Dicyanamide-intertwined assembly of two new Zn complexes based on N2O4-type pro-ligand: Synthesis, crystal networks, spectroscopic insights, and selective nitroaromatic turn-off fluorescence sensing.

Two new dicyanamide bridged multinuclear Zn complexes, [Zn2(L1)(µ1,5-dca)2(µ1-dca)]n (1) and [Zn2(L2)(µ1,5-dca)2(µ1-dca)]n (2) have been synthesized using N2O4-based pro-ligands (H2L1 = N,N'-bis(5-bromo-3-methoxysalicylidenimino)-1,3-diaminopropane, H2L2 = N,N'-bis(3-ethoxysalicylidene)-2,2-dimethyl-1,3-propanediamine) and characterized by microanalytical and spectroscopic techniques. Both complexes are stable in solution and solid-state. Thermogravimetric analysis (TGA) findings showed that complexes are stable at room temperature. Single-crystal X-ray diffraction (SCXRD) has proven that complexes are identical structures where two zinc metal ions are crystallographically independent. The directional properties of dicyanamide co-ligands via µ1,5 bridging have resulted in different connectivity of zinc metal ions leading to 1D templates. SCXRD revealed some notable non-covalent interactions (π⋯π, C-H····π, and H-bonding) in their solid-state crystal structures. 1-2 have strong fluorescence behaviour over pro-ligands, which may be quenched in the presence of various electron-deficient explosive nitroaromatic compounds (epNACs). Complex 2 fluorescence intensity is sharper than 1; hence the former retained high sensitivity and selectivity for trinitrophenol (TNP). The enhancement of fluorescence mechanism, detection limit (LOD), and the quenching constant (KSV) have been calculated using the Stern-Volmer equation (SV), where the KSV value for TNP is found to be 1.542 × 104 M-1. The solution phase quenching mechanism has been rationalized by (a) electrostatic interactions through charge-transfer complex, (b) photo-induced electron transfer (PET) by the HOMO-LUMO energy gap via DFT, and (c) fluorescence resonance energy transfer (FRET). Finally, complex 2 is applied as a sensor by turn-off fluorescence response to detecting TNP nitroaromatics in the DMF medium.

Supercritical carbon dioxide extracts of small cardamom and yellow mustard seeds have fasting hypoglycaemic effects: diabetic rat, predictive iHOMA2 models and molecular docking study.

In the present investigation, the supercritical carbon dioxide (SC-CO2) extracts of small cardamom (SC) and yellow mustard (YM) seeds have been investigated for their efficacies in combating type 2 diabetes in streptozotocin-induced Wistar albino rats. Fasting blood glucose (FBG) levels in the rats were monitored on days 8, 15 and 21. On day 15, FBG level reduced appreciably by 31·49 % in rats treated with SC seed extract and by 32·28 % in rats treated with YM seed extract, comparable to metformin (30·70 %) and BGR-34 (a commercial polyherbal drug) (31·81 %) administered rats. Either extract exhibited desirable effects on hepatic glucose-6-phosphatase, glucose-6-phosphate dehydrogenase (G6PD) and catalase activities in controlling diabetes. A molecular docking exercise was conducted to identify specific compounds in the extracts which possessed augmenting effect on G6PD. The results revealed that all the bioactive compounds in the extracts have binding affinities with the enzyme and contributed to the antidiabetic efficacies of the extracts as G6PD augmenters. The effects of the extracts on insulin sensitivity and glucose uptake were investigated using non-invasive modelling by iHOMA2 software. This in vitro approach indicated that extract administration resulted in increased both insulin sensitivity of the liver and glucose uptake in the gut. The findings of the present study attest these SC-CO2 extracts of the spices as safe alternatives of metformin and BGR-34 in combating type 2 diabetes and could be safely subjected to clinical studies. These extracts could also be employed in designing proactive food supplements in mitigating the metabolic disorder.

Application of statistical design to evaluate critical process parameters and optimize formulation technique of polymeric nanoparticles.

