management of ocular pain

how do peripheral acting agents work?

• inhibit PGE2 synthesis to prevent sensitization of receptors to substance P (NSAIDS)

or

• inhibit substance P directly to decreased nociceptor activation (capzasin- derm)

how do signal inhibiting agents work?

prevent pain signal from travelling to cortex (anesthetics)

how do central acting agents work?

act on pain perception centers in the cortex (acetaminophen/ opioids)

when do we use topical NSAIDS?

• post refractive surgery

• post cataract surgery

• post fb removal

• pre/post betadine treatment

• bullous keratopathy and acute corneal hydrops

what are the positives to topical NSAIDs?

• direct activation to site of active injury/inflammation

• less side effects

• MOA takes place in peripheral nerve system at site of nociceptor nerve endings

what is the mechanism of action for NSAIDS?

cyclo-oxygenase inhibitors that prevent/decrease the formation of prostaglandins

what does limiting prostaglandin release/formation by NSAIDS do?

• analgesic

• anti-inflammatory

• anti-platelet

• anti-pyretic

what oral NSAIDS do we utilize for acute ocular pain?

• ibuprofen (400-600mg PO QID)

• ketoprofen (50mg PO q6-8hr)

• Naproxen sodium (250-500mg PO BID)

*take with food

side effects of oral NSAIDS

• hemorrhage

• gastric distress, heartburn, duodenal ulcer

• nephrotoxicity

contraindications of oral NSAIDS

• hyphema

• gastric/peptic ulcer

• renal insufficiency of CHF

• pregnant/nursing mothers

• NO ASPIRIN for children (Reye’s syndrome risk)

Acetaminophen (tylenol)

• MOA: unknown CNS effect

• therapeutically cause analgesia and antipyretic

• no effect on inflammation or platelets

• SE: liver toxicity if too much or if in alcoholics or known liver disease

• contraindicated in chronic alcoholics

typical dosing of tylenol

325-1000mg PO q6 hr

(recommended dosing reduced from 4000mg to 3000mg a day to protect liver)

opiates/opioid analgesics

MOA: alters central nervous system perception of pain via 3 receptors (mu, kappa, delta)

therapeutic effects: analgesia, anesthesia, cough suppression, anti-diarrheal

side effects of opiates

• constipation

• dry mouth

• nausea

• sedation, dizziness, weakness

• addiction/dependence due to euphoric effects

• respiratory depression (can be fatal)

contraindications of opiates

• asthma, COPD

• pregnancy

• an unidentifiable cause of pain (ex: back pain)

what should we do when opioids are prescribed?

• take with food

• avoid driving or other activities requiring alertness

• avoid alcohol, muscle relaxants

schedule 1 controlled substance

very high abuse potential, no medical use

Ex: LSD, heroin, MDMA, peyote, quaalude, (maybe marijuana)

schedule 2 controlled substance

high abuse potential with dependency liability

EX: cocaine, amphetamines, opiates like morphine oxycodone and hydrocodone

schedule 3 controlled substance

moderate dependency, abuse potential

EX: ketamine, anabolic steroids, some opiates like tylenol 3 with codeine

schedule 4 controlled substance

less dependency/ abuse potential

EX: analgesics (tramadol), anti-anxiety agents (xanax, klonopin, valium, ativan), sleep aids like ambien/lunesta

schedule 5 controlled substance

limited abuse potential

EX: cough suppressants, antidiarrheals, cbd containing FDA approved drugs

when should we use opiates for ocular conditions?

severe, acute pain due to

• severe corneal abrasion or FB

• post prk or other corneal surface procedures

• herpes zoster and post-herpetic neuralgia

what opioids can optometrists prescribe in Ohio?

1. tramadol

2. less than or equal to 60mg of codeine

3. no more than 7.5 mg of hydrocodone

*if pain cannot be managed in 4 days then it is no longer a primary eye care problem

tramadol (AKA: ConZip)

• synthetic analog of codeine

• schedule 4 substance, requires DEA #

• dosage: 50-100mg PO q4-6 hrs

• caution of patients on anti-depressants

• also comes in combo with acetaminophen

Codeine

• prodrug of morphine

• schedule 3 substance

• can be used stand alone for cough suppression

• comes in combo with acetaminophen

• dosage: 30-60mg PO q4-6hrs

hydrocodone

• schedule 2 substance

• 6 times more potent than codeine

• less constipation/sedation

• more euphoria

• dosage: 5-7.5 mg PO q4-6 hrs

• usually dosed with either acetaminophen or ibuprofen

what can ODs not prescribe in Ohio?

oxycodone, hydromorphone (both schedule 2substances)

who consumes the most opioids in the world?

the US

what are the guidelines for risk of opioid overdose?

caution at doses over 50 MED/day

avoid doses over 90 MED/day

avoid opioid use with benzodiazepines

*MED=morphine equivalent dose

Naloxone (zimhi)

• opioid antagonist used to reverse the effects of opioid overdose

• injectable by paramedics, in ER, some trained police officers

• available as nasal spray

• fast acting!

methadone

• synthetic opioid developed as an alternative to morphine

• involved in 31% of opioid related deaths

• long average 60-hour half life (long duration = decreased cravings)

buprenorphine

• partial agonist

• lower risk since respiratory depression plateaus

naltrexone

• opioid antagonist

• used to manage long-term treatments of opioid dependence