Nano-based drug delivery systems: Conventional drug delivery routes, recent developments and future prospects

Drug delivery can be defined as the group of approaches a drug or pharmacologically active agent can be transported to the target cell to treat disease or health issue. Conventional routes for drug delivery are oral, buccal, rectal, subcutaneous, intranasal, intramuscular, intravenous, pulmonary and transdermal. These are the commonly used methods for treatment of various medical problems but have certain limitations such as instability, risk of displacement, uncontrolled release, side effect such as irritation and pain, slow absorption, enzymatic deterioration and many others. Incorporation of drug into nanocarrier is one of the efficient methods for targeted and sustained delivery of drug. Applications of nanocarriers such as solid nanoparticles, liposomes, dendrimers, polymeric nanoparticles, polymeric micelles, virus like nanoparticles, carbon nanotube and mesoporous silica nanoparticles are discussed in this review. To overcome drawbacks of drug delivery, innovative delivery systems are designed usually termed as smart drug delivery systems which include nucleic acid-based drug delivery system, cell-based drug delivery system, self-nano emulsifying drug delivery system, self-micro emulsifying drug delivery system, chemical and physical stimuli-based drug delivery system, nanoneedles, patches, ultrasound drug delivery and microchip technology. This article focuses of the basic mechanism of drug delivery, pharmacokinetic study, recent innovations and future trends of the drug delivery system.