In advanced medication, drug-loaded polymeric nanoparticles (NPs) appeared as a novel drug delivery system with lots of advantages over conventional medicines. Despite all the advantages, NPs do not gain popularity for manufacturing hurdles. The study focused on the formulation difficulties and implementation of statistical design to establish an effective model for manufacturing NPs. In this study, physico-chemical properties of the drug and polymer (PLGA) were incorporated to understand the mechanistic insights of nanoformulations. Primarily, the process controlling parameters were screened by Plackett-Burman design and the critical process parameters (Cpp) were further fabricated by Box-Behnken design (BBD). The TLM-PLGA-NPs (telmisartan loaded PLGA NPs) exhibited particle size, encapsulation efficiency and zeta potential of 232.4 nm, 79.21% and -9.92 mV respectively. The NPs represented drug loading of 76.31%. Korsmeyer-Peppas model (R 2 = 0.925) appeared to be the best fitted model for in vitro release kinetics of NPs. The model identified Fickian diffusion of TLM from the polymeric nanoparticles. The ANOVA results of variables indicate that BBD is a suitable model for the development of polymeric NPs. The study successfully identified and evaluated the correlation of significant parameters that were directly or indirectly influencing the formulations which deliberately produce desired nanoparticles with the help of statistical design.

Simultaneous determination of paclitaxel and lansoprazole in rat plasma by LC-MS/MS method and its application to a preclinical pharmacokinetic study of investigational PTX-LAN-PLGA nanoformulation.

In spite of having a remarkable anti tumor activity against a wide variety of cancers, the clinical effectiveness of the major chemotherapeutic drug paclitaxel is often limited by the issues of drug resistance that hampers the therapeutic effectiveness of the drug. The combination of proton pump inhibitor with paclitaxel is an effective approach to overcome therapeutic resistance caused by the acidic microenvironment (Warburg effect) in tumor. In the present study a new simple, precise and selective liquid chromatography tandem mass spectrometry method was developed for quantification of paclitaxel and lansoprazole using esomeprazole as an internal standard and applied for the pharmacokinetic study of investigational paclitaxel - lansoprazole loaded PLGA nanoparticles. The developed method quantifies both the drugs simultaneously irrespective of their dissimilar stability concerns. The detection was exercised with multiple reaction-monitoring mode in positive ionization that yielded highly intense response of parent-product (m/z) transition pair 854.4 → 286.1, 370.1 → 251.9 and 346 → 198 for paclitaxel, lansoprazole and Esomeprazole respectively. The chromatographic separation was achieved using phenomenex Kinetex 5 µ C18 100A 50 × 3.0 mm column and a gradient mobile phase combination of ammonium acetate in deionized water (pH 6.8, 2 mM, w/v) and acetonitrile spiked with formic acid (1:1000, v/v ). This method showed good linearity over a concentration range of 10-320 ng/mL and 100-3200 ng/mL with correlation coefficient (R2) 0.98 and 0.94 for paclitaxel and lansoprazole respectively. Using liquid liquid extraction process both the drugs were extracted from rat plasma. The intra- and inter-day precision and accuracy values were within the variability limits and both the analytes were found to be stable throughout the freeze-thaw, auto-sampler, bench top and long term stability studies. The liquid chromatography tandem mass spectrometry method was successfully validated in accordance with United States Food and Drug administration guidelines and the results were within the acceptable limits. The liquid chromatography tandem mass spectrometry method was successfully utilized for the pharmacokinetic investigation of experimental paclitaxel - lansoprazole loaded PLGA nanoparticles in rat plasma.

Nanoliposomes of Supercritical Carbon Dioxide Extract of Small Cardamom Seeds Redresses Type 2 Diabetes and Hypercholesterolemia.

