The bioavailability of drugs is dependent on several factors such as solubility and the administration route. A drug with poor aqueous solubility, therefore, poses challenges with regards to its pharmaceutical advance and ultimately its biological usage. Lipid nanoparticles have been used in pharmaceutical science due to their importance in green chemistry. Their biochemical properties as "green" materials and biochemical processes as "green" processes mean they can be environmentally sustainable. Generally, lipid nanoparticles can be employed as carriers for both lipophilic and hydrophilic drugs. The proposed administration route for nanoparticles can present advantages and disadvantages which should be considered by a formulator. Solid lipid nanoparticles and nanostructured lipid carriers are attractive delivery systems because of their ease of manufacture, biocompatibility, biodegradability and scale-up capacity of formulation constituents. The easy and simple scalability of novel solid lipid nanoparticles and nano lipid carriers, along with their various processing procedures, recent developments, limitation and toxicity, formulation optimization and approaches for the manufacture of lipid nanoparticles, lyophilization and drug release are comprehensively discussed in this review. This review also summarizes the research data related to the various preparation methods and excipients used for solid lipid nanoparticles and nanostructured lipid carriers in recent years.

Formulations that are able to control the release of drug have become an integral part of the pharmaceutical industry. In particular oral drug delivery has been the focus of pharmaceutical research for many years. This type of drug delivery has been at the centre of research due to its many benefits over conventional dosage. The focus of this review is on matrix tablets due to their widely use and simplicity of the formulation. This includes the discussion of various types of matrix tablets and factors affecting the drug release from these formulations. The mechanism of drug release from HPMC matrices is also discussed.