Pharmaceutical characterization and thermodynamic stability assessment of a colloidal iron drug product: iron sucrose.

The study objective was to evaluate the thermodynamic stability of iron sucrose complexes as determined by molecular weight (m.w.) changes. The first part of the study focused on the effect of thermal stress, pH, electrolyte or excipient dilution on the stability of a colloidal iron drug product. Part two focused on the physical and chemical evaluation of the colloidal nature of iron sucrose using a series of characterization experiments: ultracentrifugation, dialysis, particle size, zeta potential, and osmotic pressure analysis. A validated Taguchi-optimized high performance gel permeation chromatography method was used for m.w. determinations. Results indicate m.w. of the iron sucrose complex remained unchanged after excipient dilution, ultracentrifugation, dialysis, and electrolyte dilution. Electrolyte dilution studies indicated the lyophilic nature of the iron sucrose colloid with a particle size of 10nm and zeta potential of 0 mV. The complex deformed at low pH and reformed back at the formulation pH. The complex is stable under mild-to-moderate temperature <50°C but aggregates following prolonged exposure to high temperatures >70°C. In conclusion, the resistance of the complex to breakdown by electrolytic conditions, excipient dilution, ultracentrifugation and the reversible complexation after alteration of formulation pH suggest iron sucrose is a lyophilic colloid in nature and lyophilic colloidals are thermodynamically stable.

Impact of controlled ice nucleation on process performance and quality attributes of a lyophilized monoclonal antibody.

An efficient and potentially scalable technology was evaluated to control the ice nucleation step of the freezing process for a model monoclonal antibody formulation and the effect on process performance and quality attributes of the final lyophilized product was compared with the conventional shelf ramping method of freezing. Controlled ice nucleation resulted in uniform nucleation at temperatures between -2.3 and -3.2 °C while uncontrolled nucleation resulted in random nucleation at temperatures between -10 and -16.4 °C. The sublimation rate (dm/dt) during primary drying was higher in the controlled nucleation cycle (0.13 g/h/vial) than in the uncontrolled nucleation cycle (0.11 g/h/vial). This was due to the formation of larger ice crystals, leading to lower product resistance (Rp) and 19% reduction in the primary drying for the controlled nucleation cycle. Controlled ice nucleation resulted in lyophilized cakes with more acceptable appearance, no visible collapse or shrinkage and decreased reconstitution times compared with uncontrolled nucleation. There were no observed differences in the particle size, concentration (A280 nm) and presence of aggregates (A410 nm) between the two nucleation cycles when the lyophilized cakes were reconstituted. These were confirmed by SEC and protein A-HPLC analyses which showed similar peak shapes and retention times between the two cycles. However, uncontrolled nucleation resulted in cakes with larger specific surface area (0.90 m(2)/g) than controlled nucleation (0.46 m(2)/g). SEM images of the lyophilized cakes from uncontrolled nucleation revealed a sponge-like morphology with smaller pores while cakes from controlled nucleation cycle revealed plate-like structures with more open and larger pores. While controlled nucleation resulted in a final product with a higher residual moisture content (2.1±0.08%) than uncontrolled nucleation (1.62±0.11%), this was resolved by increasing the secondary drying temperature.

Oseltamivir phosphate-amberlite(TM) IRP 64 ionic complex for taste masking: preparation and chemometric evaluation.

