Formulation development and evaluation of nifedipine as pylorospasm inhibitor.

INTRODUCTION: In this study, different nifedipine-loaded formulations were prepared to treat pylorospasm, a sphincter muscle disorder characterized by delayed gastric emptying process. The efficacy of formulation was evaluated in patients by subjective assessment, gamma scintigraphic approaches, and confocal microscopy. METHODS: Nifedipine-loaded different formulations such as sucrose bead, pellets, and microparticles (slugging method, ionotropic gelation, and chemical denaturation) were designed. The studies were performed on 50 subjects, of which 30 subjects were treated with optimized nifedipine loaded microcapsules while 20 subjects were given capsule becosule-Z as a control. The efficacy of formulation was assessed by comparing symptoms like dyspepsia, abdominal pain, abdominal fullness, poor appetite, nausea, vomiting, and irregular motion. The effectiveness of formulation was also assessed by gamma scintigraphic studies by determining the rate of emptying of a radioactivity labeled standard meal from patients' stomach into the duodenum. Confocal microscopy was used to assess targeting potential of developed formulation. RESULTS: Drug-loaded alginate-chitosan microcapsules were found to be satisfactory, in terms of controlled drug release, surface morphology, and bioadhesive properties and thus selected for in vivo studies. Clinical studies revealed the efficacy of formulation in abolishing various GI symptoms at high altitude. Associated symptoms such as dyspepsia, abdominal pain, poor appetite, nausea, vomiting, and irregular motion were recovered by 75, 62, 76.5, 86.7, 85.7, and 37.5%, respectively in nifedipine-treated patients. In comparison, 73.7, 40, 33.3, 40, 20, and 0% recoveries were observed in patients given control treatment only. Gamma Scintigraphic studies in lab also revealed 2.425 ± 0.245 (p < .05) times improvement in gastric emptying rate in patients with diabetic gastroparesis. Confocal analysis showed better targeting and penetration in pyloric region when formulation was administered in form of high-density microcapsules. CONCLUSIONS: Results strongly suggest that nifedipine loaded mucoadhesive formulation has a targeting potential which accelerates gastric emptying process in gastroparesis patients, and thus the formulation might prove useful as a potent prokinetic agent.

Therapeutic efficacy of poly (lactic-co-glycolic acid) nanoparticles encapsulated ivermectin (nano-ivermectin) against brugian filariasis in experimental rodent model.

The present study reports on the antifilarial activity of poly (lactic-co-glycolic acid) nanoparticles encapsulated ivermectin (nano-IVM) against human lymphatic filariid Brugia malayi in rodent host Mastomys coucha. Nano-IVM was prepared and optimized by nanoprecipitation method. The selected nano-IVM (F5) showed a uniform spherical shape with 96 nm diameter and 74.12 % entrapment efficiency, and when used at a suboptimal dose of 100 µg/kg body weight, completely eliminated filarial parasites from systemic circulation on 60 days post-infection in animals inflicted with B. malayi. In contrast, the coadministration of nano-IVM (F5) along with standard filaricide diethylcarbamazine (DEC) was found to be competent enough to suppress microfilarial stage of parasites and successfully eliminated microfilaria at 45 days posttreatment. However, the free form of both the drugs alone or in combination was unable to impart such suppression and followed by recurrence of the infection. Interestingly, nano-IVM (F5) was also found to be effective against adult stage parasites causing 36.67 % worm mortality and 75.89 % in combination with DEC; however, female sterilization remain almost similar. Thus, the combination of entrapped IVM with DEC exhibited enhanced microfilaricidal and marginally better macrofilaricidal efficacy than any of the single formulation or drugs combination.

Solid lipid nanoparticles of anticancer drug andrographolide: formulation, in vitro and in vivo studies.

Diterpenoidal anti-cancer drug andrographolide (AD) was encapsulated into solid lipid nanoparticle (SLN) because of poor aqueous solubility and high lipophilicity. AD-SLNs were prepared by solvent injection method and characterized for droplet size, surface morphology, zeta potential, etc. In vitro drug release was carried out by dialysis-membrane method. A pharmacokinetic study was performed by UPLC/Q-TOF-MS method to determine the maximum plasma concentration (Cmax), area under the curve (AUC), etc. There was an improvement in Cmax and AUC of AD-SLNs when compared with AD, thereby enhancing the bioavailability of AD. The tmax was increased than that of AD suspension, indicating the sustained release pattern of AD-SLNs. The antitumor activity was carried out on Balb/c mice showing better results with AD-SLNs as compared to AD. Thus, the AD-loaded SLNs would be useful for delivering poorly water-soluble AD with enhanced bioavailability and improved antitumor activity.

