Ravi Sheshala

Recent advances in sample preparation techniques for effective bioanalytical methods

This paper reviews the recent developments in bioanalysis sample preparation techniques and gives an update on basic principles, theory, applications and possibilities for automation, and a comparative discussion on the advantages and limitation of each technique. Conventional liquid-liquid extraction (LLE), protein precipitation (PP) and solid-phase extraction (SPE) techniques are now been considered as methods of the past. The last decade has witnessed a rapid development of novel sample preparation techniques in bioanalysis. Developments in SPE techniques such as selective sorbents and in the overall approach to SPE, such as hybrid SPE and molecularly imprinted polymer SPE, have been addressed. Considerable literature has been published in the area of solid-phase micro-extraction and its different versions, e.g. stir bar sorptive extraction, and their application in the development of selective and sensitive bioanalytical methods. Techniques such as dispersive solid-phase extraction, disposable pipette extraction and micro-extraction by packed sorbent offer a variety of extraction phases and provide unique advantages to bioanalytical methods. On-line SPE utilizing column-switching techniques is rapidly gaining acceptance in bioanalytical applications. PP sample preparation techniques such as PP filter plates/tubes offer many advantages like removal of phospholipids and proteins in plasma/serum. Newer approaches to conventional LLE techniques (salting-out LLE) are also covered in this review article.

Punctal plug: a medical device to treat dry eye syndrome and for sustained drug delivery to the eye

Punctal plugs (PPs) are miniature medical implants that were initially developed for the treatment of dry eyes. Since their introduction in 1975, many PPs made from different materials and designs have been developed. PPs, albeit generally successful, suffer from drawbacks such as epiphora and suppurative canaliculitis. To overcome these issues intelligent designs of PPs were proposed (e.g. SmartPLUG™ and Form Fit™). PPs are also gaining interest among pharmaceutical scientists for sustaining drug delivery to the eye. This review aims to provide an overview of PPs for dry eye treatment and drug delivery to treat a range of ocular diseases. It also discusses current challenges in using PPs for ocular diseases.

Formulation and in vivo evaluation of ondansetron orally disintegrating tablets using different superdisintegrants

The aim of this study was to formulate cost effective taste-masked orally disintegrating tablets of ondansetron, a bitter drug using different superdisintegrants by a wet granulation technique. Microcrystalline cellulose (Avicel) as a diluent and disintegrant in addition to aspartame as a sweetener were used in all formulations. The prepared tablets were evaluated for weight variation, thickness, hardness, friability, drug content, water content, in vitro disintegration time and in vitro drug release. The tablets’ hardness was maintained in the range of 2–3 kg and friability was <1% for all batches. All tablet formulations disintegrated rapidly in vitro within 5.83 to 33.0 sec. The optimized formulation containing 15% Polyplasdone XL-10 released more than 90% of drug within 5 min and the release was comparable to that of a commercial product. In human volunteers, optimized formulation was found to have a pleasant taste and mouth feel and they disintegrated in the oral cavity within 12 sec. The stability results were also satisfactory. A pharmacokinetic study with the optimized formulation was performed in comparison with a reference (Zofer MD 8®) and they were found to be bioequivalent. In conclusion, a cost effective ondansetron orally disintegrating tablet was successfully prepared with acceptable hardness, desirable taste and rapid disintegration in the oral cavity.

Preparation, characterization, and in vivo evaluation of insulin-loaded PLA-PEG microspheres for controlled parenteral drug delivery.

Aim: The aim of this study was to prepare insulin-loaded poly(lactic acid)–polyethylene glycol microspheres that could control insulin release at least for 1 week and evaluate their in vivo performance in a streptozotocin-induced diabetic rat model. Methods: The microspheres were prepared using a water-in-oil-in-water double emulsion solvent evaporation technique. Different formulation variables influencing the yield, particle size, entrapment efficiency, and in vitro release profiles were investigated. The pharmacokinetic study of optimized formulation was performed with single dose in comparison with multiple dose of Humulin® 30/70 as a reference product in streptozotocin-induced diabetic rats. Results: The optimized formulation of insulin microspheres was nonporous, smooth-surfaced, and spherical in structure under scanning electron microscope with a mean particle size of 3.07 ×μm and entrapment efficiency of 42.74% of the theoretical amount incorporated. The in vitro insulin release profiles was characterized by a bimodal behavior with an initial burst release because of the insulin adsorbed on the microsphere surface, followed by slower and continuous release corresponding to the insulin entrapped in polymer matrix. Conclusions: The optimized formulation and reference were comparable in the extent of absorption. Consequently, these microspheres can be proposed as new controlled parenteral delivery system.

Validated high performance liquid chromatography (HPLC) method for the determination of sumatriptan in rabbit plasma: Application to pharmacokinetic study

A new, sensitive and specific isocratic reverse phase-high performance liquid chromatography (RPHPLC) method with fluorescence detection was developed and validated for the determination of sumatriptan in rabbit plasma using sulpiride as an internal standard (IS). Sumatriptan was extracted from plasma by a liquid-liquid extraction with a mixture of tert-butyl methyl ether, dichloromethane and ethyl acetate (2:2:3, v/v). Chromatographic separation of the analyte and internal standard was achieved on a Phenomenex C4 (250 × 4.6 mm, 5 µm) analytical column maintained at 40°C. The mobile phase was composed of 25 mM ammonium acetate (pH 6.5) and acetonitrile (85:15, v/v), pumped isocratically at a flow rate of 0.9 ml/min. Column eluent was monitored at excitation and emission wavelengths of 225 and 350 nm. The calibration curve was linear over a concentration range of 1 to 300 ng/ml (r 2 = 0.9999) with a limit of quantification, 1 ng/ml. The intra-day and inter-day precision and accuracy were between 2.24 and 4.28% and -1.10 and 2.86%, respectively. The mean recoveries of sumatriptan and sulpiride were 89.92 and 91.03%, respectively. Sumatriptan containing plasma samples were stable at -20°C for 14 days. The validated method was successfully applied for pharmacokinetic study after a single oral administration of sumatriptan (50 mg) to rabbits.

