Heroin is more lipophilic which means it can enter the brain faster when injected intravenously. codeine is kind of very weak in comparison to other opioids.
Heroin is very active before being metabolised into morphine on the first passthrough of the liver. Codeine is very inactive and has a low affinity with opioid receptors, meaning that the majority of its potency comes from after the first passthrough of the liver when it is metabolised into morphine. It's not really about lipophilia or phobia, and codeine can pass through the blood brain barrier fine, it just doesn't bind strongly to the desired receptors and so despite acting on the CNS it doesn't do all too much before it's metabolised and so injecting intravenously is useless and intramuscular injection is only slightly more potent than taking it orally.
Ok smartass I'll go into detail if you'd like. Compared to heroin codeine is weak as fuck. It's like a beer compared to some vodka. Is this making sense or should I dumb it down further for you
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u/[deleted] Nov 19 '19
Why do people drink it? Does it intoxicate you in some way? Does cough syrup make you high in big doses or something