Biomedical Engineering Reference
In-Depth Information
5.3. Jet Injectors
Jet injectors operate by employing compressed gas to push the drug liquid
or powders through a nozzle as a strong jet towards the skin to create micron-
sized channels in the stratum corneum. This technology does not require
heating the skin or using any type of needles for drug transportation. An
example of liquid jet injectors is the Medi-Jector
®
device (Antares Pharma,
USA) which can be used for delivery of insulin (Bremseth and Pass, 2001).
Solid jet injectors have been suggested for DNA vaccination using gold
microparticles (Morel et al., 2004; Giudice and Campbell, 2006).
6.
D
EVICES
U
SED IN
O
PHTHALMIC
D
RUG
D
ELIVERY
Ophthalmic drug delivery is most commonly used to treat local diseases
within the eye such as glaucoma. Eye drops are the most common ophthalmic
delivery devices. More recently, ocular inserts have been developed to
overcome inaccurate dosing offered by conventional eye drops and the
possibility of systemic side effects or subtherapeutic effects that may occur
when eye drops are used. Drainage of the eye drop liquid during
administration to the eye is a major disadvantage that made ocular inserts
really desirable. Inserts offer more accurate dosing, prolonged contact time
between the drug and ophthalmic tissues and reduced systemic adverse effects.
Ocusert
®
(Alza Pharmaceuticals, USA) is an ocular insert offering
controlled release of pilocarpine for treatment of glaucoma and reducing
intraocular pressure. This type of inserts is insoluble and consists of a
pilocarpine algenate reservoir sandwiched in between two thin films of
ethylene vinyl acetate and sealed with a ring made of the same material
(Saettone and Salminen, 1995). There are some soluble (erodible) inserts such
as the New Ophthalmic Delivery System (NODS) in which the film is
polyvinyl alcohol (Saettone and Salminen, 1995). The bioavailability of
pilocarpine using the NODS has been reported to be much higher than that
obtained by using pilocarpine eye drops (Kelly et al., 1989).