The objective of the present work was to evaluate and characterize a pediatric-friendly formulation of a bitter tasting drug, oseltamivir phosphate (drug). Amberlite IRP64 (resin) was used to make ionic complexes for masking its bitterness. Complexes of four drug-to-resin ratios, 1:1, 1:2, 1:4, and 1:6 (w/w), were prepared and characterized. At buccal pH of 6.8, drug-resin complexes of 1:1, 1:2, 1:4, and 1:6 ratios released 42.13%, 23.26%, 4.13%, and 14.94%, respectively, of loaded drug after 20 s. However, at stomach pH of 1.2 (0.1 N HCl), 61.96%, 70.18%, 85.88%, and 91.42% of drug was released from the same complexes in 6 min. Near-infrared (NIR) chemical imaging of the complexes showed homogeneous distribution of drug in the resin. Chemometric partial least squares model using NIR data of the drug showed a high correlation between calibration and predicted data (R(2) > 0.998). Overall, these results indicated the complex formation between drug and resin. The pH dependence of drug release from these complexes could minimize drug release in the mouth, whereas immediately releasing it in the stomach. Electronic tongue used to evaluate taste indicated that conductivity taste signals were different from control, suggesting taste masking of the drug.

Comparative evaluation of the in vitro efficacy of lanthanum carbonate chewable tablets.

The aims of this study were to systematically evaluate the effects of pH levels, phosphate concentrations, and tablet integrity on the phosphate binding profiles of lanthanum carbonate chewable tablets, and to compare the in vitro phosphate binding efficacy of one reference and two test products of lanthanum carbonate chewable tablets. Langmuir equation was utilized to calculate the binding constants k1 and k2 . The phosphate binding to the tablets of lanthanum carbonate product was pH dependent, with a faster binding rate at low pH. The crushed tablets bind phosphate more rapid. Compared with the whole tablets, the kinetic binding profiles from the crushed tablets were less variable under all conditions for both test and reference products. The phosphate level has a significant impact on the phosphate binding for both whole and crushed tablets under all pH conditions, with more binding at higher phosphate concentration. The phosphate binding profiles displayed significant difference among the products. For a crushed tablet, the phosphate binding to lanthanum reached equilibrium within 8 h under all conditions. The 90% confidence interval for the k2 ratio (test/reference) was well within the 80%-125% under all pH conditions. However, the k1 ratio varies from 54% to 144%. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:1370-1381, 2013.

In vitro bioequivalence approach for a locally acting gastrointestinal drug: lanthanum carbonate.

A conventional human pharmacokinetic (PK) in vivo study is often considered as the "gold standard" to determine bioequivalence (BE) of drug products. However, this BE approach is not always applicable to the products not intended to be delivered into the systemic circulation. For locally acting gastrointestinal (GI) products, well designed in vitro approaches might be more practical in that they are able not only to qualitatively predict the presence of the active substance at the site of action but also to specifically assess the performance of the active substance. For example, lanthanum carbonate chewable tablet, a locally acting GI phosphate binder when orally administrated, can release free lanthanum ions in the acid environment of the upper GI tract. The lanthanum ions directly reach the site of action to bind with dietary phosphate released from food to form highly insoluble lanthanum-phosphate complexes. This prevents the absorption of phosphate consequently reducing the serum phosphate. Thus, using a conventional PK approach to demonstrate BE is meaningless since plasma levels are not relevant for local efficacy in the GI tract. Additionally the bioavailability of lanthanum carbonate is less than 0.002%, and therefore, the PK approach is not feasible. Therefore, an alternative assessment method is required. This paper presents an in vitro approach that can be used in lieu of PK or clinical studies to determine the BE of lanthanum carbonate chewable tablets. It is hoped that this information can be used to finalize an in vitro guidance for BE studies of lanthanum carbonate chewable tablets as well as to assist with "in vivo" biowaiver decision making. The scientific information might be useful to the pharmaceutical industry for the purpose of planning and designing future BE studies.

Quality by design: impact of formulation variables and their interactions on quality attributes of a lyophilized monoclonal antibody.

