Maybe a dumb question but... Is it possible to make homemade injectable GABA??

I guess just bulk GABA powder will not work right?
Yes bulk Gaba should work. It should be micronized w/ mortar & pestal first I would imagine. The powder need not be sterile if you use sterilizing agents to make the solution. Or you could find sterile Gaba powder (I assume ...it would be prohibitively expensive) & you still should use sterlizing agents to make the solution.
Typically, solutions are sterilized either by heat or filtration. In the case of solutions containing gabapentin (a pharmacological agent that mimics the effects of GABA & is so close to its structure that we can use the following information obtained from patent filing #10808113), a sterilization process involving heat would generally be considered undesirable. This is because heat would be expected to result in decreased stability of gabapentin and increased production of gabapentin lactam. According to U.S. Pat. No. 6,054,482, "The lactams display a certain toxicity and must, therefore, be avoided as far as possible. For example, gabapentin has a toxicity (LD50, mouse) of more than 8000 mg/kg, for the corresponding lactam a toxicity of 300 mg/kg."
So lesson one in making a GABA injectable is either avoid heat or limit to that which is low enough to aid in getting the powder to dissolve but no more.
Gabapentin (and therefore GABA & I assume GABOB) is freely soluble in water and both in basic and acidic aqueous solutions.
Injectable compositions comprising gabapentin may be prepared in water, saline, isotonic saline, phosphate-buffered saline, citrate-buffered saline, and the like and may optionally mixed with a nontoxic surfactant. Dispersions may also be prepared in glycerol, liquid polyethylene, glycols, DNA, vegetable oils, triacetin, and the like and mixtures thereof. Under ordinary conditions of storage and use, these preparations may contain a preservative to prevent the growth of microorganisms.
The prevention of the action of microorganisms can be accomplished by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, sorbic acid, thimerosal, and the like. In many cases, it will be desirable to include isotonic agents, for example, sugars, buffers, or sodium chloride. Prolonged absorption of the injectable compositions can be brought about by the inclusion in the composition of agents delaying absorption--for example, aluminum monosterate hydrogels and gelatin. Excipients that increase solubility, such as cyclodextrin, may be added.
An injectable composition comprising gabapentin is an injectable composition comprising an aqueous solvent. The solvent may be water or saline. The saline may be, e.g., 0.9% (w/v) sodium chloride or a solution where just enough sodium chloride is added to make the final injectable composition isotonic. The saline may be sterile saline.
Any concentration of gabapentin may be present in an injectable composition. For example, gabapentin may be present in a solution, suspension, or dispersion at a concentration between about 0.1 mg/mL and about 100 mg/mL.
An injectable composition comprising gabapentin has a pH between about 4 and about 9. The pH of an injectable gabapentin composition may be adjusted with a pharmacologically acceptable acid, base, buffer or combination thereof...pH is adjusted with hydrochloric acid or sodium hydroxide.
Heat treatment may be performed in conjunction with another form of sterilization and/or aseptic technique. For example, heat treatment may follow filtering. An injectable gabapentin composition may be filtered through any filter capable of enhancing sterility of the composition. For example, an injectable composition comprising gabapentin may be filtered through a filter having a pore size of about a 0.2 µm or about 0.22 µm.
So there you have it. You asked a very good question that I thought was entitled to the most fact based-answer I could provide.
Plus I've been thinking about making an injectable Gaba/Gabob solution (aka pGH) myself. I know there is a patent filing somewhere but I can not find it...damn it! I need to know the exact formula so if anyone has read this far I apologize for having bored the sh1t out of you and I ask if you know the recipe ratios for pGH?