However, I'm not sure it would be effective in treating long-term withdrawal. It stops withdrawals by essentially knocking heroin off μ-opioid receptors (i.e. it is an inverse μ-opioid agonist with a very high receptor affinity). But it's effects only last a bit over an hour. Additionally, because of its inverse action, I suspect you'd experience withdrawal symptoms that are more severe than those you would experience going cold turkey.
Also, it's: "But its effects" (not it's)
I'd assume insuffilated Naloxone would last the longest, followed by intra-muscular and finally intravenous. And the inverse would be true regarding how long they would take to have an effect. I don't think taking it orally is a viable option for OD, as it would take much longer to have an effect, and much of it would be destroyed by your first-pass metabolism.
And yeah, me and apostrophes have not been getting along very well lately...
This experience provided a very good clue as to what my friend actually needed (see my comment history for the backstory).
Benzodiazepines lose effectiveness after about 4 weeks, and the patient's anxiety worsens. The mental hospital forced my friend to take the full pill every day, when she only wanted it "as needed". She decided that Heroin would help her get through her benzo withdrawal.
We got together on the second night of her plan. I said 'no no, we're not doing this again...'
She said that she wasn't going to get addicted again, she just needed it to sleep. To show me that it was barely anything at all, she prepared a second shot and injected that too.
Then she fell forward, said "I meant to do that," and went non-responsive. Her face started to turn purple.
I did not have naloxone, so I called 911. The firefighters arrived about 6 or 7 minutes after I called. Some of them looked bored.
They used two 2mg intranasal doses of naloxone. She was quite shocked at the appearance of strangers in blue uniforms...
She did very, very well for the next two weeks. I guess the anti-opiates are awesome drugs. Naltrexone (similar to naloxone) is FDA-approved for alcohol abuse too.