Local anesthetics

Question 1

Local anesthetics - 2 groups

Answer 1

Ester-type local anesthetics

Amide type local anesthetics

Question 2

Local anesthetics - MOA

Answer 2

Binds to cytoplasmic internal site of the Na channel and prolongs the inactivation state of the channel. This inhibits action potential.
Use-dependent and size-dependent blockade.
Autonomic and sensory nervers are more easily blocked than motor nerves.

Question 3

Effects of local anesthetics

Answer 3

Anesthesia
Antiarrhythmic activity (most)
Vasodilation (most)
Blockade of autonomic ganglia and neuromuscular transmission

Question 4

Administration of local anesthetics and ex of clinical uses

Answer 4

Topical: skin, mucous membranes, cornea. Pruritus, minor surgery.
Infiltration: minor surgery, dental procedures.
Ionophoresis.
Nerve block: Ocular surgery
Spinal intrataceal: block somatosensory and motor neurons.
Epidural: labour, delivery.

Question 5

Local anesthetics - contraindications

Answer 5

Myasthenia gravis

Question 6

Local anesthetics - adverse effects

Answer 6

Allergic reactions (more common in ester-type).
CNS: Restlessness, tremor, euphoria, sedation, paresthesia, nausea. Seizures, coma, resp failure.
Cardiovascular: Hypotension, cardiac depression, wide QRS-tachyarrh.
Loss of visceral and smoth muscle tone.
From spinal adm: headache, resp depression, meningitis, neurotoxicity.

Question 7

Local anesthetics - interactions

Answer 7

Potentiate neuromuscular blocking agents.
pH of tissues, acidosis, inflammation decrease efficiency.
Epinephrine: prolong action by vasoconstriction.

Question 8

Contraindications, complications and cure for using epinephrine to prolong effect of local anesthetics

Answer 8

Contra: end-artery tissue.
Complications: ischemia, necrosis.
Cure: phentolamine (nonselective alpha-blokcer)

Question 9

Ester-type local anesthetics - 6 drugs

Answer 9

Cocaine
Procaine
Proparacaine
Tetracaine
Benzocaine
Chloroprocaine

Question 10

Amide-tyme local anesthetics - 8 drugs

Answer 10

Lidocaine
Etidocaine
Bupivacaine
Levobupivacaine
Mepicvacaine
Ropivacaine
Prilocaine
Dibucaine

Question 11

Cocaine - indications

Answer 11

Nasal, laryngeal and urogenital anesthesia

Question 12

Benzocaine - indications

Answer 12

Sunburn, pruritus, cough.
Mucous membrane anesthesia.
(nonprescription)

Question 13

Proparacaine - indications

Answer 13

Ophthmalmic procedures and surgeries

Question 14

Most common anesthetic used in obstetrics

Answer 14

Bupivacaine

Question 15

Bupivacaine - adverse effects

Answer 15

More frequently cause cardiac depression.

Question 16

Which local anesthetic has lower incidence of cardiac effects?

Answer 16

Ropivacaine.

Question 17

Prilocaine - adverse effects

Answer 17

Methemoglobinemia if the metabolite is allowed to accumulate.

Question 18

Which local anesthetic is often used for hemorrhoids and rectal problems?

Answer 18

Dibucaine

Question 19

Low potency local anesthetics - 6 drugs

Answer 19

Ester-type anesthetics

Question 20

Medium potency local anesthetics - 4 drugs

Answer 20

Lidocaine
Etidocaine
Mepivacaine
Prilocaine

Question 21

High potency local anesthetics - 2 drugs

Answer 21

Bupivacaine

Ropivacaine