med chem questions...

[TotalKayOs]

hey,
i was just wondering if all choline based quaternary ammonia salts are soluble as is. meaning they do not need to be dissolved in an acid/base to be adminsitered. for example acetylcholine does not need to be dissolved in acid/base to be administered because it is a quaternary ammonia salt with Cl, butdoes pilocarpine need to be dissolved in acid or base to be administered, even though it has a NO3 ion on it and is not a quaternery ammonia salt? and are cyclic esters more stable than linear esters? thanks for any help.

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[lord999]

You need to clarify your question:

1. What do you want it dissolved in? Pilocarpine is soluble in EtOH but immiscible in H20.

2. Even Miochol needs a anion counterbalance. I believe Miochol uses a chlorine (acetylcholine chloride). Miochol is a straight choline. Pilocarpine is an alkaloid derivative, too basic and bulky to be given as a straight base. I can't think of an instance where a forced quat ammonium is not given as a salt.

3. Think of pH issues as well. It's preferable for ophthalmics to be isotonic or close. Straight pilocarpine powder would probably burn your eye.

4. Cyclic esters are more unstable than linear. The strain energy of the cyclo system makes the keto-portion more electrophilic for the purpose of breaking the ring.

Drug Dosage Design Advice: Most drugs that are not amphoteric or neutral are usually given as salts if you need a pH or cell membrane absorption is the limiting factor. Acids and bases are only given straight if the cell membrane absorption is not a problem and if tolerated.

 

[GravyRPH]

Whoa, that made my head spin.

I forgot how much they make you learn in pharmacy school that is useless to everyday practice for 90% of pharmacists.

 

[lord999]

I totally agree.

The only lesson I've taken from med chem was what drugs go into applesauce vs. ice cream vs. tea.