Novel Drug Delivery Systems: Innovative Approaches in Ophthalmic Compounding

(Newswire.net — August 2, 2023) — The development of innovative drug delivery systems (NDDS) for ophthalmic compounding has emerged as a solution to several challenges associated with traditional drug delivery methods. These include difficulty reaching the posterior eye segments, poor patient compliance, tearing wash-out, and systemic toxicity.  

It is worth noting that the problem is global; as stated by the World Health Organization, approximately 217 million adults suffered from eye conditions that resulted in visual impairment in 2015. Thanks to NDDS, the pharmaceutical landscape has experienced a significant transformation, providing increased safety, efficiency, precision, and effectiveness in drug delivery. 

Significant Benefits Of NDDS 

One of the most significant benefits of NDDS is that they enable drugs to permeate the layers of the eyes and target the primary area effectively. For instance, Avastin injection facilitates the safe delivery of the drug to the posterior segment of the eye – a feat challenging to achieve with traditional delivery methods.  

This strategy can regulate drug concentration at the targeted site, reducing side effects and improving patient outcomes because of the precise delivery. 

Innovative Approaches In Ophthalmic Compounding 

The bioavailability of conventional eye drops is only 5% because of loss through tearing and poor absorption, and systemic drugs have even lower absorption at 1-3%. But with NDDS, drugs effectively permeate the layers of the cornea or the vitreous and hurdle the drug’s interaction with enzymes or proteins in the tear film – while maintaining an adequate concentration to effectively reach and impact the primary target area.  

Here are some examples of these innovative approaches in ophthalmic compounding: 

1. Intravitreal Injections

This method involves injecting medication directly into the eye’s vitreous, the gel-like substance. It’s often used to deliver drugs to the posterior segment of the eye, targeting conditions like age-related macular degeneration (AMD) and diabetic retinopathy.  

Although Avastin (bevacizumab) is primarily a cancer medication, it has proven effective in ophthalmology, particularly in combating the progression of AMD, thus carving out a niche for itself in this field. 

2. Ocular Implants 

These are small devices inserted into the eye to provide sustained drug delivery over extended periods. They can be non-biodegradable, requiring surgical removal once the drug is depleted, or biodegradable, which dissolves over time.  

These implants ensure constant drug concentration and enhance patient compliance, enabling effective treatment of both anterior and posterior eye disorders. Here are some key drugs given via ocular implants and their corresponding conditions: 

• Fluocinolone Acetonide: This drug is FDA-approved for chronic non-infectious uveitis affecting the posterior segment of the eye. 
• Dexamethasone: This drug is approved for treating several conditions, including macular edema following retinal vein occlusion, non-infectious uveitis affecting the posterior segment of the eye, and diabetic macular edema. 
• Ganciclovir: An implant delivers ganciclovir for the treatment of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS). 
• Bimatoprost: A biodegradable implant releases bimatoprost, a prostaglandin analog. It is FDA-approved for reducing intraocular pressure in patients with open-angle glaucoma or ocular hypertension. 
• Ranibizumab: The port delivery system (PDS) with ranibizumab is a refillable eye implant that continuously delivers a customized formulation of ranibizumab, an anti-VEGF agent. It’s designed to treat neovascular (wet) age-related macular degeneration (AMD). 

They require surgical implantation and sometimes removal procedures, which can have associated risks. Therefore, the benefits and risks should be carefully considered on an individual patient basis. 

3. Nanoparticle-Based Delivery And Treatment 

Nanotechnology holds revolutionary potential for various industries, including Medicine. Nanotechnology is vital in diagnostics, drug delivery, and active therapeutic components in ophthalmic treatments. Nanoparticles containing lipids, metals, polysaccharides, or polymers exhibit diverse applications, effectively targeting the cornea and vitreous in the anterior segment, as well as the retina and choroid in the posterior area.  

Researchers are actively exploring nanotechnology’s regenerative applications in ophthalmology. Nanosized drugs or nano delivery systems have been FDA-cleared for conditions such as:  

• Dry Eye Syndrome 
• Eye Inflammation 
• Acute Keratitis associated with dry eye syndrome 
• Choroidal Neovascularization 
• Ocular Histoplasmosis Syndrome 
• Pathological Myopia 
• Antivascular endothelial growth factor (anti-VEGF) 
• Macular Edema 
• Uveitis 

Nanoemulsions or colloidal drug delivery systems are particularly effective in enhancing drug solubility, stability, and bioavailability, often utilized for poorly soluble drugs intended for topical use. 

4. Microneedles

These are minimally invasive tools capable of delivering drugs into the eye’s specific layers with less discomfort and risk than traditional injections. They can potentially target both the anterior and posterior segments of the eye. 

This mode of delivery, under clinical investigation for the treatment of fungal keratitis (FK), uses a dissolving microneedle patch consisting of hyaluronic acid (HA) and polylactic acid (PLA). Recovery is quick, and the procedure is minimally invasive.  

5. Hydrogels

These are three-dimensional, hydrophilic networks capable of absorbing high amounts of water or biological fluids. Their biocompatibility and ability to respond to environmental changes make them suitable for controlled drug release. In a nutshell, they are able to sustain drug release. 

6. Drug-Eluting Contact Lenses

These lenses are designed to release drugs gradually, boost sustained drug delivery, and improve patient comfort and treatment adherence. They can provide sustained drug delivery, thus enhancing patient comfort and compliance. An example of drug-eluting contact lenses is ACUVUE, a disposable lens released in 2022. It contains Ketotifen, an antihistamine. 

Conclusion 

Ophthalmic diseases that are poorly treated because of low absorption can lead to poor vision and blindness. NDDSs in ophthalmic compounding present significant advantages, including increased bioavailability, precise drug targeting, extended duration of effects, and improved drug metabolism. With NDDS, nanoparticles can aid in diagnosing diseases, act as couriers for drugs that can’t go through the barriers, and actively treat conditions like uveitis, macular edema, dry eyes, uveitis, and acute Keratitis, among others. 

Despite the promising potential, each method has challenges and considerations, which researchers continue to study and refine to offer safer and more effective ophthalmic treatments.