Bhavin A. Vyas

In vitro and in vivo evaluation of novel implantation technology in hydrogel contact lenses for controlled drug delivery

Glaucoma is commonly treated using eye drops, which is highly inefficient due to rapid clearance (low residence time) from ocular surface. Contact lenses are ideally suited for controlled drug delivery to cornea, but incorporation of any drug loaded particulate system (formulation) affect the optical and physical property of contact lenses. The objective of the present work was to implant timolol maleate (TM) loaded ethyl cellulose nanoparticle-laden ring in hydrogel contact lenses that could provide controlled drug delivery at therapeutic rates without compromising critical lens properties. TM-implant lenses were developed, by dispersing TM encapsulated ethyl cellulose nanoparticles in acrylate hydrogel (fabricated as ring implant) and implanted the same in hydrogel contact lenses (sandwich system). The TM-ethyl cellulose nanoparticles were prepared by double emulsion method at different ratios of TM to ethyl cellulose. The X-ray diffraction studies revealed the transformation of TM to amorphous state. In vitro release kinetic data showed sustained drug release within the therapeutic window for 168h (NP 1:3 batch) with 150μg loading. Cytotoxicity and ocular irritation study demonstrated the safety of TM-implant contact lenses. In vivo pharmacokinetic studies in rabbit tear fluid showed significant increase in mean residence time (MRT) and area under curve (AUC), with TM-implant contact lenses in comparison to eye drop therapy. In vivo pharmacodynamic data in rabbit model showed sustained reduction in intra ocular pressure for 192h. The study demonstrated the promising potential of implantation technology to treat glaucoma using contact lenses, and could serve as a platform for other ocular diseases.

Antiurolithiatic activity of saponin rich fraction from the fruits of Solanum xanthocarpum Schrad. & Wendl. (Solanaceae) against ethylene glycol induced urolithiasis in rats

ETHNOPHARMACOLOGICAL RELEVANCE A well-known traditional herb Solanum xanthocarpum is widely used in India for the management of different ailments including urolithiasis. This study was designed to rationalize the use of Solanum xanthocarpum in kidney stone and to investigate its mechanism of action. MATERIALS AND METHODS The saponin rich fraction prepared from fruits of Solanum xanthocarpum (SXS) was evaluated for antiurolithiatic activity by in vitro and in vivo studies. In ethylene glycol (EG, 0.75% in drinking water for 28 days) induced urolithiasis model, two different experimental doses (20 mg/kg and 40 mg/kg, p.o., for 28 days) of saponin rich fraction were selected by dose fixation study. After 28 days, various biochemical parameters were measured in urine, serum and kidney homogenate. Kidneys were also subjected to histopathological analysis. RESULTS In vitro calcium oxalate crystal (CaOx) nucleation as well as aggregation was inhibited in artificial urine solution by SXS. The lithogenic treatment caused polyuria, damage renal function and oxidative stress, manifested as increased malondialdehyde, depleted reduced glutathione and decreased antioxidant enzyme catalase activities of the kidneys, which were prevented by simultaneous administration with SXS. Lithogenic treatment also caused crystalluria, hyperoxaluria, hypercalciuria, hypocitrauria, and hypomagnesaemia. Deposition of CaOx in renal tissue and cellular injury were seen in histopathology. Co-administration of SXS had potential to prevent these pathological changes due to lithogenic treatment. Moreover, SXS raised level of glycosaminoglycan, a stone inhibitor macromolecule found in urine which decreased. CONCLUSION The antiurolithiatic activity in Solanum xanthocarpum is mediated possibly through the inhibition of CaOx crystal formation and its effect on the urinary concentration of stone-forming constituents and nephrolithiasis inducing factors and this study rationalizes its medicinal use in urolithiasis.

Protective effect of aqueous extract of Oroxylum indicum Linn. (root bark) against DNBS-induced colitis in rats.