An approach for lacidipine loaded gastroretentive formulation prepared by different methods for gastroparesis in diabetic patients.

The present work deals with various attempts to prepare a gastroretentive formulation of lacidipine for treating gastroparesis. High density sucrose beads were modified by coating with certain polymers, but unfortunately sustained release could not be achieved. Granules were prepared by wet granulation technology using different combinations of polymers and a release of the drug was observed. The method failed to release the drug as per desired specifications. Polymeric coating followed by wet granulation was thought to be a better process to sustain the dissolution rate. The release rate can be modified by the incorporation of different polymeric coatings, but the mucoadhesive potential of granules was only 4.23% which might be due to its large size and the presence of other ingredients. Further, the lacidipine loaded microparticles were prepared by different methods such as compression, ionic gelation with TPP, ionic gelation with TPP and glutaraldehyde, spray drying and coacervation techniques. The formulations were evaluated for average particle size, surface morphology, entrapment efficiency, % yield and mucoadhesive potential. The microparticles prepared by compression method using HPMC K4M and SCMC as mucoadhesive polymers and BaSO4 as high density diluent showed poor bioadhesion (8.3%) and poor release characteristics (100% in 120 min). Ionic gelation with tripolyphosphate yielded microspheres with poor mechanical strength. In order to improve its mechanical strength, TPP ionic gelation was combined with step-wise cross-linking with glutaraldehyde. The additional solidification step to improve mechanical strength left this procedure tedious, time consuming and cytotoxic. Spray drying method gave a very low yield with 46.67% bioadhesion. The method using CaCl2 for ionotropic gelation showed the best results with regard to physical characteristics (well formed discrete, spherical surface microcapsule), particle size (88.57 ± 0.51), in vitro bioadhesion (67.33%), yield (>85%) and loading (>70%).

Validated HPLC method for the simultaneous determination of taxol and ellagic acid in a Punica granatum fruit extract containing combination formulation.

A simple, rapid, precise and accurate isocratic reversed-phase high performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of paclitaxel and ellagic acid in a combination nanoformulation. Separation was achieved using a 25 x 4.6 mm column, particle size 5 microm C18 reverse phase column (Luna), with a mobile phase consisting of methanol and 0.05% H3PO4, in gradient elution mode with a mobile phase flow rate of 1 mL/min, using UV visible detection at 230 nm. Sharp and well defined peaks were obtained at retention times of 13.75 min. and 11.6 min. for paclitaxel and ellagic acid, respectively. Regression analysis showed a good linear relationship (r2 = 0.996 +/- 0.0011) and (r2 = 0.993 +/- 0.0011) over wide ranges of 5-500 microg/ml and 1-500 microg/ml for paclitaxel and ellagic acid, respectively. LOD and LOQ of paclitaxel were 30 ng/ml and 100 ng/ml, respectively, while for ellagic acid LOD and LOQ were 300 ng/ml and 1 microg/ml, respectively. The accuracy of the method was determined by recovery studies using the standard addition method and was found to be in the range of 99.61-101.21% and 98.70-102.22% for paclitaxel and ellagic acid, respectively. The relative standard deviation (% RSD) for precision, repeatability and robustness was less than 2%. The ellagic acid content in fruits of Punica granatum and combination formulation with paclitaxel was analyzed and found to be 0.04% w/w and 0.0012%w/w, respectively. The proposed, developed and validated HPLC method for the simultaneous quantification of ellagic acid and paclitaxel can be used for the quality control and standardization of several crude drugs and different combination formulations, in which ellagic acid is present.

Motor proteins regulate force interactions between microtubules and microfilaments in the axon.

