Gaurav K. Jain

CNS Drug Delivery Systems: Novel Approaches

The brain is a delicate organ, and nature has very efficiently protected it. The brain is shielded against potentially toxic substances by the presence of two barrier systems: the blood brain barrier (BBB) and the blood cerebrospinal fluid barrier (BCSFB). Unfortunately, the same mechanisms that protect it against intrusive chemicals can also frustrate therapeutic interventions. Despite aggressive research, patients suffering from fatal and/or debilitating central nervous system (CNS) diseases, such as brain tumours, HIV encephalopathy, epilepsy, cerebrovascular diseases and neurodegenerative disorders, far outnumber those dying of all types of systemic cancers or heart diseases. The abysmally low number of potential therapeutics reaching commercial success is primarily due to the complexity of the CNS drug development. The clinical failure of many probable candidates is often, ascribable to poor delivery methods which do not pervade the unyielding BBB. It restricts the passive diffusion of many drugs into the brain and constitutes a significant obstacle in the pharmacological treatment of central nervous system (CNS) disorders. General methods that can enhance drug delivery to the brain are, therefore, of great pharmaceutical interest. Various strategies like non-invasive methods, including drug manipulation encompassing transformation into lipophilic analogues, prodrugs, chemical drug delivery, carrier-mediated drug delivery, receptor/vector mediated drug delivery and intranasal drug delivery, which exploits the olfactory and trigeminal neuronal pathways to deliver drugs to the brain, are widely used. On the other hand the invasive methods which primarily rely on disruption of the BBB integrity by osmotic or biochemical means, or direct intracranial drug delivery by intracerebroventricular, intracerebral or intrathecal administration after creating reversible openings in the head, are recognised. Extensive review pertaining specifically, to the patents relating to drug delivery across the CNS is currently available. However, many patents e.g. US63722506, US2002183683 etc., have been mentioned in a few articles. It is the objective of this article to expansively review drug delivery systems for CNS by discussing the recent patents available.

A review on the strategies for oral delivery of proteins and peptides and their clinical perspectives

In the modern world, a number of therapeutic proteins such as vaccines, antigens, and hormones are being developed utilizing different sophisticated biotechnological techniques like recombinant DNA technology and protein purification. However, the major glitches in the optimal utilization of therapeutic proteins and peptides by the oral route are their extensive hepatic first-pass metabolism, degradation in the gastrointestinal tract (presence of enzymes and pH-dependent factors), large molecular size and poor permeation. These problems can be overcome by adopting techniques such as chemical transformation of protein structures, enzyme inhibitors, mucoadhesive polymers and permeation enhancers. Being invasive, parenteral route is inconvenient for the administration of protein and peptides, several research endeavors have been undertaken to formulate a better delivery system for proteins and peptides with major emphasis on non-invasive routes such as oral, transdermal, vaginal, rectal, pulmonary and intrauterine. This review article emphasizes on the recent advancements made in the delivery of protein and peptides by a non-invasive (peroral) route into the body.

Nano-salbutamol dry powder inhalation: a new approach for treating broncho-constrictive conditions.

Nanoparticle DPI is known to have deeper lung penetration but its clinical utility as a potentially better treatment option needs to be evaluated in the light of higher expected mucociliary movement of the nanoparticles compared to micronized DPI. The objective of this study was to make nano-salbutamol sulphate (SBS) DPI, radiolabel it with Tc-99m using a novel surface labeling methodology, characterize the formulation and assess its in vitro and in vivo deposition in healthy human volunteers to estimate its bioavailability in the target area. Nano-SBS with a mean particle of 60.71+/-35.99 nm was produced using liquid anti-solvent precipitation method. The drug particles were spherical, pure and crystalline. Anderson cascade impaction showed that blend formulations of Nano-SBS exhibited significantly higher respirable fraction of 45.2% compared to the known behavior of micronized salbutamol sulphate blends. Though the particle size tended to increase due to solid phase interaction after blending with lactose, there was definitive correlation between the radiolabeled and non-radiolabeled forms. In 10 healthy volunteers, lower oropharyngeal depositions (25.3+/-4.5%) were observed with nano-SBS formulation compared to micronized SBS formulation (58.4+/-6.1%). Furthermore, Nano-SBS formulations showed nearly 2.3-fold increase in total lung deposition compared to micronized SBS. The in vivo deposition data and the ratio of peripheral to central lung deposition (P/C) of 1.12+/-0.4 indicate that Nano-SBS is evenly distributed within different lung regions. As demonstrated for SBS, nano-sizing may enhance regional deposition and thus provide an attractive particle engineering option for the development of blend formulations for inhalation delivery.

