vitamin b12 injections in tustin B-12 Injection, 5,000 mcg/mL, 100 ml 250 mL and 500 mL vials Provides 1 Rx Vitamin B-12 (Generic) Injectable
Description
The graph below compares those amounts to the ARfD

doi: 10.1002/JPER.18-0596 221 FitzgeraldJRFosterTJCoxD

This is not richly supplied with blood vessels so the absorption rate is slow

Largest vs
