Local Anesthetics: Amides vs. Esters

Flashcards covering the basics of local anesthetics, including classes, mechanisms, examples, indications, delivery methods, vasoconstrictor use, side effects, and ocular considerations.

What are the two main classes of local anesthetics?

Amides and Esters.

What is the general mechanism of action of local anesthetics?

Block voltage-gated sodium channels in nerves, reducing sodium entry and preventing action potentials, leading to loss of pain transmission.

What is the definition of local anesthesia as described in the notes?

Drugs causing reversible block to conduction of nerve fibers without loss of consciousness or impairment of vital functions.

Name the amide local anesthetics listed in the notes.

Lignocaine (Lidocaine), Bupivacaine, Levobupivacaine, Prilocaine, Ropivacaine.

Name the ester local anesthetics listed in the notes.

Procaine, Benzocaine, Tetracaine (Tehacaine), Oxybuprocaine/Benoxinate, Amethocaine.

Which local anesthetic has a better cardiovascular safety profile than Bupivacaine?

Lignocaine (Lidocaine).

Which local anesthetic is commonly associated with methemoglobinemia?

Prilocaine.

What is the role of vasoconstrictors when co-administered with local anesthetics?

Reduce systemic absorption by decreasing regional blood flow and prolong duration of action (examples: adrenaline/epinephrine, noradrenaline, phenylephrine).

List some common adverse effects of local anesthetics.

Dizziness/drowsiness; Cardiac depression; Methemoglobinemia; Severe allergic reaction (anaphylaxis); Prolonged use can be dangerous.

What are common ENT indications for local anesthetics?

Sprays for intubation of ear, nose, throat; gels for catheter installation; solutions for ear, nose, throat surgery.

Name some techniques of delivering local anesthesia mentioned in the notes.

Infiltration, topical infiltration, spinal nerve blockade, local infiltration; subcutaneous injection for minor surgery.

What product is used for puncture in children that combines lidocaine and prilocaine?

Lignocaine-prilocaine cream/patches (EMLA) for puncture in children.

What properties are desirable for ocular use of local anesthetics?

Rapid onset; no effect on pupil; no vasodilation; good penetration; prolonged action (with increased uptake at the site of administration).

What precautions are advised when using vasoconstrictors with local anesthetics in ocular/ facial areas?

Avoid vasoconstrictors in areas with end-artery supply (eyes, fingers, toes, nose) due to risk of ischemia; use minimal amounts.

What are typical duration categories for local anesthetics?

Short-acting, intermediate-acting (about 1–2 hours), long-acting (about 4–8 hours).

What are the two main classes of local anesthetics?

Amides and Esters.

What is the general mechanism of action of local anesthetics?

Block voltage-gated sodium channels in nerves, reducing sodium entry and preventing action potentials, leading to loss of pain transmission.

What is the definition of local anesthesia as described in the notes?

Drugs causing reversible block to conduction of nerve fibers without loss of consciousness or impairment of vital functions.

Name the amide local anesthetics listed in the notes.

Lignocaine (Lidocaine), Bupivacaine, Levobupivacaine, Prilocaine, Ropivacaine.

Name the ester local anesthetics listed in the notes.

Procaine, Benzocaine, Tetracaine (Tehacaine), Oxybuprocaine/Benoxinate, Amethocaine.

Which local anesthetic has a better cardiovascular safety profile than Bupivacaine?

Lignocaine (Lidocaine).

Which local anesthetic is commonly associated with methemoglobinemia?

Prilocaine.

What is the role of vasoconstrictors when co-administered with local anesthetics?

Reduce systemic absorption by decreasing regional blood flow and prolong duration of action (examples: adrenaline/epinephrine, noradrenaline, phenylephrine).

List some common adverse effects of local anesthetics.

Dizziness/drowsiness; Cardiac depression; Methemoglobinemia; Severe allergic reaction (anaphylaxis); Prolonged use can be dangerous.

What are common ENT indications for local anesthetics?

Sprays for intubation of ear, nose, throat; gels for catheter installation; solutions for ear, nose, throat surgery.

Name some techniques of delivering local anesthesia mentioned in the notes.

Infiltration, topical infiltration, spinal nerve blockade, local infiltration; subcutaneous injection for minor surgery.

What product is used for puncture in children that combines lidocaine and prilocaine?

Lignocaine-prilocaine cream/patches (EMLA) for puncture in children.

What properties are desirable for ocular use of local anesthetics?

Rapid onset; no effect on pupil; no vasodilation; good penetration; prolonged action (with increased uptake at the site of administration).

What precautions are advised when using vasoconstrictors with local anesthetics in ocular/ facial areas?

Avoid vasoconstrictors in areas with end-artery supply (eyes, fingers, toes, nose) due to risk of ischemia; use minimal amounts.

What are typical duration categories for local anesthetics?

Short-acting, intermediate-acting (about 1-2 hours), long-acting (about 4-8 hours).

Which specific type of ion channel do local anesthetics block to prevent action potentials?

Voltage-gated sodium channels.

Do local anesthetics cause loss of consciousness when used as described?

No, local anesthetics cause a reversible block to conduction without loss of consciousness.