Enhanced bioavailability of nano-sized chitosan–atorvastatin conjugate after oral administration to rats

A novel approach to improve the bioavailability and stability of atorvastatin (AT) was developed by constructing a nano-sized polymer-atorvastatin conjugate. Firstly, a novel chitosan-atorvastatin (CH-AT) conjugate was efficiently synthesized through amide coupling reaction. The formation of conjugate was confirmed by (1)H NMR and FT-IR spectrometry. Nano-sized conjugate with a mean size of 215.3±14.2 nm was prepared by the process of high pressure homogenization (HPH). Scanning electron microscopy (SEM) revealed that CH-AT nano-conjugate possess smooth surface whereas X-ray diffraction (XRD) spectra demonstrated amorphous nature of nano-conjugate. Further, CH-AT nano-conjugate showed solubility enhancement of nearly 4-fold and 100-fold compared to CH-AT conjugate and pure AT, respectively. In vitro drug release studies in simulated gastric fluid and simulated intestinal fluid suggested sustained release of AT from the conjugate. Additionally, the nano-conjugate significantly reduced the acidic degradation of AT. The plasma-concentration time profile of AT after oral administration of CH-AT nano-conjugate (2574±95.4 ng/mL) to rat exhibited nearly 5-fold increase in bioavailability compared with AT suspension (583±55.5 ng/mL). Finally, variable bioavailability, as observed for AT suspension was also reduced when AT was administered in form of CH-AT nano-conjugate. Taken together these data demonstrate that chitosan conjugate nano-prodrugs may be used as sustained polymeric prodrugs for enhancing bioavailability.

Metallic nanoparticles: technology overview & drug delivery applications in oncology.

Importance of the field: The targeted delivery of therapeutic agents to tumour cells is a challenge because most of the chemotherapeutic agents distribute to the whole body, which results in general toxicity and poor acceptance by patients and sometimes discontinuation of the treatment. Metallic nanoparticles have been used for a huge number of applications in various areas of medical treatment. Metallic nanoparticles are emerging as new carrier and contrast agents in cancer treatment. These metallic nanoparticles have been used for imaging of tumour cells by means of active and passive targeting. Recent advances have opened the way to site-specific targeting and drug delivery by these nanoparticles. Areas covered in this review: This review summarizes the mechanisms of passive and active targeted drug delivery by metallic nanoparticles and their potential use in cancer theranostics. What the reader will gain: The reader will gain information on the development of tumour cells, advantages of modern methods of cancer treatment over the traditional method, targeted delivery of anticancer agents using nanoparticles, influence of nanotechnology on the quality and expectancy of life, and challenges, implications and future prospects of metallic nanoparticles as probes in cancer treatment. Take home message: The development of metallic nanoparticles is rapid and multidirectional, and the improved practical potential of metallic nanoparticle highlights their potency as new tools for future cancer therapeutics modalities.

