzheimer's disease. However, the drug has a short biologic half-life of 2-3 hr and gastrointestinal, cholinergic, and hepatic adverse reactions that are associated with high doses of the drug. The aim of our study was to formulate a controlled release delivery system of tacrine that could be used to minimize the side effects associated with the drug. Microparticles of tacrine were formulated using poly(D,L-lactide-co-glycolide) (PLG). PLG and tacrine were dissolved in mixed organic solvents and added to a polyvinyl alcohol solution that was stirred at a constant rate. The organic solvent was evaporated overnight and the formed microparticles were collected by filtration, dried, and sieve-sized. The effects of such formulation variables, as molecular weight of polymer, stir speed during preparation, and drug loading on encapsulation efficiency (EEF), and in vitro release profiles of tacrine were investigated. An increase in the molecular weight of polymer from 8,000 to 59,000 and 155,000 resulted in approximately 10-fold increase in EEF, but the rate of release decreased with increasing molecular weight. Stir speed during preparation had an effect on the EEF but not on the rate of release. Drug loading did not have a significant effect on the EEF but had an effect on the rate of tacrine release. The results suggest that tacrine could be delivered at controlled levels for weeks for the treatment of Alzheimer's disease.

Solubilization of liposomes by weak electrolyte drugs. II. Cefotaxime

The solubilization of dimyristoylphosphatidylcholine (DMPC) liposomes by the weak electrolyte drug, cefotaxime (CFX), has been studied as a function of pH, DMPC, temperature, presence of cholesterol (CHOL), and method of liposome preparation. At 7.5 mM CFX the lag time for solubilization increased, the rate of solubilization decreased, and the minimum turbidity reached increased as a function of DMPC at pH 1.0 and 40 degrees C. Solubilization was most pronounced at pHs below the pKa but inhibited at least one pH unit above the pKa. The critical mole ratio of unionized CFX:DMPC, Rec, for solubilization was estimated to be 0.12. Reducing the temperature slowed the rate of solubilization as did the addition of CHOL. Encapsulation of CFX in liposomes did not significantly reduce CFX degradation,. k1 = 0.048 h-1 at 40 degrees C and a complex of DMPC and a degradation product of CFX precipitated as rectangular crystals. As a result, an increase in the turbidity of solubilized systems was observed from about 20 h to 48 h depending on the conditions. Liposomes in the gel state or with at least 20% CHOL did not undergo an apparent reversal of solubilization. It is concluded that the inclusion of weak electrolyte drugs existing predominantly as the unionized species in liquid crystalline state liposomes may undergo a slow solubilization process not necessarily recognized during characterization.

Dissolution profiles of flurbiprofen in phospholipid solid dispersions

This study is concerned with the development of a solid dispersion formulation of flurbiprofen (FLP) and phospholipid (PL) with improved dissolution characteristics. The FLP powders were blended with PL to produce FLP-PL physical mixtures or made into solid dispersions with PL by the solvent method. The FLP exhibited significantly improved dissolution rates in PL coprecipitate (coppt) compared to the physical mixtures or FLP alone. The dissolution studies suggested that less than a 20:1 ratio of FLP to PL was required to disperse FLP completely in the carrier. The coppt yielded a ninefold greater initial dissolution rate. Also, the total amount dissolved after 60 min was twofold greater at a 10:1 ratio of FLP to L-(-dimyristoyl phosphatidylglycerol (DMPG). Similar results were observed with a ratio as low as 20:1 (FLP:DMPG). Increasing the DMPG content did not increase the rate to any significant extent. Thus, a small PL:FLP ratio improved the dissolution to a significant level. Thus, an FLP:PL dispersion may have the clinical advantages of quick release and excellent bioavailability.

Solubilization of multilamellar liposomes in the presence of non-ionized drug

The solubilization of multilamellar liposomes by metoprolol tartrate (MPL) has been studied as a function of pH, [MPL], [dimyristoylphosphatidylcholine (DMPC)], temperature and lipid composition. The solubilization of liposomes at 37 degrees C by 7.3 nM MPL occurred at different rates at different pH values. MPL completely solubilized by 7.2 mM DMPC liposomes after about 17 h at pH 12, but only a partial solubilization occurred at pH 10 and 11. Between pH 7 and 9 no change in turbidity was observed after 1 week. Addition of cholesterol (CHOL) to DMPC (2:1 mol) had very little effect on solubilization after 24 h, however with DMPC:CHOL (5:1 mol) the decrease in turbidity was observed after 24 h, even though solubilization was much less compared with that of DMPC alone. The rate of solubilization was decreased when dipalmitoylphosphatidylcholine liposomes were employed. Addition of dicetylphosphate (DCP) to DMPC liposomes reduced the rate of solubilization significantly. The solubilization of liposomes by 7.3 mM MPL as a function of [DMPC], indicated that the lower the liposome concentration the greater the effect on solubilization. It is concluded that MPL in the non-ionized form has a solubilizing effect on liposomes, and addition of CHOL or DCP to DMPC has a stabilizing effect against solubilization.