Objective: Aqueous root extract of Oroxylum indicum was evaluated in rats against dinitrobenzene sulfonic acid (DNBS) induced colitis. Materials and Methods: Rats were pre-treated orally for seven days and continued for four days after the induction of colitis with OIaq (100, 200, and 400 mg/kg) or vehicle. Colitis was induced by intracolonic instillation of 25 mg of DNBS per rat dissolved in 50% alcohol and 4 days later, the colonic mucosal damage was analyzed along with food intake, body weight, colon weight, spleen weight, histological damage, myeloperoxidase (MPO) activity, malondialdehyde (MDA) levels, reduced glutathione (GSH), and nitric oxide levels in colonic tissue homogenate. Results: Significant reduction in gross damage area, weight loss and increase in colonic and spleen weight were evident in test substance-pretreated animals’ dose dependently as compared to vehicle treated control. These effects were confirmed biochemically by a reduction in colonic myeloperoxidase activity, malondialdehyde levels, nitric oxide levels, and increase in reduced glutathione (GSH) levels. Furthermore, microscopic examination revealed diminution of inflammatory cell infiltration and submucosal edema in colon segments of rats treated with OIaq. Conclusion: The results demonstrate the protective effect of OIaq in the animal model of acute colitis possibly through an antioxidant, anti-lipoperoxidative or due to reduction in nitric oxide generation.

Design and optimization of a novel implantation technology in contact lenses for the treatment of dry eye syndrome: In vitro and in vivo evaluation

Contact lenses are widely used for ophthalmic drug delivery, but incorporation of drug or formulation in the contact lenses affects its optical and physical property. In the present study, we have designed a novel hyaluronic acid (HA)-laden ring implant contact lenses (modified cast moulding method), to circumvent the changes in critical lens property. The objective was to improve the ocular residence time of HA, by providing sustained ocular HA delivery through implant contact lenses for the treatment of dry eye syndrome. Optimization of HA-implant was carried out using 32 factorial design by tailoring the amount of cross linker and thickness of implant, to achieve sustained HA release with constraint on effective ion diffusivity. The in vivo pharmacokinetic study in rabbit tear fluid showed sustained HA release up to 15days, by fabricating implant (80μgHA loading) with 78.4μm thickness (total thickness of lens=100μm) using 0.925% of cross linker, with effective ion diffusivity>1.5×10-6mm2/min. In vivo efficacy study in benzalkonium chloride induced dry eye syndrome rabbits showed faster healing with implant contact lenses in comparison to positive control group. The study demonstrated the promising potential of implantation technology to deliver hyaluronic acid without compromising optical and physical properties of contact lens. STATEMENT OF SIGNIFICANCE The limitation of contact lenses to be used as therapeutic device for controlled drug delivery is focused in this study. Incorporation of drug or formulation in the biomaterial affects the optical and physical property of contact lenses. The significance of project was to design a novel hyaluronic acid-laden ring implant contact lenses, to by-pass the changes in critical property of biomaterial.

Effect of Boerhaavia diffusa in experimental prostatic hyperplasia in rats

Objective: Present investigation was undertaken to study the effectiveness of hydroalcoholic extract of roots of Boerhaavia diffusa in experimental benign prostatic hyperplasia (BPH) in rats using various animal models. Materials and Methods: BPH in rats was induced by subcutaneous injection of testosterone (5 mg/kg) daily for 28 days. Rats were divided in to five groups (six rats each). A negative control group received arachis oil (1 ml/kg s.c.) and four groups were injected testosterone. These four groups were further divided into reference group (finasteride 1 mg/kg), model group (testosterone), study group A (B. diffusa 100 mg/kg), and study group B (B. diffusa 250 mg/kg). On the 29th day, rats were sacrificed and body weight, prostate weight, bladder weight, and serum testosterone level were measured and histological studies were carried out. Further in vitro analysis of B. diffusa extract on contractility of isolated rat vas deferens and prostate gland, produced by exogenously administered agonists were carried out. All results were expressed as mean ± SEM. 0 Data were analyzed by one-way analysis of variance followed by Tukeys test. Results: B. diffusa (100 mg/kg) treatment for 28 days resulted in significant inhibition of prostate growth (P < 0.05). Drug extract did not have significant change on serum testosterone level. Histopathological analysis of prostate gland supported above results. Results of in vitro experiment suggest that extracts had attenuated the contractile responses of isolated vas deferens and prostate gland to exogenously applied agonists. Conclusion: The results suggested that treatment with B. diffusa may improve symptoms of disease and inhibit the increased prostate size. In vitro study implies that herbal extracts has the machinery to produce beneficial effect on prostatic smooth muscle, which would relieve the urinary symptoms of disease. B. diffusa could be a potential source of new treatment of prostatic hyperplasia.

