Development of 3D printed drug-eluting contact lenses

Volumetric printing and non-destructive drug quantification of water-soluble supramolecular hydrogels

Vat photopolymerisation 3D printing is being actively explored for manufacturing personalised medicines due to its high dimensional accuracy and lack of heat application. However, several challenges have hindered its clinical translation, including the inadequate printing speeds, the lack of resins that give soluble matrices, and the need for non-destructive quality control measures. In this study, for the first time, a rapid approach to producing water-soluble vat photopolymerised matrices and a means of non-destructively verifying their drug content were investigated. Volumetric printing, a novel form of vat photopolymerisation, was used to fabricate personalised warfarin-loaded 3D-printed tablets (printlets). Eight different formulations containing varying amounts of warfarin (0.5-6.0% w/w) were used to print two different sized torus-shaped printlets within 6.5 to 11.1 s. Nuclear magnetic resonance (NMR) spectroscopy revealed the presence of only trace amounts of unreacted acrylate monomers, suggesting that the photopolymerisation reaction had occurred to near completion. All printlets completely solubilised and released their entire drug load within 2.5 to 7 h. NIR spectroscopy (NIRS) was used to non-destructively verify the dose of warfarin loaded into the vat photopolymerised printlets. The partial least square regression model built showed strong linearity (R2 = 0.980), and high accuracy in predicting the drug loading of the test sample (RMSEP = 0.205%). Therefore, this study advances pharmaceutical vat photopolymerisation by demonstrating the feasibility of producing water-soluble printlets via volumetric printing and quantifying the drug load of vat photopolymerised printlets with NIRS.

Treatment of glaucoma with drug-loaded contact lenses: A systematic review and meta-analysis

OBJECTIVE

This study is a systematical review regarding the glaucoma treatment with drug-loaded contact lenses. The effectiveness and safety about that were summarized, which providing effective suggestions and guidance for clinical research.

METHODS

The studies published up to May 1, 2024 on the treatment of glaucoma with sustained-release contact lenses were searched from CNKI, Wanfang Data, VIP, PubMed, Embase, Cochrane Library, and Medline. CAMARADES was used to evaluate literature quality. The safety, endpoints of intraocular pressure reduction (IOPR) and duration of intraocular pressure (IOP) decline during glaucoma treatment were analyzed by means of qualitative and quantitative methods. The protocol registration number is CRD42024487157.

RESULTS

47 studies were included. In clinical trials, glaucoma patients showed a 50% reduction in IOP and no corneal tissue destruction after wearing contact lenses. In animal experiments, the endpoint IOPR [MD = 0.58, 95%CI (0.37, 0.80), P < 0.00001] of the medicated contact lenses group was significantly better than that of the eye drops group. Subgroup analysis showed that contact lenses loaded with timolol (TML), with TML + dorzolamide, and with TML + latanoprost, which compared to eye drops, had a better effect on reducing IOP, while contact lenses loaded with puerarin, latanoprost, and TML + bimatoprost showed no statistical difference. Most studies demonstrated the duration of IOP reduction and drugs release in vitro for ≥3 days during contact lenses treatment.

CONCLUSION

Most drug-loaded contact lenses exhibit excellent effectiveness and safety. The nanoparticle-loaded contact lenses containing TML for glaucoma treatment is recommended in future clinical research.

Drug releasing contact lenses and their application to disease presentations

Eye drops, the most common method for anterior segment treatment, face challenges of inefficiency, with less than 7% instilled drugs typically reaching target tissues of interest. The advent of contact lens drug delivery systems offers a paradigm shift, enhancing drug residence time and bioavailability on the ocular surface. This review focuses on the considerations and challenges in developing contact lenses for drug delivery, particularly for managing four categories of ocular diseases: anterior segment infections, dry eye disease, ocular allergies, and glaucoma. Each disease category requires tailored therapeutic approaches, and the technical intricacies of drug-releasing contact lenses must address concerns related to lens properties, drug release duration, and safety. The aim of this review is to provide insights into the therapeutic needs of ocular diseases and offer a comprehensive overview of the progress made in this innovative approach. The emergence of a commercially available ketotifen fumarate-releasing lens serves as a testament to the feasibility and potential benefits of this innovative approach, paving the way for further refinement and targeted applications in ocular therapeutics.

