Silver nanoparticles (AgNPs) have recently become very attractive for the scientific community due to their broad spectrum of applications in the biomedical field. The main advantages of AgNPs include a simple method of synthesis, a simple way to change their morphology and high surface area to volume ratio. Much research has been carried out over the years to evaluate their possible effectivity against microbial organisms. The most important factors which influence the effectivity of AgNPs against microorganisms are the method of their preparation and the type of application. When incorporated into fabric wound dressings and other textiles, AgNPs have shown significant antibacterial activity against both Gram-positive and Gram-negative bacteria and inhibited biofilm formation. In this review, the different routes of synthesizing AgNPs with controlled size and geometry including chemical, green, irradiation and thermal synthesis, as well as the different types of application of AgNPs for wound dressings such as membrane immobilization, topical application, preparation of nanofibers and hydrogels, and the mechanism behind their antimicrobial activity, have been discussed elaborately.

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Hyperpigmentation is a dermal condition of melanocyte proliferation, induced by various factors like ultraviolet radiation producing reactive oxygen species, DNA damage, and apoptosis. The application of topical antioxidants through the different type of formulations can help to prevent oxidative damage to the skin. L-ascorbic acid (vitamin C) is a water-soluble compound and the most abundant antioxidant in human skin, but this vitamin is unstable and loses its potency with poor formulation strategies. Nanotechnology has been effectively used to promote stability and therapeutic activity of various drug molecules. With this context, the objective of the work was set to formulate a topical delivery system of vitamin C nanoparticles incorporated into the polymeric gel. Vitamin C (50 mg) was loaded into ethyl cellulose nanoparticles, of varying concentrations (50-250 mg), by the solvent evaporation method and subsequently incorporated into hydroxypropyl methyl cellulose gels (3, 5, and 7%). The formulations were characterized for various physico-chemical properties such as particle size, drug content, entrapment efficiency, and drug-polymer interactions. In vitro, drug release studies were conducted by using dialysis bag method and Franz diffusion cell for the nanoparticles and gel formulations, respectively. The optimized formulation exhibited sustained release over 8 h. The ex vivo skin permeation studies were performed and the amount of drug retained and released through the skin were determined. The results obtained from the study proved the potentiality and suitability of this novel system to treat hyperpigmentation.

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T he guanine derivative antiviral drug acyclovir (ACV) is one of the oldest molecules laying successful market until date, being commercially available in various dosage forms for oral, topical and parenteral administrations. Clinical application of this drug is superior to new antiviral agents due to its potential values such as suppression of recurrence, safety profile, minimal drug interactions, and being inexpensive. ACV is slightly water-soluble, less permeable and poorly bioavailable, yet more potential antiviral molecule, the physicochemical modifications and novel dosage form approaches resulted with more than 100 research works within a decade. The survey of literature showed enormous reports on ACV formulation development, which includes modified tablets, particulate drug delivery, vesicular drug delivery, polymeric nanoparticles, bioadhesive systems, floating dosage forms, in situ gelling systems, transdermal delivery, implantable systems, emulsified dosage forms, polymeric films/patches, etc. As the drug could be administered via multiple routes for effective site targeted action at various doses, and attracted the attention of many researches, the review of the current approaches for the delivery of ACV could be more beneficial for the new scientists. This paper is a review of recent researches highlighting the development of newer techniques and novel dosage forms of ACV for better therapeutic efficacy, which were aimed at enhancing its solubility, permeability and bioavailability.Durai: Recent formulation designs of acyclovir How to cite this article: Durai RD. Drug delivery approaches of an antiviral drug: A comprehensive review. Asian J Pharm 2015;9:1-12.