Anesthesia: Opioids

Pre-anesthetics:

• Agonists

• Partial agonists

• Agonist-Antagonists

Use analgesia:

• Pre op

• Intra op

• Post op

Pre-anesthetics and anangesics may be used with:

Tranquilizers or sedatives.

Define neuroleptanalgesia:

A profound state of sedation and analgesia induced by simultaneous administration of an opioid and a tranquilizer/sedative.

List the opioids:

• Morphine

• Hydromorphone

• Buprenorphine

• Butorphanol

• Oxymorphone

• Fentanyl

• Methadone

What can happen if you use more than one drug of either side while doing a neuroleptanalgesia?

You will have drug interactions.

List reasons you would perform a neuroleptanalgesia:

• Sedation for minor procedures

• Induction of general anesthesia- dogs

  • ASA 3-5

  • no cats

Main job of opioids:

Produce analgesia and sedation.

What do agonists do?

Bind to and stimulate target tissue.

What do antagonists do?

Binds to target but do not stimulate receptor.

What do partial-agonists do?

Bind to and partially stimulate receptors.

What do agonist-antagonists do?

Binds to receptors and block others.

If you are using an agonist, and you follow it up with an agonist-antagonist, what happens?

You reverse it.

List the agonist opioids as well as their drug schedule:

• C II

• Morphine

• Hydromorphone

• Methadone

• Fentanyl

List the partial-agonist and its drug schedule:

• C III

• Buprenorphine

List the agonist-antagonist and its drug schedule:

• C IV

• Butorphanol

List the antagonists and their drug schedule:

• Not controlled but still locked up

• Naloxone

Adverse effects of opioids:

Minimal cardiovascular/respiratory depression.

Even though HR and RR will be lowered, why are opioids still safe to use?

They are pure agonists— they’re reversible.

Opioids mainly act on the _________ and _________.

Brain and spinal cord.

What are the two types of receptors?

• Mu

• kappa (k)

• delta

• sigma

Of mu and kappa, which receptor is the strongest?

Mu.

Agonists are best for what kind of pain?

Moderate to severe pain

• Visceral and somatic pain

• severe injuries or ortho procedures

Agonizing mu —> better ___________ ___________.

Pain control.

what do partial agonists do?

Prevent binding of other opioids to receptors.

What do agonist-antagonists do?

Bind to mu and kappa receptors, but stimulate only kappa receptors.

What do antagonists do?

Bind to but don’t stimulate mu and kappa receptors.

Reversal agents.

No analgesia.

Effects of opioids in dogs:

• Sedation

• Narcosis - sleep-like state

Effects of opioids in cats:

• Excitement, no sedation

• use a lower dose (they have more opioid receptors.)

Other effects of opioids:

• Hypoventilation

• Miosis- dogs

• Mydriasis- cats, horses, ruminants

• Hypothermia- dogs

• Hyperthermia- cats

Adverse effects of opioids:

• GI speed up

• Gi stasis follows gi stimulation

  • no feces production

Butorphanol drug class and drug schedule:

• Agonist-antagonist

• Schedule IV

Butorphanol only reverses ____________ action.

Mu action.

• Partially reverses.

Butorphanol can also be used as a ____________.

Antitussitive.

Buprenorphine drug class and schedule:

• Partial agonist

• Schedule III

Buprenorphine administration routes:

• IV

• IM

• SQ

• Transmucosal

Buprenorphine is better for _______.

Cats.

2 different types of Buprenorphine:

• Zorbium— transdermal

• Simadol- SQ long acting buprenorphine

Morphine drug class and schedule:

• Agonist

• Schedule II

• One of the first opioids

• Epidurals

Side effects of morphine:

• Severe vomiting

• Histamine release- not good for MCT

What is the delayed onset for morphine?

30-45 minutes.

Hydromorphone drug class and schedule:

• Agonist (Pure mu)

• Schedule II

What are the side effects of hydromorphone?

3 P’s!

• Pooping

• Puking

• Panting— a lot

Oxymorphone drug class and schedule:

• Agonist (Pure mu)

  • Agonist of choice for cats

• Schedule II

Oxymorphone has ______ GI side effects.

Less GI side effects.

Methadone drug class and schedule:

• Agonist (Pure mu)

• Schedule II

Methadone has ______ action.

NMDA antagonist action

• treats wind up pain.

Methadone has _________ GI and respiratory side effects.

Less.

Methadone has a lot of sedation on its own, so it is rarely needed to be used with neuroleptanalgesia.

True or false?

False

• It does not have good sedation on its own.

What is wind up pain?

Patient is so painful, they feel pain when there is none.

Fentanyl drug class and schedule:

• Agonist (pure mu)

• Schedule II

Side effects of fentanyl:

• Severe bradycardia

• Respiratory depression

Fentanyls rapid onset:

Rapid— 2-5 minutes.

Fentanyl is given ____, followed by a ____.

Given IV and followed by a CRI.

What do opioid antagonists do?

Reverse undesirable effects.

Naloxone hydrochloride drug class and schedule:

• Antagonist

• Not controlled— still needs to be locked up.

How do we give naloxone?

IV (slowly and diluted), 2 minutes to reversal.

Adverse effects of opioid antagonists:

• Sudden analgesia loss

• Excitement

• Anxiety

• Sympathetic nervous system stimulation

When would inquire the use of opioid antagonists?

• Emergencies

• Overdose

• Reverse neuroleptanalgesia

• Reviving neonates delivered by C-section

Inability to coordinate movement:

Ataxia.

A temporary absence of spontaneous breathing:

Apnea.

An interaction between two drugs in such a way that the total effect us greater than the sum of the individual effects:

Synergistic.

A rhythmic, involuntary oscillation of both eyes:

Nystagmus.

Severe abdominal pain of sudden onset caused by a variety of conditions including obstruction, twisting, or spasm of the intestinal tract:

Colic.

Anxiety, uneasiness, and restlessness most often produced by opioids; the opposite of euphoria:

Dysphoria.

Involuntary muscle twitching:

Fasciculations.

The breathing passages and tubes that convey fresh oxygen from the source to the alveoli, but in which no gas exchange can occur:

Dead space.

A breathing pattern, most often seen during dissociative anesthesia, in which there is a a pause for several seconds at the end of the inspiratory phase, followed by a short, quick expiratory phase:

Apneustic.