Ocular Delivery is a controlled delivery system
- Release at a constant rate for a long time
- Enhanced corneal absorption
- Drug with not serious side effect or tolerate by the patient
- Prolonged release of drug from vehicle but blurred vision, patient non compliance and oil entrapment are the drawbacks.
- Comfortable, less blurred vision but the drawbacks are matted eyelids and no rate control on diffusion.
Ocular Delivery Methods Its not all eyedrops!!!
There are so many different types of ocular delivery systems.
Ocular Drug Delivery
ROUTES OF OCULAR DRUG DELIVERY
There are several possible routes of drug delivery into the ocular tissues . The selection of the route of administration depends primarily on the target tissue. Traditionally topical ocular. Design of the dosage form can have big influence on the resulting drug concentrations and on the duration of drug action.
Topical ocular:
Typically topical ocular drug administration is accomplished by eye drops, but they have only a short contact time on the eye surface. The contact, and thereby duration of drug action, can be prolonged by formulation design. During the short contact of drug on the corneal surface it partitions to the epithelium and in the case of lipophilic compounds it remains in the epithelium and is slowly released to the corneal stroma and further to the anterior chamber. After eye drop administration the peak concentration in the anterior chamber is reached after 20–30 min.
TRANSPORTERS IN EYE
The traditional approach to improve ocular bioavailability is to modify the drug chemically to achieve the desired solubility and lipophilicity. However, a more rational approach would be a transporter-targeted modification of the drug. Transporters are membrane-bound proteins that play an important role in active transport of nutrients across biological membranes. The presence of transporters has been reported on various ocular tissues
Advantages of Ocular Delivery systems
There are so many different types of ocular delivery systems.
- intravitreal injections
- Subconjunctival
- SubTenon
- Retrobulbar
- Periocular
- Intracamerular
- Sub-retinal
- Intrascleral / Scleral plug
- Suprascleral / Transscleral iontophoresis
- Intrastromal administration
- Suprachoroidal
- Eye drops
Ocular Drug Delivery
- Ophthalmic preparation, Applied topically to the cornea, or instilled in the space between the eyeball and lower eyelid
- Dilute with tear and wash away through lacrimal apparatus
- Administer at frequent intervals◦Suspension
- Longer contact time
- Irritation potential due to the particle size of drug◦Ointment
- Longer contact time and greater storage stabilityProducing film over the eye and blurring vision
ROUTES OF OCULAR DRUG DELIVERY
There are several possible routes of drug delivery into the ocular tissues . The selection of the route of administration depends primarily on the target tissue. Traditionally topical ocular. Design of the dosage form can have big influence on the resulting drug concentrations and on the duration of drug action.
Topical ocular:
Typically topical ocular drug administration is accomplished by eye drops, but they have only a short contact time on the eye surface. The contact, and thereby duration of drug action, can be prolonged by formulation design. During the short contact of drug on the corneal surface it partitions to the epithelium and in the case of lipophilic compounds it remains in the epithelium and is slowly released to the corneal stroma and further to the anterior chamber. After eye drop administration the peak concentration in the anterior chamber is reached after 20–30 min.
TRANSPORTERS IN EYE
The traditional approach to improve ocular bioavailability is to modify the drug chemically to achieve the desired solubility and lipophilicity. However, a more rational approach would be a transporter-targeted modification of the drug. Transporters are membrane-bound proteins that play an important role in active transport of nutrients across biological membranes. The presence of transporters has been reported on various ocular tissues
Advantages of Ocular Delivery systems
- Increased accurate dosing. To overcome the side effects of pulsed dosing produced by conventional systems
- To provide sustained and controlled drug delivery
- To increase the ocular bio availability of drug by increasing the corneal contact time.
- To provide targeting within the ocular globe so as to prevent the loss to other ocular tissues
- To circumvent the protective barriers like drainage
- To provide comfort, better compliance to the patient and to improve therapeutic performance of drug
- To provide better housing of delivery system.