Memory Aid
Posted by Amy in Study/Sleep Aids on March 17, 2011
After a looooong night of studying, I'm about to leave the house to take my second-to-last (woot!) exam. The topic today is neuromuscular blockers and reversals. We've covered this material before - during one of the first few weeks of school, actually - but are covering it in greater detail this go around. One thing that's always tripped me up is keeping two of the reversal agents, pyridostigmine and physostigmine, straight.
As you may recall, pyridostigmine is a quaternary amine cholinesterase inhibitor. Due to it's chemical structure, it is highly ionized and does not easily cross membranes, including the blood brain barrier. It is often used to treat Myasthenia Gravis due to it's longer duration of action. Physostigmine, on the other hand, is a tertiary amine cholinesterase inhibitor. As such, it is lipid soluble and crosses the blood brain barrier with ease. It is therefore used to treat Central Cholinergic Syndrome, which typically affects children given overly large amounts of atropine or scopolamine, two cholinergics/antimuscarinics which can also cross the blood brain barrier and cause CNS effects. Physostigmine was also previously used to reverse lingering CNS effects following anesthesia. For this reason, it was given the trade name Antilirium. (Clever, right?)
Although the two anticholinesterase drugs are quite different from one another, their names are similar and I was having a hard time differentiating between the two. But, I figured out a memory aid and thought I'd be all Angelina Jolie with you guys and share. I now refer to physostigmine as "psychostigmine", in light of it's CNS effects and unique ability to cross the blood brain barrier. This helps me differentiate it from pyridostigmine.
Happy studying!
