Analgesics and pain meds

Gabapentin

Used for neuropathic pain and mild sedation

Methocarbamol

Muscle relaxant used for spasms

Chondroprotectives function

Protect cartilage and support joint health

Examples chondroprotectives

Glucosamine Chondroitin PSGAGs

Opioids mechanism

Act on central nervous system to decrease perception of pain

Opioids do not treat

Inflammation or underlying cause of pain

NSAIDs mechanism

Inhibit cyclooxygenase COX enzymes to decrease prostaglandin production

COX-1 function

Protects stomach lining and maintains kidney blood flow

COX-2 function

Produces prostaglandins involved in inflammation

Glucocorticoids mechanism

Inhibit phospholipase blocking arachidonic acid formation

Local anesthetics mechanism

Block sodium channels preventing nerve impulse conduction

Gabapentin mechanism

Inhibits calcium channels reducing neuropathic pain signaling

Methocarbamol mechanism

Depresses CNS to reduce muscle spasms

NSAID + steroid

Never use together due to severe GI ulcer risk

Multiple NSAIDs

Never use together due to increased toxicity

NSAIDs in dehydration

Avoid due to risk of kidney damage

NSAIDs in cats

Use caution high risk of renal toxicity

Acetaminophen in cats

Fatal due to toxic metabolites

Ibuprofen in pets

Toxic causes GI ulcers and kidney failure

Steroids and corneal ulcers

Never use delays healing and worsens condition

Steroids long term stop

Never stop abruptly must taper

Low albumin NSAIDs

Increases toxicity due to more free drug

Tissue injury releases

Phospholipase

Phospholipase produces

Arachidonic acid

Arachidonic acid produces

Prostaglandins

Prostaglandins cause

Pain inflammation swelling

NSAIDs act on

Cyclooxygenase COX pathway

Steroids act on

Phospholipase earlier in pathway

COX-1 inhibition results

GI ulcers decreased kidney perfusion

COX-2 inhibition results

Reduced inflammation

COX-2 selective drugs

Carprofen Meloxicam Deracoxib Firocoxib Robenacoxib

More COX-2 selective means

Fewer GI side effects

Mu agonists

Provide strongest analgesia

Examples mu agonists

Morphine Fentanyl Hydromorphone Methadone

Fentanyl

Very potent short acting used as CRI or patch

Fentanyl potency

Approximately 200 times stronger than morphine

Butorphanol

Kappa agonist mu antagonist mild analgesia and antitussive

Butorphanol duration

Short acting about 2-3 hours

Buprenorphine

Partial mu agonist long lasting analgesia

Buprenorphine administration

Transmucosal especially in cats

Tramadol

Weak mu agonist used for chronic pain

Opioid side effects

Respiratory depression sedation vomiting

Opioids in cats and horses

May cause excitation instead of sedation

Steroids act earlier

Block phospholipase before arachidonic acid formation

NSAIDs act later

Block COX after arachidonic acid is formed

Steroids potency

More powerful anti-inflammatory than NSAIDs

NSAIDs effect

Reduce inflammation pain and fever

Steroids effect

Reduce inflammation and suppress immune system

NSAIDs side effects

GI ulcers renal toxicity bleeding

Steroids side effects

PU PD PP muscle wasting infection risk

NSAIDs preferred first

Used before steroids when possible

Steroid taper rule

Must taper to prevent adrenal suppression

Steroids long term risk

Iatrogenic Cushing’s disease

NSAIDs monitoring

Check kidney and liver values

Morphine

Mu agonist strong analgesia respiratory depression risk

Fentanyl

Mu agonist extremely potent short acting avoid improper patch use

Butorphanol

Kappa agonist mu antagonist mild analgesia avoid for severe pain

Buprenorphine

Partial mu agonist long acting difficult to reverse

Tramadol

Weak mu agonist chronic pain sedation and variable effect

Carprofen

COX inhibitor preferential COX-2 avoid with steroids or other NSAIDs

Meloxicam

COX-2 preferential inhibitor avoid in dehydration or renal disease

Deracoxib

COX-2 selective inhibitor avoid with other NSAIDs or steroids

Firocoxib

COX-2 selective inhibitor avoid GI disease or renal compromise

Robenacoxib

COX-2 selective inhibitor caution in cats renal risk

Aspirin

Nonselective COX inhibitor causes GI ulceration avoid in cats

Phenylbutazone

Nonselective COX inhibitor causes GI and bone marrow toxicity avoid in small animals

Flunixin meglumine

Nonselective COX inhibitor for visceral pain avoid in dehydrated patients

DMSO

Free radical scavenger topical penetrates skin wear gloves avoid contamination

Acetaminophen

Weak prostaglandin inhibition causes liver toxicity fatal in cats

Prednisone

Glucocorticoid inhibits phospholipase avoid with NSAIDs taper required

Dexamethasone

Potent glucocorticoid strong anti-inflammatory avoid infection and GI ulcers

Methylprednisolone

Glucocorticoid anti-inflammatory avoid long term use and taper

Gabapentin

Calcium channel inhibitor neuropathic pain sedation

Methocarbamol

CNS depressant muscle relaxant high doses cause weakness and ataxia

Lidocaine

Sodium channel blocker local anesthetic toxicity causes CNS and cardiac effects

Bupivacaine

Long acting sodium channel blocker cardiotoxic at high doses

COX inhibitor causing GI ulcers

Aspirin or nonselective NSAIDs

COX-2 selective safer NSAID

Carprofen Meloxicam Deracoxib Firocoxib

Drug that blocks phospholipase

Glucocorticoids

Drug fatal to cats with one dose

Acetaminophen

Drug class never combined with NSAIDs

Glucocorticoids

Opioid used for cough suppression

Butorphanol

Opioid with hardest reversal

Buprenorphine

Most potent opioid listed

Fentanyl

Local anesthetic toxicity target

Heart and CNS