Pharmaceutical Nanotechnology (v.3, #4)

Editorial: by Ijeoma Uchegbu (223-223).

Technologies for the Evaluation of Efficacy of Nanoformulation for Removal of Radiological Contamination by Navneet Sharma, Rakesh Kumar Sharma, Rajeev Goel, Mani Silambarasan, Dharam Pal Pathak (228-238).
Background: Radiological contamination is the presence of the unwanted radioactive material in the form of dust, particle or liquid droplets. Several macro-formulations and nano-formulations have been developed for skin decontamination. These includes simple soap solutions, Ethylenediaminetetraacetic acid (EDTA) & Diethylenetriaminepentaacetic acid (DTPA) lotion formulations and p-tertbutylcalix[4]arene Nanoemulsion. Rapid, sensitive and specific techniques need to be employed for evaluation of decontamination efficacy of such formulations.
Objective: Current review highlights the various technologies available for the evaluation of the efficacy of Macro- and Nano-formulations for removal of radiological contamination from skin. These include Whole Body Counting (WBC), Gamma Scintigraphy, Inductively Coupled Plasma (ICP) Atomic Emission Spectroscopy (AES) and ICP- Mass Spectroscopy (MS).
Method: Contamination of selected skin patch of experimental animal with radioactive compounds and its subsequent decontamination using cotton swaps dipped in formulation following swirling motion, and mounting of rat skin on Franz cells, was employed in these studies.
Conclusion: There are several techniques available for the evaluation of the decontamination efficacy of the topical formulations. These techniques are based on the qualitative/quantitative estimation of radionuclides and the evaluation of the sequestering/complexation capability of the formulation on the skin. There is a need to adopt suitable technique for the evaluation of the external/internal contamination with respect to addressing the issue of decontamination efficacy evaluation and incorporation of radioactivity inside the body.

Dendrimer-drug Conjugates in Drug Delivery and Targeting by Anurag K. Singh, Sonam Chaudhary, Sarita Rani, Ashok K. Sharma, Lokesh Gupta, Umesh Gupta (239-260).
Background: Conjugation of several bio-actives to macromolecular nanocarriers is a promising approach to improve the efficiency and reduce side effects. Dendrimer represents a novel class of synthetic nanocarriers, comprised of different branched materials with tailor-made functionalities to conjugate wide varieties of bioactive molecules, therapeutic agents and different pharmacological substances including antibodies, ligands etc. Such opportunistic properties has been equally explored for the purpose of diagnostic applications as well.
Methods: We have accomplished thorough bibliographic search and compilation of referred/indexed peer-reviewed literature to concisely review the above mentioned concept. The organized study was carried out concerned for dendrimer-drug conjugates employed in drug delivery and targeting to specific sites for their biological and clinical evaluation.
Results: One hundred forty one papers were referred in this review after throughout literature survey. The conjugation is favorable and is easy to perform with the carriers like dendrimers due to its unique properties and multiple functional groups at the surface. The present review highlights the general properties class and applications of dendrimers in drug delivery. The focus is particularly on the dendrimer drug conjugates which are comparatively less explored area than the non-covalent dendrimer drug interactions.
Conclusion: Conjugation of drugs to the dendrimers has particularly resulted into the increased drug payload and improved drug activity as evidenced by the reports discussed here in this article. Therefore in future it would be more advantageous to explore the dendrimer drug conjugation approaches for delivering drugs through dendrimers.

Modified Polysaccharides as Carriers for Biomolecules by Soma Patnaik, Priyanka Bhatnagar, Ruby Bansal, Joyita Sarkar, Ashok Kumar, Pradeep Kumar, Kailash C. Gupta (261-287).
Background: Synthetic and natural polymers and their modified derivatives are widely being used in various biomedical applications. Recently, natural polymers (polysaccharides) and their modified analogs, in particular, have attracted the attention of the researchers to use these materials specifically as drug delivery systems and macromolecular prodrugs. These applications have opened up new avenues to design and develop such materials capable of delivering therapeutic drugs (conventional and nucleic acid-based) to the targeted tissues/cells in a controlled manner. Biodegradability, biocompatibility and non-toxic nature have made them quite useful for such applications.
Methods: Various polysaccharide-based delivery agents, developed over the last ten years, and their applications have been reviewed in detail.
Results: Polysaccharides conjugated to various ligands have been shown to deliver anticancer drugs and genetic materials inside the cells. Some of them have displayed their targeting ability i.e. delivery of a drug / gene to a specific tissue/cell. For gene delivery applications, these polysaccharides have been modified to incorporate cationic charge density facilitating interactions of the complexes with the cell membranes and their uptake. Likewise, anti-cancer drugs have been delivered by self-assembled formulations of modified polysaccharides in a controlled manner. Besides, a brief description of the methods of their preparation has also been outlined. These formations have clearly demonstrated the significance of polysaccharide-based delivery agents. Some of these formulations are in various phases of clinical trials.
Conclusion: A wide range of polysaccharide-based conjugates have been designed, synthesized and evaluated for their ability to transport drug/gene inside the cells. Further studies would establish the superiority of such formulations in the medical applications.

