Pain 2

• Pain management is the topic

Opioids

• Opioids, opiates, and narcotic analgesics are used interchangeably.

Confusing terms

• Opium is naturally occurring milky extract from unripe poppy plant seeds
• It contains morphine, codeine, and 18 other substances
• Opiates are naturally occurring chemical compounds extracted from opium
• Opioids are drugs derived from the opium formula, either synthetic or natural
• Narcotics are morphine-like drugs that induce analgesia and CNS depression
• Associated with illegal use, for example, hallucinogens, heroin, amphetamines, marijuana, etc.

Opioids Purpose & Schedule

• Opioids are a therapeutic mainstay in moderate to severe pain management and can be combined with other therapies for chronic or complicated pain.
• MOST opioids do not have ceiling doses and should be titrated upward as needed, but this causes dependence.
• Titrate downward as patient tolerance increases
• Most opioids are Schedule I, while some are Schedule II

Opioid Mechanism of Action

• Opioids are agonists for receptors mu (1 and 2), kappa, delta, sigma, and epsilon (opiate)
• When a synaptic knob is activated by an opioid agonist, pain neurotransmitters like substance P and glutamate will be inhibited
• Substance P is involved in acute pain transmission
• Opioids work by preventing the release of substance P by inhibiting mu or kappa receptors
• This process reduces the depolarization of ascending pain neurons, thus blocking pain transmission.
• Dopamine plays an important part in the mesolimbic reward pathway and the reinforcing effects of opioids
• Dopamine release contributes to the pleasurable sensations from opioids
• Dopamine is not directly responsible for analgesia but plays a role in addition and reinforcement

Opioid ADME

• Absorption varies depending on the route of administration
• Distribution distributes to skeletal muscle, liver, kidneys, lungs, intestinal tract, spleen, and the brain
• 20-35% Protein binding
• Peak plasma concentration is 1 hour when taken orally, and 3-4 hours if its extended release
• Peak plasma concentration is 20 mins if administered via IV
• Hepatic Metabolization via conjugation
• Elimination via urine and feces
• Metabolites might cause toxicity with renal insufficiency

Opioid Receptor Effects

• Mu1 receptor induces:
• Analgesia
• Euphoria
• Confusion
• Dizziness
• Nausea
• Sedation
• Histamine release
• Dopamine release
• mu2 receptor induces:
• Respiratory depression
• Cardiovascular effects (hypotension)
• GI effects (slow motility)
• Urinary retention
• Miosis
• Delta receptor induces:
• Analgesia
• Cardiovascular effects
• Respiratory depression
• Kappa receptor induces:
• Analgesia
• Psychomimetic effects (nightmares)

Opioid Efficacy

• High efficacy opioids include:
• Fentanyl (80-100 times more potent than morphine)
• Hydromorphone (Dilaudid) – 5x stronger than morphine
• Meperidine (Demerol)
• Morphine
• Methadone (Metadol)
• Moderate efficacy opioids include:
• Hydrocodone
• Oxycodone (OxyNeo)
• Oxycontin
• Tramadol (Ultram)
• Combo drugs: Percocet, Percodan, Vicodin, Tramacet
• Codeine is not for kids

Combination Drugs

• Combination drugs contain Opioids and Non-narcotic Analgesics which have a synergistic effect
• One benefit is that dependence on opioids can be reduced
• Examples include:
• Percocet (oxycodone + acetaminophen)
• Percodan (oxycodone + ASA)
• Vicodin (hydrocodone + acetaminophen)
• Tramacet (Tramadol + acetaminophen)
• Atasol (Acetaminophen + Caffeine + Codeine)
• Tylenol #1-#4 (Amount of codeine present)

Opioid Side Effects

• CNS Depression
• Drowsiness
• Dizziness
• Confusion
• Mental clouding
• Excessive sedation or unresponsiveness in higher doses
• Respiratory depression manifests as shallow breathing
• Apnea may occur in severe cases
• Cardiovascular:
• Bradycardia, tachycardia during compensation
• Hypotension, palpitations
• Gastrointestinal:
• Constipation due to slowed intestinal motility
• Nausea, vomiting, or reduced appetite
• Genitourinary
• Urinary retention
• Integumentary
• Pruritis