BACKGROUND & OBJECTIVES: In our previous investigation, oral administration of 1,8- cineole-rich supercritical carbon dioxide extract of small cardamom seeds in Wistar albino rats resulted in achieving normal fasting blood glucose (FBG) and serum cholesterol levels. The objective of this study was to further protect the aforesaid extract and to enhance its in vivo therapeutic efficacies in redressing type 2 diabetes and hypercholesterolemia, by encapsulating it as nanoliposomes. Patents related to nanoliposomes have been revised thoroughly. METHODS: PEGylated nanoliposomes of the aforesaid extract were formulated using soya phosphatidylcholine and Tween 80 by probe-sonication. These nanoliposomes were subjected to in vitro characterizations and were orally administered to Wistar albino rats at three different doses viz. 550, 175 and 55 mg/kg b.w. for detailed investigation of their antidiabetic and hypocholesterolemic efficacies. RESULTS: FT-IR, DSC and XRD analyses, HLB value (16), entrapment efficiency (84%) and release kinetics (obeying Higuchi model) revealed that the nanoliposomes were o/w type and were hydrophilic. They exhibited appreciable in vitro antioxidant potency (59% DPPH scavenging activity) owing to a synergistic consortium of antioxidants present therein. Oral administration of the liposomes in rats at 550 mg/kg b.w. could restore their normal FBG levels and serum lipid profiles on day 35, with desirable up-down regulations of related key enzymes. The iHOMA2 model could successfully predict the effects of nanoliposomes on insulin sensitivity and glucose uptake in rat liver and brain, respectively. CONCLUSION: Nanoliposome of 1,8-cineole rich extract of small cardamom seeds is a new biotherapeutic in redressing type 2 diabetes and hypercholesterolemia.

Simultaneous Determination and Quantitation of Diosmetin and Hesperetin in Human Plasma by Liquid Chromatographic Mass Spectrometry With an Application to Pharmacokinetic Studies.

Among the secondary metabolites which are widely distributed in plants and foods in plant origin flavonoids is important one. Flavonoids have antioxidant activities as free radical scavenging action. They also have anti-inflammatory, antiulcer and anti-carcinogenic activities. Diosmin and hesperidin, the metabolites of which are diosmetin and hesperitin respectively are considered in the present study. Diosmetin has anticancer, antioxidant and blood lipid lowering activities. It also enhances venous tone and microcirculation and by reducing systemic oxidative stress it protects capillaries. Hesperitin also has antioxidant, anti-inflammatory, blood lipid and cholesterol lowering, anti-carcinogenic activities. In the present study efforts were given to develop and validate a bioanalytical method for simultaneous estimation of diosmetin and hesperitin in human plasma by liquid chromatography electron spray ionization mass spectrometry with an application to the analysis of plasma samples obtained from the comparative pharmacokinetic studies on healthy human volunteers under the framework of bioequivalence study. The developed method for simultaneous determination and quantification of diosmetin and hesperitin in human plasma was validated as per the US-FDA guidelines. The validation parameters found within the specified regulatory limit, hence acceptable. The present method also has a short run time (6.0 min) and easy extraction process. The developed method was found to be simple, specific, highly selective, sensitive and reproducible. This was applied for the analysis of the volunteer plasma samples. On the basis of comparison of the AUC0-t, the relative bioavailability of the test preparation was found 100.94 and 95.09% for diosmetin and hesperitin respectively of that of the reference preparation.

A chemotherapeutic approach targeting the acidic tumor microenvironment: combination of a proton pump inhibitor and paclitaxel for statistically optimized nanotherapeutics.

Paclitaxel (PTX) is a major chemotherapeutic drug that is effective against a wide variety of cancers, particularly breast, ovarian and lung cancer. For a weakly basic chemotherapeutic drug such as PTX, the development of the acidic tumor microenvironment (Warburg effect) has a remarkable impact on therapeutic resistance. The present approach takes advantage of the acidic tumor microenvironment by incorporating lansoprazole (LAN), a proton pump inhibitor (PPI), with PTX as a potent therapeutic combination that is capable of reversing PTX resistance. To deliver optimal amounts of the drugs to neoplastic cells, a nano drug delivery system was selected. To design the nanoformulation process in a limited framework, typical formulation parameters were optimized and validated by the application of response surface methodology (RSM) using Box-Behnken design (BBD). On the basis of critical quality aspects, the experimental design helped to determine the optimal particle size (243.7 nm), zeta potential (-9.14 mV) and encapsulation efficiencies (88.91% and 80.35% for PTX and LAN respectively). The optimized formulation (PTX-LAN-PLGA-NPs) exhibited sustained in vitro release profiles over 384 hours for both the encapsulated drugs. The Korsmeyer-Peppas model was found to be the best fitted model for the release kinetics, where the release mechanism follows Fickian diffusion. In in vitro anti-tumor efficacy experiments using Michigan Cancer Foundation-7 (MCF-7) breast cancer cells, the PTX-LAN-PLGA-NPs exhibited a steep decrease in cell viability compared to the pure drugs. Taken together, the results strongly support that incorporation of PTX and LAN in nanoparticles (NPs) is a promising approach for cancer chemotherapy.