Effect of surfactant chain length on drug release kinetics from microemulsion-laden contact lenses

The effect of surfactant chain lengths [sodium caprylate (C8), Tween 20 (C12), Tween 80 (C18)] and the molecular weight of block copolymers [Pluronic F68 and Pluronic F 127] were studied to determine the stability of the microemulsion and its effect on release kinetics from cyclosporine-loaded microemulsion-laden hydrogel contact lenses in this work. Globule size and dilution tests (transmittance) suggested that the stability of the microemulsion increases with increase in the carbon chain lengths of surfactants and the molecular weight of pluronics. The optical transmittance of direct drug-laden contact lenses [DL-100] was low due to the precipitation of hydrophobic drugs in the lenses, while in microemulsion-laden lenses, the transmittance was improved when stability of the microemulsion was achieved. The results of in vitro release kinetics revealed that drug release was sustained to a greater extent as the stability of microemulsion was improved as well. This was evident in batch PF127-T80, which showed sustained release for 15days in comparison to batch DL-100, which showed release up to 7days. An in vivo drug release study in rabbit tear fluid showed significant increase in mean residence time (MRT) and area under curve (AUC) with PF-127-T80 lenses (stable microemulsion) in comparison to PF-68-SC lenses (unstable microemulsion) and DL-100 lenses. This study revealed the correlation between the stability of microemulsion and the release kinetics of drugs from contact lenses. Thus, it was inferred that the stable microemulsion batches sustained the release of hydrophobic drugs, such as cyclosporine from contact lenses for an extended period of time without altering critical lens properties.

pH triggered controlled drug delivery from contact lenses: Addressing the challenges of drug leaching during sterilization and storage

In the present work a novel cyclosporine-loaded Eudragit S100 (pH-sensitive) nanoparticles-laden contact lenses were designed to provide sustained release of cyclosporine at therapeutic rates, without leaching of drug during sterilization and storage period (shelf life). The nanoparticles were prepared by Quasi-emulsion solvent diffusion technique using different weight ratios of cyclosporine to Eudragit S100. The contact lenses with direct drug entrapment were also fabricated (DL-50) for comparison. The percentage swelling and optical transparency of nanoparticles-laden contact lenses were improved in comparison to DL-50 lenses. The nanoparticles-laden contact lenses showed sustained drug release profiles, with inverse relationship to the amount of nanoparticles loaded in the contact lenses. It was interesting to note that nanoparticles form nanochannels/cavities after dissolution of Eudragit S 100 in tear fluid pH=7.4 (in vitro release study). This followed the precipitation of drug in hydrogel matrix of contact lenses. As the amount of nanoparticles loading increased, more number of cavities were formed, which caused the formation of large cavities in contact lens matrix. This in turn precipitated the drug. The nanoparticles-laden contact lenses with 1:1 (drug: Eudragit) weight ratio showed the most promising results of sustaining the drug release up to 156h, without affecting optical and physical properties of contact lenses. Packaging study confirmed that the drug was not leached in packaging solution (buffer, pH=6.5) from nanoparticles-laden lenses during shelf life period. In-vivo study in rabbit tear fluid showed sustained release up to 14days. The study revealed the application of pH-sensitive nanoparticles-laden contact lenses for controlled release of cyclosporine without altering the optical and physical properties of lens material.