3D printing of pharmaceutical dosage forms: Recent advances and applications

Three-dimensional (3D) printing, also referred to as additive manufacturing, is considered to be a game-changing technology in many industries and is also considered to have potential use cases in pharmaceutical manufacturing, especially if individualization is desired. In this review article the authors systematically researched literature published during the last 5 years (2019 - spring 2024) on the topic of 3D printed dosage forms. Besides all kinds of oral dosage forms ranging from tablets and capsules to films, pellets, etc., numerous reports were also identified on parenteral and cutaneous dosage forms and also rectal, vaginal, dental, intravesical, and ophthalmic preparations. In total, more than 500 publications were identified and grouped according to the site of administration, and an overview of the manuscripts is presented here. Furthermore, selected publications are described and discussed in more detail. The review highlights the very different approaches that are currently used in order to develop 3D printed dosage forms but also addresses remaining challenges.

Contact Lenses in Therapeutic Care: A Comprehensive Review of Past Innovations, Present Applications, and Future Directions

Contact lenses have become integral tools in the realm of ocular therapeutics, extending beyond their primary function of refractive correction to encompass a diverse array of therapeutic applications. This review explores the evolving role of contact lenses in managing various ocular conditions, highlighting their efficacy in enhancing patient outcomes. Initially developed to correct refractive errors, contact lenses now serve as effective vehicles for delivering medications directly to the ocular surface, offering targeted treatment for conditions such as dry eye syndrome and corneal ulcers. Their ability to provide sustained moisture and facilitate drug absorption makes them indispensable in promoting corneal healing and managing chronic ocular surface diseases. Specialized contact lenses designed for irregular corneas, such as those affected by keratoconus, provide both optical correction and structural support, significantly improving visual acuity and patient comfort. Additionally, orthokeratology lenses have shown promise in controlling myopia progression in children by reshaping the cornea overnight, thereby reducing reliance on corrective eyewear during waking hours. In post-surgical settings, therapeutic contact lenses aid in epithelial regeneration and minimize discomfort, accelerating recovery and improving surgical outcomes. They also play a crucial role in protecting the cornea from external irritants and promoting a stable tear film, crucial for maintaining ocular health. Looking ahead, ongoing advancements in contact lens materials and designs promise further innovation in ocular therapeutics, paving the way for personalized treatment strategies and improved patient care. As such, contact lenses continue to evolve as essential therapeutic tools, offering tailored solutions for a spectrum of ocular conditions and contributing to enhanced quality of life for patients worldwide.

Manufacturing and characterisation of 3D-printed sustained-release Timolol implants for glaucoma treatment

Timolol maleate (TML) is a beta-blocker drug that is commonly used to lower the intraocular pressure in glaucoma. This study focused on using a 3D printing (3DP) method for the manufacturing of an ocular, implantable, sustained-release drug delivery system (DDS). Polycaprolactone (PCL), and PCL with 5 or 10% TML implants were manufactured using a one-step 3DP process. Their physicochemical characteristics were analysed using light microscopy, scanning electronic microscopy (SEM), differential scanning calorimetry (DSC) / thermal gravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR). The in vitro drug release was evaluated by UV-spectrophotometry. Finally, the effect of the implants on cell viability in human trabecular meshwork cells was assessed. All the implants showed a smooth surface. Thermal analysis demonstrated that the implants remained thermally stable at the temperatures used for the printing, and FTIR studies showed that there were no significant interactions between PCL and TML. Both concentrations (5 & 10%) of TML achieved sustained release from the implants over the 8-week study period. All implants were non-cytotoxic to human trabecular cells. This study shows proof of concept that 3DP can be used to print biocompatible and personalised ocular implantable sustained-release DDSs for the treatment of glaucoma.

Chitosan nanoparticles laden contact lenses for enzyme-triggered controlled delivery of timolol maleate: A promising strategy for managing glaucoma

To improve drug bioavailability, eye drops can be replaced by drug-eluting contact lenses. However, issues of drug leaching from lenses during manufacture and storage, and sterilization, currently limit their commercial application. To address the issues, stimuli-(lysozyme)-sensitive chitosan nanoparticles were developed to provide controlled ocular drug delivery. Nanoparticles were prepared by ionic gelation and characterized by TEM, X-ray diffraction, DSC, and FTIR. In the flux study, conventional-soaked contact lenses (SM-TM-CL) showed high-burst release, while with direct drug-only laden contact lenses (DL-TM-CL) the drug was lost during extraction and sterilization, as well as having poor swelling and optical properties. The nanoparticle-laden contact lenses (TM-Cht-NPs) showed controlled release of timolol for 120 h in the presence of lysozyme, with acceptable opto-physical properties. In the shelf-life study, the TM-Cht-NPs contact lenses showed no leaching or alteration in the drug release pattern. In animal studies, the TM-NPs-CL lenses gave a high drug concentration in rabbit tear fluid (mean = 11.01 µg/mL for 56 h) and helped maintain a low intraocular pressure for 120 h. In conclusion, the chitosan nanoparticle-laden contact lenses demonstrated the potential application to treat glaucoma with acceptable opto-physical properties and addressed the issues of drug-leaching during sterilization and storage.

