I am certinly not the only one who can answer this, hence the reason I will close it...
When I IV a drug, my protocall isto pull back to ensure I am in a vein, inject a little, pull back, then finish - with ketamine I would be to far gone before I could even pull back for the second time... it hits hard and fast ... when you IM you have plenty of time...
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PACK.MY.BEAK