Stimulants Methylphenidate nasal spray (heat sterilization question)

[tucker10]

I have a glass nasal sprayer and I want to use it for a methylphenidate nasal spray
I have 10mg IR ritalin, first I dissolve it in distilled water
Cool and filter it to remove some of the filler
Then pour it into the sprayer
Finally I use a cigarette lighter to heat the liquid in the glass sprayer to boiling point to sterilize it then seal the sprayer

I want to know is there any problem with heating methylphenidate or any of the fillers to 100 degrees C?
Will anything breakdown and produce toxic byproducts?

 

[sekio]

methylphenidate will eventually break down to small amounts of methanol & its inactive metabolite, ritalinic acid - similar to cocaine breaking down into methanol & benzoylecgonine. Heat, time and strong acids/bases will all contribute to the hydrolysis. I think at room temperature you should get at least a day or two out of the solution before it degrades too much.

It is probably better to boil the water 1st, cool it, and then dissolve the methylphenidate and filter it. The filter will keep things sterile. Boiling methylphenidate in water for too long will only encourage breakdown.

 

[tucker10]

Thanks for your reply

Is methylphenidate so unstable that it will really hydrolyse significantly in around two days? I'm a molecular biologist not a chemist but that seems really fast to me.
If I added ethanol up to around 3% of the solution, do you think that could shift the equilibrium to such that the majority of the compound is kept as either methyl/ethylphenidate and minimize buildup of inactive ritalinic acid and therefore increase the effective shelf life?

 

[sekio]

3% ethanol won't do much, I'm afraid.

A study showed that the half life of methylphenidate in 20 degree C water is about 24 hours or so.[ref] So if you make a solution in water keep it as cold as possible and use it quickly - make fresh solution every day.