It has long been known that microtubule depletion causes axons to retract in a microfilament-dependent manner, although it was not known whether these effects are the result of motor-generated forces on these cytoskeletal elements. Here we show that inhibition of the motor activity of cytoplasmic dynein causes the axon to retract in the presence of microtubules. This response is obliterated if microfilaments are depleted or if myosin motors are inhibited. We conclude that axonal retraction results from myosin-mediated forces on the microfilament array, and that these forces are counterbalanced or attenuated by dynein-mediated forces between the microfilament and microtubule arrays.

Formulation of PEG-ylated L-asparaginase loaded poly (lactide-co-glycolide) nanoparticles: influence of Pegylation on enzyme loading, activity and in vitro release.

The present paper describes the advantage of PEG-ylation of L-asparaginase before encapsulation over its incorporation in the native form. During encapsulation a considerable amount of native protein undergoes denaturation and forms insoluble aggregates. In an effort to overcome this problem, L-asparaginase was PEG-ylated before subjecting it to the harsh conditions as encountered during double emulsion solvent evaporation technique. L-asparaginase was conjugated with succinimidyl succinate derivative of polyethylene glycol (SS-PEG, MW 5000) followed by characterization of the formed conjugate using size exclusion-HPLC and SDS PAGE. The PEG-ylated L-asparaginase consisted of different isomers from mono to multi PEG-ylated depending upon the number of Lysine residues (14 in case of L-asparaginase) with about 5% as native protein. The specific activity as retained after PEG-ylation was 62.84 +/- 8.2% and further about 82.7% of activity was recovered from the particles. Imitated studies with the native protein confirmed the enhanced stability of the conjugated protein when exposed to the organic solvent and sonication and showed comparatively less encapsulation efficiency due to increased hydrophilicity. Release profiles for native as well as conjugated proteins consisted of sustained release of about 66.66% and 44.45% in 28 days, respectively. The decrease in the release can be attributed to the increase in the molecular weight of the conjugated protein. The study finally proved that PEG-ylation protected the enzyme and prevented it from denaturation during encapsulation.

Force generation by cytoskeletal motor proteins as a regulator of axonal elongation and retraction.

Axons elongate and retract in response to environmental signals during the development of the nervous system. There is broad agreement that these signals must affect the cytoskeleton to elicit bouts of elongation or retraction. Most contemporary studies have speculated that bouts of elongation involve polymerization of the cytoskeleton whereas bouts of retraction involve depolymerization of the cytoskeleton. Here we present an alternative view, namely that molecular motor proteins generate forces on the cytoskeletal polymers that can affect their distribution and configuration. In this view, bouts of axonal elongation involve net forward movement of cytoskeletal elements whereas bouts of retraction involve net backward movements. We propose that environmental cues elicit bouts of elongation or retraction via biochemical pathways that modulate the activities of relevant motors.

The transport properties of axonal microtubules establish their polarity orientation.

It is well established that axonal microtubules (MTs) are uniformly oriented with their plus ends distal to the neuronal cell body (Heidemann, S. R., J. M. Landers, and M. A. Hamborg. 1981. J. Cell Biol. 91:661-665). However, the mechanisms by which these MTs achieve their uniform polarity orientation are unknown. Current models for axon growth differ with regard to the contributions of MT assembly and transport to the organization and elaboration of the axonal MT array. Do the transport properties or assembly properties of axonal MTs determine their polarity orientation? To distinguish between these possibilities, we wished to study the initiation and outgrowth of axons under conditions that would arrest MT assembly while maintaining substantial levels of preexisting polymer in the cell body that could still be transported into the axon. We found that we could accomplish this by culturing rat sympathetic neurons in the presence of nanomolar levels of vinblastine. In concentrations of the drug up to and including 100 nM, the neurons actively extend axons. The vinblastine-axons are shorter than control axons, but clearly contain MTs. To quantify the effects of the drug on MT mass, we compared the levels of polymer throughout the cell bodies and axons of neurons cultured overnight in the presence of 0, 16, and 50 nM vinblastine with the levels of MT polymer in freshly plated neurons before axon outgrowth. Without drug, the total levels of polymer increase by roughly twofold. At 16 nM vinblastine, the levels of polymer are roughly equal to the levels in freshly plated neurons, while at 50 nM, the levels of polymer are reduced by about half this amount. Thus, 16 nM vinblastine acts as a "kinetic stabilizer" of MTs, while 50 nM results in some net MT disassembly. At both drug concentrations, there is a progressive increase in the levels of MT polymer in the axons as they grow, and a corresponding depletion of polymer from the cell body. These results indicate that highly efficient mechanisms exist in the neuron to transport preassembled MTs from the cell body into the axon. These mechanisms are active even at the expense of the cell body, and even under conditions that promote some MT disassembly in the neuron. MT polarity analyses indicate that the MTs within the vinblastine-axons, like those in control axons, are uniformly plus-end-distal.(ABSTRACT TRUNCATED AT 400 WORDS)

