LEC 8,9 - General + Local Anesthetics Flashcards Preview

Pharmacology II > LEC 8,9 - General + Local Anesthetics > Flashcards

Flashcards in LEC 8,9 - General + Local Anesthetics Deck (156):
1

General anesthetic effects (5)

Analgesia 

Loss of conciousness 

Amnesia 

Inhibition of snesory + ANS reflexes 

Muscle relaxation 

2

Drugs for analgesia (2)

N2O 

Opiods

 

3

Drugs for loss of conciousness (2)

IV anesthetics 

N2O 

4

Drugs for amensia (3)

Midazolam 

Droperidol 

Ketamine

5

Drugs for ANS inhibition (3)

Atropine 

Opiates 

Scopolamine

6

Drugs for muscle relaxation

Depolarizing + Nondepolarizing muscle relaxants

7

What is the purpose of pre-medications?

Facilitate anesthesia + surgery 

improves rapidity + smoothness of: 

Iduction 

Anxiety 

Analgesia/Amnesia 

 

8

What are the four major drug groups used for pre-meds?

Opiods 

tranquilizers 

Anticholinergics

Central muscle relaxants

9

What is the purpose of opioids in pre-meds?

Analgesia 

10

What is the purpose of tranquilizers in pre-meds?

Pre-operative sedation + amnesia 

Prevent/counteract CNS stimulation 

11

What is the purpose of anticholinergics in pre-meds?

Prevent salivation + bradycardia

12

Propofol - Mechanism

Activates GABAa receptors 

13

Propofol - admin 

IV 

14

Propofol - Distribution

Rapid redistribution + metaboolism 

15

Propofol - Effects on cerebral pressure 

Decreases blood flow + oxygen consumption 

Safe for animals with head trauma

16

Propofol - Duration of anesthesia

2 to 10 min 

17

Propofol - Distribution/breeds to watch out for

Distributes to fat 

Sighthounds 

18

Propofol - Metabolism

Glucoronidation 

19

Propofol - 1/2 life

1 to 2 hours

20

Propofol - Adverse effects 

Myoclonic twitching 

Myocardial depression 

Transient apnea

21

Etomidate - Mechanism

Sedative hypnotic nonbarbiturate 

Facilitates GABA transmission 

22

Etomidate - Effects

Decrease cerebral blood flow 

Metabolic rate 

oxygen consumption 

23

Etomidate - Uses 

Good for patients with: 

Cardiac dysfuncton 

Head trauma 

Critically ill 

24

Etomidate - Metabolism

Heptaic hydrolysis 

No accumulation 

25

Etomidate - 1/2 life

3 hours

26

Etomidate - Adverse effects 

Very hypertonic 

Pain + Hemolyssi upon IV injection

27

Alfaxalone - Mechanism

Synthetic neuroactive steroid 

Interacts with GABA receptors 

Anesthesia + Muscle relaxtion 

28

Alfaxalone - 1/2 life

< 1 hour

29

Alfaxalone - Pharmacokinetic curce

non-linear aka zero order

30

Alfaxalone - Use

General anesthesia 

Bolus or CRI 

 

31

Alfaxalone - Adverse effects 

CNS depression 

Hypotension 

32

Ketamine - Use

FDA approval in cats 

Induction 

CRI for general anestehsia 

Sedation for chemical restraint 

33

Ketamine - Mechanism

Inhibits excitaory NT ACh + L-glutamate in spinal cord 

Non-competitive antagonist of NNMDA receptor

Dissociative anesthesia 

Analgesia 

34

Ketamine - Admin

IM/IV - Cats + Dogs + Small Ruminants + Swine

IV - Adult horses 

35

Ketamine - Metabolism

CYP450 

Congugated with glucuronide

36

Ketamine - Excretion

Kidneys - 

Unchanged in cats 

37

Ketamine - 1/2 life

Cat

Calf 

Horse 

= 1 to 1.5 hours

38

Ketamine - Adverse side effects

Seizures (Horses + Dogs ) 

Profuse salivation (Cats) 

SNS stimulation = Inc CO + HR 

Rougher induction/recovery 

Increase muscle tone 

Apneustic breathing pattern 

CSF pressure increased

39

What muscle relaxers are given with ketamine?

