Numerous animal and human studies demonstrate that 5-HTP administered orally or parenterally reaches the brain, via active transport, and is converted to serotonin by serotonergic neurons, thereby amplifying serotonin synthesis, levels, and neurotransmission, e.g., (49, 50, 55, 67-69)
Dry lyophilized powder may tolerate short periods at room temperature better than a mixed solution, but warm storage is still not the preferred plan for retaining quality
The only verification methods are third-party analytical testing (HPLC, mass spectrometry) or biological assay, neither practical for individual users
If you inject into tissue outside of the vein, you could develop an abscess (a severe skin infection)