The plus ends of stable microtubules are the exclusive nucleating structures for microtubules in the axon.

Microtubules (MTs) in the axon have a uniform polarity orientation that is recapitulated during recovery from episodes of MT depolymerization (Heidemann, S. R., M. A. Hamborg, S. J. Thomas, B. Song, S. Lindley, and D. Chu. 1984. J. Cell Biol. 99:1289-1295). This tight regulation of their organization indicates that axonal MTs are spatially regulated by discrete nucleating structures comparable in function to the centrosome. Several authors have proposed that an especially stable class of MTs in the axon may serve as these nucleating structures. In a previous report (Baas, P. W., and M. M. Black. 1990. J. Cell Biol. 111:495-509), we determined that the axons of cultured sympathetic neurons contain two classes of MT polymer, stable and labile, that differ in their sensitivity to nocodazole by roughly 35-fold. The stable and labile polymer represent long-lived and recently assembled polymer, respectively. We also determined that these two classes of polymer can be visually distinguished at the immunoelectron microscopic level based on their content of tyrosinated alpha-tubulin: the labile polymer stains densely, while the stable polymer does not stain. In the present study, we have taken advantage of these observations to directly identify MT nucleating structures in the axon. Neuron cultures were treated with nocodazole for 6 h to completely depolymerize the labile polymer in the axon, and substantially shorten the stable polymer. The cultures were then rinsed free of the drug, permitted to reassemble polymer for various periods of time, and prepared for immunoelectron microscopic localization of tyrosinated alpha-tubulin. Serial reconstruction of consecutive thin sections was undertaken to determine the spatial relationship between the stable MTs and the newly assembled polymer. All of the new polymer assembled in direct continuity with the plus ends of stable MTs, indicating that these ends are assembly competent, and hence capable of acting as nucleating structures. Our results further indicate that no self-assembly of MTs occurs in the axon, nor do any MT nucleating structures exist in the axon other than the plus ends of stable MTs. Thus the plus ends of stable MTs are the exclusive nucleating structures for MTs in the axon.

Microtubule nucleation and release from the neuronal centrosome.

We have proposed that microtubules (MTs) destined for axons and dendrites are nucleated at the centrosome within the cell body of the neuron, and are then released for translocation into these neurites (Baas, P. W., and H. C. Joshi. 1992. J. Cell Biol. 119:171-178). In the present study, we have tested the capacity of the neuronal centrosome to act as a generator of MTs for relocation into other regions of the neuron. In cultured sympathetic neurons undergoing active axonal outgrowth, MTs are present throughout the cell body including the region around the centrosome, but very few (< 10) are directly attached to the centrosome. These results indicate either that the neuronal centrosome is relatively inactive with regard to MT nucleation, or that most of the MTs nucleated at the centrosome are rapidly released. Treatment for 6 h with 10 micrograms/ml nocodazole results in the depolymerization of greater than 97% of the MT polymer in the cell body. Within 5 min after removal of the drug, hundreds of MTs have assembled in the region of the centrosome, and most of these MTs are clearly attached to the centrosome. A portion of the MTs are not attached to the centrosome, but are aligned side-by-side with the attached MTs, suggesting that the unattached MTs were released from the centrosome after nucleation. In addition, unattached MTs are present in the cell body at decreasing levels with increasing distance from the centrosome. By 30 min, the MT array of the cell body is indistinguishable from that of controls. The number of MTs attached to the centrosome is once again diminished to fewer than 10, suggesting that the hundreds of MTs nucleated from the centrosome after 5 min were subsequently released and translocated away from the centrosome. These results indicate that the neuronal centrosome is a highly potent MT-nucleating structure, and provide strong indirect evidence that MTs nucleated from the centrosome are released for translocation into other regions of the neuron.