Nanocarrier based formulation of Thymoquinone improves oral delivery: Stability assessment, in vitro and in vivo studies

This research aims to formulate and characterize solid lipid nanoparticles (SLNs) of Thymoquinone (THQ-SLNs) for the effective treatment of liver cirrhosis. Formulations were prepared using solvent injection method and optimized by the Box-Behnken experimental design to get the desired particle size having maximized entrapment efficiency as well as percentage release. Optimized THQ-SLNs (ST-1) with appropriate characteristics (particle size=166.1±10.96 nm; zeta potential=-11.34±3.54 mV; entrapment efficiency=71.60±3.85%; maximum % release=70.95±2.47%) were fabricated. DSC and XRD studies were carried out which collectively proved the reduced crystallinity and stability enhancing effect of the SLNs. Improved drug stability was further established by the subjection of the THQ-SLNs to accelerated stability studies (as per ICH guidelines) in contrast to the THQ-suspension. In vivo studies revealed a nearly 5 fold increase in the bioavailability of ST-1 (AUC(0→∞)=2998.91±260.503 μg/mL/h) as compared to THQ suspension (AUC(0→∞)=484.23±21.755 μg/mL/h). Pharmacodynamic data exhibited a significant decrease in the serum biomarker enzymes (SGOT, SGPT and ALP) after oral administration of THQ-SLNs as compared to control and marketed (SILYBON(®)) formulations against paracetamol (PCM)-induced liver cirrhosis. The effect of the treatment was confirmed by the histopathology of the liver microtome sections.

Investigation of Nanoemulsion System for Transdermal Delivery of Domperidone: Ex-vivo and in vivo Studies

The aim of the present study was to investigate the nanoemulsion system for enhanced percutaneous penetration of domperi- done. Pseudoternary phase diagrams were constructed in order to optimize the surfactant, cosurfactant and surfactant: cosurfactant weight ratios (Smix). Nine nanoemulsion formulations were selected, characterized and their ex-vivo permeation studies using rat skin were per- formed. The nanoemulsion formulations had small droplet size (<90 nm), uniform size distribution (PI, < 0.2) and low viscosity (<160 mP). The results demonstrated that the droplet size and viscosity of nanoemulsion decreased following decrease in the concentration of polysorbate 20, whereas transdermal flux was increased. The optimized formulation NE-B1, which contained oleic acid (4 % w/w), polysorbate 20 (10 % w/w), diethylene glycol monoethyl ether (20 % w/w) and water (64 % w/w) showed significant increase (P < 0.01) in the transdermal flux (169.32 ± 8.33 � g.h -1 cm -2 ). The in vivo studies revealed a 3.5 fold increase in relative bioavailability through transdermal application of NE-B1 formulation compared to oral drug suspension. Moreover, the effective drug plasma concentration was maintained for 16 hour after the transdermal application indicated that the developed nanoemulsion systems could be a promising carrier for the transdermal delivery of domperidone for prolonged period. Microemulsions are quaternary systems composed of an oil phase, a water phase, surfactant frequently in combination with cosurfactant (1-3). These spontaneously formed systems possess specific physicochemical properties such as transparency, optical isotropy, low viscosity and thermodynamic stability. In stable mi- croemulsion, droplet diameter is usually within the range of 10-100 nm (100-1000 A°), and therefore these systems are also termed as nanoemulsions (NE) (4). Due to their unique physicochemical properties, NE offer advantages over traditional topical and trans- dermal drug delivery formulations. Many studies have shown that NE formulations possess improved transdermal and dermal delivery properties both in vitro (5-17), as well as in vivo (18-22). The high solubilizing capacity of NE enables them to increase the solubility of poorly water-soluble drugs. Both, increase in solute concentra- tion and the tendency of the drug to favor partitioning into the stra- tum corneum make NE a useful vehicle to enhance transdermal drug permeability (23). As demonstrated by a recent publication (18), the transdermal permeation rate of a lipophilic drug significantly increased from NE as compared to macroemulsions. In macroemulsions the free mobil- ity of the active material between the internal (disperse) phase to the external (continuous) phase within the structure of the formu- lated system is limited due to the strong interactions between the surfactants that form tight interfacial film. In NE, the co-surfactant lowers the interfacial tension of the surfactant film, resulting in a more flexible and dynamic layer (3,14). The drug in this energy- rich system can diffuse across the flexible interfacial surfactant film, a thermodynamic process that increases partitioning and diffu- sion into the stratum corneum. This article is intended to demonstrate the feasibility of new o/w NE system for transdermal delivery of domperidone. Domperi- done is a dopamine (D2 receptor) antagonist with predominant peripheral activity. It is clinically effective in conditions such as diabetic gastroparesis, chronic dyspepsia, pediatric vomiting, cancer chemotherapy induced nausea and emesis (24). Owing to its high portion of hepatic first pass metabolism (~85 %) (25), its low mo- lecular weight (426 Da), its moderate lipophilicity (Log P, 3.9) as