The purpose of this study was to use QbD approaches to evaluate the effect of several variables and their interactions on quality of a challenging model murine IgG3κ monoclonal antibody (mAb), and then to obtain an optimized formulation with predefined quality target product profile. This antibody was chosen because it has a propensity to precipitate and thus represents a challenge condition for formulation development. Preliminary experiments were conducted to rule out incompatible buffer systems for the mAb product quality. A fractional factorial experimental design was then applied to screen the effects of buffer type, pH and excipients such as sucrose, sodium chloride (NaCl), lactic acid and Polysorbate 20 on glass transition temperature ( [Formula: see text] ), monoclonal antibody concentration (A(280)), presence of aggregation, unfolding transition temperature (T(m)) of the lyophilized product, and particle size of the reconstituted product. A Box-Behnken experimental design was subsequently applied to study the main, interaction, and quadratic effects of these variables on the responses. Pareto ranking analyses showed that the three most important factors affecting the selected responses for this particular antibody were pH, NaCl, and Polysorbate 20. The presence of curvature in the variables' effects on responses indicated interactions. Based on the constraints set on the responses, a design space was identified for this mAb and confirmed with experiments at three different levels of the variables within the design space. The model indicated a combination of high pH (8) and NaCl (50mM) levels, and a low Polysorbate 20 (0.008 mM) level at which an optimal formulation of the mAb could be achieved. Moisture contents and other analytical procedures such as size exclusion chromatography, protein A analysis and SDS-PAGE of the pre-lyophilized and final reconstituted lyophilized products indicated an intact protein structure with minimal aggregation after formulation and lyophilization. In conclusion, experimental design approach was effective in identifying optimal concentrations of excipients and pH for this challenging monoclonal antibody formulation.

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 ß-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 ß-sheet present.

Application of quality by design elements for the development and optimization of an analytical method for protamine sulfate.

The purpose of this study was to develop a robust reverse phase-HPLC method for the separation of hydrolyzed protamine sulfate peptides using a quality by design approach. A Plackett-Burman experimental design was utilized to screen the effects of mobile phase pH, flow rate, column temperature, injection volume and methanol concentration on peak resolution and USP tailing. Multivariate regression and Pareto ranking analyses showed that mobile phase pH, column temperature and injection volume were statistically significant (p<0.05) factors affecting the resolution and tailing of the peaks. A Box-Behnken experimental design with response surface methodology was then utilized to evaluate the main, interaction, and quadratic effects of these three factors on the selected responses. A desirability function applied to the optimized conditions predicted peak resolutions between 1.99 and 3.61 and tailing factor between 1.02 and 1.45 for the four peptide peaks of protamine sulfate with the following chromatographic conditions; an isocratic mobile phase consisting of 100mM monosodium phosphate buffer pH 2.25, 1.8% acetonitrile and 0.3% methanol. The injection volume was 20 µl, with a column temperature of 24 °C and a flow rate of 1.0 ml/min and a total run time of less than 25 min. The optimized chromatographic method was validated according to ICH Q2R1 guidelines and applied to separate and compare the peaks of protamine sulfate from five different sources. Analyses of the peptide peaks of the five protamine sulfate samples showed no significant differences in their compositions. The results clearly showed that quality by design concept could be effectively applied to optimize an HPLC chromatographic method for protein analysis with the least number of experimental runs possible.

A QbD case study: Bayesian prediction of lyophilization cycle parameters.

As stipulated by ICH Q8 R2 (1), prediction of critical process parameters based on process modeling is a part of enhanced, quality by design approach to product development. In this work, we discuss a Bayesian model for the prediction of primary drying phase duration. The model is based on the premise that resistance to dry layer mass transfer is product specific, and is a function of nucleation temperature. The predicted duration of primary drying was experimentally verified on the lab scale lyophilizer. It is suggested that the model be used during scale-up activities in order to minimize trial and error and reduce costs associated with expensive large scale experiments. The proposed approach extends the work of Searles et al. (2) by adding a Bayesian treatment to primary drying modeling.

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.

Thermodynamic stability assessment of a colloidal iron drug product: sodium ferric gluconate.

