Analgesia (Final) Flashcards
1
Q
What are the four steps of nociception, and where do they each take place?
A
- transduction (peripheral tissue)
- transmission (via peripheral nerves)
- modulation (in spinal cord)
- perception (in the brain)
2
Q
Local Anesthetics
- main action
- chemical structure
A
- cause reversible blockade of transmission in peripheral nerves or spinal cord (stops pain signals)
- consist of an aromatic group joined to a tertiary amine group by either an amide or ester
- all weak bases
3
Q
Describe the MOA of local anesthetics
A
- block propagation of an action potential by inhibiting influx of Na through voltage-gated Na channels
- must be non-ionized to enter cell, but inside, the ionized form interacts with the Na receptor
4
Q
Describe the metabolism of local anesthetics
A
- ester LAs are rapidly broken down by plasma esterases
- amide LAs are mainly metabolized in the liver
- metabolites are excreted in the urine
5
Q
What are the clinical uses of local anesthetics?
A
- regional anesthesia (minor procedures, lameness localization)
- pre and post-operative analgesia (nerve blocks, epidurals)
- operative analgesia (with sedation)
- treatment of ventricular arrhythmias
6
Q
What are adverse affects of local anesthetics?
A
- local irritation
- CNS stimulation (muscle twitch, tremors, seizures)
- CNS depression (unconsciousness, respiratory arrest)
- cardiovascular depression (bradycardia, vasodilation, hypotension)
7
Q
Lidocaine
- type of drug
- onset/duration
- which animals are more sensitive?
- contraindication?
A
- amide local anesthetic
- rapid onset, medium duration
- cats more sensitive than dogs
- sheep more sensitive that other livestock
- banned in food animals
8
Q
Systemic use of Lidocaine
A
- class 1B antiarrhythmic used to control ventricular arrhythmias
- CRI as adjunctive analgeisa (MLK drips)
- CRI as a GI prokinetic/anti-inflammatory
- prevention of reperfusion injury/endotoxemia
9
Q
Local use of Lidocaine
- formulations
A
- solution for injection
- may contain epinephrine
- some mixed with sodium bicarbonate to reduce pain
- used topically
- EMLA cream
10
Q
Bupivacaine
- type of drug
- onset/duration
- caution
A
- amide local anesthetic
- slow onset and duration
- most cardiotoxic of LAs
11
Q
Mepivacaine
- type of drug
- use
- duration
A
- amide local anesthetic
- used for diagnostic nerve blocks in horses
- duration longer than lidocaine
12
Q
Procaine
- type of drug
- use
- caution
A
- ester local anesthetic
- won’t use as an LA, but is in some penicillin G preparations
- toxic, can cause CNS stimulation, don’t give IV
13
Q
Proparacaine
- type of drug
- use
- onset/duration
A
- ester local anesthetic
- used topically, ophthalamic
- allows for corneal and conjunctival manipulation
- rapid onset, short duration
14
Q
What is the function of TXA2, and why do we block it?
A
- promotes platelet aggregation
- block to prevent thromboembolism from certain diseases
15
Q
Describe the actions of PGE1
A
- involved with GI mucosal maintenance and vasodilation in kidney, in response to decreased blood flow
16
Q
What is produced by COX-1?
By COX-2?
A
COX-1: prostaglandins important for homeostasis
COX-1: prostaglandins produced during inflammation
17
Q
What are the types of NSAIDs?
4
A
- COX-1 selective inhibitors
- non-specific COX inhibitors
- COX-2 preferential inhibitors
- COX-2 selective inhibitors
18
Q
Describe the anti-inflammatory effects of NSAIDs
A
- inhibit synthesis of eiconsanoids (thromboxane, prostacyclin, prostaglandins)
- not as potent as glucocorticoids
- do not delay wound healing or lead to immunosuppression
- greater effect on acute inflammation than chronic
19
Q
Describe the analgesic effects of NSAIDs
A
- provide analgesia whether there is inflammation or not
- decreases PG sensitization of neurons
- central
20
Q
Piroxicam
- type of drug
- use
A
- NSAID
- used to block COX-2, resulting in anti-neoplastic effects
21
Q
What are some adverse effects of NSAIDs
A
- GI irritation/ulceration (PGs involved in maintenance of GI homeostasis)
- renal damage (PGs control vasodilation of renal vascular beds)
- hepatotoxicity
- increased bleeding time
- bone marrow suppression
22
Q
Flunixin Meglumine
- type of drug
- administration
- cautions
A
- large animal NSAID
- given PO, IV, IM
- labeled only for IV use in cattle and IM in swine
- do not use IM in equines
- intracarotid injection can cause seizures/CNS stimulation
- caution with GI, renal, hepatic, or hematologic diseases
- do not use in small animals, avoid in birds
23
Q
Phenylbutazone
- type of drug
- animals
- use
- administration
- cautions
A
- NSAID
- used in horses, banned in dairy cattle
- used for musculoskeletal pain
- PO, labeled for IV
- do not give IM/SC (very irritating)
- caution with GI, renal, hepatic, or hematologic disease
- can mask lameness
24
Q
Carprofen
- type of drug
- use
- administration
A
- COX-2 preferential NSAID
- used in small animals as analgesic and anti-inflammatory agents
- oral and injectible
25
Firocoxib
- type of drug
- administration
- COX-2 selective NSAID
- oral paste for horses
- chewable tablets for dogs
26
Robenacoxib
| - type of drug
COX-2 selective NSAID
| - approved for multiple doses in cats
27
Explain the washout periods for switching between NSAIDs and steroids
NSAID to steroid: sufficient washout period, 1-2 weeks
Steroid to NSAID: wean the steroid, then have at least 1 week washout period
NSAID to another NSAID: washout based on half-life or use at least 1 week
28
Which drug is the only NSAID labeled for cattle, and what is it used for?
- Flunixin meglumine
| - control of pyrexia associated with bovine respiratory disease, endotoxemia, and mastitis
29
Grapiprant
| - type of drug
- non-COX inhibiting NSAID
| - antagonist at prostaglandin E2 EP4 receptor