Alpha2 agonists - to horses for muscle relaxation 

Diazepam/Midazolam/etx. - to cats/dogs for seizure prevention + skeletal muscle relaxation 

40

Midazolam - Mechanism

Benzodiazapine 

Increases effects of GABA 

Increases frequency of open Cl- channel 

41

Midazolam - Use 

Induction

Neonatal seizures 

Status epilepticus 

42

Midazolam - Neuroleptanalgesic combo

+ Opioid

43

Midazolam - Muscle relaxation combo

Ketamine

44

Midazolam - Protein bidning

94 to 97% bound 

Unbound crosses BBB to enter CSF 

45

Midazolam - Admin

SC + IM + IV 

46

Midazolam - metabolism

Glucuronidation in liver

47

Midazolam - Affinity vs. Potency

2x's affinity for GABA 

3x's potency

48

Midazolam - Adverse effects 

Cardiorespiratory depression 

Paradoxical excitement 

Dysphoria 

w/ drugs that have protein binding will increase CSF concentration 

49

Midazolam - reversal

Flumazenil 

50

Flumazenil - Mechanism

Competitive antagonist for BZD receptors

51

Tiletamine/Zolazepam - Use

Chemical resitrant in fracitous cats 

Short term anesthesia in dogs/cats 

52

Tiletamine/Zolazepam - Admin 

Deep IM 

53

Tiletamine/Zolazepam - Adverse effects 

Excessive salivation 

Erratic recovery 

Muscle twitching 

54

How do you treat excessive salivation with Tiletamine/Zolazepam administration?

Atropine

55

Barbiturates - Mechanism

Bind to GABA Cl- channels 

Increase duration of opening 

= hyperpolarization of neurons

56

Barbiturates - effects

Transient hypotension + increased HR 

Depress respiratory centers (Cats > Dogs) 

General anesthesia 

57

Barbiturates - overdose

Apnea 

Cardiovascular depression 

Death

58

Barbiturates - Distribution factors

Lipid solubility 

Protein binding 

Ionization 

59

What type of drugs cross the BBB?

Non-protein bound

-- and -- 

Non-ionized 

60

Why are thiobarbiturates rapid in onset?

High lipid solubiltiy 

 

61

Characteristics of ultrashort acting barbiturates

very lipid soluble 

Onset rapid 

Duration short (10 to 30min)

62

Methohexital - use

Dogs/Cats 

Ultra short procesures 

63

Methohexital - Duration of action

5 to 15 minutes

64

Methohexital - Time of onset

15 to 60 seconds

65

Methohexital - Distribution

No effect on fetus so safer for C-section 

Can reduce O2 in pups so move fast 

Does not move to fat - good in greyhounds 

66

Methohexital - Adverse effects

More likely to cause period of excitement during induction 

Profound respiratory depression

67

Pentobarbital - Four main uses

Sedation 

General anesthesia 

Seizure control 

Euth

68

Pentobarbital - Sedation uses

Mechanical ventilation 

Ruminants + Horses

69

Pentobarbital - General Anesthetic uses

Cats/Dogs 

 

70

Pentobarbital - Seizure uses

Refractory to phenobarbital or diazepam 

71

Pentobarbital - duration of action

30 to 60 min 

72

Pentobarbital - 1/2 life

Ruminants - 0.9 hours 

Dogs - 8 hours 

73

Pentobarbital - Adverse effects

Low doses - ecitement phase 

74

Phenobarbital - mechanism

Long-acting

75

Phenobarbital - uses

Anticonvulsant in status epilepticus treatment 

Excess, chronic drooling in dogs

Chlorinated hydrocarbon detox in cattle 

76

Phenobarbital - ADmin

PO 

IV loading in horses

77

Phenobarbital - Duration of action

6 to 12 hours

78

Phenobarbital - Metabolism

Liver 75 % 

Urine, unchanged 25% 

 

