Treating posterior segment eye diseases
Intravitreal injections involve the administration of small volumes of drug, typically between 20 and 100 µL into the vitreous – the jelly like fluid inside the eyeball. Injections are prepared by technicians and administered by experienced retina specialists in clinical settings. The standard of care is to inject the patient using various types of devices such as syringe and vial or pre-filled syringes. This route is very effective for treating a range of retinal diseases such as AMD as it can easily bypass all ocular barriers. However, this type of injection to the eye is invasive and can sometimes cause retinal damage as it is less targeted than other methods of ocular delivery.
The therapeutic agent is injected at the front of the eye but travels to the choroid and retina. This delivery route is indicated for patients with neovascular age-related macular degeneration, diabetic retinopathy, uveitis and more. The main advantage is that this technique delivers the drug to specific tissues at high concentrations, as opposed to being spread into both affected and healthy tissues. However, this method does require extra training for healthcare professionals, especially if microneedles are used as preparation and delivery of small liquid volumes can be challenging.
This technique is performed in an operating room and is the standard method for injecting gene therapy for people with retinal diseases. This drug delivery route is very targeted but also very invasive and can lead to complications and additional risks for patients.
Drug eluting implants
For the last 15 years, treatment options for people with retinal diseases have been limited. While intra ocular injections are effective in treating diseases, many patients require regular monthly (or bi-monthly) injections to optimise drug efficiency. More recently, cutting-edge ocular implants have been revolutionising the treatment of retinal diseases. Current implants come in two categories: biodegradable (bioresorbable – which are inserted and absorbed by the body over time) and non-biodegradable (biodurable – implants that do not break down in the eye and have to be removed or refilled once the treatment is complete).
A prime example of a biodurable implant is the port delivery system developed by Genentech/Roche to deliver ranibizumab for the treatment of wet, or neovascular age-related macular degeneration (AMD). The port device is implanted surgically and is a permanent refillable eye implant, approximately the size of a grain of rice, designed to continuously deliver a customised formulation of ranibizumab over a period of months. This process can reduce the treatment burden associated with frequent eye injections. Other examples of a bioabsorbable implant is Allergans Ozurdex® – a small implant that slowly releases corticosteroid medication over time, without the need for monthly injections. It dissolves naturally and does not need to be surgically removed.
Overall, implants offer patients many improvements for ocular treatments compared to injections. However, the development of manufacturing controls to ensure homogenous drug concentrations is essential. In addition, the development of surgical procedures, including identification and assessment of associated human factors risks, require considerable expertise to manage.
At Team Consulting, we have a 35-year history of developing novel drug delivery technologies to treat a wide range of therapy areas. We would be delighted to talk about how we can help solve your ocular delivery challenges. Get in touch.
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Timo Kangastupa, A New Platform ofr Suprachoroidal Drug Delivery Using Standard Commercially Available Needles. ONdrugDelivery, 2022, Issue 130.