Opioid Side Effect Management

• Nausea and vomiting usually resolves in a few days
• Antiemetics or switching opioids can help
• Sedation can be treated by decreasing the dose
• Constipation can be treated by:
• Stool softeners
• Osmotic stimulants
• Peripherally-acting mu-opioid antagonists
• Switching opioids
• Avoiding bulking agents
• Pruritus can be treated by switching opioids or using antihistamines
• Urinary retention can be treated by switching opioids

Morphine

• Morphine has the brand names, and is an opioid analgesic/opiate receptor agonist
• Tablets and parenteral are dose forms
• Morphine's MOA is to bind to opiate receptors (mu, kappa, delta) in the CNS, acting as agonists of endogenously occurring opioids (enkephalins, endorphins, and dynorphins), reducing perception of and response to pain
• Indications include moderate to severe pain
• Contraindications include:
• Hypersensitivity
• Severe respiratory disease
• Head Injury
• Adverse/Common side effects include:
• Severe respiratory/CNS depression
• Constipation
• Urinary retention
• Pruritus
• What to assess:
• Type, location and intensity of pain prior to and at peak following administration
• Use equianalgesic chart when changing routes, or from one opioid to another
• Patient education involves:
• Instructing patient on how and when to ask for pain meds
• Informing patients about dizziness or drowsiness, slow making position changes
• Avoide concurrent use of alcohol or other CNS depressants

Naloxone/Narcan

• Used when respiratory depression is seen in less than 10% of opioid users, mainly in those who are naive to opioid therapy
• Indicated when the respiratory rate falls below 8-10 and the client has an altered mental status.
• Narcan's MOA blocks mu and kappa receptors
• Administer carefully and slowly, just until the client starts to respond, has an increased respiratory rate and a clearing mental status.
• Onset in 2-4 minutes
• Duration of action - 45 min
• If given to chronic opioid-user, the client will wake up with aggressive behaviors (euphoria)

Naloxone details

• Naloxone comes under the brand name Narcan
• Its of the Opioid antidote (antagonist) class
• It must be administered via Parenteral or intranasal means only
• MOA involves Competitively blocking the effects of opioids, including CNS and respiratory depression, without producing any agonist (opioid-like) effects
• Indications include Reversal of CNS depression and respiratory depression due to suspected opioid overdose
• Contraindications include Hypersensitivity.
• Adverse/Common side effects include Ventricular arrhythmia.
• What to assess:
• Monitor respiratory rate, rhythm and depth
• Pulse, ECG, BP and level of consciousness frequently for 3-4 hours after expected peak.
• Dilute and administer in slow increments for sensitive patients (<1 week opioid use)
• Assess for signs of opioid withdrawal
• Patient Education:
• Explain purpose and effects to patients, as medication becomes effective

Nursing Considerations

• Adequately assess pain.
• Treat pain holistically
• Treat all patients adequately
• Base the treatment plan on the patient's stated goals
• Use pharmacologic and non-pharmacologic pain strategies
• Use a multimodal approach to pain management.
• Regularly monitor pain management strategies to ensure patient's goals are being met
• Continually educate and inform patients about the medications

Pain Management Strategies

• For pain less than 4/10, consider non-opioid medications
• less invasive route, e.g. PO
• Consider NSAIDs, and Tylenol
• For pain between 4-6/10, opioids are more likely to me used
• less invasive route, e.g. PO
• Consider synergy, combination drugs, Morphine
• For pain greater than 6/10, more potent opioids more likely to be used
• Consider IV route
• Consider PCA

PCA

• Patient Controlled Analgesia device is a programmable pump
• PCA delivers the opioid infusions according to individualised settings
• Bolus dose
• Lockout time
• Dose duration
• Background infusion

Pain is Subjective

• Everyone filters their experiences of pain through their own experience, avoid bias.
• This includes:
• Personal use of medications or non-pharmacologic methods
• Family or significant other's history or experience with substances
• Remember that pain is an individual subjective experience, and “is what the patient says it is"