There are no documented direct interactions between berberine and L-carnitine, but evidence for their combined use is limited
You would withdraw the same amount into the syringe that you would do with the 5m vial
Athauda D, Maclagan K, Skene SS, Bajwa-Joseph M, Letchford D, Chowdhury K, Hibbert S, Budnik N, Zampedri L, Dickson J, Li Y, Aviles-Olmos I, Warner TT, Limousin P, Lees AJ, Greig NH, Tebbs S, Foltynie T (2017) Exenatide once weekly versus placebo in Parkinsons disease: a randomised, double-blind, placebo-controlled trial
High humidity and intense sun exposure can affect how our bodies utilize and process nutrients