How does one calculate fine particle fraction by the dry powder inhalation formulation?
The fine particle fraction (FPF) is the fraction of emitted particles that are less than a particle size that is considered the upper limit of respirable. Some say this is 5 micron, some use 3.5 micron MMAD. The lower number appears to have better correlation with in vivo deposition.
The literature is actually very confusing in this regard. As Jim points people use different size cutoffs. People also use different comparators. Some express the percentage as a percentage of the nominal dose loaded into a capsule or blister. Others use the emitted dose or delivered dose as Jim states. Still others use only the dose that is delivered to the impactor stages, i.e., the dose that makes it past the USP throat. This makes it very challenging when comparing publications, and review articles can be especially misleading...
Dear Sir,
Many thanks for your reply. I am completely agreed with you. I also have gone through literature and find different cut off diameters and methodologies for the same.
High Regards
Charan
Charan Singh
I think, as Dr Fink mentioned, the emitted dose is more reliable.
because we should be sure about the exact dose which can be in terminal alveoles.
so, FPF: Emitted dose/3.5 or 5 micron
Different regulatory agencies use different definitions for expressing FPF/FPM as measured by ACI or NGI, for example.
- Badges
- Science topic
- Similar topics
- Engineering
- Materials Engineering
- Powders