Assessment of preclinical pharmacokinetics and acute toxicity of pioglitazone and telmisartan combination.

The prevalence of hypertension is very common amongst the diabetic patients and is reported as the major cause of mortality in diabetes. Pioglitazone reported to have an ability to alter the blood cholesterol level and cardioprotective efficiency along with its antidiabetic activity. Telmisartan, through activation of PPAR-γ receptor exerts insulin sensitizing property in addition to its primary cardioprotective efficiency. Theoretically, a combination of pioglitazone and telmisartan may be beneficial to effectively control the high blood glucose level and management of coexisting cardiovascular complication in diabetes. The aim of this research was to experimentally evaluate the pharmacokinetic interaction of pioglitazone and telmisartan when are coadministered in rat. Pioglitazone and telmisartan were administered orally as a single dose individually and in combination to the rats. The plasma samples of the pharmacokinetic study were analyzed using a validated LCMS method. The acute toxicity of the combination with a high dose in rats was also evaluated as a part of the determination of its safety profile. There was no significant change in pharmacokinetic parameters were resulted due to the coadministration of pioglitazone and telmisartan in rat. Absence of major toxicological effect supports the in vivosafety of the combination.

Safety against nephrotoxicity in paclitaxel treatment: Oral nanocarrier as an effective tool in preclinical evaluation with marked in vivo antitumor activity.

Oral paclitaxel (PTXL) formulations freed from cremophor® EL (CrEL) is always in utmost demand by the cancerous patients due to toxicities associated with the currently marketed formulation. In our previous investigation [Int. J. Pharm. 2014; 460:131], we have developed an oral oil based nanocarrier for the lipophilic drug, PTXL to target bioavailability issue and patient compliance. Here, we report in vivo antitumor activity and 28-day sub-chronic toxicity of the developed PTXL nanoemulsion. It was observed that the apoptotic potential of oral PTXL nanoemulsion significantly inhibited the growth of solid tumor (59.2 ± 7.17%; p < 0.001) without causing any explicit toxicity. The 6.5 mg/kg and 3 mg/kg oral PTXL nanoemulsion dose did not cause any notable alteration in haematological, biochemical/structural characteristics during 28-day sub-chronic toxicity studies in the experimental mice. Whereas, the toxicity of 12.8 mg/kg body weight dose showed decrease in RBC, haemoglobin and neutrophil counts. In contrast, marketed PTXL (Taxol®) was found to be comparatively more toxic to the experimental animals. Taxol® treatment resulted glomerulonephritis in histopathological examination, which could be correlated with increased level of creatinine and associated nephrotoxicity. This investigations conclude that the developed oral nanoemulsion presents a viable therapeutics bio-system to step towards clinical application as well as substitute CrEL based PTXL formulations.

LC-MS/MS assay for quantitation of enalapril and enalaprilat in plasma for bioequivalence study in Indian subjects.

