Aptar’s Ophthalmic Squeeze Dispenser: A Versatile Delivery System
Challenges associated with eye care formulations
Eye drops can be very different from each other and their behavior is extremely difficult to predict. Artificial tears used to supplement the tear film do not contain active ingredients but vary in rheological properties such as viscosity depending on patients’ need from low to highly viscous. Eye drops containing active drugs, for glaucoma treatment as an example, may contain several of auxiliary compounds to stabilize the formulation. The dropper should always deliver an appropriate drop size, the formulation must be stable for the storage and in use period, and the forces to deliver a drop should remain in a reasonable range.
How the Ophthalmic Squeeze Dispenser (OSD) works
To understand the delivery system, its flexibility as well as technical limits, it is important to explain how it works. It follows a purely mechanical approach to prevent microbial contamination of the product and uses the “tip seal technology”, a specifically developed outlet valve technology, and sterile filtration of the venting air. Like any other conventional dropper bottle, OSD needs to be held in angular or complete upside down position to deliver drops. The system is primed by squeezing the bottle until the first drop is delivered. During the actuation process (squeezing the bottle) the pressure within the system rises and the liquid is forced through the liquid channel into the space between spray pin and applicator. As soon as the liquid pressure exceeds the valve spring force of the tip seal, the central part of the spray pin is forced backwards and the orifice opens and liquid is dispensed. The special outer geometry of the orifice allows the product to form and deliver a drop. The tip seal outlet valve closes immediately with an outward movement when the pressure drops below a defined threshold. This function is self-regulating and prevents any backflow into the system and thus potential microbial contamination.
The wider use of preservative free multi-dose delivery devices for eye drops has started in Europe for artificial tears. Patients and consumers appreciate the convenient and intuitive handling of OSD, properties which are important for the further success of this device. For pharmaceutical manufacturers, the cost effectiveness of OSD is another important aspect.