Help. Anyone with chemistry knowledge? I have no idea what pka is and I need to explain it for a presentation on monday.

Specifically this sentence: "local anesthetics are weak bases with alkaline pKa values that are greater than physiologic pH"

I've watched a few youtube videos and tried reading up on some websites but i swear to god it makes no fu.cking sense to me.

Top | Newest First | Oldest First

DarkHeaven · Best Comment

pKa is defined as the pH at which the ionized and unionized forms exist in equal concentrations.

Because all local anesthetics are weak bases, those with pKa that lies near physiologic pH (7.4) will have more molecules in the unionized, lipid-soluble form. At physiologic pH less than 50% of the drug exists in unionized form. The unionized form must cross the axonal membrane to initiate neural blockade. The latency of a local anesthetic can also be shortened by using a higher concentration and carbonated local anesthetic solutions to adjust the local pH.