BACKGROUND: Enalapril (EPL) is an angiotensin-converting enzyme inhibitor for the treatment of hypertension and chronic heart failure. Enalaprilat (EPLT) is an active metabolite that contributes to the overall activity of EPL. AIM: To quantitate EPL along with its metabolite EPLT using LC-MS/MS, a bioanalytical method was developed and validated with tolbutamide in human plasma using a protein precipitation technique. RESULTS: The sensitive and selective method has an LLOQ of 1 ng/ml with a linearity range of 1-500 ng/ml for both EPL and EPLT using 300 µl of plasma without any matrix effect. CONCLUSION: Linearity, specificity, accuracy, precision and stability, as well as its application to the analysis of plasma samples after oral administration of 20 mg of EPL maleate in healthy volunteers demonstrate applicability to bioavailability/bioequivalence studies.

Development and validation of a high throughput LC-MS/MS method for simultaneous quantitation of pioglitazone and telmisartan in rat plasma and its application to a pharmacokinetic study.

Management of cardiovascular risk factors in diabetes demands special attention due to their co-existence. Pioglitazone (PIO) and telmisartan (TLM) combination can be beneficial in effective control of cardiovascular complication in diabetes. In this research, we developed and validated a high throughput LC-MS/MS method for simultaneous quantitation of PIO and TLM in rat plasma. This developed method is more sensitive and can quantitate the analytes in relatively shorter period of time compared to the previously reported methods for their individual quantification. Moreover, till date, there is no bioanalytical method available to simultaneously quantitate PIO and TLM in a single run. The method was validated according to the USFDA guidelines for bioanalytical method validation. A linear response of the analytes was observed over the range of 0.005-10 µg/mL with satisfactory precision and accuracy. Accuracy at four quality control levels was within 94.27%-106.10%. The intra- and inter-day precision ranged from 2.32%-10.14 and 5.02%-8.12%, respectively. The method was reproducible and sensitive enough to quantitate PIO and TLM in rat plasma samples of a preclinical pharmacokinetic study. Due to the potential of PIO-TLM combination to be therapeutically explored, this method is expected to have significant usefulness in future.

Comparative biodistribution and safety profiling of olmesartan medoxomil oil-in-water oral nanoemulsion.

Poor aqueous solubility and unfavourable de-esterification of olmesartan medoxomil (a selective angiotensin II receptor blocker), results in low oral bioavailability of less than 26%. Improvement of oral bioavailability with prolonged pharmacodynamics activity of olmesartan in Wistar rats had been approached by nanoemulsification strategy in our previous article [Colloid Surface B, 115, 2014: 286]. In continuation to that work, we herewith report the biodistribution behaviour and 28-day repeated dose sub-chronic toxicity of olmesartan medoxomil nanoemulsion in Wistar rats following oral administration. The levels of olmesartan in collected biological samples were estimated using our validated LC-MS/MS technique. Our biodistribution study showed significantly higher brain concentrations of olmesartan (0.290 ± 0.089 µg/mL, 0.333 ± 0.071 µg/mL and 0.217 ± 0.062 µg/mL at 0.5, 2.0 and 8.0 h post dosing, respectively) when administered orally as nanoemulsion formulation as compared to the aqueous suspension. In addition, the olmesartan nanoemulsion was found to be safe and non-toxic, as it neither produced any lethality nor remarkable haematological, biochemical and structural adverse effects as observed during the 28-days sub-chronic toxicity studies in experimental Wistar rats. It is herewith envisaged that the developed nanoemulsion formulation approach for the delivery of olmesartan medoxomil via oral route can further be explored in memory dysfunction and brain ischemia, for better brain penetration and improved clinical application in stroke patients.

Drug release, preclinical and clinical pharmacokinetics relationships of alginate pellets prepared by melt technology.

INTRODUCTION: Alginate pellets prepared by the aqueous agglomeration technique experience fast drug dissolution due to the porous pre-formed calcium alginate microstructure. OBJECTIVE: This study investigated in vitro drug release, preclinical and clinical pharmacokinetics relationships of intestinal-specific calcium acetate-alginate pellets against calcium-free and calcium carbonate-alginate pellets. METHOD: Alginate pellets were prepared by solvent-free melt pelletization instead of aqueous agglomeration technique using chlorpheniramine maleate as model drug. RESULTS: A fast in situ calcium acetate dissolution in pellets resulted in rapid pellet breakup, soluble Ca(2+) crosslinking of alginate fragments and drug dissolution retardation at pH 1.2, which were not found in other pellet types. The preclinical drug absorption rate was lower with calcium acetate loaded than calcium-free alginate pellets. In human subjects, however, the extent and the rate of drug absorption were higher from calcium acetate-loaded pellets than calcium-free alginate pellets. The fine, dispersible and weakly gastric mucoadhesive calcium alginate pellets underwent fast human gastrointestinal transit. They released the drug at a greater rate than calcium-free pellets in the intestine, thereby promoting drug bioavailability. CONCLUSION: Calcium acetate was required as a disintegrant more than as a crosslinking agent clinically to promote pellet fragmentation, fast gastrointestinal transit and drug release in intestinal medium, and intestinal-specific drug bioavailability.

Docking analysis of gallic acid derivatives as HIV-1 protease inhibitors.

HIV-1 Protease (HIV-1 PR) enzymes are essential for accurate assembly and maturation of infectious HIV retroviruses. The significant role of HIV-1 protease in viral replication has made it a potential drug target. In the recent past, phytochemical Gallic Acid (GA) derivatives have been screened for protease inhibitor activity. The present work aims to design and evaluate potential GA-based HIV-1 PR phytoinhibitors by docking approach. The ligands were prepared by ChemDraw and docking was performed in HEX software. In this present study, one of the GA analogues (GA4) emerged as a potent drug candidate for HIV-1 PR inhibition, and docking results showed it to be comparable with anti-HIV drugs, darunavir and amprenavir. The GA4 derivative provided a lead for designing more effective HIV-1 PR inhibitors.

Method Development and Validation of Liquid Chromatography-Tandem Mass Spectrometry for Angiotensin-II in Human Plasma: Application to Study Interaction Between Atorvastatin & Olmesartan Drug Combination.

Simple and sensitive Liquid Chromatography-Tandem Mass Spectrometry (LCMS/MS) method was developed and validated, then was implicated on hypertensive human subjects to study drug interaction of atorvastatin (ATVS) and Olmesartan (OLM) on status of Angiotensin-II (ANG-II). The ANG-II in plasma was extracted with 5 mL methanol containing 5 % formic acid through C18 (cartridges) liquid-liquid extraction, dried and reconstituted with 1 mL of 16 % acetonitrile in 0.1 % formic acid in water. The chromatographic separation of ANG-II with a Agilent technology 6410 Triple quadrupole was carried multiple reaction monitoring scan mode with a Agilent 1290 Infinity LC system for UHPLC. The sample were separated on a (Thermo Scientific) Hy-Purity advance (50 × 4.6 mm, 5 µm) using Mobile Phase A: 16 % acetonitrile in 0.1 % formic acid in water and Mobile Phase B: 0.1 % formic acid in methanol at a flow rate of 0.3 mL/min, performed at ambient temperature. The mobile phase gradient of 16 % acetonitrile in water was linearly increased to 38 % acetonitrile over 10 min and subsequently the mobile-phase was increased to 100 % acetonitrile over 15 min. The developed method was validated for specificity, accuracy, precision, stability, linearity, sensitivity and recovery. The method was linear between peak area ratio of standard and internal standard over the range of 50-800 ng/mL. The method was successfully applied for the drug interaction study revealed levels of ANG-II were significantly higher in ATVS + OLM treatment condition as compared to individual treatment of OLM. This reflects the reason of low effectiveness of ATVS + OLM in combination instead of synergistic activity.

Assesment of endocrinal and biochemical entities through liquid chromatography-tandem mass spectrometry/mass spectrometer: Inter-relative investigation of the interaction based cardiovascular formulation.

