The popularity of hydrogels as biomaterials lies in their tunable physical properties, ability to encapsulate small molecules and macromolecular drugs, water holding capacity, flexibility, and controllable degradability. Functionalization strategies to overcome the deficiencies of conventional hydrogels and expand the role of advanced hydrogels such as DNA hydrogels are extensively discussed in this review. Different types of cross-linking techniques, materials utilized, procedures, advantages, and disadvantages covering hydrogels are tabulated. The application of hydrogels, particularly in buccal, oral, vaginal, and transdermal drug delivery systems, are described. The review also focuses on composite hydrogels with enhanced properties that are being developed to meet the diverse demand of wound dressing materials. The unique advantages of hydrogel nanoparticles in targeted and intracellular delivery of various therapeutic agents are explained. Furthermore, different types of hydrogel-based materials utilized for tissue engineering applications and fabrication of contact lens are discussed. The article also provides an overview of selected examples of commercial products launched particularly in the area of oral and ocular drug delivery systems and wound dressing materials. Hydrogels can be prepared with a wide variety of properties, achieving biostable, bioresorbable, and biodegradable polymer matrices, whose mechanical properties and degree of swelling are tailored with a specific application. These unique features give them a promising future in the fields of drug delivery systems and applied biomedicine.

Due to complicated anatomical and physical properties, targeted drug delivery to ocular tissues continues to be a key challenge for formulation scientists. Various attempts are currently being made to improve the in vivo performance of therapeutic molecules by encapsulating them in various nanocarrier systems or devices and administering them via invasive/non-invasive or minimally invasive drug administration methods. Biocompatible and biodegradable lipid nanoparticles have emerged as a potential alternative to conventional ocular drug delivery systems to overcome various ocular barriers. Lipid-based nanocarrier systems led to major technological advancements and therapeutic advantages during the last few decades of ocular therapy, such as high precorneal residence time, sustained drug release profile, minimum dosing frequency, decreased drug toxicity, targeted site delivery, and, therefore, an improvement in ocular bioavailability. In addition, such formulations can be given as fine dispersion in patient-friendly droppable preparation without causing blurred vision and ocular sensitivity reactions. The unique advantages of lipid nanoparticles, namely, solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions, and liposomes in intraocular targeted administration of various therapeutic drugs are extensively discussed. Ongoing and completed clinical trials of various liposome-based formulations and various characterization techniques designed for nanoemulsion in ocular delivery are tabulated. This review also describes diverse solid lipid nanoparticle preparation methods, procedures, advantages, and limitations. Functionalization approaches to overcome the drawbacks of lipid nanoparticles, as well as the exploration of new functional additives with the potential to improve the penetration of macromolecular pharmaceuticals, would quickly progress the challenging field of ocular drug delivery systems.

Curcumin, an organic phenolic molecule that is extracted from the rhizomes of Curcuma longa Linn, has undergone extensive evaluation for its diverse biological activities in both animals and humans. Despite its favorable characteristics, curcumin encounters various formulation challenges and stability issues that can be effectively addressed through the application of nanotechnology. Nano-based techniques specifically focused on enhancing solubility, bioavailability, and therapeutic efficacy while mitigating toxicity, have been explored for curcumin. This review systematically presents information on the improvement of curcumin’s beneficial properties when incorporated, either individually or in conjunction with other drugs, into diverse nanosystems such as liposomes, nanoemulsions, polymeric micelles, dendrimers, polymeric nanoparticles, solid-lipid nanoparticles, and nanostructured lipid carriers. Additionally, the review examines ongoing clinical trials and recently granted patents, offering a thorough overview of the dynamic landscape in curcumin delivery. Researchers are currently exploring nanocarriers with crucial features such as surface modification, substantial loading capacity, biodegradability, compatibility, and autonomous targeting specificity and selectivity. Nevertheless, the utilization of nanocarriers for curcumin delivery is still in its initial phases, with regulatory approval pending and persistent safety concerns surrounding their use.

