Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Pharmacology > Local Anaesthetic agents > Flashcards

Local Anaesthetic agents Flashcards

1
Q

Local anaesthesia function?

A

prevents transmission of
the nerve impulse in the
region to which it is
applied, without affecting
consciousness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

LA Irr/revsersible?

A

revsersible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Local anaesthetics?

A

Local anaesthetics are drugs which upon topical application or local
administration causes reversible loss of sensory perception,
especially pain in a localized area of the body

 No structural damage to neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Local anaesthetics chemical structure?

A

-Weak bases
-Lipophilic ring
-Hydrophilic amine
-Intermediate chain: amide or ester

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Local anaesthetic topical drugs?

A

Local TOP Benzo’s

Lignocaine
Tetracaine
Oxybuprocaine
Prilocaine
Benzocaine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Local anaesthetic injectable drugs?

A

My Role Leaves Lover Boys

Mepivacaine
Ropivacaine
Lignocaine
Levobupivacine
Bupivacaine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Local anaesthetic MOA?

A

 block voltage-gated sodium channels & reduce influx of sodium
ions
 preventing depolarization of the membrane blocking conduction
of the action potential

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

LA bases or acids?

A

All LA agents are weak bases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the two forms that LA exist in?

A

Unionised and ionised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

The importance of pKa of a LA?

A

The pKa of a weak base defines the pH at which both forms exist
in equal amounts

 As the pH of tissues differs from the pKa of the specific drug,
more of the drug exists either in its charged or uncharged form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Relationship of pKa and ionisation for local anaesthetics

A

Decrease in pKA, increases ionisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Infected tissue pH variations?

A

 Infected tissue reduced pH
 Fraction of unionised LA is reduced –> effect
reduced/ineffective
 Infected tissue increased blood supply - more LA removed
from local area before it can have an effect on the neuron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What makes LA more potent-explain the chemistry too?

A

-Longer hydrocarbon chain length
more lipophilic

-More lipophilic more potent:
penetrates the cell membrane
more easily to exert effect

-Bupivacaine high potency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What affects LA tissue binding ability?

A

-More protein binding. More protein bound, the tighter is binds and longer the duration of action.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Different types of nerve fibres of LA?

A

Type A:(heavy myelination)
Alpha: Proprioception, Motor
Beta: Touch, pressure
Gamma: Muscle Spindle
Delta: Pain, temperature

Type B:(light myelination)
Preganglionic autonomic

Type C:
Dorsal Root-pain(zero myelination)
Sympathetic-post ganglionic(zero myelination)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Influence of LA blocking based on diameter?

A

Small diameter nerve fibers (e.g. C-fibers) are more readily blocked
than large fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Influence of LA blocking based on myelination?

A

Myelinated fibers are more susceptible to blockade than unmyelinated fibers of the same size (mechanism not clear)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What order are fibres blocked in?

A
  1. Sympathetic and pain
  2. Temperature
  3. Light touch and proprioception
  4. Motor
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What order does recovery of drugs occur in?

A
  1. Motor
  2. Light touch and proprioception
  3. Temperature
  4. Sympathetic and pain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Benefit of motor being last order of LA blockage?

A

This is exploited to produce analgesia with minimal or no motor block,
by using lower concentrations of LA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Addition of vasoconstrictor on LA?

A

Increases duration of action added to injectables

 Localize the anaesthetic at desired site
 Prolongs duration of action of LA
 Reduce local haemorrhage
 Reduce amnt of LA absorbed into
systemic circ
 Decrease toxicity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the drug interactions precautions to use of vascoconstrictors?

A

 Tricyclic antidepressants (e.g.: Amitriptyline)
 potentiates hypertensive effect
 Non selective beta blockers (e.g.: Propranolol)
 increase BP, reflex decr HR, monitor BP
 Cocaine, methamphetamine abusers
 increase risk HT crisis, stroke, MI , postpone 24 hours
 Digoxin
 narrow TI, may ppt cardiac arrythmias
 Undergoing general anaesthesia (e.g.: Halothane)
 increase dysrhythmic effects of

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Contraindications of vasoconstrictors?

A

 Severe heart disease
 Uncontrolled hyperthyroidism
 Sulphite allergies
 Asthmatics (corticosteroid-dependant)
 Pheochromocytoma-releases and increase overstimulate CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

LA P/K?

A

LA administered to areas to be
blocked: skin, s.c tissues, intrathecal, epidural spaces

 Some of the drug will be
absorbed into systemic
circulation
 Intrinsic effects of drugs
 Vascularity of tissue/area
 Additives
Pharmacokinetics
 High vascularity to low:
 IV > tracheal > intercostal > caudal > epidural > brachial > sciatic > s.c

