Nanoparticle subcutaneous/intramuscular

We will here focus on nanoparticles as a typical example of nano-carriers. Nanoparticles can be seen as sub-micron colloidal objects with a predominantly elastic mechanical behaviour (solid-like bodies), which can be loaded with therapeutically active compounds on their surface, in their bulk or both. Drug-loaded nanoparticles have been administered as nano-carriers in water-based dispersions through virtually all parenteral routes, i.e., intravenous, subcutaneous, intramuscular and also intraperitoneal, but they have also been used to prepare macroscopic materials in situ (Fig. 12.1). 

Nanoparticles with insulin adsorbed onto the surface (Douglas et al, 1987) or liposomes loaded with insulin have also been utilized for sustained release after subcutaneous, intramuscular, or intraperitoneal administration (Patel and Ryman, 1976 Couvreur et al, 1980 Stevenson et al., 1982 Weiner eta/., 1985 Spangler, 1990). However, most injected liposomes and their content of insulin apparently remained at the subcutaneous injection site(Spangler, 1990). 

Parenteral is defined as situated or occurring outside the intestine, and especially introduced otherwise than by way of the intestines —pertaining to essentially any administration route other than enteral. This field is obviously too broad for an adequate focus in one book, let alone one chapter. Many have nonetheless used the term synonymously with injectable drug delivery. We restrict ourselves to this latter usage. This would thus include intravenous, intramuscular, subcutaneous, intrathecal, and subdural injection. In this chapter we discuss the theoretical and practical aspects of solubilizing small molecules for injectable formulation development and will examine the role of surfactants and other excipients in more recent parenteral delivery systems such as liposomes, solid-drug nanoparticles and particulate carriers. 

Microparticles and nanoparticles incorporate drug in matrix or encapsulated form, delivered to the body via injection (intramuscular intravenous, or subcutaneous), via the oral cavity or via the nose. For nasal or oral delivery, the particles are typically in the 20-100 pm size range, because smaller particles can be inhaled and may make their way to the lung for alveolar delivery. For injectable delivery, to achieve prolonged duration of effect, the partieles tend to be in the 50-100 pm range. Nanopartieles are classified as having diameters below I pm and tend to be used specifically for targeted delivery, usually via the injectable route. 

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