2.2 Targeted drug delivery systems

Targeted drug delivery system (TDDS) is popularly known as smart drug delivery system. The aim of the TDDS is to localize, target and to have a protected interaction of a drug with the diseased cells/tissues of interest for a prolonged period of time. TDDS helps in maintaining the requisite plasma and tissue drug levels in the body and protects the healthy tissues from damage may be some times caused by the drugs [1]. It offers various benefits over conventional DDS such as localization of a drug to the desired or specific site, enhancement of therapeutic efficacy, reduction in the dosing frequency and toxic side effects, controlled biodistribution of drug, modulated pharmacokinetics, and improved patient compliances [2]. The TDDS is a highly integrated DDS which needs the coordinated effort from various experts such as biologist, chemist, engineers for its fabrication and optimization.

#### 2.3 Nanotechnology vs. drug delivery systems

Nanotechnology is defined as the technology which allows studying, controlling, manipulating and manufacturing of structures or devices in the nanoscale. It is a multi-disciplinary scientific field applying engineering and manufacturing principles at the molecular level. These nanosized objects/structures/devices, e.g. "nanoparticles" exhibit unique properties and function that distinctly differ from those seen from the items made up from the same materials. Nanomaterials possess many unique characteristics such as mechanical, optical, magnetic, electrical, and biochemical, which provoke them to intermingle with complex cellular functions in an exceptional manner [3].

Since its introduction in 1959, the nanotechnology brought a great revolution in all areas of sciences and particularly in drug formulation and drug delivery system design. Nanomedicine is the medical application of nanotechnology, which plays an imperative role in the medical biology, diagnosis, monitoring, prevention and treatment of diseases. Since last few decades, owing to the rapid developments in nanotechnology and carrier materials, a great advancement in the nanoparticulate DDS has been noticed and they are taking the lead among all types of DDS [4].

The nanoparticulate DDS possesses numerous advantages such as higher intracellular uptake (cells and tissues have a greater affinity and acceptability to the nanoparticles as compared to micro/macro molecules), ability to penetrate into submucosal layer (nanometric size), greater suitability for administration through the systemic circulation (nanometric size), greater feasibility/flexibility to develop into a targeted DDS for targeting various sites/organs. Thus, the nanometric size, tailored surface, and cross functionality of these nanoparticles will continue to explore many unexplored research areas and may help in designing and developing new biomedical applications [5].

#### 2.4 Colloidal drug carrier and solid lipid nanoparticles

The term "colloid" is applied to the dispersed system where the dispersed phase particles size are very fine and generally below 1 μm. Thus, the biphasic drug carrier containing very fine dispersed phase particles (<1 μm) which sequester, transport

## Solid Lipid Based Nano-particulate Formulations in Drug Targeting DOI: http://dx.doi.org/10.5772/intechopen.88268

steady-state plasma concentration as desired for a specific time period and may not be able to deliver the drugs to the specific site of organ or tissues may be because of barriers in transportation for which it may be needed to administer with multiple doses at a regular time interval or need to go for targeted drug delivery systems.

Targeted drug delivery system (TDDS) is popularly known as smart drug deliv-

Nanotechnology is defined as the technology which allows studying, controlling, manipulating and manufacturing of structures or devices in the nanoscale. It is a multi-disciplinary scientific field applying engineering and manufacturing principles at the molecular level. These nanosized objects/structures/devices, e.g. "nanoparticles" exhibit unique properties and function that distinctly differ from those seen from the items made up from the same materials. Nanomaterials possess many unique characteristics such as mechanical, optical, magnetic, electrical, and biochemical, which provoke them to intermingle with complex cellular functions in

Since its introduction in 1959, the nanotechnology brought a great revolution in all areas of sciences and particularly in drug formulation and drug delivery system design. Nanomedicine is the medical application of nanotechnology, which plays an imperative role in the medical biology, diagnosis, monitoring, prevention and treatment of diseases. Since last few decades, owing to the rapid developments in nanotechnology and carrier materials, a great advancement in the nanoparticulate DDS has been noticed and they are taking the lead among all types of DDS [4]. The nanoparticulate DDS possesses numerous advantages such as higher intracellular uptake (cells and tissues have a greater affinity and acceptability to the nanoparticles as compared to micro/macro molecules), ability to penetrate into submucosal layer (nanometric size), greater suitability for administration through the systemic circulation (nanometric size), greater feasibility/flexibility to develop into a targeted DDS for targeting various sites/organs. Thus, the nanometric size, tailored surface, and cross functionality of these nanoparticles will continue to explore many unexplored research areas and may help in designing and developing new

The term "colloid" is applied to the dispersed system where the dispersed phase particles size are very fine and generally below 1 μm. Thus, the biphasic drug carrier containing very fine dispersed phase particles (<1 μm) which sequester, transport

ery system. The aim of the TDDS is to localize, target and to have a protected interaction of a drug with the diseased cells/tissues of interest for a prolonged period of time. TDDS helps in maintaining the requisite plasma and tissue drug levels in the body and protects the healthy tissues from damage may be some times caused by the drugs [1]. It offers various benefits over conventional DDS such as localization of a drug to the desired or specific site, enhancement of therapeutic efficacy, reduction in the dosing frequency and toxic side effects, controlled biodistribution of drug, modulated pharmacokinetics, and improved patient compliances [2]. The TDDS is a highly integrated DDS which needs the coordinated effort from various experts such as biologist, chemist, engineers for its fabrication

2.2 Targeted drug delivery systems

Role of Novel Drug Delivery Vehicles in Nanobiomedicine

2.3 Nanotechnology vs. drug delivery systems

and optimization.

an exceptional manner [3].

biomedical applications [5].

96

2.4 Colloidal drug carrier and solid lipid nanoparticles

and retain the active drug en route, while they deliver the drug within or in the vicinity of a target is popularly known as colloidal drug carrier. These colloidal drug carriers comprise nanoparticles, liposome, niosome, nanospheres, multiple emulsion, and nanosuspensions, etc. [6]. Colloidal carriers aid in solubilization of lipophilic drug, protect the sensitive drug from degradation in biological fluid, reduce toxic side effect, improve patient compliances, prolong the duration of action and drug targeting potentiality [7].

Though the polymeric nanoparticulate DDS have shown hugely impressive performance for providing therapeutic benefits in the case of long term delivery of a therapeutic agent, but still, the number of polymeric nanoparticulate formulations in the market is still limited. This is because of polymeric toxicity, high cost of polymers, and lack of feasibility for scaling up. Lipid based nanoparticulate DDSs are proposed as an alternative to polymeric nanoparticulate DDS and gained tremendous attention in the field of nanomedicine. These comprise liposomes, niosomes, nanoemulsions, solid lipid nanoparticles (SLNs) and nanostructured lipid carrier (NLCs), etc. [5].

SLNs are the second generation lipid nanocarriers that overcome most of the limitations associated with conventional drug delivery system and other colloidal lipid/polymeric nano carriers. It promises to offer numerous benefits including biocompatibility and biodegradability, physiochemical stability, lower toxicity, ability to incorporate both hydrophilic and lipophilic drugs, improved bioavailability, enhanced in vitro and in vivo stability of drugs, controlled-release characteristics, site specificity in drug delivery as well as feasibility in pilot scale up along with its suitability in drug delivery through different routes of administration [4].
