They are sold pre-mixed, but there are good reasons to keep them separate: their half-lives and the quantities used differ substantially, so a fixed blend forces one schedule and one ratio onto two compounds that suit different ones
Fatigue and decreased energy levels affect some users, particularly during the first few weeks
The complete list of injectable peptides shows just how broad the applications are, and the nasal spray peptides article covers non-injectable delivery methods for those exploring alternatives
For example, in various cell culture lines, c-Met phosphorylation can result in downstream activation of Akt, Erk/MAPK, JNK, or FAK signaling (reviewed by Organ and Tsao, in vitro and in vivo (Cunningham et al., Understanding hair cell death mechanisms activated by specific ototoxins can help shed light on what molecular signals to therapeutically target for each toxic agent