79

Phenobarbital - Adverse effects

Ataxia + Lethargy + depression 

PU/PD/PP 

Coagulopathies + Adrenal insufficency in cats 

Increased liver enzymes in dogs 

80

Define: MAC

1 mac = [ ] at 1 atm that prevents skeletal muscle movemnet in painful stim in 50% of the population

81

Oil : Gas ppartition coefficients 

Measure of potency 

82

MAC-awake 

Inhibits voluntary movements

83

MAC-BAR

Blunting autonomic reflexs

84

MIR

Eliminates reflexes used to judge depth of anestehisa 

85

Blood : Gas Partition Coeffcient 

Rate of increase of Pa towards Pi 

Inversely related to solubility of anesthetic to blood 

86

Partition coefficient = 

Solubility of inhaled anesthetic in different body components 

87

Nitrous Oxide - Effects 

Direct myocradial function depression 

SNS stimulation 

No sensitization of myocardium to epi

88

Nitrous Oxide - Use

Not very potant 

Combine with other inhaled anesthetics to make more stable anesthesia 

Analgesic 

89

Nitrous Oxide - Secondary effects

Second gas effect 

Diffusional hypozia 

90

Describe second gas effect

Nitrous + Other inhalant anesthetic 

NO highly diffusible, quick to leave alveoli 

[  ] of other compoundss increase in alveoli 

[ ] effect increases theri absorption into the blood 

= decrease concentration needed 

91

Nitrous Oxide - Distribution

Accumulations in gas filled spaces 

Rumen of cattle 

Cecum of horses

92

Describe diffusion hypoxia

NO is turned off 

NO quickly diffuses out of blood into alveoli 

Intra-alveolar oxygen [  ] is decreased 

93

Treatment for diffusion hypoxia 

100% oxygen 

 

94

Preventing diffusion hypoxia

Wean patients off of NO 

95

Isoflurane - Effects

Decrease arterial BP 

Depresses CV function 

Catecholamine sensitization = Cardiac arrhythmias 

RR + TV decreased 

Increases effect of non-depolarizing muscle relaxers 

96

Isoflurane - MAC that effects cerebral blood floow 

1.2

97

Isoflurane - Use

Dog + Cats + Birds + Horses 

Anesthetic 

Status epilepticus in Dogs (refractory to benzodiazepines) 

98

Isoflurane - kinetics 

Low blood : gas partition coeffiecent 

Rapid induction/recovery 

Exhaled unmetabolized 

99

Isoflurane - Adverse effects 

Malignant hyperthermia 

Higher risk of causing vasodilation 

(Responsive to fluid bolus) 

100

Sevoflurane - Effects 

Decrease SV 

Depresses myocardial contractility 

Decreases arterial BP 

 

101

Sevoflurane - Kinetics 

Low blood : Gas partition coefficient 

Fast induction/recovery 

102

Sevoflurane - Elimination

Liver - 2 to 5% 

The rest is exhaled 

103

Sevoflurane - Adverse effects

Malignant hyperthermia 

104

What is the order in which euthanasia should take place?

Rapid loss of conciousness 

Loss of motor function 

Arrest of respiratory + cardiac functions 

Permanent loss of brain function 

105

Barbiturates for Euth - mechanism

Depress CNS in descending order 

Cerebral cortex w/ loss of conciousness to anesthesia 

Repsiratory center depression 

Cardiac arrest 

106

Barbiturates for Euth - Food animals

NEVER TO BE USED IN ANIMALS IN THE FOOD CHAIN 

107

Dissociative agents + Alpha2 antagonist - use in euth 

Can be given prior to the admin of euthanasia solutions to minimize animal distress + help with restraint + easier euthanasia for O 

108

Acceptable euthanasia methods - Cats 

IV barbiturates 

Anesthetic OD 

109

Acceptable euthanasia methods - Cattle 

IV Barbiturates

110

Acceptable euthanasia methods - Dogs

IV barbiturates 

Anesthetic OD 

111

Acceptable euthanasia methods - Horse

IV barbiturates

112

Acceptable euthanasia methods - Poultry 

Injected barbiturates 

Anesthetic OD 

113

Acceptable euthanasia methods - Swine

Injected barbiturates

114

What are the two types of local anesthetics?

