Not to be nit-picky, but if Wikipedia's information on the Gabapentin (Neurontin) and Pregabalin (Lyrica) pages are correct, Neurontin doesn't have a direct action on GABA receptors. It was created with a chemical structure similar to that of GABA out of the hopes that it would have a similar action at GABA receptors, and its effects can resemble those of benzodiazepines. But it actually acts at a calcium channel located in the CNS. Also, Lyrica (I'm not sure about Neurontin) increases the activity of glutamic acid decarboxylase. That enzyme synthesizes GABA from glutamate, so it increases the amount of GABA present in the CNS.
My friend will be ordering Picamilon, which is the nicotinic acid ester of GABA, and seeing how that works in combination with elf spice. Nicotinic acid is not like nicotine -- it's a form of niacin, which is mentioned in the "niacin as an antidote to LSD" thread. (We don't expect niacin will mess with DMT effectiveness, but that is a possibility.) Picamilon crosses the blood-brain barrier, unlike GABA. Then, once inside the brain, it dissociates into GABA and nicotinic acid. So theoretically, it should have a similar effect to a benzo, or to Neurontin/Lyrica. We'll see how it works in practice.
If Picamilon reduces the pre-flight anxiety, that would be awesome. My friend finds that he has trouble getting blastoff-level doses of DMT into his system because he gets too scared by the pre-blastoff anxiety, and can't think clearly enough to realize that it's going to disappear in 30 seconds whether or not he takes another spicy inhalation.