Vitamin B 12 Injection, 5,000 mcg mL, 100 mL at Tractor Supply Co B12 Injections for Energy: Benefits and How It Works AZ IV Medics CYANOCOBALAMIN Vitamin B12 Injectable Solution for Horses, 5000 mcg, 100 mL Easy Refills Chewy Rx Types of injections explained Intramuscular (IM) Inserted at 90 to deliver medication deep into the muscle, allowing relatively fast absorption due to rich blood supply. Subcutaneous (SC) Inserted at about 45