acetyl l carnitine injectable L-Carnitine Pen Injectable L-Carnitine 500mg/ml (20ml) Health
Description
[DOI] [PubMed] [Google Scholar] 32.Agar E., Bosnak M., Amanvermez R., Demir S., Ayyildiz M., Celik C

If its for humans, you can figure out the glutathione dog dosage by assuming its for a 150-lb person and adjust for your dogs weight

doi: 10.3390/antiox11020236

But B12 seems to be lost in modern, high-speed farming methods, so there appears to be a lot less B12 in meat and dairy than there used to be, resulting in a lot more people with B12 deficiency
