Here are the articles and info on GABA crossing the blood brain barrier.
GABA
The only way to deliver GABA effectively is to circumvent the blood-brain barrier. Indeed, there are a small, limited number of over-the-counter supplements that are derivatives of GABA, such as phenibut and picamilon combines niacin and GABA and crosses the blood–brain barrier as a prodrug that later hydrolyzes into GABA and niacin.
Phenibut
There are numerous reports of withdrawal symptoms on Internet forums and blogs including "nervousness and shakiness, psychomotor agitation, feeling easily annoyed and irritated, fatigue, poor appetite, heart pounding and racing, nausea, insomnia, and feeling tense and keyed up", consistent with its GABAB agonist properties. There has been no systematic study of this problem
http://www.ncbi.nlm.nih.gov/pubmed/23391959
http://www.ncbi.nlm.nih.gov/pubmed/21476277
http://www.ncbi.nlm.nih.gov/pubmed/20841974
http://www.ncbi.nlm.nih.gov/pubmed/19899708
http://www.ncbi.nlm.nih.gov/pubmed/19334514
http://www.ncbi.nlm.nih.gov/pubmed/18607733
Picamilon
Picamilon is able to cross the blood–brain barrier and then is hydrolyzed into GABA and niacin. The released GABA in theory would activate GABA receptors potentially producing an anxiolytic response. The second released component, niacin acts as a strong vasodilator, which might be useful for the treatment of migraine headaches.
Reported side effects include, but are not limited to, lightheadedness and decrease in blood pressure.
Phemibut has been researched more completely than picamilon. Neither are to be taken with benzos,
http://www.ncbi.nlm.nih.gov/pubmed/14558352
http://www.ncbi.nlm.nih.gov/pubmed/2736292
Here are the articles and info on GABA crossing the blood brain barrier.