Making Own Depot/Long Acting Injection?

[anterogradient]

I saw one related thread, but about meth, and I'm more focused on opiates.

Say one has a short acting opiate. How could one make a longer acting injectable?

I know it's not an exact comparison, but I always think of how testosterone has esters like enanthate that make the testoerone release slowly. Now obviously it is not going to work the same with salts vs esters, and obviously we don't want an opiate to release over a month.

However, having a short acting opiate release over say 6 to 8 hours of effective relief versus say 2 to 3, would be very nice to my mind.

The only thin I can think to do is slap on something like a long carbon chain salt like decanoate, enanthate, similar to testosterone, or do something like lisdexamphetamine, but that is a bit more complex than I would like to think is doable for most.

Any thoughts on this?

 

[anterogradient]

Pretty much figured it out from one angle

Haloperidol is a chemical that has a decanoate ester. It is very closely related to pethidine. If one has a4 phenyl piperidine like pethidine, during synthesis one can introduce a long acting ester, or perhaps the typical propionate has solubility, and it can be dissolved in a sterile oil and voila, drug depot