What Is Nanotechnology?
Nanotechnology is a field of science and engineering dedicated to designing and manufacturing minute devices and structures. Using this technology, any device or product can be created or changed by manipulating matter at the nanoscale. Scientists can develop nanomaterials less than 100 nanometers thick by altering the atoms and molecules. The obtained materials can be implicated in many realms, such as healthcare, sports, energy, textiles, and electronics.
What Is the Role of Nanotechnology in Drug Delivery?
The drug delivery system has made it possible to effectively transport and deliver a drug safely and precisely to its site of action. Various novel drug delivery technologies are introduced in the pharmacological market each year by studying every body part as a potential route for administering both classical and new medicines. Drug delivery provides promising ways of delivering poorly soluble drugs, proteins, and peptides.
Nanotechnology in drug delivery allows a controllable release of the therapeutic compound and more targeted drug delivery. The main goal of controlled release and targeted drug delivery is to manage better drug pharmacodynamics, pharmacokinetics, immunogenicity, non-specific toxicity, and biorecognition of systems for improved efficacy.
What Is the Importance of Nanotechnology in Ocular Drug Delivery?
Ocular drug delivery is one of the most challenging and captivating ventures faced by pharmaceutical scientists. This is due to the critical and pharmacokinetically specific environment in human eyes. The human eye's anatomy, physiology, and biochemistry do not allow entrance or passage to foreign substances.
The inner and outer blood-retinal barriers in the eye separate the retina and the vitreous from the systemic circulation, reducing molecules' convection. Taking note of all these complications in the anatomy of the eye, the development of a drug delivery system is becoming prominent in treating vitreoretinal diseases. This drug delivery system facilitates drug efficacy and reduces side effects.
In ocular diseases, such as choroidal neovascularization (CNV), central retinal vein occlusion, diabetic retinopathy, and intraocular solid tumors, precise drug delivery can be a significant mode of treatment. The retina has a distinct environment with no lymph system, so enhanced permeability and retention (EPR) effects are suitable for drug targeting. The main goals of ocular drug delivery are to enhance drug molecule movement into and within the biological environment, control the release of drugs, and target drugs.
What Are the Benefits of Nanotechnology in Ocular Drug Delivery?
The development of drug delivery systems in nanotechnology has made it possible to overcome many ocular obstacles. There are three main advantages to using drug delivery systems in ophthalmology: promoting absorption through tissues acting as a barrier, controlled timed and sustained release, and targeted drugs that act specifically on the target tissues.
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A nano-material carrier can enter the tiny blood vessels through the circulation, penetrate the gap between the cells, enter the lesion, and be absorbed by the cells along with dissolved small molecules to improve the material's bioavailability.
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Nano-carrier particles are very minute and have a high specific surface area. So, they can bind well to hydrophobic substances, thereby improving solubility and reducing the adverse effects of conventional solvents.
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Modifications for a nano-material carrier in the targeting group can be made to realize targeted drug delivery, which can reduce the side effects and dosage of a drug, such as magnetic and folic acid-modified nanoparticles.
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Nanocarriers can improve interactions between drugs and different parts of the eyes, so the bioavailability of drugs and delivery efficiency can be improved.
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Nanocarriers have the efficiency to pass through the different barriers of the body that limit the substance effects, such as the blood-eye barrier, the blood-brain barrier, and the cell biomembrane barrier.
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Nano-carriers increase effective blood concentration time, prolong the elimination half-life of a substance, reduce the frequency of use, increase efficiency, and reduce toxic and side effects.
What Are the Nanoparticles Used in Ocular Drug Delivery?
Nanoparticles are defined as particles with dimensions less than one micron and various biodegradable materials, like natural or synthetic polymers, phospholipids, lipids, and even metals. They possess unique properties that make them perfect candidates for ocular drug delivery, such as a high surface area-to-volume ratio, the ability to encapsulate a wide range of drugs, and tunable surface and size characteristics.
Common nanoparticles used in ocular drug delivery include:
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Liposomes - They are made up of phospholipid bilayers. They can encapsulate hydrophobic (insoluble in water) and hydrophilic (capable of interacting with water) drugs. So, these carriers can penetrate ocular tissues efficiently and control the manner of drug release, prolonging their action time in the eye.
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Polymeric Nanoparticles - These include poly (lactic-co-glycolic acid) (PLGA) and chitosan nanoparticles. They can encapsulate various kinds of drugs and release their kinetics. They can enhance mucoadhesion (the binding between two materials, one of which is a mucosal surface). This property allows for prolonged drug retention on the surface of the eyes.
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Dendrimers - They are macromolecular compounds consisting of a series of branches around an innermost core. The nanometer size range, their ability to display different copies of surface groups for biological recognition, and ease of preparation and functionalization make them efficient drug delivery systems. All these properties make them a potential vehicle for ophthalmic drug delivery.
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Niosomes - Niosomes are self-assembled vesicles made of cholesterol, hydrating non-ionic surfactants, or other amphiphilic molecules. Structure-wise, niosomes and liposomes have similar characteristics and have been developed as an alternative liposome option. The benefits of niosomes over liposomes are their longer storage time, chemical stability, and continuous drug administration. Also, niosomes are non-immunogenic and biodegradable.
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Contact Lenses - Contact lenses are polymer devices positioned over the cornea to correct refractive errors. They are made up of hydrophilic or hydrophobic polymers. Based on the materials used, they are classified into two main types: soft contact lenses and rigid gas-permeable contact lenses. Contact lenses that are drug-loaded can be in close contact with the cornea. Hence, they prolong drug retention time in the eyes and improve ocular bioavailability by at least 50 percent. They can decrease the required drug dose, systemic drug absorption, and frequency of administration.
Conclusion
Nanotechnology is being utilized in various fields, including the medical field. In ophthalmology, ocular drug delivery offers effective solutions to overcome the limitations of conventional formulations. Nanoparticle-based drug delivery systems work by sustained, targeted, and controlled release of drugs to the tissues of the eyes, leading to boosted therapeutic outcomes and improved patient compliance.