Advancements in Ocular Therapy: A Review of Emerging Drug Delivery Approaches and Pharmaceutical Technologies

Eye disorders affect a substantial portion of the global population, yet the availability of efficacious ophthalmic drug products remains limited. This can be partly ascribed to a number of factors: (1) inadequate understanding of physiological barriers, treatment strategies, drug and polymer properties, and delivery systems; (2) challenges in effectively delivering drugs to the anterior and posterior segments of the eye due to anatomical and physiological constraints; and (3) manufacturing and regulatory hurdles in ocular drug product development. The present review discusses innovative ocular delivery and treatments, encompassing implants, liposomes, nanoparticles, nanomicelles, microparticles, iontophoresis, in situ gels, contact lenses, microneedles, hydrogels, bispecific antibodies, and gene delivery strategies. Furthermore, this review also introduces advanced manufacturing technologies such as 3D printing and hot-melt extrusion (HME), aimed at improving bioavailability, reducing therapeutic dosages and side effects, facilitating the design of personalized ophthalmic dosage forms, as well as enhancing patient compliance. This comprehensive review lastly offers insights into digital healthcare, market trends, and industry and regulatory perspectives pertaining to ocular product development.

Towards Precision Ophthalmology: The Role of 3D Printing and Bioprinting in Oculoplastic Surgery, Retinal, Corneal, and Glaucoma Treatment

In the forefront of ophthalmic innovation, biomimetic 3D printing and bioprinting technologies are redefining patient-specific therapeutic strategies. This critical review systematically evaluates their application spectrum, spanning oculoplastic reconstruction, retinal tissue engineering, corneal transplantation, and targeted glaucoma treatments. It highlights the intricacies of these technologies, including the fundamental principles, advanced materials, and bioinks that facilitate the replication of ocular tissue architecture. The synthesis of primary studies from 2014 to 2023 provides a rigorous analysis of their evolution and current clinical implications. This review is unique in its holistic approach, juxtaposing the scientific underpinnings with clinical realities, thereby delineating the advantages over conventional modalities, and identifying translational barriers. It elucidates persistent knowledge deficits and outlines future research directions. It ultimately accentuates the imperative for multidisciplinary collaboration to enhance the clinical integration of these biotechnologies, culminating in a paradigm shift towards individualized ophthalmic care.

Technological Advances in a Therapy of Primary Open-Angle Glaucoma: Insights into Current Nanotechnologies

Glaucoma is a leading cause of irreversible blindness and is characterized by increased intraocular pressure (IOP) and progressive optic nerve damage. The current therapeutic approaches for glaucoma management, such as eye drops and oral medications, face challenges including poor bioavailability, low patient compliance, and limited efficacy. In recent years, nanotechnology has emerged as a promising approach to overcome these limitations and revolutionize glaucoma treatment. In this narrative review, we present an overview of the novel nanotechnologies employed in the treatment of primary open-angle glaucoma. Various nanosystems, including liposomes, niosomes, nanoparticles, and other nanostructured carriers, have been developed to enhance the delivery and bioavailability of antiglaucoma drugs. They offer advantages such as a high drug loading capacity, sustained release, improved corneal permeability, and targeted drug delivery to the ocular tissues. The application of nanotechnologies in glaucoma treatment represents a transformative approach that addresses the limitations of conventional therapies. However, further research is needed to optimize the formulations, evaluate long-term safety, and implement these nanotechnologies into clinical practice. With continued advancements in nanotechnology, the future holds great potential for improving the management and outcomes of glaucoma, ultimately preserving vision and improving the lives of millions affected by this debilitating disease.