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Metabolism P/K?
ESTERS  Metabolism  Plasma cholinesterase's to inactive compounds Shorter time AMIDES  Metabolism  In Liver hepatic cytochromes Longer process
26
Administration of LA formulation for oral and injections?
 Water solubility of a LA is greatest in its ionised form  Injectionable preparations are formulated as HCL salts  Increasing alkalinity of injection solution increases the speed of acti
27
Several administrations of LA?
1. Topical 2. Infiltration 3. Peripheral nerve block 4. Central nerve block (epidural and spinal) 5. Intravenous regional
28
Topical Anaesthesia?
 High concentrations of LA in an oily vehicle slowly penetrate the skin or mucous membrane
29
Topical Anaesthesia duration?
Provides short term pain relief
30
Topical Anaesthesia drugs?
Long TOP's Benzo Lignocaine Tetracaine Oxybuprocaine Prilocaine Benzocaine
31
Examples of topical administration of LA?
o Creams o Gels o Lozenges o Sprays o Eye drops o Patches
32
Infiltration of LA?
 LA is injected intradermally or subcutaneously by the area to be anaesthetised
33
Infiltration of LA time?
 Produces numbness faster than topical anaesthesia
34
Infiltration of LA usuage now?
 Used extensively in dentistry – lignocaine is the most widely used injected anaesthetic
35
Infiltration drugs?
Mouth Really Be Laughing Mepivacaine Ropivacaine Bupivacaine Lignocaine
36
Peripheral Nerve Block Anaesthesia?
 Injection of LA solution around a nerve trunk  Produces fields of anaesthesia distal to site of injection
37
Peripheral Nerve block usuage?
 E.g. a brachial plexus block is used to anaesthetise the whole arm
38
Peripheral Nerve Usuage drugs?
Bupivacaine Lignocaine Mepivacaine Ropivacaine
39
Central nerve block anaesthesia ?
 LA is injected near the spinal cord  Produces anaesthesia above and below site of injection  Epidural anaesthesia used extensively during labo
40
Central nerve block anaesthesia drugs?
Bupivacaine Lignocaine Ropivacaine
41
Intravenous regional anaesthesia?
 LA is injected into a limb after application of tourniquet
42
Intravenous uses?
 Used for manipulation of fractures and minor surgical procedures
43
Intravenous IV drug?
lignocaine
44
Local Anaesthetic Systemic Toxicity (LAST)?
SAMS Slurred or difficult speech Altered Central Nervous System Muscle Twitching Seizures
45
LA systemic toxicity CNS?
Symptoms: Tingling of lips Slurred speech Reduces level of consciousness Sezures
46
LA systemic toxicity Prevention?
Prevention/Treatment Oxygen for loss of conciousness Benzodiazepines thiopentone for seizures
47
LA respiratory toxicity mean?
Respiratory Arrest
48
LA respiratory toxicity symptoms ?
Reduced myocardial contractility Arrythmias Hypotension Ventricular fibrillation - bupivacaine
49
LA prevention for hypotension?
Vasopressors (ephedrine/ phenylephrine) Inotropes (adrenaline)
50
Prevention of toxicity?
 Use max safe dose  Aspirate regularly during injection  Adrenaline if appropriate  Test doses  Stabilise needle carefully  Monitor patients vitals
51
Amides -Bupivacaine P/K?
 Long-acting LA {doa usually 3 hours, peripheral blocks: 2-24hrs: dose & site}  Slow onset of action: 30 mins  Bupivacaine is a potent LA capable of producing prolonged anaesthesia  Widely used during labour or postoperatively
52
Amides -Bupivacaine I?
 Local infiltration, regional block, spinal & epidural anaesthesia  Chiefly used for surgical anaesthesia (0.5%)  Useful in providing several days of Analgesia (admin. via indwelling catheters & continuous infusions)
53
Amides Metabolism?
Liver
54
Amides toxicity?
Cardiotoxic
55
Amides-lignocaine indications?
INDICATIONS:  Local/topical  Infiltration  Intravenous regional anaesthesia (biers block)  Epidural anaesthesia  Eye block
56
Amides-lignocaine P/K?
Onset of action: rapid Duration: Intermediate
57
Amides-lignocaine CI?
Heart block and conduction disturbance
58
Amides-lignocaine DI?
-Cimetidine/Beta Blockers
59
Mepivacaine I?
INDICATIONS:  Infiltration and nerve blocks  Metabolism: Liver enzymes
60
Mepivacaine Duration?
Intermediate acting
61
Ropivacaine duration?
LONG ACTING LA
62
Ropivacaine indications?
 Epidural anaesthesia  Local nerve block  Infiltration  Analgesia
63
Ropivacain metabolism and cautions?
METABOLISM: Liver enzymes CAUTIONS: partial or complete heart block, elderly, liver dysfunction
64
Amides-articane I?
Infiltration  Nerve block
65
Amides-articaine P/K?
 An amide but contains ester side chain which is hydrolysed - plasma esterases  Elimination half life: 20-40min  High lipid solubility - thiophene ring  Rapid onset
66
Prilocaine P/K?
Topical anaesthesia Available in combination with lignocainE
67
Prilocaine skin P/K?
Mucosa: apply and leave unoccluded for 10-15min Intact skin: apply a thick layer and cover with an occlusive dressing for 1-2 hours (analgesia: for +/-2 hrs after removal of dressing)
68
Lignocaine P/K?
 Topical spray: larynx  Jelly: urethral anaesthesia & haemorrhoids  Patch: (5%, S4) neuropathic pain relief (PHN)
69
Tetracaine uses?
Uses:  Topical cream: pain relief in haemorrhoids and minor skin burns  Eye drops: ophthalmology in tonometry, foreign body removal, suture removal  Oral gel: pain relief of mucous membranes of mouth, lips, gums
70
Benzocaine uses?
Topical gel: dentistry injection sites: minimize sensation  Lozenge: Surface anaesthetic - pain relief of sore throats  Throat spray  Throat gargl
71
Oxybuprocaine
Uses:  Eye drops: ophthalmology in tonometry, foreign body removal, suture removal  Has additive bactericidal activity

Pharmacology (44 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions