Through mucosal membrane - high surface area and very well perfused. Posterior nasal passages and sinuses harder to reach.
Local action required but maybe distributed into circulation directly or by ciliated cells transporting mucous which takes drug particles with it. Can lead to systemic effect – side effects
Some drug metabolising enzymes exist in the nasal cavity. Once in general circulation, they will be subject to first pass metabolism.
Cleared out with mucous. Slower for drugs administered by spray rather than by drops, as drops are often held on ciliated surfaces. More cilia are present on posterior and middle cavities, so clearance quicker from here.
Excretion following metabolism if in systemic circulation.
Nasal drops Vs Sprays
Nasal drops: theoretically less likely to cause systemic side effects as larger droplets that run off the surface, so less contact time for absorption. More difficult to measure accurate dose.
Nasal spray: pump mechanism for accurate measured dose. Better mucosal distribution and slower clearance from drug spray generated
There are two main drug groups administered via the nasal route. Select an option below to learn more.