Recent Advances of Ocular Drug Delivery Systems: Prominence of Ocular Implants for Chronic Eye Diseases

Chronic ocular diseases can seriously impact the eyes and could potentially result in blindness or serious vision loss. According to the most recent data from the WHO, there are more than 2 billion visually impaired people in the world. Therefore, it is pivotal to develop more sophisticated, long-acting drug delivery systems/devices to treat chronic eye conditions. This review covers several drug delivery nanocarriers that can control chronic eye disorders non-invasively. However, most of the developed nanocarriers are still in preclinical or clinical stages. Long-acting drug delivery systems, such as inserts and implants, constitute the majority of the clinically used methods for the treatment of chronic eye diseases due to their steady state release, persistent therapeutic activity, and ability to bypass most ocular barriers. However, implants are considered invasive drug delivery technologies, especially those that are nonbiodegradable. Furthermore, in vitro characterization approaches, although useful, are limited in mimicking or truly representing the in vivo environment. This review focuses on long-acting drug delivery systems (LADDS), particularly implantable drug delivery systems (IDDS), their formulation, methods of characterization, and clinical application for the treatment of eye diseases.

Review of Potential Drug-Eluting Contact Lens Technologies

The field of ophthalmology is expanding exponentially, both in terms of diagnostic and therapeutic capabilities, as well as the worldwide increasing incidence of eye-related diseases. Due to an ageing population and climate change, the number of ophthalmic patients will continue to increase, overwhelming healthcare systems and likely leading to under-treatment of chronic eye diseases. Since drops are the mainstay of therapy, clinicians have long emphasised the unmet need for ocular drug delivery. Alternative methods, i.e., with better compliance, stability and longevity of drug delivery, would be preferred. Several approaches and materials are being studied and used to overcome these drawbacks. We believe that drug-loaded contact lenses are among the most promising and are a real step toward dropless ocular therapy, potentially leading to a transformation in clinical ophthalmic practice. In this review, we outline the current role of contact lenses in ocular drug delivery, focusing on materials, drug binding and preparation, concluding with a look at future developments.

Innovation in the Development of Synthetic and Natural Ocular Drug Delivery Systems for Eye Diseases Treatment: Focusing on Drug-Loaded Ocular Inserts, Contacts, and Intraocular Lenses

Nowadays, ocular drug delivery still remains a challenge, since the conventional dosage forms used for anterior and posterior ocular disease treatments, such as topical, systemic, and intraocular administration methods, present important limitations mainly related to the anatomical complexity of the eye. In particular, the blood-ocular barrier along with the corneal barrier, ocular surface, and lacrimal fluid secretion reduce the availability of the administered active compounds and their efficacy. These limitations have increased the need to develop safe and effective ocular delivery systems able to sustain the drug release in the interested ocular segment over time. In the last few years, thanks to the innovations in the materials and technologies employed, different ocular drug delivery systems have been developed. Therefore, this review aims to summarize the synthetic and natural drug-loaded ocular inserts, contacts, and intraocular lenses that have been recently developed, emphasizing the characteristics that make them promising for future ocular clinical applications.

3D-printed long-acting 5-fluorouracil implant to prevent conjunctival fibrosis in glaucoma

OBJECTIVES

To develop a sustained release 5-fluorouracil (5-FU) implant by three-dimensional (3D) printing to effectively prevent conjunctival fibrosis after glaucoma surgery.

METHODS

3D-printed implants composed of polycaprolactone (PCL) and chitosan (CS) were fabricated by heat extrusion technology and loaded with 1% 5-FU. Light microscopy and scanning electron microscopy were used to study the surface morphology. The 5-FU concentration released over 8 weeks was measured by ultraviolet visible spectroscopy. The effects on cell viability, fibroblast contractility and the expression of key fibrotic genes were assessed in human conjunctival fibroblasts.

KEY FINDINGS

The PCL-CS-5-FU implant sustainably released 5-FU over 8 weeks and the peak concentration was over 6.1 μg/ml during weeks 1 and 2. The implant had a smooth surface and its total weight decreased by 3.5% after 8 weeks. The PCL-CS-5-FU implant did not affect cell viability in conjunctival fibroblasts and sustainably suppressed fibroblast contractility and key fibrotic genes for 8 weeks.

CONCLUSIONS

The PCL-CS-5-FU implant was biocompatible and degradable with a significant effect in suppressing fibroblast contractility. The PCL-CS-5-FU implant could be used as a sustained release drug implant, replacing the need for repeated 5-FU injections in clinic, to prevent conjunctival fibrosis after glaucoma surgery.

