Pharm - topical anesthetics Flashcards
amide anesthetics
- lidocaine (MC)
- mepivacaine
- bupivacaine
- ropivacaine
ester anesthetics
- procaine
- 2-chloroprocaine
- teracaine
- benzocaine
what determines potency and time to onset of anesthetics
- *lipid solubility
- those w/ greater lipid solubility are able to permeate nerve membranes more rapidly
effects of alkalinization on the percent nonionized local anesthetic molecules
- Sodium bicarbonate increases the fraction of nonionized local anesthetic molecules
- decreases onset time of local anesthetic effect
Identify the effect of injection site on speed of onset
- SC/tissue infiltration: onset almost immediate
- Intrathecal injection for spine: onset very rapid
- Brachial plexus block: prolonged
short acting local anesthetics
- chloroprocaine
- procaine
moderate-acting local anesthetics
- lidocaine
- mepivacaine
long acting local anesthetics
- bupivacaine
- ropivavoine
- tetracaine
What is the order of function lost after a nerve block?
- 1st: sympathetic function
- 2nd: loss of sensation of sharp pain, temp, pressure
- last: motor function
What is the purpose of adding epi to local anesthetics?
- to decrease absorption of local anesthetics from tissues
- slow absorption can decrease potential toxicity and prolong duration of drug
dosage for lidocaine w/ vs. w/o epi
-lidocaine w/o: 4 mg/kg
MAX: 300 mg
-lidocaine w/: 7 mg/kg
MAX: 500 mg
lidocaine
- onset
- duration
- onset: w/i 2-5 min
- duration: 30 min - 2 hrs
- 3 hrs if epi added
bupivicaine
- onset
- duration
- onset: 5-10 min
- duration: up to 6 hrs
mepivacaine
- onset
- duration
- onset: 2-5 min
- duration: up to 2 hrs
- 3 hrs if epi added
What is the most potent amide anesthetic?
bupivacaine
In what situations is bupivacaine an advantage?
- longer procedures
- pts w/ CIs to epi injections
- in situation where there will be a delay b/w infiltration of anesthetic and procedure
- instances where prolonged post-procedure pain control is preferred
what anesthetics are CI in pregnancy? (2)
- bupivacaine
- mepivacaine
Indications for local anesthetics
Effective for pain control during procedures including:
- skin surgeries
- open wound repairs
- abscess drainage
- FB removal
- vascular access procedures
- LP
what does the choice of agent depend on?
- duration of procedure
- need for hemostasis
- pt sensitivity to catecholamines
- pt allergy to local anesthetics
allergy CI to the use of local anesthetics
- true allergy is a CI for that anesthetic and others in it’s class - local admin of one from another class is usu ok as long as previous rxn wasn’t urticaria/anaphylaxis
- try using preservative free
- consult allergy specialist for life threatening rxns
medical condition CIs to local anesthetics
- large wounds in pts w/ conditions that may be exacerbated by systemic epi effects (hyperthyroid, pheochromocytoma, severe HTN, CAD)
- digital anesthesia in pts w/ compromised digital circulation
- periorbital inflitration in pts w/ narrow angle glaucoma
- not recommended for management of large/multiple lacs where total dose needed for good effect is close to max dose
drug interactions
- lurasidone - hypotension
- ergot alkaloids - extensive HTN
- beta blockers
- MAOIs
- tricyclic andtidepressants
methods that can be used to decrease injection pain
- buffering w/ bicarb
- patient distraction
- gentle pinching/vibration adjacent to site of injection
- use of small needles
- slow rate of injection
- subQ rather than IM
- reduce pressure of injection w/ small volume syringes
- inject needle at 90 degrees rather than 45 when penetrating intact skin
complications secondary to local anesthetic use
- systemic toxicity: if dose is exceeded, major vessel inadvertently injected
- CNS effects: metallic taste, tinnitus, tingling of lips, agitation, seizures
- CV effects: bradycardia, decreased myocardial contractility, AV block, vasodilation, ventricular arrhythmias, cardiac arrest
