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During recent years carbon nanotubes (CNTs) have been attracted by many researchers as a drug delivery carrier. CNTs are the third allotropic form of carbon-fullerenes which were rolled into cylindrical tubes. To be integrated into the biological systems, CNTs can be chemically modified or functionalised with therapeutically active molecules by forming stable covalent bonds or supramolecular assemblies based on noncovalent interactions. Owing to their high carrying capacity, biocompatibility, and specificity to cells, various cancer cells have been explored with CNTs for evaluation of pharmacokinetic parameters, cell viability, cytotoxicty, and drug delivery in tumor cells. This review attempts to highlight all aspects of CNTs which render them as an effective anticancer drug carrier and imaging agent. Also the potential application of CNT in targeting metastatic cancer cells by entrapping biomolecules and anticancer drugs has been covered in this review.

The drug delivery system using solid lipid nanoparticles (SLN) came into being about two decades ago and since then lot of work has been done in this field.1-5) SLN for oral drug administration are specifically used to target the uptake of the drug by lymphatic system which prevents its first pass metabolism. Lymphatic uptake of drugs follow two routes which include transcellular transport through the enterocyte and phagocytosis of the drugs by Mast cells of payer's patches lining the intestinal mucosa. [6][7][8] The production of this nano particulate system is based on the principle of solidification of lipid nano emulsion.9) The different technologies available for the fabrication of SLN are high shear homogenization, ultrasound, high pressure homogenization (cold homogenization and hot homogenization), solvent emulsification/evaporation and microemulsion method.10) The major excipients used in the development of the SLN are fatty acids, mono, di and triglycerides, phospholipids etc., which are part of the physiological composition and thus are biocompatible to the body. [11][12][13] SLN have been shown to have superior advantages over polymeric nanoparticles, fat emulsion and liposomes.14) SLN can be produced on large scale and are also biocompatible to the body as compared to polymers, the monomeric unit of which are cytotoxic to the body.15,16) SLN exhibit sustained release effect due to the immobility of drug within lipid as compared to the emulsion formulations 17) and also exhibit better physical and chemical stability of drug compared to liposome.18) This delivery system has been extensively used as carriers for proteins, protein drugs, vaccines and lipophilic water insoluble drugs. 19) SLN are potential delivery system for lipophilic drugs where aqueous solubility of the drug is the limiting factor for its absorption. [20][21][22] Moreover, the incorporation of such drugs within SLN is easier due to their affinity for the lipid. On the other hand, entrapment of hydrophilic drug inside the hydrophobic matrix of SLN is a real challenge as the drug has maximum tendency to partition in the water during the fabrication process. Although a few hydrophilic molecules have been incorporated into SLN like thymocratin, 23) insulin, 24) diminazene 25) and thymopentin, 26) lot more scope still remains for the entrapment of hydrophilic drugs into lipid nanoparticles.Zidovudine (AZT), a hydrophilic drug has been used in the present investigation. It belongs to the class of nucleoside reverse transcriptase inhibitor and is used in the treatment of AIDS. This drug has various disadvantages like short biological half life due to extensive first pass metabolism and dose related bone marrow toxicity. AZT is a potential candidate for delivery via lipid based nanoparticulate system as this would help to improve lymphatic uptake, avoid hepatic first pass metabolism and thus reduce the dose requirement and decrease the side effects. 27) Furthermore, sustained drug release would reduce dosing frequency and at the same time ma...

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Extensive attempts to overcome problems related to solubility of drugs for maximizing bioavailability at targeted sites in the body have been made.

Gellan gum has been reported to have wide pharmaceutical applications such as tablet binder, disintegrant, gelling agent and as a controlled release polymer. Multiparticulate delivery systems spread out more uniformly in the gastrointestinal tract and reduce the local irritation. The purpose of this study is to explore possible applicability of gellan macro beads as an oral controlled release system of a sparingly soluble drug, amoxicillin. Gellan gum beads were prepared by ionotropic gelation with calcium ions. The effect of drug loading, stirring time, polymer concentration, electrolyte (CaCl2) concentration, curing time etc. influencing the preparation of the gellan gum macro beads and the drug release from gellan gum beads were investigated in this study. Optimal preparation conditions allowed very high incorporation efficiency for amoxicillin (91%) The release kinetics of amoxicillin from gellan beads followed the diffusion model for an inert porous matrix in the order: 0.1 N HCl > phosphate buffer > distilled water. Change in curing time did not significantly affect the release rate constant, but drug concentration, polymer concentration and electrolyte concentration significantly affect the release rate of amoxicillin from the beads. The gellan macro beads may be suitable for gastro retentive controlled delivery of amoxicillin.

5-FU is a pyrimidine analogue commonly used to treat many epithelial cancers. It acts by interacting with S phase cells (those actively synthesizing DNA). Therefore, it is suitable to treat squamous cell carcinoma because squamous tumours are composed of rapidly proliferating abnormal epithelial cells. It has limited side effects on the normal ocular surface epithelium.1) 5-FU is an inexpensive drug, easily handled by medical personnel and patients, and is stable in aqueous solution for at least 3 weeks. It does not need to be stored in a refrigerator. Topical solution of this drug is always prepared extemporaneously. The acute and chronic side effects of mitomycin C (MMC) are definitely much more frequent and serious than those induced by 5-FU, as referred to by clinicians using MMC for pigmented conjunctival lesions. 1)Currently 1% of 5-FU solution is used by the ophthalmologist which is a high concentration for ophthalmic application. Bioavailability at anterior segment of eye is obtained less than 5% of applied eye dose because of drainage and lacrimation and low retention exposure to the absorption surface.Non ophthalmic nanoparticles of 5-FU using polymers such as poly(butylcyanoacrylate), 2) poly(lactic acid), poly-(lactide-co-glycolide)3) and chitosan [4][5][6] have been reported, but investigators have not explored the application of 5-FU loaded nanoparticles (DNPs) for the treatment of ocular application.Ocular therapy by 5-FU can be improved and its toxicity diminished by facilitating the specific accumulation in the tumor infected regions with prolonged exposure of the cells to this agent. In this sense, the association of anticancer drugs to delivery systems has been an interesting approach for selectively delivering these agents and, at the same time, reducing their toxicity. Another benefit of 5-FU loaded nanoparticles in the targeted tissues could be an improvement in its pharmacokinetics profile.Polymeric nanoparticulate systems have been evaluated as ocular drug delivery to enhance the absorption of therapeutic drugs to improve bioavailability, reduce side effects, and sustain intraocular drug levels.7) In addition, chitosan (CH) is suitable for fabrication of nanogel/nanoparticles of 5-FU because it is positively charged, making it able to adhere to the negatively charged ocular surface and is soluble in diverse acids and able to interact with polyanions to form complex and nanogel. The cornea and conjunctiva have negative charge so the mucoadhesive polymer might interact intimately with these structures and increase the concentration and residence time of the associated drug at the disease site. Among the mucoadhesive polymers, chitosan exhibits several favourable properties, such as biodegradability, nontoxicity, biocompatibility, and mucoadhesiveness. In fact, an ionic interaction between the positively charged amino groups of CH and negatively charged sialic acid residues in mucus has been proposed as the mucoadhesion mechanism. This unique combination of properties makes it a novel versat...