Improvement of Oral Bioavailability of Lopinavir Without Co-administration of Ritonavir Using Microspheres of Thiolated Xyloglucan.

Lopinavir is a BCS Class IV drug exhibiting poor bioavailability due to P-gp efflux and limited permeation. The aim of this research was to formulate and characterize microspheres of lopinavir using thiolated xyloglucan (TH-MPs) as carrier to improve its oral bioavailability without co-administration of ritonavir. Thiomeric microspheres were prepared by ionotropic gelation between alginic acid and calcium ions. Interaction studies were performed using Fourier transform infrared spectroscopy (FT-IR). The thiomeric microspheres were characterized for its entrapment efficiency, T80, surface morphology, and mucoadhesion employing in vitro wash off test. The microspheres were optimized by 32 factorial design. The optimized thiomeric microsphere formulation revealed 93.12% entrapment efficiency, time for 80% drug release (T80) of 358.1 min, and 88% mucoadhesion after 1 h. The permeation of lopinavir from microspheres was enhanced 3.15 times as determined by ex vivo study using everted chick intestine and increased relative bioavailability over 3.22-fold over combination of lopinavir and ritonavir as determined by in vivo study in rat model.

Formulation of piperine solid lipid nanoparticles (SLN) for treatment of rheumatoid arthritis.

The purpose of this work was to formulate piperine solid lipid nanoparticle (SLN) dispersion to exploit its efficacy orally and topically. Piperine SLN were prepared by melt emulsification method and formula was optimized by the application of 32 factorial design. The nanoparticulate dispersion was evaluated for particle size, entrapment efficiency and zeta potential (ZP). Optimized batch (128.80 nm average size, 78.71% entrapment efficiency and -23.34 mV zeta potential) was characterized for differential scanning calorimetry (DSC), X-ray diffraction which revealed amorphous nature of piperine in SLN. The prepared SLN were administered orally and topically to CFA-induced arthritic rats. Ex vivo study using Franz diffusion cell indicate that piperine from SLN gel formulation accumulates in the skin. Pharmacodynamic study result indicates both the topical and oral piperine evoked a significant response compared to orally administered chloroquine suspension. The results of ELISA show significant reduction in TNFα in treated rat which might be the reason behind the DMARD action of piperine SLN.

Improving oral bioavailability of acyclovir using nanoparticulates of thiolated xyloglucan.

Acyclovir a BCS class III drug exhibits poor bioavailability due to limited permeability. The intention of this research work was to formulate and characterize thiolated xyloglucan polysaccharide nanoparticles (TH-NPs) of acyclovir with the purpose of increasing its oral bioavailability. Acyclovir-loaded TH-NPs were prepared using a cross-linking agent. Interactions of formulation excipients were reconnoitered using Fourier transform infrared spectroscopy (FT-IR). The formulated nanoparticles were lyophilised by the addition of a cryoprotectant and characterized for its particle size, morphology and stability and optimized using Box Behnken Design.The optimized TH-NP formulation exhibited particle size of 474.4±2.01 and an entrapment efficiency of 81.57%. A marked enhancement in the mucoadhesion was also observed. In-vivo study in a rat model proved that relative bioavailability of acyclovir TH-NPs is ∼2.575 fold greater than that of the marketed acyclovir drug suspension.

Fabrication and efficacy evaluation of chloroquine nanoparticles in CFA-induced arthritic rats using TNF-α ELISA.

Rheumatoid arthritis (RA), a chronic systemic autoimmune disease, stimulates various immune cells especially macrophages, causing release of various proinflammatory cytokines such as TNF-α leading to persistent synovitis. Chloroquine, an anti-malarial drug inhibits the production of TNF-α, thus, halting the disease progression. The aim of the present study was fabrication, characterization and demonstration of kinetic and dynamic efficacy of chloroquine loaded solid lipid nanoparticles (CQ-SLNs) in arthritic rats and in lowering TNF-α levels. CQ-SLNs were prepared using melt homogenization method and subjected to lyophilization. The particle size, zeta potential, PDI and entrapment efficiency were found to be 113.6±0.15nm, -27.8±1.21mV, 0.125±0.03 and 93.45±0.43% respectively. Ex vivo endocytic uptake studies revealed engrossment of endocytic pathways in the uptake of SLN from intestine. Plasma drug profile upon pharmacokinetic evaluation demonstrated increased AUC, half-life and decreased elimination rate of the drug. Pharmacodynamic studies revealed reduction in the paw volume, bone erosion and cartilage destruction, the same was also reflected in histopathological studies. The TNF-α ELISA concluded that the TNF-α level was significantly reduced in the synovial fluid upon treatment with CQ-SLN, thus, leading to the conclusion that CQ-SLN could be used as a potential in reducing inflammatory TNF-α at the arthritic site and halting the disease progression.

