Injecting bypasses the gut entirely no absorption bottlenecks, and you avoid the bacterial conversion to TMAO (a metabolite linked to cardiovascular risk) that happens when you take carnitine orally
They showed peribronchiolar airway inflammation, accumulation of lymphocytes and eosinophils, elevated IL-5 and IL-6, and airway hyperresponsiveness to inhaled methacholine
10.1212/wnl.50.5.1346 84 GrahamD
You can do that with oral antibiotics as well, especially for very sensitive people, who experience Herxheimer reactions badly, rather than put them on day after day of antibiotics, take this antibiotic for two days and stop, and then you have the rest of the week to clear up, then two days and stop
Zigouras, S., et al., Alpha-lipoic acid reduces LDL-particle number and PCSK9 concentrations in high-fat fed obese Zucker rats