Microscopic and spectroscopic evaluation of novel PLGA–chitosan Nanoplexes as an ocular delivery system

The interaction of PLGA-chitosan Nanoplexes with ocular mucosa was investigated ex vivo and in vivo to assess their potential as ocular delivery system. Fluorescent Rhodamine Nanoplexes (Rd-Nanoplexes) were prepared by ionotropic gelation method. The size and morphology of Nanoplexes was investigated by TEM, SEM and PCS. The corneal retention, uptake and penetration of Nanoplexes were analyzed by spectrofluorimetry and confocal microscopy. Corneas from Rd-Nanoplexes-treated rabbits were evaluated for the in vivo uptake and ocular tolerance. The Nanoplexes prepared were round with a mean diameter of 115.6±17nm and the encapsulation efficiency of Rd was 59.4±2.5%. Data from ex vivo and in vivo studies showed that the amounts of Rd in the cornea were significantly higher for Nanoplexes than for a control Rd solution, these amounts being fairly constant for up to 24h. Confocal microscopy of the corneas revealed paracellular and transcellular uptake of the Nanoplexes. The uptake mechanism postulated was adsorptive-mediated endocytosis and opening of the tight junctions between epithelial cells. No alteration was microscopically observed after ocular surface exposure to Nanoplexes. Taken together, these data demonstrate that Nanoplexes are potentially useful as ocular drug carriers.

Development and clinical trial of nano-atropine sulfate dry powder inhaler as a novel organophosphorous poisoning antidote

The aim of the work was to develop, characterize, and carry out a clinical trial with nano-atropine sulfate (nano-AS) dry powder inhaler (DPI), because this route may offer several advantages over the conventional intramuscular route as an emergency treatment, including ease of administration and more rapid bioavailability. Different batches of nanoparticles of AS were produced using variants of nanoprecipitation method. The influence of the process parameters, such as the types and quantity of solvent and nonsolvent, the stirring speed, the solvent-to-nonsolvent volume ratio, and the drug concentration, was investigated. The methodology resulted in optimally sized particles. Bulk properties of the particles made by the chosen methodology were evaluated. A clinical trial was conducted in six healthy individuals using a single DPI capsule containing 6 mg nano-AS DPI in lactose. Early blood bioavailability and atropinization pattern confirmed its value as a potential replacement to parenteral atropine in field conditions. The formulation seems to have the advantage of early therapeutic drug concentration in blood due to absorption through the lungs as well as sustained action due to absorption from the gut of the remaining portion of the drug.

Cancer targeted metallic nanoparticle: targeting overview, recent advancement and toxicity concern.

The targeted delivery of theranostic agents to the cancer cells is one of the major challenges and an active field of research in the development of cancer chemotherapeutic approaches. Theranostic metallic nanoparticles (TMNPs) have garnered increasing attention in recent years as a novel tool for theranostic application such as imaging, diagnosis, and therapeutic delivery of active agents to tumour specific cells. This paper attempts to unveil the multidimensional theranostic aspects of multifunctional metallic nanoparticles (MNPs)including passive and active targeting (HER2, Folate, Angiogenesis etc.) as well as the RES escaping approach. Special attention is given to the theranostic application of MNPs in oncology. Patents issued by the US office in this nanotechnological arena are also included emphasising the importance of MNPs in current cancer treatment/imaging research scenario. Keeping in mind the blooming research in clinical application directed nanotechnology; toxicity concerns related with MNPs are. also discussed, in element.