Formulation of mucoadhesive gastric retentive drug delivery using thiolated xyloglucan.

Tamarind seed xyloglucan is a polymer reported to possess mucoadhesive property. In the present work, role of cysteine derivative of tamarind seed polysaccharide (thiomer) to enhance the mucoadhesion and its influence on drug permeation has been studied. The xyloglucan was first chemically modified to carboxymethyl derivative which was further converted to thiomer by conjugation with cysteine in presence of a coupling agent, EDAC. The matrix tablets of simvastatin prepared using thiomer demonstrated drug release retardation, increased mucoadhesion force and increased ex vivo permeation, the same were proportional to the increase in the amount of thiomer. The in vivo residence of thiomer placebo was more than 7h in rabbit. Pharmacokinetic evaluation in rabbits indicated higher AUC for the formulation with highest content of thiomer and level 'A' correlation could be established from the generated dissolution and bioavailability data.

Synthesis and characterization of a novel mucoadhesive derivative of xyloglucan.

A novel polymer in the form of a thiolated derivative of natural tamarind seed polysaccharide or xyloglucan was synthesized and its chacteristics as a mucoadhesive polymer were studied as a part of the study undertaken herein. The synthetic route followed involves a two-step reaction mechanism of firstly oxidizing xyloglucan and then further conjugating it with l-cysteine to form thiolated xyloglucan or thiomer via imine linkage. The thiomer thus formed was characterized using various analytical techniques as differential scanning calorimetry (DSC), X-ray diffraction analysis (XRD), and nuclear magnetic resonance (NMR). Ellman's method was used to determine the numbers of thiol groups/g of thiolated xyloglucan. Zeta potential measurements were carried out for thiolated xyloglucan. Viscosities of the formulated xyloglucan and thiolated xyloglucan gels were comparatively evaluated along with the evaluation of mucoadhesive properties of the gels using ex vivo bioadhesion study employing freshly excised sheep intestinal mucosa.

Design and development of SMEDDS for colon-specific drug delivery.

CONTEXT: Lipoidal systems have particularly shown potential for specific accumulation in areas with inflamed tissue increasing the selectivity of local drug delivery. OBJECTIVE: Formulation and evaluation of self-microemulsifying drug delivery system (SMEDDS) for colon-specific drug delivery for effective treatment of colonic diseases. METHOD: Ternary phase diagram was used to optimize level of oil, surfactant and co-surfactant to optimize SMEDDS and were evaluated for percent transmittance, emulsification time, in vitro release, myeloperoxidase (MPO) activity and intestinal accumulation. The spray dried SMEDDS were filled in capsules which were enteric coated with Eudragit S-100 at 10% weight gain to ensure SMEDDS delivery at colon. The spray dried SMEDDS were also evaluated for IR, DSC, XRD, SEM and stability study. RESULT: In ternary phase diagram, Capmul MCM C8 and Capmul PG12 NF with surfactant (Tween 20) and co-surfactant (PG) in ratio 2:1 and 3:1, respectively, showed maximum emulsification area. These liquid SMEDDS show maximum transmittance, globule size of 90-30 nm. The spray-dried SMEDDS with diluents show good flow property. The units of MPO activity show lower level as compared to pure drug and control group, histopathology results supports better healing with SMEDDS. This was attributed to accumulation of SMEDDS in inflammatory area as compared to drug which was further proved by accumulation study. Enteric-coated capsule containing SMEDDS are able to deliver drug, specifically at the colonic region. CONCLUSION: Higher accumulation of lipoidal drug in inflammatory area and specific release of liposomes by enteric-coated capsules provide better option for the treatment of colonic disease.

In-vivo bioavailability and lymphatic uptake evaluation of lipid nanoparticulates of darunavir.

