Nanoparticles are small particles between 1 nm and 100 nm, and there is growing interest in nanotechnology in energy, electronics, materials science and biomedicine.
Source: TWI
The global healthcare nanotechnology market was worth around $320 billion in 2023, and could be worth as much as $894 billion by 2032. Nanoparticles have potential in imaging, diagnostics, bio-implants and tissue engineering. One of their growing roles is in targeted and controlled drug delivery.
The benefits of nanoparticles in drug delivery
The small size of a nanoparticle means that they can evade scavenging by the mononuclear phagocyte system in the liver and filtration by inter-endothelial cells in the spleen, increasing the systemic circulation time. This increases the amount of drug available for absorption.
The large surface area to volume ratio of a nanoparticle means that they have a large loading capacity for their size.
Nanoparticles can be engineered to deliver drugs to specific cells or tissues. By taking therapeutics, particularly drugs with toxic effects and narrow therapeutic windows, directly to their site of action, allows doses to be higher where needed and lower in the systemic circulation. This can increase efficacy and reduce side effects.
Targeted delivery can be achieved by attaching targeting molecules to the surface of the nanoparticle, such as antibodies, peptides, lectins, saccharides or hormones. By adding polymers that are sensitive to pH or temperature, nanoparticles can release their contents at specific locations in the body. Targeted delivery can also be passive; nanoparticles can accumulate in places with vascular abnormalities, such as tumours. Tumour vessels can also be permeable and the lymphatic drainage is lower than in healthy tissues. This is known as the enhanced permeability and retention effect (EPR), and results in improved drug delivery to tumours.
Nanoparticles can also be engineered to deliver drugs gradually over a period of time, reducing the frequency of dosing, improving convenience for patients and carers/healthcare professionals, and potentially leading to better drug adherence.
Types of nanoparticles
The types of nanoparticles in development or on the market in healthcare applications include:
● nanocrystals
● liposomes
● polymeric micelles/nanoparticles
● nanoemulsions and solid lipid nanoparticles
● dendrimers
● metal nanoparticles
● carbon nanotubes
● quantum dots.
Nanocrystals
Reducing drug particle size to below 100 nm can change the solubility and dissolution of poorly soluble drugs, providing potential for oral, injectable and topical administration.
Examples of nanocrystals include:
● Invega Hafyera (Janssen, launched in 2021) – paliperidone palmitate nanocrystals for the intramuscular treatment of schizophrenia
● Apretude (Viiv Healthcare, launched in 2021) – cabotegravir nanocrystals for the gluteal intramuscular treatment of HIV-1 infection
Liposomes
Liposomes are spheres made up of a lipid bilayer. They self-assemble from natural or synthetic phospholipids, and can carry drug molecules within the lipophilic bilayer or the aqueous core. Liposomes can be administered via ocular, oral, pulmonary, transdermal and parenteral routes. Changing the formulation of the liposome can prolong its circulation, change the biodistribution profile, increase drug effectiveness and allow targeting to specific tissues. Liposomes have poor stability during storage, but this can be improved by freeze-drying.
Examples of liposomal nanoparticles:
● Vyxeos (Jazz Pharmaceuticals, launched in 2017) – daunorubicin/cytarabine liposome for the intramuscular, intrathecal or su...
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