Furthermore there is some evidence that -lyase activity in the kidney varies among species, being an order of magnitude lower in humans than in rats
Furthermore, EAAC1-deficient mice exhibit age-related cognitive decline, increased oxidative stress in the hippocampus, and decreased levels of brain GSH
Kenakin says this is always a hazard: If you have an oral drug, the organ that receives the highest dose is the liver 50% of all drugs fail on liver toxicity, he says

Commonly Reported Research Observations Injection-site redness or irritation Temporary swelling or warmth sensation at the administration site Burning or stinging during administration Temporary skin sensitivity or irritation Mild headaches Temporary fatigue or tiredness Mild nausea Temporary itching or flushing sensations Temporary blue-tinted discoloration beneath the administration area in some research settings Copper-Related Research Considerations Because GHK-Cu is a copper-binding peptide, some research protocols may monitor for: Copper- and zinc-balance variability Increased sensitivity in higher-frequency protocols Temporary skin-related response variability Individual differences in antioxidant-response pathways Research involving prolonged or higher-frequency protocols commonly investigates the inclusion of: Zinc supplementation Vitamin C supplementation alongside GHK-Curelated research models

"There's often no apparent rhyme or reason to the wellness peptide doses people are taking," he adds