Hydrogels are greatly used in drug delivery systems in immunology, cardiology, pain management, medicine and cardiology. These hydrogels consists of a network of cross-linked polymers and large amount of water. This huge water content provides biocompatibility to the hydrogels and it also enhances its ability to encapsulate hydrophilic drugs. Hydrogels are mostly formed of aqueous solutions, so the risk of aggregation and denaturation of drugs is highly minimized.
Hydrogels are three-dimensional materials and the huge amount of water incorporation makes them excellent drug delivery biomedical materials. Various studies have been carried out in the past few years for incorporating hydrophilic molecules in hydrogels. Hydrogels have different architecture, function and sizes, and all these features determine their use in drug delivery. Hydrogels hugely resemble living tissues and have also creatednew possibilities in the biomedical area. Hydrogels are currently used in manufacturing hygiene products, wound dressings, contact lenses and tissue engineering scaffolds.
As per statistics provided by Coherent Market Insights, The global hydrogel-based drug delivery system market is estimated to be valued at US$ 4,785.4 million in 2022 and is expected to exhibit a CAGR of 6.9% during the forecast period (2022-2030).
Chemical hydrogels can be created using two different methods, three-dimensional polymerization and polymerization. In three-dimensional polymerization, a cross-linking agent is used for polymerizing a hydrophilic monomer, by using a cross-linking agent. In polymerization, compounds like ammonium peroxodisulphate and benzoyl peroxide, 2, 2-azo-isobutyronitrile are used for generating free radicals, which initiates polymerization. Electron beam-radiation or UV- gamma radiations can be used for generating free radicals.
The use of hydrogels in drug delivery is done due to their unique physical properties. For adjusting the porosity of these hydrogels the density of cross-links in matrix and their affinity in water must be controlled. The porous structure allows in loading drugs and then releasing them. Hydrogels offer the advantage of sustainably releasing drugs by maintaining high concentration of an active pharmaceutical ingredient for a long period.
The initial configuration of drug-loaded hydrogels is optimized to minimize the burst effect. The initial drug concentration is tuned using hydrogel stiffness, which reduces the diffusivity of the drug molecules. Due to this drug-release kinetics are faster than those of soft gels. The stiffness of hydrogels influences the overall release profile. Thus, the overall effect of a hydrogel-based drug delivery system is to provide a targeted therapeutic solution for various medical conditions.
There has been a rise in awareness regarding targeted therapies. This technology is also increasingly used in clinical trials to deliver drugs to patients who cannot tolerate or are allergic to certain medications. The major disadvantage about this product is its high cost, low mechanical strength, and low compatibility with few drugs.
Composite hydrogel systems are particularly attractive for intrathecal drug delivery in the spinal cord. These systems combine spatial and temporal control over drug carriers. The drug carriers used in the composite hydrogels can diffuse throughout the CNS, reducing localization at the site of injury. Moreover, high CSF turnover speeds the expulsion of the drug, outpacing its diffusion into tissue. As such, these systems are promising in intrathecal drug delivery in the CNS.
Hydrogels are an attractive option for developing new medicines. They can be implanted directly into lesion cavities. They also serve as tissue engineering scaffolds. Thus, one hydrogel construct can serve as a drug delivery device and a scaffold for tissue engineering. Since they have the same material properties as natural CNS tissue, they help in limiting mechanical stress on healthy spinal cord tissues.
One of the major challenges of hydrogel-based drug delivery systemis that hydrogels are non-biodegradable, slow to respond, and inactive. They can release drug due to swelling or bursting. Hence, different approaches are necessary to overcome these drawbacks.