Darunavir is effective against wild-type and PI-resistant HIV, and has an oral bioavailability of 37%. It needs to be combined with ritonavir, which increases the bioavailability to 82%. The aim of this study was to evaluate the in-vivo efficacy of the darunavir-SLN and demonstrate lymphatic transport as a contributing pathway in increasing the drug bioavailability. The SLN was prepared by hot-homogenization technique using GMS as lipid. In-vitro drug release from SLN at the 12th hour was retarded (80.6%) compared to marketed tablet (92.6%). Ex-vivo apparent permeability of the freeze-dried SLN across everted rat intestine was 24 × 10-6 at 37 °C and 5.6 × 10-6 at 4 °C. The presence of endocytic process inhibitors like chlorpromazine and nystatin reduced it to 18.8 × 10-6 and 20.2 × 10-6, respectively, which established involvement of endocytic mechanism in the uptake of SLN. In-vivo pharmacokinetic studies on rats demonstrated increase in the AUC of SLN (26) as compared to that of marketed tablet (13.22), while the presence of lymphatic uptake inhibitor cycloheximide lowered the AUC of SLN to 17.19 which further led credence to the involvement of lymphatic uptake behind improved bioavailability. The detection of darunavir in the lymphatic fluid of the rats administered with darunavir-SLN further reinforced the conclusion of SLN being taken up by the lymphatic system.

Design and development of liposomes for colon targeted drug delivery.

BACKGROUND: Local delivery to bowel tissue through oral administration is a challenging but a desirable goal to treat diseases like inflammatory bowel disease (IBD). Colon specific drug delivery system should be capable of protecting the drug en route colon. PURPOSE: Liposomes have shown potential to specific accumulation at inflammation site thus reduce toxicity; hence it can be used for effective treatment of IBD. METHODS: Liposomes prepared using thin film hydration method. Statistical design was used for optimization. Colitis was induced using acetic acid. Inverted sac method was used as ex vivo model for IBD. Myeloperoxidase (MPO) activity and histopathology comparative study was carried out. Liposomes were formulated in enteric coated capsules to deliver the liposome specifically in initial segment of colon. RESULTS: Particle size and entrapment efficiency were between 200 and 300 nm and 40 and 60%, respectively. In vivo and ex vivo study indicates higher accumulation of liposomes in colonic region as compared to pure drug. Enteric coated capsules delivered the drug after 5 h lag time. DISCUSSION: Low particle size is attributed to low lipid content and stabilization due to surfactant. At higher cholesterol level, vesicles cannot reshuffle into smaller vesicles due to rigidization. Study shows higher accumulation of liposomes due to its lipoidal nature as compared to pure drug due to membrane transfer mechanism of drug thus MPO significantly lowers as compared to standard group (p < 0.05). CONCLUSIONS: Higher accumulation of liposomal drug in inflammatory area and specific release of liposomes by enteric coated capsules provide better option for the treatment of colonic disease.

Optimization of Carboxymethyl-Xyloglucan-Based Tramadol Matrix Tablets Using Simplex Centroid Mixture Design.

The aim was to determine the release-modifying effect of carboxymethyl xyloglucan for oral drug delivery. Sustained release matrix tablets of tramadol HCl were prepared by wet granulation method using carboxymethyl xyloglucan as matrix forming polymer. HPMC K100M was used in a small amount to control the burst effect which is most commonly seen with natural hydrophilic polymers. A simplex centroid design with three independent variables and two dependent variables was employed to systematically optimize drug release profile. Carboxymethyl xyloglucan (X 1), HPMC K100M (X 2), and dicalcium phosphate (X 3) were taken as independent variables. The dependent variables selected were percent of drug release at 2nd hour (Y 1) and at 8th hour (Y 2). Response surface plots were developed, and optimum formulations were selected on the basis of desirability. The formulated tablets showed anomalous release mechanism and followed matrix drug release kinetics, resulting in regulated and complete release from the tablets within 8 to 10 hours. The polymer carboxymethyl xyloglucan and HPMC K100M had significant effect on drug release from the tablet (P > 0.05). Polynomial mathematical models, generated for various response variables using multiple regression analysis, were found to be statistically significant (P > 0.05). The statistical models developed for optimization were found to be valid.

Development and evaluation of carvedilol-loaded transdermal drug delivery system: In-vitro and in-vivo characterization study.

CONTEXT: The transdermal drug delivery system was prepared and the bioavailability of the selected drug was enhanced by reducing first-pass metabolism. OBJECTIVE: The objective of this study was to enhance the bioavailability of carvedilol through transdermal patches. MATERIALS AND METHODS: To develop a matrix-type transdermal patch containing carvedilol with different ratios of polymer combinations by solvent evaporation technique. RESULTS AND DISCUSSION: In-vitro permeation studies were performed by Franz diffusion cells. The results followed Higuchi kinetics, and mechanism of release was diffusion mediated. On the basis of the in-vitro and physicochemical parameters of carvedilol patches, the code F-1(PVP: Ethyl Cellulose = 4:1) was chosen for the study of in-vivo, ex-vivo, histocompatibility study, and pharmacological study. The bioavailability studies in rats indicated that the carvedilol-loaded transdermal patches provided steady-state plasma concentration and improved bioavailability of 72% in comparison to oral administration. The ex-vivo permeation study in rat's skin indicated that the flux and permeability co-efficient of optimized F-1 patch was 30.08 ± 0.7 µg/cm(2)/h and 0.416 ± 0.05 µg/cm(2)/h, respectively, which was more as compared to plain carvedilol. The histocompatibility study of the F-1 patch on the rat's skin after 24 h ex-vivo study gave less pathological changes as compared to other. The antihypertensive activity of the patch in comparison with oral administration was studied using N-nitro-L-arginine methyl ester-induced hypertensive rats. It was observed that the optimized patch (F-1) significantly controlled hypertension (p < 0.05). CONCLUSION: The developed patch increases the efficacy of carvedilol through enhancement of bioavailability for the therapy of hypertension.