Background: Rare, or 'orphan', diseases are defined as lifethreatening or chronic debilitating conditions affecting a small number of patients, and present a significant public health challenge in terms of the lack of scientific knowledge, clinical expertise, and available therapies for these complex pathologies. Indeed, the difficulties involved in generating new treatments for a limited patient population, and the likely financial loss in bringing such products to market, has deterred research and development by the pharmaceutical industry. To address these issues, sponsors of new therapies can apply to regulatory authorities for 'orphan designation', which confers incentives for development such as reduced fees for scientific advice, tax incentives, and market exclusivity for an approved product; although the qualifying criteria vary between regions.
Focus: This review provides a global overview of orphan diseases and designation, and focuses on the potential of the rapidly expanding and exciting field of pharmaceutical nanotechnology and fabricated nanosystems (nanomaterials and nanodevices), including nanomedicines and nanosimilars for the therapeutic, diagnostic, or theranostic (development of more specific, individualised therapies for various diseases, and combining diagnostic and therapeutic capabilities into a single system) applications for rare diseases.

Background: Stability testing is key to assurance of quality of pharmaceuticals. All types of conventional and modified formulations, including nanopharmaceuticals, need to be subjected to extensive stability study program.
Objective: To highlight the role of stability testing; nature of studies in different phases of drug and product development; discuss peculiarities of nanopharmaceuticals in difference to conventional and modified release products and outline differences in stability testing protocols.
Method: A critical review was done of stability testing protocols employed in published reports during the development of nanopharmaceuticals.
Results: The reported investigations rightly focused on the stability of carrier materials and changes in physical characteristics of formulations, but an important aspect missed out was the development of stabilityindicating analytical methods, without which it is difficult to determine chemical change in the drug with time and monitor formation of degradation products. Also, stability studies were conducted at very variable storage conditions.
Conclusion: Stability testing of developmental nanopharmaceuticals must be done extensively, and systematically. It has to focus on functionality, integrity, size of particulates, carrier material stability, drug stability, degradation products, etc. It shall be ensured that the selected stability storage conditions are relevant for the specific product and studies are done in intended market packs.

Dendrimer Based Formulation of Erlotiniib HCl: Development, Characterization and In-Vitro Evaluation by Rachna D. Singh, Vaibhav Khare, Farnaz Yusuf, Abid Hamid, Asha Chaubey, Shashank Singh (315-321).
Background: Erlotinib-HCl is a quinazoline derivative used as a first line drug in the treatment of advanced non-small-cell lung cancer. Conventionally, erlotinib HCl tablets has poor solubility in water and its dissolution is much lower in the fasting state as compared to the fed state. Oral absorption of erlotinib HCl is higher when administered with food. It is due to food which delays the gastric emptying time and allows more time for erlotinib HCl to exposes to fat in which it is more soluble. Thus, oral bioavailability of erlotinib HCl in fasting state has limitation in comparison to fed state, it affect the therapeutic efficacy of erlotinib HCl. Therefore, there is a need to improve art of delivery of erlotinib HCl which can overcome bioavailability issues. In the present study, we formulated dendrimers based formulation in order to improve its PK-PD profiles.
Methods: Methods described in detail in the article for design and synthesis of Silica based Erlotinib dendrimer which was further evaluated mechanistically for bio efficacy and its toxicities.
Results: The quinazoline dendrimer had an effective average particle size of about 100-1000 nm with drug loading efficiency of 0.571% and encapsulation efficiency was 38 %. In vitro cytotoxicity against panel of EGFR overexpressing cell line reveals lowest IC50 values 3.4 µ;M in A431 cell line, whereas 0.2 µ;M for NCI-H322 cell line. To assess the effect on DNA cell cycle by test material hypo diploid sub-G1 DNA fraction (<2n DNA) of the cells measured in treated cells using flowcytometer at 0.5, 1, 1.5 µ;M and was found to be 21.5, 15.4 and 17.2% respectively. The loss of mitochondrial membrane potential indicate it induces programmed cell death in cells via intrinsic pathway. Induction of genotoxic DNA damage indicate that dendrimer treated NCI-H322 cells resulted formation of comets with head DNA of 69.95 and 41.4% at concentration 0.5 and 1.5 µ;M respectively.
Conclusion: In vitro results of dendrimer based nano scaled formulation showing promising results as compared to the free drug reveal that the formulation can further be evaluated for development as alternative delivery system.

SiRNA Mediated Gene Silencing: Hurdles, Strategies and Applications by Prajakta Tambe, Pramod Kumar, Virendra Gajbhiye, K. M. Paknikar (322-333).
Background: RNA interference (RNAi) has emerged as one of the most extensively explored areas of research that has promising applications in therapeutics. As an endogenous regulatory pathway, RNAi can be used for silencing targeted genes involved in the progression of diseases. Small interfering RNAs (siRNA) are 21-25 nucleotides in length and work on the principle of RNA interference. Owing to their high degree of safety, specificity, efficacy, easy synthesis and unrestricted choice of target, siRNAs are considered appropriate for gene silencing.
Objective: This review discusses siRNA gene silencing mechanism, the challenges posed in siRNA delivery and the strategies developed to overcome some of these hurdles using nanocarriers. A few applications of siRNA in therapeutics are presented to highlight the utility of these strategies.
Conclusion: In spite of advantages of siRNA technology, several shortcomings such as off-target effects, hurdles in delivering, endosomal trapping, stimulation of immune response and short half-life limit the practical use of siRNA. However, the situation has been improved considerably using nanotechnology based tools.