MicroWick and Microcatheter sustained release devices are used in:

Ans is 'd' i.e. Delivering drug to the round membrane Repeat from Nov 08Micro Wick and Microcatheter are methods of delivery of medications directly to the inner ear.Intratympanic direct therapy for inner ear diseases has several advantages over the conventional systemic and indirect therapy:Increased therapeutic concentrations in the inner ear Reduced side-effectsCan be used when systemic therapy is contraindicatedCan be used when systemic therapy failsIn direct therapy to the inner ear, the drug is delivered at the Round window membrane. Round window membrane separates the middle ear from the inner ear. A large range of substances are able to cross the RWM, including antimicrobials, corticosteroids, anesthetics etc.Delivery methods: Typical intratympanic injection- Drug is administered directly around RWM using injection after a myringotomy. There are several drawbacks of intratympanic injection method i.e. the injected medication may leak down the Eustachian tube, escape out of the external auditory canal, or be sequestered in the middle ear. In order to address these problems, several sustained release vehicles have been developed.Gelfoam method- A dry gelfoam pad can be placed directly in the round window niche. The medication is directly injected over the gelfoam pad.Mechanical sustained release devices- there are 2 devices that are presently used for sustained release of the medication:The Silverstein Micro Wick- It is made of polyvinyl acetate. It's a wick measuring 1x9 mm small enough to fit through a tympanostomy tube. The wick absorbs medication which can be instilled into the external auditory canal by the patient at home and delivers it to the RWM.The Intra Ear Microcatheter- consists of an electronic pump connected to a catheter tip that is placed directly on the RWM. Implantation of the Microcatheter is more invasive and requires the elevation of a tympanomeatal flap.Fully implantable micro pump system- This device is made from pure titanium, polyethylene, and silicone and is designed for life-long implantation in humans. To place the device, a cavity is drilled in the mastoid bone to house the pump and the reservoir system, a procedure that is similar to the one used to place cochlear implants or implantable hearing devices. This device can deliver drugs which require chronic and continuous application.