Preparation and characterization of nanocapsules for colon-targeted drug delivery system.

CONTEXT: Nanoparticles for colon-specific drug delivery system are known for their specific accumulation in the inflamed tissue in the colon and may therefore allow a selective delivery to the site of inflammation for the treatment of inflammatory bowel disease (IBD). OBJECTIVE: The objective of this study was to formulate and evaluate nanocapsules (NC), an oral system designed to achieve site-specific and instant drug release in colon for effective treatment of IBD. MATERIALS AND METHODS: Prednisolone (PD), a typical glucocorticoid, has been widely used for the treatment of IBD. In this study, nanoprecipitation method was used to prepare polymeric NC of PD with pH responsive polymer Eudragit S100. The effect of several formulation variables such as surfactant, oil, and polymer on the PD-NC properties (average size, drug release rate, and drug entrapment) was investigated. In vitro drug release study was done by changing pH method and an in vivo study on rat was done to ascertain efficiency of PD-NC to release drug specifically in colon. RESULTS AND DISCUSSION: The optimized formulations lead to the preparation of PD-NC with a mean size of 567.87 nm, high encapsulation efficiency of 90.21%. In vitro studies reveal that NC releases the drug after 4.5-h lag time corresponding to time to reach colonic region, and in vivo studies show that NC release drug after 3-h lag time in rat corresponds to arrival in colon. CONCLUSION: The above NC formulation of PD is the targeted drug to the colon and may provide effective way of treatment of colonic disease.

Statistical optimization of floating pulsatile drug delivery system for chronotherapy of hypertension.

INTRODUCTION: A pulsatile drug delivery system is characterized by a lag time that is an interval of no drug release followed by rapid drug release. The purpose of this work was to develop hollow calcium alginate beads for floating pulsatile release of valsartan intended for chronopharmacotherapy. Floating pulsatile concept was applied to increase the gastric residence of the dosage form having lag phase followed by a burst release. MATERIALS AND METHODS: To overcome the limitations of various approaches for imparting buoyancy, hollow/porous beads were prepared by simple process of acid-base reaction during ionotropic crosslinking by low viscosity sodium alginate and calcium chloride as a crosslinking agent. In this study, investigation of the functionality of the sodium alginate to predict lag time and drug release was statistically analyzed using the response surface methodology (RSM). RSM was employed for designing of the experiment, generation of mathematical models and optimization study. The chosen independent variables, i.e. sodium alginate and potassium bicarbonate were optimized with a 3(2) full factorial design. Floating time and cumulative percentage drug release in 6 h were selected as responses. RESULTS: Results revealed that both the independent variables are significant factors affecting drug release profile. A second-order polynomial equation fitted to the data was used to predict the responses in the optimal region. The optimized formulation prepared according to computer-determined levels provided a release profile, which was close to the predicted values. The floating beads obtained were porous (21-28% porosity), hollow with bulk density <1 and had Ft(70) of 2-11 h. The floating beads provided expected two-phase release pattern with initial lag time during floating in acidic medium followed by rapid pulse release in phosphate buffer. CONCLUSION: The proposed mathematical model is found to be robust and accurate for optimization of time-lagged formulations for programmable pulsatile release of valsartan.

Design, development and in vitro-in vivo study of a colon-specific fast disintegrating tablet.