Effect of Oroxylum indicum on intestinal motility in rodents

Oroxylum indicum is traditional herbal medicine in India, China and Japan used for its anti-diarrhoeal/anti-dysenteric activity, also found to be active against experimentally induced (DNBS induced) inflammatory bowel disease in rats with potential reduction in diarrhoea. It promotes us to evaluate effects of Oroxylum indicum on intestinal motility, both in vitro and in vivo, in rodents. Flavonoids rich fraction of O. indicum was obtained and the effect of extract on contraction of acetylcholine, barium chloride and electrical field stimulation was studied on isolated rabbit ileum. Anti-diarrhoeal activities were investigated using castor oil and magnesium sulphate-induced diarrhoeal models in mice. Effect on intestinal motility was studied using gastrointestinal motility and antienteropooling assay methods. Antimicrobial activity of extract was evaluated using disc diffusion assay method. Extract inhibited the contractions induced by acetylcholine, barium chloride and electrical field stimulation. Verapamil potentiates inhibitory effect of extract. Extract showed significant and dose-dependent anti-diarrhoeal effect devoid of altering gastrointestinal motility in normal animals. It also inhibited the microbial growth in disc diffusion assay method. Extract normalized intestinal motility altered by inflammatory stimulus and possesses antidiarrhoeal activity. Alteration of intestinal motility may involve modification in L-type Ca2+ channels.

Multiple response optimisation of processing and formulation parameters of pH sensitive sustained release pellets of capecitabine for targeting colon

Abstract Purpose: To optimise the Eudragit/Surelease®-coated pH-sensitive pellets for controlled and target drug delivery to the colon tissue and to avoid frequent high dosing and associated side effects which restrict its use in the colorectal-cancer therapy. Methods: The pellets were prepared using extrusion-spheronisation technique. Box–Behnken and 32 full factorial designs were applied to optimise the process parameters [extruder sieve size, spheroniser-speed, and spheroniser-time] and the coating levels [%w/v of Eudragit S100/Eudragit-L100 and Surelease®], respectively, to achieve the smooth optimised size pellets with sustained drug delivery without prior drug release in upper gastrointestinal tract (GIT). Results: The design proposed the optimised batch by selecting independent variables at; extruder sieve size (X1 = 1 mm), spheroniser speed (X2 = 900 revolutions per minute, rpm), and spheroniser time (X3 = 15 min) to achieve pellet size of 0.96 mm, aspect ratio of 0.98, and roundness 97.42%. The 16%w/v coating strength of Surelease® and 13%w/v coating strength of Eudragit showed pH-dependent sustained release up to 22.35 h (t99%). The organ distribution study showed the absence of the drug in the upper part of GIT tissue and the presence of high level of capecitabine in the caecum and colon tissue. Thus, the presence of Eudragit coat prevent the release of drug in stomach and the inner Surelease® coat showed sustained drug release in the colon tissue. Conclusion: The study demonstrates the potential of optimised Eudragit/Surelease®-coated capecitabine-pellets for effective colon-targeted delivery system to avoid frequent high dosing and associated systemic side effects of drug.

Contact lenses with dual drug delivery for the treatment of bacterial conjunctivitis

ABSTRACT Currently, bacterial conjunctivitis is treated by frequent administration of antibiotic eye drop solutions, which is tedious and patient noncompliant. Contact lenses could be ideal medical devices to sustain the release of ophthalmic drugs, but the incorporation of the latter can alter the optical and physical properties of the lenses. In addition, many contact lens users have reported the pink eye syndrome, making them unsuitable as ocular medical devices. In the present study, we have designed a novel type of lenses containing semi‐circular rings loaded with moxifloxacin HCl (a broad spectrum antibiotic) and hyaluronic acid (a comfort agent), respectively, in order to treat bacterial conjunctivitis without altering the critical lens properties. The drug loaded rings were implanted separately within the periphery of the contact lenses using the modified cast moulding technology. The atomic force microscopy report showed an average roughness of 22.27nm for the implant lens, which was significantly lower in comparison to the marketed Freshlook® (116.27nm) contact lens. The major amount of moxifloxacin HCl was leached (68.16–74.55%) during the monomer extraction and wet sterilization (autoclave) steps; hence the lenses were terminally sterilized by radiation and packaged under dry condition (dehydrated). The in vitro release data showed release for moxifloxacin HCl and hyaluronic acid up to 96h. The in vivo drug release studies showed significant improvement [>MIC for Staphylococcus aureus] in the drug residence time in comparison to the eye drop therapy. The in vivo efficacy study in the staphylococcus aureus induced conjunctivitis showed equivalent healing effect with the single implant contact lens in comparison to the frequent high dose eye drop therapy. The study demonstrated the successful application of the implantation technology to co‐deliver moxifloxacin HCl and hyaluronic acid from the contact lenses for the extended period of time to treat conjunctivitis.