An essential role for katanin in severing microtubules in the neuron.

Several lines of evidence suggest that microtubules are nucleated at the neuronal centrosome, and then released for transport into axons and dendrites. Here we sought to determine whether the microtubule-severing protein known as katanin mediates microtubule release from the neuronal centrosome. Immunomicroscopic analyses on cultured sympathetic neurons show that katanin is present at the centrosome, but is also widely distributed throughout the neuron. Microinjection of an antibody that inactivates katanin results in a dramatic accumulation of microtubules at the centrosome, indicating that katanin is indeed required for microtubule release from the centrosome. However, the antibody also causes an inhibition of axon outgrowth that is more immediate than expected on this basis alone. It may be that katanin severs microtubules throughout the cell body to keep them sufficiently short to be efficiently transported into developing processes. Consistent with this idea, there were significantly fewer free ends of microtubules in the cell bodies of neurons that had been injected with the katanin antibody compared with controls. These results indicate that microtubule-severing by katanin is essential for releasing microtubules from the neuronal centrosome, and also for regulating the length of the microtubules after their release.

Cytoplasmic dynein and dynactin are required for the transport of microtubules into the axon.

Previous work from our laboratory suggested that microtubules are released from the neuronal centrosome and then transported into the axon (Ahmad, F.J., and P.W. Baas. 1995. J. Cell Sci. 108: 2761-2769). In these studies, cultured sympathetic neurons were treated with nocodazole to depolymerize most of their microtubule polymer, rinsed free of the drug for a few minutes to permit a burst of microtubule assembly from the centrosome, and then exposed to nanomolar levels of vinblastine to suppress further microtubule assembly from occurring. Over time, the microtubules appeared first near the centrosome, then dispersed throughout the cytoplasm, and finally concentrated beneath the periphery of the cell body and within developing axons. In the present study, we microinjected fluorescent tubulin into the neurons at the time of the vinblastine treatment. Fluorescent tubulin was not detected in the microtubules over the time frame of the experiment, confirming that the redistribution of microtubules observed with the experimental regime reflects microtubule transport rather than microtubule assembly. To determine whether cytoplasmic dynein is the motor protein that drives this transport, we experimentally increased the levels of the dynamitin subunit of dynactin within the neurons. Dynactin, a complex of proteins that mediates the interaction of cytoplasmic dynein and its cargo, dissociates under these conditions, resulting in a cessation of all functions of the motor tested to date (Echeverri, C.J., B.M. Paschal, K.T. Vaughan, and R.B. Vallee. 1996. J. Cell Biol. 132: 617-633). In the presence of excess dynamitin, the microtubules did not show the outward progression but instead remained near the centrosome or dispersed throughout the cytoplasm. On the basis of these results, we conclude that cytoplasmic dynein and dynactin are essential for the transport of microtubules from the centrosome into the axon.

Techniques to develop and characterize nanosized formulation for salbutamol sulfate.

The present study relates to enhancing the dosing efficiency of pharmaceutical dry powder formulations administered by pulmonary inhalation. In particular, the study relates to the provision of dry powder inhalers (DPI) by forming nanosized particles of salbutamol sulfate (SBM) in order to augment the drug penetrability and deposition in the lungs. SBM, an antiasthmatic was selected to be developed into a nanosized formulation by different techniques like solvation, high-pressure homogenization, and spray drying, which were then compared on the basis of particle shape, particle size, and particle size distribution. In case of solvation method the nanosuspension was prepared by dispersing SBM into a nonsolvent and adding Tween-80 as a surfactant to prevent the agglomeration, the particles obtained therein were in the range of 2-10 mu. The second attempt was made by passing the suspension of SBM through high-pressure homogenizer at 10,000-15,000 psi. A treatment of six cycles of homogenization in presence of a Tween-80 as surfactant was found to give a nanosuspension within a size range 50-100 nm. The only drawback seemed with this technique was the low-product yield and high-processing time (3-4 h). In order to overcome this drawback spray-drying technique was further explored; the solution of SBM containing Tween-80 was stirred on magnetic stirrer at 1,200 rpm and finally dried by using spray dryer at an inlet and outlet temperature of 75 degrees C and 56 degrees C, respectively. The feed rate for spray dryer was kept to be 91 ml/h. The sample was collected and analyzed for particle size distribution which was found to be in the range of 50-100 nm. Keeping in view the positive outcomes in terms of higher yield and lower processing time, the spray-drying technique was taken to give the optimized formulation. Nanosized particles, thus obtained were evaluated for particle size, surface topology and particles size distribution, by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), and Quasi-elastic light scattering (QELS) technique, respectively. The nanosized particles were subjected to investigate changes on the physical stability of the powder, for this different analytical method was used as: Fourier transform infrared spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC) and X-ray diffraction (XRD) analysis and thus the result indicates that there was no physical disparity when compared with the commercial SBM sample.

