Local Anesthetic

Question 1

Procaine

Answer 1

1. Ester , local anesthetic
   use: infiltration of anesthetics and diagnostic nerve block
2. Well absorbed, rapidly metabolized by psuedocholinetestase, short duration of action, lack topical activity
   - metabolic product is PABA: inhibits sulfonamides
4. Procaine Hydrochloride with epi: epi vasoconstrictor- dec the rate of anesthetic absorption (doubles duration)
5. All other local anesthetics are measured relative to procaine- potency=1
   Procaine administration causes minimal system toxicity, and no local irritation

Question 2

Tetracaine

Answer 2

1. Ester, local anesthetic,
   Use: ophthalmic procedures, spinal anesthesia
2. long duration, long onset,
   preferred use*

Question 3

Benzocaine

Answer 3

1. Ester, local anesthetic
   Use: topical use for minor sunburns, burns, and pruritus
2. Very lipophillic, pKa=3.5 - non-ionized at physiological pH
   - may be linked to methmoglobinemia

Question 4

Cocaine (Local anesthetic)

Answer 4

1. Ester type drug, local anesthetic
   use: topical anesthesia of mucous membranes, inhibits Na channels in addition to inc. catecholamines
2. Short acting
3. May reduce bleeding
4. Drug interactions: Inc effect of catecholamine stimulating drugs
5. Adverse Effects
   -Tolerance, abuse, hyperpyrexia and OD toxicity
   CNS: euphoria and dysphoria followed by depression
   CV effects: Blocks uptake of catecholamines- tachycardia, vasoconstriction resulting in HTN, caution with HTN, CV, and thyrotoxicosis pts

Question 5

Lidocaine

Answer 5

1. Amide, Standard for local anesthestics
   use: wide range of applications inc infiltration and epidurals, moderate topical activity
2. intermediate duration of action, absorbed rapidly and metabolized by p450
3. Rapid onset anesthesia, minimal local irritation
4. Lidocaine hydrocholride administered with/without epi
5. Do not use with spinal blocks= TNS

Question 6

Bupivacaine

Answer 6

1. Amide, local anesthetic
   Use: sensory block no motor- used for labour post op pain, spinal anesthetic, infiltration blocks, and epidural anesthesia
2. Long duration of action
3. Greater cardiotoxicity than other amides- dissociated from the cardiac Na channels slower than other LA
   * preferred ov
   -

Question 7

Ropicacaine

Answer 7

1. Amide, local anesthetic
   use: peripheral blocks and epidural blocks for labour and post op pain
2. S enantiomer of bupivacaine- less cardiotoxic, less lipid soluble, cleared faster, and adverse effects are less likely all compared to bupivacaine

Question 8

Mepivacaine

Answer 8

1. Amide, local anesthetic
   use: peripheral nerve block (*** do not use in pregnancy- toxic to neonate)
2. Intermediate duration of action, similar to lidocaine but less drowsiness and sedation

Question 9

Prilocaine

Answer 9

1. Amide, local anesthetic
   use: dentistry
2. Intermediate duration of action, highest rate of clearance of all amides
3. Side effects
   - risk of methmoglobin so limited to dentistry
   * CI in pts with cardiac or respiratory disease or with congenital methemoglobinemia (bc toludine metabolites produce methemoglobin

methmoglobinemia reversed by methylene blue

Question 10

Etidocaine

Answer 10

1. Amide, local anesthetic
   use: limited
2. Long duration of action
3. Effectts:
   - causes motor block before sensory block
   - rarely used for infiltration nerve block, peripheral nerve blocks, or epidurals

Question 11

Articaine

Answer 11

1. amide with an additional ester, local anesthetic
   use: dental
2. Short duration of action, metabolized by plasma esterases and amide metabolism?- short half life, lipophilic- inc tissue penetration, allow for multiple drug injections
3. large therapeutic window, and low potential for system toxicity (due to fast metabolism)
4. Adverse Effects: persistent parethesias

Question 12

Dibucaine

Answer 12

1. Amide, local anesthetic, inhibits butyrlcholinesterase
   use: spinal anesthetic (world), topical (us)

Dibucaine number