GC: n
S: FDA – http://www.fda.gov/downloads/Drugs/GuidanceComplianceRegulatoryInformation/Guidances/UCM389370.pdf (last access: 17 November 2015); SADC – http://www.ich.org/fileadmin/Public_Web_Site/ABOUT_ICH/Organisation/SADC/Guideline_on_Bioavailability_and_Bioequivalance.pdf (last access: 17 November 2015); FNB – http://fnb.sagepub.com/content/24/3_suppl1/S20.full.pdf (last access: 19 November 2015).
N: 1. Word composed by the word-forming element bio-, from Greek bios-, “life” and the word availability, from available, meaning “at one’s disposal, capable of being made use of”, and the word-forming element -ity making abstract nouns from adjectives and meaning “condition or quality of being”, from Latin -itatem (nominative -itas), suffix denoting state or condition.
2. Bioavailability refers to the rate and extent to which the Active Pharmaceutical Ingredient (API), or its active moiety, is absorbed from a pharmaceutical product and becomes available at the site of action.
Bioavailability is assessed using three main pharmacokinetic variables:
- the area under the blood drug concentration versus time curve (AUC)
- the maximum blood concentration (Cmax)
- the time to reach maximum concentration (Tmax)
3. It may be useful to distinguish between:
- “absolute bioavailability” of a given dosage form as compared with that (100 %) following intravenous administration (e.g. oral solution vs. iv.), and
- “relative bioavailability” as compared with another form administered by the same or another non- intravenous route (e.g. tablets vs. oral solution)
4. Bioavailability and bioequivalence sound very similar but they are very different and cannot be used interchangeably. In fact, if two medicines are bioequivalent there is no clinically significant difference in their bioavailability.
The term “bioavailability” refers to the extent to which a drug/nutrient reaches its site of action or a biological fluid such as blood that has access to its site of action. “Relative bioavailability” is assessed using a reference product and “absolute bioavailability” is determined using the iv as 100%.
The term “bioequivalence” refers to pharmaceutically equivalent drug products where the rates/extents of bioavailability of the actives are not significantly different under suitable test conditions. In other words, this is a comparison of two or more products with respect to their bioavailability.
S:1. OED – http://goo.gl/OE3rCc (last access: 19 November 2015). 2. SADC – http://www.ich.org/fileadmin/Public_Web_Site/ABOUT_ICH/Organisation/SADC/Guideline_on_Bioavailability_and_Bioequivalance.pdf ; BPAC – http://www.bpac.org.nz/BPJ/2009/generics/docs/bpjse_generics_bio_pages_4-8.pdf (last access: 20 November 2015). 3. SADC – http://www.ich.org/fileadmin/Public_Web_Site/ABOUT_ICH/Organisation/SADC/Guideline_on_Bioavailability_and_Bioequivalance.pdf (last access: 20 November 2015). 4. Epichealth – http://www.epic4health.com/bioeqandbioa.html (last access: 20 November 2015).
SYN:
S:
CR: drug therapy