Lacidipine encapsulated gastroretentive microspheres prepared by chemical denaturation for pylorospasm.

The purpose of this research work was to formulate and systematically evaluate in vitro performance of mucoadhesive microspheres of lacidipine for treatment of pylorospasm. Lacidipine microspheres containing chitosan were prepared by chemical denaturation using glutaraldehyde as a cross-linking agent. The microspheres were evaluated for physical characteristics such as particle size, particle shape and surface morphology by scanning electron microscopy, drug entrapment efficiency and in vitro mucoadhesion. Results of preliminary trials indicated that the polymer concentration, cross-linking agent and stirring speed had a noticeable effect on size and surface morphology. A central composite design was employed to study the effect of independent variables, polymer concentration (X(1)), volume of glutaraldehyde (X(2)), stirring speed (X(3)) and cross-linking time (X(4)) on dependent variables, drug entrapment efficiency and percentage mucoadhesion. The entrapment efficiency varied from 14-40.82% depending upon the polymer concentration, volume of cross-linker and stirring speed. All batches of microspheres exhibited good mucoadhesive property (73-83%) in the in vitro wash-off test. It was observed that polymer concentration and glutaraldehyde volume had a more significant effect on the dependent variables. Maximum entrapment (36.53%) and mucoadhesion (81.33%) was predicted at 3.5% chitosan, 3 ml glutaraldehyde, 3000 rpm stirring speed and 75 min cross-linking time under optimized process condition. The selected formulation showed controlled release for more than 6 h. The release followed Higuchi kinetics via a Fickian diffusion.

Exploration of skin permeation mechanism of frusemide with proniosomes.

The present study explored the transdermal permeation enhancing mechanism of non-ionic surfactant vesicles (proniosomes) of frusemide across rat skin. Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC), activation energy and histological examination were carried out to study the mode of action of the optimized proniosome formulations PGS [Span 40:soyalecithin:cholesterol (4.5:4.5:1)] and PGD [Span 40:dicetylphosphate:cholesterol (4.5:4.5:1)]. The IR spectra showed a prominent decrease in peak areas and heights of CH2 stretchings but did not show shift of these peaks and shift in amide bands. DSC studies also confirmed the IR findings. It was concluded that the proniosomes disrupted the lipid bilayer by extracting the lipids thereby creating pathways for drug penetration. The significant decrease in activation energy for frusemide permeation across rat skin indicated the SC lipid bilayers were significantly disrupted (p<0.05). Histological investigations were carried out. Disruption and extraction of lipid bilayers as distinct voids and empty spaces were visible in the epidermal region. Overall, our findings suggested that proniosomal formulations offer a promising means for non-invasive delivery of frusemide, especially due to their ability to modulate drug transfer and serve as non-toxic permeation enhancers.

Optimization of chitosan succinate and chitosan phthalate microspheres for oral delivery of insulin using response surface methodology.

In the present study, a Box-Behnken experimental design was employed to statistically optimize the formulation parameters of chitosan phthalate and chitosan succinate microspheres preparation. These microspheres can be useful for oral insulin delivery system. The effects of three parameters namely polymer concentration, stirring speed and cross linking agent were studied. The fitted mathematical model allowed us to plot response surfaces curves and to determine optimal preparation conditions. Results clearly indicated that the crosslinking agent was the main factor influencing the insulin loading and releasing. The in vitro results indicated that chitosan succinate microspheres need high amount of crosslinking agent to control initial burst release compared to chitosan phthalate microspheres. The reason may be attributed that chitosan succinate is more hydrophilic than chitosan phthalate. The relative pharmacological efficacy for chitosan phthalate and chitosan succinate microspheres (18.66 +/- 3.84%, 16.24 +/- 4%) was almost three-fold higher than the efficacy of the oral insulin administration (4.68 +/- 1.52%). These findings suggest that these microspheres are promising carrier for oral insulin delivery system.