A high performance gel permeation chromatography (HP-GPC) method was developed, validated and used to determine the molecular weight (MW) of sodium ferric gluconate following various stress conditions. The intra-day accuracy (90-103%), intra-day precision (1.5-2.7%), inter-day accuracy (91-105%), inter-day precision (1.3-3.2%) were within acceptable range stated in FDA guidance. The MW of sodium ferric gluconate remained unchanged after: (1) autoclaving (121 degrees C), (2) moderate thermal stress (30 days at 50 degrees C or 7 days at 70 and 90 degrees C), (3) excipient dilution, (4) basic buffer dilution (pH of 8 and 9), (5) ultracentrifugation, (6) dialysis, and (7) electrolyte dilution. However sodium ferric gluconate showed signs of instability at higher temperatures (>90 degrees C) after 30 days and at pH of 10-11. Sodium ferric gluconate was found to be a lypophilic colloidal solution with an average particle size of 10 nm and a zeta potential of -13 mV. The colloid osmotic pressure was 3.5 mmHg and remained unchanged after moderate thermal stress. Additionally, in-house drug products with similar MW to sodium ferric gluconate were produced by three different synthetic procedures, suggesting that this colloidal iron drug product might be thermodynamically stable.

Complexation between risperidone and amberlite resin by various methods of preparation and binding study.

PURPOSE: The purpose of this work was to investigate the effect of preparation methods and the drug-to-resin ratio on complex formation between risperidone and amberlite resin. METHODS: The existence of such resin complex may provide taste-masking properties to the dosage forms. It is important to determine when and how the complex forms. Therefore, in this study, the complexes of risperidone and amberlite resin were prepared by granulation, solution, and freeze-drying methods at various drug-to-resin ratios. The physical mixtures of drug-resin were used to compare the results of complexes prepared by granulation, solution, and freeze drying. The complexes were evaluated by various methods of characterization including differential scanning calorimetry, X-ray diffraction, spectroscopy (near infrared, Fourier transform infrared, and Raman), drug release, and binding studies. RESULTS: Complexation between risperidone and amberlite was investigated for various preparation methods. It was found that complexation occurred at lower amounts of amberlite resin (drug-to-resin ratios of 1:1 and 1:2) when solution form of drug was contacted with the resin as in the case of solution and freeze-drying techniques compared with granulation (drug-to-resin ratios of 1:4 and 1:6). Characterization studies such as differential scanning calorimetry, X-ray diffraction, spectroscopic techniques, and drug release studies differentiated complexes from the physical mixtures. Binding studies between them revealed that the binding was linear with solubility of the drug limiting the adsorption capacity. CONCLUSIONS: Results of the study highlighted the importance of the preparation methodologies to formulate complexes. When the drug and the resin were simply mixed physically, no complexation occurred. Thus, a careful evaluation of manufacturing procedure would indicate the nature and extent of complexation.

Complexation of risperidone with a taste-masking resin: novel application of near infra-red and chemical imaging to evaluate complexes.

The purpose of the study was to investigate the complexation between a weakly basic drug (risperidone) and an ion exchange resin (amberlite IRP-64) used as a taste-masking agent via two preparation methods: physical mixture and solvent evaporation. Both methods were prepared in different drug-to-resin ratios by weight (1:1, 1:2, 1:4, 1:6). Physicochemical characterizations were performed using differential scanning calorimetry, x-ray diffraction, infra-red spectroscopy, Raman spectroscopy, near infra-red spectroscopy, chemical imaging and drug release studies. These physicochemical techniques revealed that risperidone formed complex with the resin via the solvent evaporation method where enhanced dissolution occurred but not with the physical mixtures.

Disintegration of highly soluble immediate release tablets: a surrogate for dissolution.