3D Printing Technologies in Personalized Medicine, Nanomedicines, and Biopharmaceuticals

3D printing technologies enable medicine customization adapted to patients' needs. There are several 3D printing techniques available, but majority of dosage forms and medical devices are printed using nozzle-based extrusion, laser-writing systems, and powder binder jetting. 3D printing has been demonstrated for a broad range of applications in development and targeting solid, semi-solid, and locally applied or implanted medicines. 3D-printed solid dosage forms allow the combination of one or more drugs within the same solid dosage form to improve patient compliance, facilitate deglutition, tailor the release profile, or fabricate new medicines for which no dosage form is available. Sustained-release 3D-printed implants, stents, and medical devices have been used mainly for joint replacement therapies, medical prostheses, and cardiovascular applications. Locally applied medicines, such as wound dressing, microneedles, and medicated contact lenses, have also been manufactured using 3D printing techniques. The challenge is to select the 3D printing technique most suitable for each application and the type of pharmaceutical ink that should be developed that possesses the required physicochemical and biological performance. The integration of biopharmaceuticals and nanotechnology-based drugs along with 3D printing ("nanoprinting") brings printed personalized nanomedicines within the most innovative perspectives for the coming years. Continuous manufacturing through the use of 3D-printed microfluidic chips facilitates their translation into clinical practice.

Fabrication of 3D-Printed Contact Lens Composed of Polyethylene Glycol Diacrylate for Controlled Release of Azithromycin

Since three-dimensional (3D)-printed tablets were approved by the United States Food and Drug Administration (FDA), 3D printing technology has garnered increasing interest for the fabrication of medical and pharmaceutical devices. With various dosing devices being designed for manufacture by 3D printing, 3D-printed ophthalmic formulations to release drugs have been one such target of investigation. In the current study, 3D-printed contact lenses designed for the controlled release of the antibiotic azithromycin were produced by vat photopolymerization, and the effect of the printer ink composition and a second curing process was investigated. The azithromycin-loaded contact lenses were composed of the cross-linking reagent polyethylene glycol diacrylate (PEGDA), PEG 400 as a solvent, a photoinitiator, and azithromycin. The 3D-printed contact lenses were fabricated successfully, and formulations with lower PEGDA concentrations produced thicker lenses. The mechanical strength of the PEGDA-based contact lenses was dependent on the amount of PEGDA and was improved by a second curing process. Drug release from 3D-printed contact lenses was reduced in the samples with a second curing process. The azithromycin-loaded contact lenses exhibited antimicrobial effects in vitro for both Gram-positive and -negative bacteria. These results suggest that 3D-printed contact lenses containing antibiotics are an effective model for treating eye infections by controlling drug release.

3D printing in Ophthalmology: From medical implants to personalised medicine

3D printing was invented thirty years ago. However, its application in healthcare became prominent only in recent years to provide solutions for drug delivery and clinical challenges, and is constantly evolving. This cost-efficient technique utilises biocompatible materials and is used to develop model implants to provide a greater understanding of human anatomy and diseases, and can be used for organ transplants, surgical planning and for the manufacturing of advanced drug delivery systems. In addition, 3D printed medical devices and implants can be customised for each patient to provide a more tailored treatment approach. The advantages and applications of 3D printing can be used to treat patients with different eye conditions, with advances in 3D bioprinting offering novel therapy applications in ophthalmology. The purpose of this review paper is to provide an in-depth understanding of the applications and advantages of 3D printing in treating different ocular conditions in the cornea, glaucoma, retina, lids and orbits.

Additive Manufacturing Strategies for Personalized Drug Delivery Systems and Medical Devices: Fused Filament Fabrication and Semi Solid Extrusion

Novel additive manufacturing (AM) techniques and particularly 3D printing (3DP) have achieved a decade of success in pharmaceutical and biomedical fields. Highly innovative personalized therapeutical solutions may be designed and manufactured through a layer-by-layer approach starting from a digital model realized according to the needs of a specific patient or a patient group. The combination of patient-tailored drug dose, dosage, or diagnostic form (shape and size) and drug release adjustment has the potential to ensure the optimal patient therapy. Among the different 3D printing techniques, extrusion-based technologies, such as fused filament fabrication (FFF) and semi solid extrusion (SSE), are the most investigated for their high versatility, precision, feasibility, and cheapness. This review provides an overview on different 3DP techniques to produce personalized drug delivery systems and medical devices, highlighting, for each method, the critical printing process parameters, the main starting materials, as well as advantages and limitations. Furthermore, the recent developments of fused filament fabrication and semi solid extrusion 3DP are discussed. In this regard, the current state of the art, based on a detailed literature survey of the different 3D products printed via extrusion-based techniques, envisioning future directions in the clinical applications and diffusion of such systems, is summarized.