Inhibition of microtubule nucleation at the neuronal centrosome compromises axon growth.

We tested the dependence of axon growth on microtubule (MT) nucleation from the neuronal centrosome. Nocodazole diminished MTs in freshly plated neurons by > 99%. Within 5 min of drug removal, MTs reassembled at the centrosome. This response was inhibited in cells microinjected with gamma-tubulin antibody. Within 2 hr of drug removal, uninjected neurons grew > 500 microns of axon. In roughly half of the antibody-injected cells, axon growth was abolished and MT levels were reduced by approximately 87% compared with uninjected cells. In the other antibody-injected cells, axon growth was compromised but not abolished, and MT levels were reduced by approximately 38%. Thus inhibition of MT nucleation at the centrosome hindered MT reassembly, and depending on the severity of this response, axon growth was either compromised or abolished.

Transdermal therapeutic system of enalapril maleate using piperidine as penetration enhancer.

The aim of this work was to formulate transdermal therapeutic system (TTS) of an antihypertensive drug, enalapril maleate (EM) using a new penetration enhancer, piperidine hydrochloride (PH), belonging to the class of Dihydropyridines. The TTS of EM was prepared by solvent evaporation technique using polymers Eudragit E100 and polyvinyl pyrrolidone K-30 in varying ratios, 5% w/w dibutylphthalate as plasticizer and 10% w/w PH as penetration enhancer. The TTS was evaluated for in-vitro drug release using paddle over disc method and ex-vivo skin permeation using modified Keshary and Chein diffusion cell. The interaction studies were carried out by comparing the results of assay, UV and TLC analysis for pure drug and medicated and TTS formulation. Skin irritation potential of TTS was assessed by visual examination of treated rat skin. Stability studies were conducted according to ICH guidelines at a temperature of 40+/-0.5 degrees C and 75+/-5% RH. The optimized formulation was evaluated for preclinical bioavailability and antihypertensive efficacy using albino rat model. The optimized formulation provided 87.3% drug release in-vitro and a flux of 380 microg/cm(2)/hr over a period of 48 hours. No chemical interaction was found between the drug and excipients and there were no signs of skin irritation on application of patch. The optimized formulation was stable with a tentative shelf life of two years. Significant fall in BP (p<0.001) was observed in experimental hypertensive rats which was maintained for 2 days. There was 3 fold improvement in bioavailability with TTS vis-à-vis marketed tablet (AUC(0 to t) : 1253.9 ng.h/ml vs. 422.88 ng.h/ml). These preclinicial studies indicate the feasibility of matrix-type TTS of EM for 2 day management of hypertension. Further studies on human beings are warranted to establish clinical utility of the above TTS.

Alpha ketoglutarate nanoparticles: A potentially effective treatment for cyanide poisoning.

The purpose of this research work was to prepare nanosized formulation of alpha ketoglutarate as dry powder inhaler for cyanide poisoning. Nanosizing can be approached by solid phase and liquid phase method. The different conditions encountered in both these approaches can greatly affect the particle characteristics. In this study milling and precipitation technique were compared to study their effect on α-KG particles characteristics. Differences in choice of stabilizers were observed between the two processing techniques. Sonication processes followed by HPH produced small sized particles in which Pluronic F68 was employed as stabilizing agent. Precipitation approach produced ultrafine drug particles by utilizing combination of stabilizers (PVA+PEG 400). Amongst the two sonication processes, probe sonication process produced well stabilized small sized particles. The designed particles showed 43.13±2.36% lung deposition when compared with ultrasonication and precipitation technique that showed 31.69% and 21.67% respirable fraction. The MMAD of the designed particles was found suitable for deep alveolar deposition. Clinical studies (Phase-I trial) showed whole lung deposition of 52.51% for DPI. The P/C ratio was found to be 1.02 suggesting uniform distribution of particles in different lung compartments.