So what is this Brain Blood Barrier (BBB) that so far prevents delivery of most medications to the brain? Wikipedia has, as often, an excellent entry on the BBB topic [1]. In a nutshell, the "barrier" is more like a filter, filtering out bacteria and other large molecules. The Generic Look encyclopedia has a good layman entry on the BBB [2].
[![][1]][2]
Blood Capillaries at the Blood-Brain Barrier (Wikipedia)
Certainly the BBB isn't perfect and some nasty brain bacterial infections, such as meningitis, can occur [3]. How does certain pathogens defeat the BBB is not clear and involves complex physical chemistry. [4,5]. But clearly if the certain bacteria and viruses can traverse the barrier, researchers should be able to find a way to send across medication too.
What if medication were riding on very small "nanoparticle" size entities to penetrate the BBB? ( a nanometer is one billionth of a meter). Such research is ongoing [6] "…The plant virus, cow pea mosaic virus (CPMV), has recently been explored as a nanoparticle delivery system for therapeutics targeting a number of diseases including cancer and neurodegeneration…"
Other types of nanometer range size vectors, or drug carriers, are being explored, such as polymers [7]
Additional ways to bypass the BBB for MS treatments include Intranasal Delivery [9]: ""…intranasal delivery to the CNS, with a discussion of pathways from the nasal cavity to the CNS involving the olfactory and trigeminal nerves, the vasculature, the cerebrospinal fluid, and the lymphatic system…" _Sounds like going through the backdoor of the brain to me, as opposed to breaking through…_Keep in mind that nasal delivery is not as simple as it seems. The [OptiNose Company ][3]has an interesting video describing a nasal delivery system.
Talk to your Doctor about this exciting ongoing research.
Sources:
[1] [Blood-Brain Barrier, Wikipedia][4]
[2] Blood Brain Barrier; [GenericLook Encyclopedia][5]
[3] [emedicine health, brain infections][6]
[4] [Trends in Microbiology][7]; "How do extracellular pathogens cross the blood-brain barrier?" 2002 May;10(5):227-32
[5] Science ; ""Meningococcal type IV pili recruit the polarity complex to cross the brain endothelium" ; 2009 Jul 3;325(5936):83-7. Epub 2009 Jun 11
[6] [Journal of NeuroImmunology][8]; "Viral nanoparticles associate with regions of inflammation and blood brain barrier disruption during CNS infection";
[7] [BMC Neuroscience][9]; "Nanotechnology approaches to crossing the blood-brain barrier and drug delivery to the Central Nervous System"
[8][Expert Opinion drug Delivery ][10]" Polymeric nanoparticles for the drug delivery to the central nervous system "
[9][Journal of Pharmaceutical Sciences][11]; "Intranasal delivery to the central nervous system: mechanisms and experimental considerations"; J Pharm Sci. 2010 Apr;99(4):1654-73
Technorati Tags: [BBB][12], [Blood Brain Barrier][13], [Drug Delivery][14], [MND][15], [multiple sclerosis][16], [Research Progress][17]
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[1]: http://www.medinewsdigest.com/wp-content/uploads/2011/09/Wiki_Blood_Capillaries_Brain-e1315195204604.png (Wiki_Blood_Capillaries_Brain)
[2]: http://www.medinewsdigest.com/wp-content/uploads/2011/09/Wiki_Blood_Capillaries_Brain.png
[3]: http://www.optinose.com/
[4]: http://en.wikipedia.org/wiki/Blood-brain_barrier
[5]: http://www.genericlook.com/anatomy/Blood-Brain-Barrier/
[6]: http://www.emedicinehealth.com/brain_infection/page2_em.htm
[7]: http://www.ncbi.nlm.nih.gov/pubmed/11973156
[8]: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2858070/
[9]: http://www.biomedcentral.com/1471-2202/9/S3/S4
[10]: http://www.ncbi.nlm.nih.gov/pubmed/18248316
[11]: http://www.ncbi.nlm.nih.gov/pubmed/19877171
[12]: http://technorati.com/tag/BBB
[13]: http://technorati.com/tag/Blood+Brain+Barrier
[14]: http://technorati.com/tag/Drug+Delivery
[15]: http://technorati.com/tag/MND
[16]: http://technorati.com/tag/multiple+sclerosis
[17]: http://technorati.com/tag/Research+Progress
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