What does "Scopolamine base" mean?

[aelephant]

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I understand that Scopolamine hydrobromide & Scopolamine butylbromide are 2 different salts of Scopolamine, but what is Scopolamine base? Apparently it has different pharmacokinetics. How do I convert from Scopolamine hydrobromide to Scopolamine base, for instance? Can I? The patch in the US is Scopolamine base, but the patch I'm working with overseas is Scopolamine hydrobromide. How can I determine what sort of properties it has if it is not the same as the US patch?

Thanks in advance for any insight.

 

[DedicationNSU11]

hey I'm only a P1 but I'll take a shot at this from what I've learned so far. The base will be in it's neutral form and also nonpolar form. This means that all pHs in the body, it will be absorbed in all tissues because it can diffuse across membranes (I do not know its solubility properties though so I may be wrong). The salt form will be more water soluble. As far as how to make it, you can put it into a separation funnel that has ether and water, and then drain out the water (the charged salt will stay in water) and you have separated the free base scopolamine.

 

[xiphoid2010]

I understand that Scopolamine hydrobromide & Scopolamine butylbromide are 2 different salts of Scopolamine, but what is Scopolamine base? Apparently it has different pharmacokinetics. How do I convert from Scopolamine hydrobromide to Scopolamine base, for instance? Can I? The patch in the US is Scopolamine base, but the patch I'm working with overseas is Scopolamine hydrobromide. How can I determine what sort of properties it has if it is not the same as the US patch?

Thanks in advance for any insight.

Ok, here is the medchemist in me talking. Scopolamine is an alkolid, so it's a base. As a base, it can be made into a salt by reacting with an acid, eg. Hydrobromide. As salts, the ionized molecule is more soluble in a polar solvent, eg water, insoluble in nonpolar solvents such as oil. The skin is more like oil so a free base will penetrate better, while the salt form is more soluble in water so better for making injections. But I don't have exact info how much PK differs between foreign and US patches differ.

To convert the salt back to freebase is easy in a chemistry lab but not easy when you got a patch in the pharmacy. If I was back in the lab, I would dissolve the salt in water, add an organic solvent such as ether or dichloromethane, basify the aqueous layer using sodium carbonate, extract the free base by shaking up the layers in a sep funnel and drain off the organic layer. Evaporate off the organic solvent will leave you the free base within. Easy 15 minutes work... in a lab.

 

[aelephant]

Thanks for the replies.

From what I've read, it sounds like Scopolamine HBr will be less absorbed through a transdermal patch than Scopolamine base would be. The Scopolamine HBr patch I have also only contains 0.34mg (340mcg), while the product in the US contains 1.5mg.

I'm guessing the 0.34mg of Scopolamine HBr would *already* contain less actual Scopolamine than 0.34mg of Scopolamine base. To figure out exactly how much less, can I just look at the MW of Scopolamine base & HBr (303.3g/mol & 80.9g/mol, respectively) & work from there?

I feel like a dunce because these are relatively simple Pharmacy calculations, but I'm obviously quite rusty.

Edit:

I came up with 78.9% Scopolamine. So 100mg of Scopolamine HBr will be equivalent to 78.9mg of Scopolamine base. Is that right?

 

[Dr.J MS13]

Just don't take a SSRI with it