BACKGROUND: Combinatory oral dosage treatment of atorvastatin (ATVS) and olmesartan (OLM) drugs to cardiovascular patients reflects unpredicted results instead of its individual therapy, which was accessed on quantification of endocrinal and biochemicals of plasma through liquid chromatography-tandem mass spectrometry/mass spectrometer (LCMS/MS). OBJECTIVE: Mission was to track the remarkable biochemical variation in the plasma after induction of the combined formulation, to evaluate the pharma-market rumor on its efficiency. METHODS: To fulfil undergoing research objectives for digging-up of market insult, human patient volunteers were chosen according to the required criteria along with bioethical regulation. A sensitive, rapid and precise method was developed and validated to estimate aldosterone (ALD), angiotensin (ANG-II) and the Mevalonate (MVA) not Mevalonic acid through LCMS/MS over least samples of cardiovascular patients. Level of each endogenous biochemicals were determined in three stages - without drugs, with a single drug (OLM/ATVS) and with their combination that was then correlate with blood pressure of respective volunteers. RESULT AND DISCUSSION: Comparative and correlative studies panaroma among these analytes was detected. The selectivity, specificity, linearity, precision, accuracy, extraction recovery, limit of detection and limit of quantification, stability were the essential points of validation of the developed methodology. And the significance of each endogenous analyte data were based on P ≥ 0.001. Thus, low value of ALD and reciprocally higher in ANG-II on administered single drug than its combination and equal concentration of mevalonate in both stages, was discovered. CONCLUSION: This concludes that the cardiovascular dosage formulation entrenched in the market are not synergistic and effective compared with a single drug as antihypertensive drug.

Method development and validation of liquid chromatography-tandem/mass spectrometry for aldosterone in human plasma: Application to drug interaction study of atorvastatin and olmesartan combination.

In the present investigation, a simple and sensitive liquid chromatography-tandem mass spectrometry (LC/MS/MS) method was developed for the quantification of aldosterone (ALD) a hormone responsible for blood pressure in human plasma. The developed method was validated and extended for application on human subjects to study drug interaction of atorvastatin (ATSV) and olmesartan (OLM) on levels of ALD. The ALD in plasma was extracted by liquid-liquid extraction with 5 mL dichloromethane/ethyl ether (60/40% v/v). The chromatographic separation of ALD was carried on Xterra, RP-Column C18 (150 mm× 4.6 mm × 3.5 µm) at 30°C followed by four-step gradient program composed of methanol and water. Step 1 started with 35% methanol for first 1 min and changed linearly to 90% in next 1.5 min in Step 2. Step 3 lasted for next 2 min with 90% methanol. The method finally concluded with Step 4 to achieve initial concentration of methanol that is, 35% thus contributing the total method run time of 17.5 min. The flow rate was 0.25 mL/min throughout the process. The developed method was validated for specificity, accuracy, precision, stability, linearity, sensitivity, and recovery. The method was linear and found to be acceptable over the range of 50-800 ng/mL. The method was successfully applied for the drug interaction study of ATSV + OLM in combination against OLM treatment on blood pressure by quantifying changes in levels of ALD in hypertensive patients. The study revealed levels of ALD were significantly higher in ATSV + OLM treatment condition when compared to OLM as single treated condition. This reflects the reason of low effectiveness of ATSV + OLM in combination instead of synergistic activity.

Nanoemulsion strategy for olmesartan medoxomil improves oral absorption and extended antihypertensive activity in hypertensive rats.

Olmesartan medoxomil (OM) is hydrolyzed to its active metabolite olmesartan by the action of aryl esterase to exert its antihypertensive actions by selectively blocking angiotensin II-AT1 receptor. Poor aqueous solubility and uncontrolled enzymatic conversion of OM to its poorly permeable olmesartan limits its oral bioavailability. The aim of the current study was to formulate a novel nanoemulsion of OM to improve its pharmacokinetics and therapeutic efficacy. The oil-in-water (o/w) nanoemulsion of OM was developed using lipoid purified soybean oil 700, sefsol 218 and solutol HS 15. We have characterized the nanoemulsions by considering their thermodynamic stability, morphology, droplet size, zeta potential and viscosity and in vitro drug release characteristics in fasting state simulated gastric fluid (pH 1.2) and intestinal fluid (pH 6.5). The thermodynamically stable nanoemulsions comprises of spherical nanometer sized droplets (<50 nm) with low polydispersity index showed enhanced permeability through the Caco-2 cell monolayer. The concentration of active olmesartan in rat plasma following oral absorption study was determined by our validated LC-MS/MS method. The result of the pharmacokinetic study showed 2.8-fold increased in area under the curve (AUC0-27) of olmesartan upon oral administration of OM nanoemulsion and sustained release profile. Subsequent, in vivo studies with nanoemulsion demonstrated better and prolonged control of experimentally induced hypertension with 3-fold reduction in conventional dose. By analysing the findings of the present investigations based on stability study, Caco-2 permeability, pharmacokinetic profile and pharmacodynamic evaluation indicated that the nanoemulsion of OM (OMF6) could significantly enhance the oral bioavailability of relatively insoluble OM contributing to improved clinical application.