Hydrolysis and stability of acetylsalicylic acid in stearylamine-containing liposomes

The hydrolysis and the stabilization of acetylsalicylic acid (ASA) in liposomes at 30 degrees C were studied. The liposomes consisted of dimyristoylphosphatidylcholine (DMPC) and stearylamine. At pH 4.0 and 8.0, the pseudo-first-order rate constants (kobs) in DMPC: stearylamine (2: 1 mole ratio) liposomes were approximately 60% of the values in control solutions (kB) if ASA was incorporated via the organic phase. In contrast, when ASA was added via the aqueous phase, kobs = kB at pH 4.0 but kobs < kB at pH 8.0 and kobs increased with the fraction of stearylamine in the liposomes. However, when ASA was added via the organic phase, reactions occurred which resulted in the loss of ASA as a function of the time period between phase admixture and the point of film hydration. A product of the reactions was determined by IR and TLC to be N-stearylacetamide. Both the initial loss of ASA and the increase in stability decreased as the DMPC: stearylamine mole ratio increased. A mechanism of aminolysis occurring in the organic solvent and at liposome surfaces between ASA and stearylamine or DMPC at pH 8.0 has been suggested. It is concluded that the orientation of ASA and the ordered structural environment of the bilayers minimizes the aminolytic and hydrolytic reactions.

Photostabilization of riboflavin by incorporation into liposomes

The influence of liposomes on the photostabilization of riboflavin in an aqueous formulation was studied under fluorescent light at various conditions. Liposomal composition, concentration, pH, and ionic strength were varied. The photostability of riboflavin was found to increase in the presence of neutral and negatively-charged liposomes but to decrease in association with positively-charged liposomes. Furthermore, increasing the concentration of dimyristoyl-phosphatidylcholine (DMPC) in the composition of the liposomes resulted in an enhancement in the photostability of riboflavin such that at 5.8mM DMPC concentration a 2.3 fold increase in photostability was observed compared to control buffer solution. The pH of the medium influenced the photostability of riboflavin. However, the ionic strength of solution appeared to demonstrate no significant effect. The photodegradation reactions appeared to follow first-order kinetics in the presence and absence of liposomes.

Effect of certain additives on photodegradation of tetracycline hydrochloride solutions

The photostability of tetracycline hydrochloride solutions in the presence of selected potential stabilizers under various light sources was investigated. Reduced glutathione (GSH) demonstrated the greatest photostabilizing effect followed by p-aminobenzoic acid (PABA), ethylenediamine tetraacetic acid (EDTA) disodium salt, DL-cysteine, thiourea, sodium thiosulfate, and DL-methionine in a descending order. The photostabilizing effect of GSH was found to be dependent on its concentration, pH and buffer species of the medium, the light source, and the temperature of the solutions exposed to light.

Photostabilization of doxorubicin hydrochloride with radioprotective and photoprotective agents: potential mechanism for enhancing chemotherapy during radiotherapy

p-Aminobenzoic acid (PABA), urocanic acid, and sodium urate were found to significantly enhance the photostability of doxorubicin hydrochloride [adriamycin, (ADR)]. d1-Methionine, thiourea, and glycine also increased the photostability of this drug, but to a lesser degree. Sodium thiosulfate on the other hand, was found to be detrimental to the photostability of ADR. The photostabilizing effect of PABA was found to increase with increase of its concentration and was influenced by the pH and the buffer species of the vehicle. The findings would have an impact on the enhancement of therapeutic efficacy of adriamycin when administered during radiation therapy.

Photostabilization of menadione sodium bisulfite by glutathione

Photodecomposition of solutions of menadione sodium bisulfite (MSB) in the presence and absence of glutathione (GSH) under artificial sunlight was investigated. In presence of 0.02% (GSH), an appreciable increase in photostability was observed when clear glass vials were used. The pH and the temperature of the solution significantly influenced the stability of MSB. Photodegradation of MSB appeared to follow first-order kinetics. Photostabilization of MSB was attributed in part to complex formation between MSB and GSH and the antioxidant property of the latter. Stability constants for the various solutions were determined at several temperatures. Thermodynamic parameters were calculated and were found to support complex formation.

Complex formation between metronidazole and sodium urate: effect on photodegradation of metronidazole

Photodegradation of solutions of metronidazole in the presence and absence of sodium urate was studied. Photodegradation appeared to follow zero-order kinetics and was found to be dependent on the pH, buffer species, sodium urate concentration, and light source. Complex formation between metronidazole and sodium urate accounted for the photostabilization of metronidazole. The dissociation constant for this complex was calculated to be 3.4 x 10(-3) M.