Preparation and in vitro characterization of non-effervescent floating drug delivery system of poorly soluble drug, carvedilol phosphate

Abstract The objective of the study was to enhance the solubility of carvedilol phosphate and to formulate it into non-effervescent floating tablets using swellable polymers. Solid dispersions (SD) of carvedilol were prepared with hydrophilic carriers such as polyvinylpyrrolidone and poloxamer to enhance solubility. Non-effervescent floating tablets were prepared with a combination of optimized solid dispersions and release retarding polymers/swellable polymers such as xanthan gum and polyethylene oxide. Tablets were evaluated for physicochemical properties such as hardness, thickness and buoyancy. SD prepared with the drug to poloxamer ratio of 1:4 by melt granulation showed a higher dissolution rate than all other dispersions. Formulations containing 40 mg of polyethylene oxide (C-P40) and 50 mg xanthan gum (C-X50) were found to be best, with the drug retardation up to 12 hours. Optimized formulations were characterized using FTIR and DSC and no drug and excipient interactions were detected.

Anti-Inflammatory, Antibacterial and Analgesic Potential of Cocos Nucifera Linn.: A Review

At present, approximately 25%of drugs in modern pharmacopoeia are derived from plant sources (phytomedicines) that can be developed for the treatment of diseases and disorders. Many other drugs are synthetic analogues built on the prototype compounds isolated from plants. Cocos nucifera Linn. (Arecaceae), which is commonly known as coconut, is a plant possessing a lot of potential as an ingredient in traditional medicines for the treatment of metabolic disorders and particularly as an anti-inflammatory, antimicrobial and analgesic agent. This review emphasizes on the recent literature and research findings that highlight the significant biological activities of C. nucifera Linn. such as its anti-inflammatory, antimicrobial and analgesic properties. This review can help researchers keen on exploiting the therapeutic potential of C. nucifera Linn. which may motivate them to further explore their commercial viability.

Formulation, characterization, in vitro, in vivo, and histopathological evaluation of transdermal drug delivery containing norfloxacin and Curcuma longa

Objective: In an attempt for better treatment of bacterial infections and burn wounds, semisolid formulations containing norfloxacin (NF) and natural wound healing agent Curcuma longa were prepared. The rationale behind employing combination of NF and Curcuma longa is to obtain synergistic wound healing effect. The prepared formulations were compared with silver sulfadiazine cream 1%, USP. Materials and Methods: Various ointments containing NF and C. longa were prepared using standard procedures. These formulations were evaluated for antimicrobial activity against various strains of aerobic and anaerobic microorganisms. The wound healing property was evaluated by histopathological examination and by measuring the wound contraction. Results: The significant antimicrobial and wound healing effects were demonstrated by formulations which are comparable with silver sulfadiazine 1% cream (P < 0.05). Various morphological changes were observed by histopathology during the study period (days 1, 4, 8, and 12) which also supported the wound healing process. Conclusion: Based on the observed antimicrobial and wound healing effects, the formulations containing combination of NF and Curcuma longa could be employed as an alternative to commercial silver sulfadiazine 1% cream. This innovative mode of formulation can be employed for making burn wound healing process more effective.

Recent Advances in Non-Invasive Delivery of Macromolecules using Nanoparticulate Carriers System.

BACKGROUND The drug delivery of macromolecules such as proteins and peptides has become an important area of research and represents the fastest expanding share of the market for human medicines. The most common method for delivering macromolecules is parenterally. However parenteral administration of some therapeutic macromolecules has not been effective because of their rapid clearance from the body. As a result, most macromolecules are only therapeutically useful after multiple injections, which causes poor compliance and systemic side effects. METHOD Therefore, there is a need to improve delivery of therapeutic macromolecules to enable non-invasive delivery routes, less frequent dosing through controlled-release drug delivery, and improved drug targeting to increase efficacy and reduce side effects. RESULT Non-invasive administration routes such as intranasal, pulmonary, transdermal, ocular and oral delivery have been attempted intensively by formulating macromolecules into nanoparticulate carriers system such as polymeric and lipidic nanoparticles. CONCLUSION This review discusses barriers to drug delivery and current formulation technologies to overcome the unfavorable properties of macromolecules via non-invasive delivery (mainly intranasal, pulmonary, transdermal oral and ocular) with a focus on nanoparticulate carrier systems. This review also provided a summary and discussion of recent data on non-invasive delivery of macromolecules using nanoparticulate formulations.

In Situ Gelling Ophthalmic Drug Delivery System: An Overview and Its Applications.

Ophthalmic drug delivery system is very interesting and challenging due to the normal physiologically factor of eyes which reduces the bioavailability of ocular products. The development of new ophthalmic dosage forms for existing drugs to improve efficacy and bioavailability, patient compliance and convenience has become one of the main trend in the pharmaceuticals industry. The present review encompasses various conventional and novel ocular drug delivery systems, methods of preparation, characterization and recent research in this area. Furthermore, the information on various commercially available in situ gel preparations and the existing patents of in situ drug delivery systems i.e. in situ gel formation of pectin, in situ gel for therapeutic use, medical uses of in situ formed gels and in situ gelling systems as sustained delivery for front of eye are also covered in this review.