Solid lipid nanoparticles (SLNs) are being extensively exploited as topical ocular carrier systems to enhance the bioavailability of drugs. This study investigated the prospects of drug-loaded SLNs to increase the ocular permeation and improve the therapeutic potential of clarithromycin in topical ocular therapy. SLNs were formulated by high-speed stirring and the ultra-sonication method. Solubility studies were carried out to select stearic acid as lipid former, Tween 80 as surfactant, and Transcutol P as cosurfactant. Clarithromycin-loaded SLN were optimized by fractional factorial screening and 3² full factorial designs. Optimized SLNs (CL10) were evaluated for stability, morphology, permeation, irritation, and ocular pharmacokinetics in rabbits. Fractional factorial screening design signifies that the sonication time and amount of lipid affect the SLN formulation. A 3² full factorial design established that both factors had significant influences on particle size, percent entrapment efficiency, and percent drug loading of SLNs. The release profile of SLNs (CL9) showed ~80% drug release in 8 h and followed Weibull model kinetics. Optimized SLNs (CL10) showed significantly higher permeation (30.45 μg/cm²/h; p < 0.0001) as compared to control (solution). CL10 showed spherical shape and good stability and was found non-irritant for ocular administration. Pharmacokinetics data demonstrated significant improvement of clarithromycin bioavailability (p < 0.0001) from CL10, as evidenced by a 150% increase in C_max (~1066 ng/mL) and a 2.8-fold improvement in AUC (5736 ng h/mL) (p < 0.0001) as compared to control solution (C_max; 655 ng/mL and AUC; 2067 ng h/mL). In summary, the data observed here demonstrate the potential of developed SLNs to improve the ocular permeation and enhance the therapeutic potential of clarithromycin, and hence could be a viable drug delivery approach to treat endophthalmitis.

The clinical efficacy of antiretroviral therapy in NeuroAIDS is primarily limited by the low perfusion of the drug to the brain. The objective of the current investigation was to design and develop an in situ mucoadhesive gel loaded with darunavir to assess the feasibility of brain targeting through the intranasal route. Preliminary batches (F1–F9) were prepared and evaluated for various pharmaceutical characteristics. A full factorial design of the experiment was applied to optimize and assess the effect of two influencing variables (Carbopol 934P (X₁) and Poloxamer 407 (X₂)) on the response effects (gelation temperature (Y₁) and % drug release (Y₂) at 8 h). The data demonstrate that both influencing variables affect the response variables significantly (p < 0.05). The optimized formulation (F7) exhibited favorable rheological properties, adequate mucoadhesion, sustained drug release, and greater permeation across the nasal mucosa. An in vitro ciliotoxicity study confirms the nontoxicity of the optimized in situ gel (D7) on the nasal mucosa. An in vivo pharmacokinetic study in rats was performed to assess drug targeting to the brain following the nasal application of the selected in situ gel (D7). Significantly higher (p < 0.0001) C_max (~4-fold) and AUC_0-α (~3.5-fold) values were noticed in the brain after nasal application, as compared to the intravenous route. However, less systemic exposure to darunavir was noticed with nasal therapy, which confirms the low absorption of the drug into the central compartment. Overall, the data here demonstrate that the optimized in situ mucoadhesive nasal gel is effective in targeting darunavir to the brain by the nasal route and could be a viable option for the treatment of NeuroAIDS.

Glycyrrhiza glabra L. (belonging to the family Leguminosae), commonly known as Licorice, is a popular medicinal plant that has been used in traditional medicine worldwide for its ethnopharmacological efficacy in treating several ailments. Natural herbal substances with strong biological activity have recently received much attention. The main metabolite of glycyrrhizic acid is 18β-glycyrrhetinic acid (18βGA), a pentacyclic triterpene. A major active plant component derived from licorice root, 18βGA has sparked a lot of attention due to its pharmacological properties. The current review thoroughly examines the literature on 18βGA, a major active plant component obtained from Glycyrrhiza glabra L. The current work provides insight into the pharmacological activities of 18βGA and the potential mechanisms of action involved. The plant contains a variety of phytoconstituents such as 18βGA, which has a variety of biological effects including antiasthmatic, hepatoprotective, anticancer, nephroprotective, antidiabetic, antileishmanial, antiviral, antibacterial, antipsoriasis, antiosteoporosis, antiepileptic, antiarrhythmic, and anti-inflammatory, and is also useful in the management of pulmonary arterial hypertension, antipsychotic-induced hyperprolactinemia, and cerebral ischemia. This review examines research on the pharmacological characteristics of 18βGA throughout recent decades to demonstrate its therapeutic potential and any gaps that may exist, presenting possibilities for future drug research and development.