Lec 1 - Common Analgesia

What are some drug classes commonly used in pain management?

- Opioid

- Alpha-2 agonist

- NSAID

- Dissociative anesthetic

- Infiltrative and local anesthetics

what are opioids commonly used for?

-Analgesia

-sedation

-restraints

-antitussive

What are some advantages of using opioids?

- Rapid onset of action

- Safe

- Reversible

- Potent analgesia

What are the three main opioid receptors?

Mu, Delta, Kappa

What is an opioid agonist?

An opioid that activates and binds to a receptor to cause a physiological activity

What is an opioid antagonist?

An opioid that blocks another drug from combining with a receptor

What are the 4 different classes of opioids?

- Pure Mu Agonists

- Partial Mu Agonists

- Agonist-Antagonist

- Antagonist

Of the 4 opioid classes, which should be used for a pronounced analgesic effect?

Pure Mu Agonists

-binds on receptor and produce desired therapeutic effect

Of the four opioid classes, which has a wide safety margin, a long duration of action, and is one of the best analgesics for cats?

Partial Mu Agonists

ex. Buprenorphone

-binds on receptors but are unable to produce maximal response

Of the four opioid classes, which produces mixed effects and can be used for short procedures with little pain?

Agonist-Antagonist

ex. Butorphanol

-able to bind on one type of receptor while blocking another

Of the four opioid classes, which should be used as a reversal?

Antagonist

-binds on receptor completely blocking effect

What is an example of an opioid antagonist?

Naloxone

What are some examples of opioid pure mu agonists?

Fentanyl, Methadone, Hydromorphone, and Morphine

What is an example of an opioid partial mu agonist?

Buprenorphine

-produces a mild to moderate analgestic effect

IV or PO

What is an example of an opioid agonist-antagonist?

Butorphanol

-produces and very mild analgesic effect

-less analgesic compared to NASIDS

what is the common concerning negative side effect of Alpha-2 agonist?

decreased CO cardiac output

What are some potential side effects of opioids?

- Excitement/dysphoria

- Respiratory depression

- Bradycardia

- Histamine release (Morphine)

- Vomiting

- Urine retention

- Panting (Hydromorphone)

What are two examples of commonly used Alpha-2 Agonists?

Dexmedetomidine and Xylazine

Of dexmedetomidine and xylazine, which is more predictable and has greater sedation/analgesia effects?

Dexmedetomidine

because it has a high affinity to alpha -2 receptors and provides a more consistent and reliable sedative effect compared to Xylazine.

What are the main effects of Alpha-2 agonists?

- Antinociception

- Sedation

- Decreased heart rate and blood pressure (bradycardia and hypotension)

- Emesis (esp. cats)

What is the reversal used for Dexmedetomidine?

Atipamezole (Antisedan)

What is the reversal for Xylazine?

Yohimbine

What are some contraindications for using Alpha-2 agonists?

- Geriatric patients

- Cardiac patients

- Increased intracranial pressure

- Patients with preexisting hypotension, hypoxia, or bradycardia

What are some common NSAIDs used in VetMed?

- Meloxicam (Metacam)

- Carprofen (Rimadyl)

- Deracoxib (Deramaxx)

- Ketoprofen (Anafen)

- Robenacoxib (Onsior)

- Grapiprant (Galliprant)

What enzymes do NSAIDs inhibit?

COX-1 and COX-2

Of the two COX enzymes, which one do we want NSAIDs to inhibit?

COX-2

Of the two COX enzymes, which one do we not want NSAIDs to inhibit?

COX-1

What are the major side effects of NSAIDs?

- Gastric irritation/ulceration

- Decreased renal blood flow

- Decreased platelet activity

- Hepatic effects

Meloxicam (Metacam) is an example of what type of NSAID?

COX-2 Selective Inhibitor meaning it preferentially inhibits the COX-2 enzyme (the not so good enzyme)

Ibuprofen is an example of what type of NSAID?

Non-Selective COX Inhibitor meaning it inhibits both COX-1 and COX-2 enzymes

What are some examples of COX-2 selective inhibitors?

Carprofen (Rimadyl) and Meloxicam (Metacam)

What are some examples of highly selective COX-2 inhibitors?

Robenacoxib (Onsior) and Deracoxib (Deramaxx)

why should you give NSAIDs with food?

To minimize gastrointestinal side effects, such as irritation or ulceration.

What are some side effects of ketamine? List 3

- Increased cerebral blood flow and intracranial pressure

- Increased heart rate and blood pressure

- Increased cardiac workload (positive inotropy)

- may not close eyes

- Emergence delirium

- Poor muscle relaxation

- Excessive salivation (cats)