How effective is pseudoephedrine (or ephedrine) at crossing the blood-brain barrier?

The wikipedia article on ephedrine states ephedrine does cross the blood-brain barrier (BBB), but not as effectively as the less polar phenylethylamine, methylamphetamine. I would like to know specifically how great of an effect ephedrine has especially in comparison to amphetamine or methylamphetamine.

I.e. In terms of CNS effect, what is the amphetamine dose equivalent of 120 mg of ephedrine/pseudoephedrine?

The reason I’m asking is because of my use of Sudafed for its decongestant (and stimulant) effects and I want to know how much damage I might be causing to my brain – e.g. depletion of dopaminergic receptors for one example.

If you can at least give me a link to a database with this kind of information I’d immensely appreciate it. Thank you.
Thank you for the data on the cLogP's. I converted those numbers to more usable forms for directly comparing solubilities. Basically did 10^(cLogP).
Pseudoephedrine: 10^(cLogP) = 7.7
Amphetamine: 10^(cLogP) = 55.2
Methamphetamine: 10^(cLogP) = 77.3
This way I can compare the relative strengths in terms of crossing the BBB. To get the equivalent CNS effect of 1 mg of amphetamine, I would need to take 7.145 mg of pseudoephedrine. So 120 mg of pure pseudoephedrine (which is what I'm taking in Sudafed) is equivalent to 16 mg of amphetamine. This is not a negligible dose at all. Its higher than what I anticipated actually. I suspect that ephedrine's primary means of crossing the BBB is not by conversion to methamphetamine as indicated by the cLogP data. So, now my question is are there any flaws in m reasoning in determining equivalent doses of pseudoephedrine relative to amphetamine?
Your answer helps out a tonne. The cLogP data is just the thing I was looking for. Thank you.

2 Responses to “How effective is pseudoephedrine (or ephedrine) at crossing the blood-brain barrier?”

  1. Az R Says:

    There’s several databases that require a subscription of several thousand a year to get into.

    Psuedoephedrine’s cLogP is 0.888
    Amphetamine’s cLogP is 1.742
    Methamphetamine’s cLogP is 1.888

    Also. Keep in mind that psuedoephedrine is a far poorer drug than amphetamine or methylamphetamine. It produces far less of an effect.

    You are not doing damage to your brain. You are not depleting your dopamine receptors in any significant way. The only way to do that with psuedoephedrine is to take … probably in the triple digit gram range of raw psuedoephedrine daily, and even then it’s not the psuedoephedrine, it’s the tiny amount that gets converted into methamphetamine.

    Since amphetamine and methylamphetamine appear to have both enhanced release and reuptake inhibition properties, they can’t even be compared in potency to psuedoephedrine. It’s like comparing a cup of coffee and a shot of adrenaline into a vein.

  2. Graham Says: