B12 and B-complex options are common for energy and focus
For a syringe I believe that you can use the same type you use for insulin
Storage : Store at the coldest possible temperature (-80C) as a lyophilized powder
The cardiovascular and respiratory side effects include chest pain, tachycardia (increased heart rate), heart palpitations, low blood pressure, and chest tightness, cough with or without production of pink frothy sputum, wheezing and difficulty breathing
Frequently Asked Questions About B12 Injections How soon will I feel a difference with B12 Injections
Troy Vitamin B12 for Sheep and Cattle is indicated for the treatment of Vitamin B12 deficiency in lambs, calves, sheep and cattle