Esters 

-- and -- 

Amides

115

Characteristics of esters

Shorter duration 

Increased toxicity 

116

How does sterochemistry effect local anesthetics?

Potency 

Clinical properties 

117

What is the purpose of salts in local anesthetics?

Increase stability + solubility 

118

pKa of local anesthetics

7.5 to 9 

119

Predominant form of Local anesthetic in body

Ionized form LAH+ 

120

Where is the binding site for the local anesthetics?

Inner membrane 

121

What is steps in which local anesthetics enter the cell?

Non-ionized cross membrane 

Become ionized within the cell and become stuck 

Ionized form binds within the cell 

aka Hydrophobic pathway 

122

Target of local anesthetics

Block Na+ channel = inhibit neuronal firing 

123

effect of local anesthetics on the neuron

Increased t-hold for excitation 

Slowed impulse conduction 

 

124

What is the amount by which the local anesthetic blocks the area dependent on?

Voltage 

Firing time 

 

125

What channel type are local anesthetics have the highest affinity for?

Acitvated + inactivated 

126

What neuronal activity level do local anesthetics have the highest affinity for?

Rapidly firing 

127

Where are the adverse effects targeted with local anesthetics?

CNS + Cardiac 

128

Duration of action dependent on = 

Time at site

129

Toxic effects dependent on =

 1/2 life

130

What effect does epi have on local anesthetics?

Decreased diffusion of the drug 

Prolongs duration of action 

Decreases systemic absorption 

Decreases risk of systemic toxicity 

131

Amides - Elimination 

Metabolized by liver CYP450s 

 

132

Amides - Toxicity 

seen with - 

Hepatic disease 

Reduced hepatic blood flow

133

Local anesthetics - Secretion 

Renal 

134

Esters - Metabolism

Rapid metabolism by butyrylcholinesterase in plasma 

135

What are the four major adverse effects with local anesthetics?

CNS 

CV system 

Methemoglobinemia 

Tissue damage 

136

Local Anesthetics - CNS adverse effects 

Skeletal muscle twitching first sign 

Tonic-clonic seizures normally first clinical sign 

137

Local Anesthetics - MetHg adverse effect

Use of prilocaine + benzocaine in cats and rabbits

138

Local Anesthetics - Tissue damage

Neurotoxicity 

Myotoxicity 

139

Local Anesthetics - CV system adverse effects

Prolonged PR + QRS interval due to slowed impulse conduction 

Hypotension 

Decreased myocardial strength 

140

Tetracaine - Use

Opthalmological 

 

141

Tetracaine - Mechanism

Ester

142

Tetracaine - Onset of action

 > 10 mintues

143

Tetracaine -  Duration of action

2 to 3 hours

144

Tetracaine - Adverse effects

Burning + Chemosis 

Allergic reaction 

Chornic use = keratitis 

Supressed blink reflex 

 

145

Lidocaine - use

Correct Vtach + SVT + PVT in dogs 

Analgesia (Dogs +Horses) 

Prokinetic effects (Horses) 

 

146

Lidocaine - Mechanism

Amide

147

Lidocaine - Duration

Rapid absorption 

Intermediate duration of action 

 

148

Bupivacaine - Mechanism

Amide 

149

Bupivacaine - use

Post-op pain control 

150

Bupivacaine - Adverse affect

Greater cardiotoxicity 

Binds more Na channels 

Dissociates slower from the channels 

 

151

Proparacaine - Mechanism

Amide

152

Proparacaine - Action

Fast onset 

Short duration 

Cats = 15 min 

Dogs = 45 min 

153

Mepivacaine - Mechanism

Amide

154

Mepivacaine - Use

Equine limb block 

Diffuses through surrounding tissue 

Les postinjection edema

155

Benzocaine - Mechanism

Ester

156

Benzocaine - Use

Topically absobed - 

Lozenges 

Fish anesthesia