Local Anesthetics Flashcards
In general, how do local anesthetics work?
In general, they work b inhibiting neuronal axon propagation, by blocking Sodiumreceptors. Sodium cannot come into the nerve, therefore threshold potential will not be reached and no pain sensory information can be carried.
What are the two major classes of local ansthetics?
PET LAB
Procaine, Esters, Tetracaine
Lidocaine, Amides, Bupivacaine
What happens to local anesthetics in infected tissue?? Why???
Infected tissue is usually acidic.. being that local anesthetics are weak bases, they will then become non-ionized enter the cell. THE LOCAL ANESTHETICS WORK BEST AT PH OF 8-9!!! AT THIS PH THEY ARE IONIZED and bind the sodium receptor.
What is usually administered ith local anesthetics? WHy??
Local anestheticsare typically administered withepinephrine because this acts as a vasoconstrictor, reducing the systemic effects of the drug.
How are the amides metabolized and what is their half life??
The amides (Lidocaine and bupivacaine) are metabolized by the liver and have a rather long half life. They enter systemic tissues and then eventually the gut and fat.
How are the esters usually matabolized and what is their half life??
Theesters (procaine and tetracaine) are usually metabolized in the circulation by floating cholinesterases. There half life is very short.
What nerves are affected first by local anesthetics??
Small, myelinated (A-delta and C pain fibers), and circumferential nerves are hit first.
Large, unmyelinated nerves (MOTOR NERVES) are affected later/slower.
When you inject a local anesthetic in the extremitiy, where does it act first??
It will act first proximally, because those sensory fibers are more superficial. Proximal then distal blockage occurs.
What are the main toxicities involved with the local anesthetics???? TOP 2 Negrito!!
So, if the local anesthetic get systemic… then they can co into the brain and block inhibitory centers…. this can lead to convulsions, respiratory depression and excitation.
Also, they act on sodium receptors in the heart!!! CAn cause bradycardia and arrhythmias. Also (all but cocaine) will cause decreased contractility.
If someone is havig a seizure while on local anesthetics… what should u have them do??
You should have them hyperventilate… hyperoxemia will cause put the sodium channels in their resting state, so then sodium can enter.
What is one unqiue caracteristic of Bupivcaine??
If given systemically it will cause CV collapse. Has a LONG DURATION OF ACTION.
