Biomedical Engineering Reference
In-Depth Information
increase the residence time of formulation within the nose and consequently
enhance the systemic absorption of the active ingredient. Nasal sprays are of
two types which are squeezed bottle sprays and metered-dose (nasal pump)
sprays.
4.2.1. Squeezed Bottle Sprays
Squeezed bottle sprays comprise a plastic container and an outlet jet
having a tiny hole on top of it to release a liquid spray when the lower region
of the container is manually squeezed (Kublik and Vidgren, 1998). Squeezed
bottle sprays may not give reproducible output because the method and
strength of squeezing the bottle vary from one patient to another,.. The dose
delivered and site of deposition within the nose have been reported to be
highly affected by the mode of use (Mygind and Vesterhauge, 1978).
4.2.2. Metered Dose (Pump) Sprays
Metered dose sparays are also called nasal pumps or pump sprays.
Compared to squeezed bottle sprays, the metered dose sprays deliver more
precise drug doses to the nasal cavity, are reliable and convenient to use
(Kublik and Vidgren, 1998). Nasal pumps can deliver precisely metered
volumes of up to 200µl. However, the angle of the device can affect the site of
deposition within the nasal cavity. The pump sprays can be propellant-free or
propellant-driven (pressurised). The pressurised pumps operate in a manner
similar to that previously explained for pMDIs (Southall and Ellis, 2000).
Nasal pump devices can also be divided into multiple dose sprays and
single dose sprays. Single dose sprays overcome the microbial contamination
problems that are likely to occur when multiple dose sprays are used, however,
aseptic filling is required. Thus, preservatives may not be needed for single
dose nasal devices (Kublik and Vidgren, 1998). An example of single-dose
pump sprays is the Monospray device. The output on actuation from this
device is reported to be between 70 to 90% depending on the mode of
administration (Kublik and Vidgren, 1998).
Microbial contamination of formulation within multi-dose spray container
may be brought about by replcement of the released liquid volume and some
of air within the container by external air, for instance, when squeezed bottle
systems are used. This problem can be overcome by using collapsable
container systems, for instance, the Nasal 360 device. After each dose
delivered the container would decrease in volume (Kublik and Vidgren, 1998).
Alternatively, some devices are designed so that the dose released is replaced