The purpose of the work was to investigate correlation between disintegration and dissolution for immediate release tablets containing a high solubility drug and to identify formulations where disintegration test, instead of the dissolution test, may be used as the acceptance criteria based on International Conference on Harmonization Q6A guidelines. A statistical design of experiments was used to study the effect of filler, binder, disintegrating agent, and tablet hardness on the disintegration and dissolution of verapamil hydrochloride tablets. All formulation variables, i.e., filler, binder, and disintegrating agent, were found to influence tablet dissolution and disintegration, with the filler and disintegrating agent exerting the most significant influence. Slower dissolution was observed with increasing disintegration time when either the filler or the disintegrating agent was kept constant. However, no direct corelationship was observed between the disintegration and dissolution across all formulations due to the interactions between different formulation components. Although all tablets containing sodium carboxymethyl cellulose as the disintegrating agent, disintegrated in less than 3 min, half of them failed to meet the US Pharmacopeia 30 dissolution criteria for the verapamil hydrochloride tablets highlighting the dependence of dissolution process on the formulation components other than the disintegrating agent. The results identified only one formulation as suitable for using the disintegration test, instead of the dissolution test, as drug product acceptance criteria and highlight the need for systematic studies before using the disintegration test, instead of the dissolution test as the drug acceptance criteria.

Comparative evaluation of flow for pharmaceutical powders and granules.

The objective of the present work was to carry out a systematic evaluation of flow of pharmaceutical powders and granules using compendial and non-compendial methods. Angle of repose, bulk density, tapped density, Carr's compressibility index, and Hausner ratios were evaluated. Additionally, flow was characterized using a powder rheometer in which a sensitive force transducer monitors the forces generated as a result of the sample displacement. The critical attributes such as cohesivity index, caking strength, and flow stability were determined for samples. The samples consisted of different grades of magnesium stearate powder including bovine, vegetable, and food grade, physical mixture powder blend consisting of a model formulation, granules prepared by various methods including slugging, high shear granulator, and fluid bed dryer. Lubricant efficiency was also determined for granules lubricated with various concentrations of magnesium stearate. It was observed that the compendial methods were often non-discriminating for minor variations in powder flow. The additional characterization such as cohesivity, and caking strength were helpful in understanding the flow characteristics of pharmaceutical systems. The flow stability test determined that the powders were not affected by the test conditions on the rheometer. The non-compendial tests were discriminating to even minor variations in powder flow.

Functionality of magnesium stearate derived from bovine and vegetable sources: dry granulated tablets.

Magnesium stearate is a functional excipient used to ensure efficient ejection of tablets. This study compares the functionality of a vegetable and bovine grade of magnesium stearate. Tablets were prepared by direct compression and dry granulation of a model formulation. Physical and chemical tests were performed on bulk powders, granule intermediates, and finished tablets to provide a comprehensive comparison of the two grades of magnesium stearates. Raw material characterization of the two grades showed no difference in particle size, surface area, true density, and total moisture content. However, significant differences in fatty acid composition, surface tension, and zeta potential were detected. Tablet ejection force for the physical mixture formulations was variable, showing similar ejection force for the two grades of magnesium stearate at some concentrations and different ejection forces at other concentrations. The dry granulated formulation containing vegetable-based magnesium stearate showed a lower ejection force than the formulation containing bovine-based magnesium stearate. There was no difference between the dissolution profiles of the tablets containing the two grades of magnesium stearate prepared by both methods. The results indicated that magnesium stearate interchangeability with respect to lubricant efficiency depends upon the level in which it is used and the manufacturing method.

Stability of ranitidine syrup re-packaged in unit-dose containers.