OBJECTIVE: Targeted delivery systems for the treatment of Inflammatory bowel disease (IBD) are designed to increase local tissue concentrations of anti-inflammatory drugs from lower doses compared with systemic administration. The objective of this study was to formulate and evaluate an oral system designed to achieve site-specific and instant drug release in the colon for effective treatment of IBD. MATERIALS AND METHODS: The system consists of a core tablet containing the model drug diclofenac sodium, superdisintegrant sodium starch glycolate, and coated with enteric polymer Eudragit FS 30 D to achieve different total percentage weight gain. Drug release studies were carried out using a changing pH method. A placebo formulation containing barium sulphate in the tablet was administered to human volunteers for in vivo X-ray studies. SEM studies were performed to determine coating thickness and film topography. RESULTS: In vitro studies revealed that the tablet with 10% coating level released the drug after 5 h lag time corresponding to the colonic region. Tablets with 10% coating level could maintain their integrity in human volunteers for 5 h, approximating colon arrival time and release the drug instantaneously. DISCUSSION: Colon-targeting and instant drug release for 10% coating level was due to the dissolution of the Eudragit FS 30 D and the immediate release effect of superdisintegrant. It was observed that as the coating level increased, the lag time also increased. This was because of increased diffusion path length and tortuosity at higher coating levels. CONCLUSION: An in vivo-in vitro study revealed that not only the sensitivity of the polymer to the pH environment but also the thickness of coating plays an important role in colon delivery and the tablet with 5% superdisintegrant and 10% coating level achieved the desired performance of the colon targeting.

Synthesis of MCC-PEG conjugate and its evaluation as a superdisintegrant.

PEGylated conjugate of microcrystalline cellulose (MCC) was synthesized by reacting MCC with polyethylene glycol (PEG) 200 in the presence of catalyst at elevated temperature. Conjugation between MCC and PEG was confirmed by FT-IR and (1)H NMR studies. The conjugate showed 61% PEG content increase in molecular weight determined by mass spectroscopy. PEGylation did not improve solubility of cellulose significantly. The physico-chemical properties of conjugate were compared against MCC. This conjugate was evaluated for water vapor uptake isotherms, maximum water saturation, water penetration rate, disintegration time, superdisintegration power, and dissolution study. After comparing its results with that of commercial superdisintegrants, it can be concluded that MCC-PEG conjugate can prove to be a good superdisintegrant.

Formulation design and optimization of novel taste masked mouth-dissolving tablets of tramadol having adequate mechanical strength.

The purpose of this work was to develop novel taste masked mouth-dissolving tablets of tramadol that overcomes principle drawback of such formulation which is inadequate mechanical strength. Tramadol is an opioid analgesic used for the treatment of moderate to severe pain. Mouth-dissolving tablets offer substantial advantages like rapid onset of action, beneficial for patients having difficulties in swallowing and in conditions where access to water is difficult. The crucial aspect in the formulation of mouth-dissolving tablets is to mask the bitter taste and to minimize the disintegration time while maintaining a good mechanical strength of the tablet. Mouth-dissolving tablets of tramadol are not yet reported in the literature because of its extreme bitter taste. In this work, the bitter taste of Tramadol HCl was masked by forming a complex with an ion exchange resin Tulsion335. The novel combination of a superdisintegrant and a binder that melts near the body temperature was used to formulate mechanically strong tablets that showed fast disintegration. A 3(2) full factorial design and statistical models were applied to optimize the effect of two factors, i.e., superdisintegrant (crospovidone) and a mouth-melting binder (Gelucire 39/01). It was observed that the responses, i.e., disintegration time and percent friability were affected by both the factors. The statistical models were validated and can be successfully used to prepare optimized taste masked mouth-dissolving tablets of Tramadol HCl with adequate mechanical strength and rapid disintegration.

Preparation and evaluation of miconazole nitrate-loaded solid lipid nanoparticles for topical delivery.

The purpose of this study was to prepare miconazole nitrate (MN) loaded solid lipid nanoparticles (MN-SLN) effective for topical delivery of miconazole nitrate. Compritol 888 ATO as lipid, propylene glycol (PG) to increase drug solubility in lipid, tween 80, and glyceryl monostearate were used as the surfactants to stabilize SLN dispersion in the SLN preparation using hot homogenization method. SLN dispersions exhibited average size between 244 and 766 nm. All the dispersions had high entrapment efficiency ranging from 80% to 100%. The MN-SLN dispersion which showed good stability for a period of 1 month was selected. This MN-SLN was characterized for particle size, entrapment efficiency, and X-ray diffraction. The penetration of miconazole nitrate from the gel formulated using selected MN-SLN dispersion as into cadaver skins was evaluated ex-vivo using franz diffusion cell. The results of differential scanning calorimetry (DSC) showed that MN was dispersed in SLN in an amorphous state. The MN-SLN formulations could significantly increase the accumulative uptake of MN in skin over the marketed gel and showed a significantly enhanced skin targeting effect. These results indicate that the studied MN-SLN formulation with skin targeting may be a promising carrier for topical delivery of miconazole nitrate.