Improvement of cellular uptake, in vitro antitumor activity and sustained release profile with increased bioavailability from a nanoemulsion platform.

Paclitaxel, a potential anticancer agent against solid tumors has been restricted from its oral use due to poor water solubility as well as Pgp efflux property. The present study was aimed to improve the oral bioavailability of paclitaxel through development of (o/w) nanoemulsion consisting of Capryol 90 as internal phase with Tween 20 as emulsifier with water as an external phase. Formulations were selected from the nanoemulsion region of pseudo-ternary phase diagrams, formulated by aqueous titration method. The developed nanoemulsion has been characterized by its thermodynamic stability, morphology, droplet size, zeta potential, viscosity where in vitro release was evaluated through dialysis. Paclitaxel nanoemulsion exhibited thermodynamical stability with low viscosity, nano-sized oil droplets in water with low poly-dispersity index. The shelf life of the paclitaxel nanoemulsion was found to be approximately 2.38 years. Increased permeability through the Caco-2 cell monolayer and decreased efflux is great advantageous for nanoemulsion formulation. The effects of paclitaxel nanoemulsion on breast cancer cell proliferation, morphology and DNA fragmentation were analyzed in vitro which showed significant anti-proliferation and decreased IC50 values in nanoemulsion group which may be due to enhanced uptake of paclitaxel through the oil core. Moreover, the absolute oral bioavailability and sustained release profile of the paclitaxel nanoemulsion evaluated in mouse model was found to improve up to 55.9%. The concentration of paclitaxel in mice plasma was determined by our validated LC-MS/MS method. By reviewing the significant outcome of the present investigation based on stability study, Caco-2 permeability, cell proliferative assay and pharmacokinetic profile it may be concluded that the oral nanoemulsion has got encouraging advantages over the presently available formulations of this injectable chemotherapeutic drug.

Development and validation of RP-HPLC method: scope of application in the determination of oil solubility of paclitaxel.

A simple, reproducible, feasible and innovative reversed-phase high-performance liquid chromatographic method was developed and validated for the quantitative determination of paclitaxel dissolved in various oils. The method was validated after extraction of the analyte from capryol 90, triacetin and olive oil. The method was conducted on a Hypersil BDS C18 column, 250 × 4.6 mm, 5 µm particle size, with a mobile phase composed of acetonitrile: 10 mM KH2PO4 buffer (pH 3.5) (55:45, v/v) and detection at 227 nm. The linearity, in the range of 5 to 50 µg/mL, presented determination coefficients of 0.9983, 0.9997 and 0.9990 in capryol 90, triacetin and olive oil, respectively, calculated by the least-squares regression method. Intra-day precision values for percentages recovered were 0.68 to 0.80, 0.83 to 1.13 and 0.97 to 1.88, and inter day precision values were 1.52 to 1.92, 1.43 to 1.83 and 1.26 to 2.06 for capryol 90, triacetin and olive oil, respectively. The recovery of paclitaxel from the capryol 90, triacetin and olive oil ranged from 97.94 to 103.55, 96.85 to 103.27 and 97.14 to 103.64%, respectively. This developed and validated method was successfully applied to quantitatively assess paclitaxel dissolved in various oils. The solubility of paclitaxel was found to be higher in triacetin than in other tested oils.