PURPOSE: The stability of ranitidine syrup re-packaged in unit-dose containers was studied. METHODS: Oral ranitidine hydrochloride syrup containing 16.8 mg/mL of ranitidine hydrochloride (equivalent to 15 mg of ranitidine) in original bulk containers and re-packaged in unit-dose amber-colored glass bottles sealed with aluminum caps were obtained from commercial sources. For extended-stability determinations, samples were stored for 52 weeks at 25 degrees C and 40% relative humidity and analyzed at 0, 4, 13, 26, 39, and 52 weeks. For accelerated stability determinations, samples were stored for 13 weeks at 40 degrees C and 25% relative humidity and analyzed at 0, 4, 9, and 13 weeks. Stability was assessed using high-performance liquid chromatography and by measuring changes in pH and sample weight. The principal impurity and total impurities were also measured. RESULTS: No significant changes in pH were demonstrated, and all values remained well within acceptable limits. The weight change in samples was greater for re-packaged samples stored in accelerated conditions compared with that of samples in the original packaging; however, the differences were not significant. Ranitidine hydrochloride samples in both types of packaging remained stable when stored at 25 degrees C and 40% relative humidity for 52 weeks and at 40 degrees C and 25% relative humidity for 13 weeks. The impurity profiles remained within acceptable limits for all samples. CONCLUSION: Re-packaged ranitidine syrup was stable for up to 52 weeks when stored at 25 degrees C and 40% relative humidity and for up to 13 weeks when stored at 40 degrees C and 25% relative humidity.

Process analytical technology: chemometric analysis of Raman and near infra-red spectroscopic data for predicting physical properties of extended release matrix tablets.

The purpose of this work was to develop a correlation between pharmaceutical properties such as hardness, porosity, and content with prediction models employed using Raman and near infra-red (NIR) spectroscopic methods. Metoprolol tartrate tablets were prepared by direct compression and wet granulation methods. NIR spectroscopy and chemical imaging, and Raman spectra were collected, and hardness, porosity, and dissolution were measured. The NIR PLS model showed a validated correlation coefficient of >0.90 for the predicted versus measured porosity, hardness, and amount of drug with raw and second derivative NIR spectra. Raman spectra correlated porosity of the tablets using raw data for directly compressed tablets and wet granulated tablets (r(2) > 0.90). A very close root-mean square error of calibration (RMSEC) and root-mean square error of prediction (RMSEP) values were found in all the cases indicating validity of the calibration models. Raman spectroscopy was used for the first time to predict physical quality attribute such as porosity successfully. Chemical imaging utilizing NIR detector also demonstrated to show physical changes due to compression differences. In conclusion, sensor technologies can be potentially used to predict physical parameters of the matrix tablets.

Cytotoxicity evaluation of enzyme inhibitors and absorption enhancers in Caco-2 cells for oral delivery of salmon calcitonin.

The usefulness of enzyme inhibitors and absorption enhancers with least mucosal cell cytotoxicity was evaluated on Caco-2 cell monolayers. The temporal cytotoxicity of several protease inhibitors at 500 microg/mL (e.g., turkey and chicken ovomucoids, aprotinin, and Protease Inhibitor Cocktail) and absorption enhancers [e.g., cholate (3%), glycocholate (3%), glycosursodeoxycholate (3%), ethylenediaminetetraacetic acid (EDTA, 0.1%), hydroxypropyl-beta-cyclodextrin (HP-beta-CD, 5%), hydroxypropyl-gamma-cylcodextrin (HP-gamma-CD, 5%), gamma-cylcodextrin (gamma-CD, 5%), tetradecyl-beta-D-maltoside (0.25%), octylglucoside (0.25%), citric acid (10%), glycyrrhetinic acid (0.34 mM), and Tween-80 (0.1%)] was measured by monitoring their effect on Caco-2 cell viability. Cell viability was measured by mannitol permeability measurements, transepithelial electrical resistance (TEER) measurements, DNA-propidium iodide staining assay, and WST-1 assay (tetrazolium salt based assay). Sodium dodecyl sulfate (0.1%), a potent surfactant, was used as a positive control. Chicken and turkey ovomucoids were nontoxic to cells as evaluated by all the methods used. Aprotinin decreased the TEER, whereas plasma membrane damage was seen with Protease Inhibitor Cocktail after a 24-h period. With respect to the absorption enhancers, the toxicity increased directly as a result of an increase in the time of incubation. The enhancers EDTA and HP-beta-CD can be used safely for a short period of time, whereas glycosursodeoxycholate, glycyrrhetinic acid, octylglucoside, HP-gamma-CD, and gamma-CD can be used for a longer period.