Opiates

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• Opiates

Choices
Conversions
Consequences
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Pain Defined

• Unpleasant Somato-Psychic Experience

NO FUN
It affects the mind
It originates in the body (most of the time)
It is what the patient says it is
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TOTAL PAIN
SOMATIC INPUT
ANXIETY
ANGER / EMOTION
DEPRESSION
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Individualized Therapy

• Indications
• Dosing and Titration
• The WHO Analgesic Ladder

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Indications

• PAIN
• Acute, Chronic, Terminal
• Generally Opioid Sensitive Pains
• DYSPNEA
• AGGITATION
• Trial for patients unable to communicate needs

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Principles of Care

• Prevent Pain - Dont Chase It
• Give enough RTC that PRN
• Give equivalent daily dose RTC and PRN
• If using MSO4 180 mg daily RTC (60 mg q 8h) then
  allow up to 180 mg daily in rescue dosing (30
  mg q 4h)

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Inadequate Dosing

• How do you know?
• The patient is still in pain !
• When have you gone too far?
• Side effects outweigh benefits !
• (notice no comment on dose)

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WHO Ladder
Opioid for moderate to severe pain ? Non -
opioid ? Adjuvant
Opioid for mild to moderate pain Non - opioid ?
Adjuvant

• PAIN

Non - opioid ? Adjuvant
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Choices

• Receptors and Relationships
• Classes
• Cost

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Receptors

• m

• k

• d

• ? (mu)
• morphine receptor
• analgesia, respiratory depression, miosis,
  euphoria, reduced gastrointestinal motility

• ? (kappa)
• ketocyclazocine receptor
• analgesia, dysphoria, psychomimetic effects,
  miosis, respiratory depression

• ? (delta)
• enkephalin receptor
• analgesia

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Agonist vs. Partial Agonist vs. Agonist/Antagonist
POTENCY
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Classes

• Phenanthrene Derivatives
• Morphine
• Codeine
• Hydrocodone
• Hydromorphone
• Oxycodone
• Phenylpiperidine Derivatives
• Meperidine
• Fentanyl
• Diphenylheptane Derivatives
• Methadone

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Costs
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Routes

• Preferred Routes
• Oral
• Rectal
• ? Transdermal
• SC
• IV
• Epidural
• Intrathecal
• IM

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Conversions

• Drugs
• Common Ground
• Caution in changing classes
• Routes
• ParenteralOral
• 13 with chronic dosing
• 110 acute
• Reduce by 33-50 and allow for abundant prn dosing

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Consequences
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Constipation

• Most common side effect - expected
• Mediated spinally and in GI tract
• Decreased peristalsis decreased intestinal
  secretions
• Tolerance does not readily occur
• Treat with peristaltic agent and softeners -
  prophylactically

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Pruritis

• Caused by opioid induced histamine release
• Tolerance generally develops quickly
• Difficult cases may require a change in opioid
• Usually treated with transient use of
  antihistamines

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Somnolence / Sedation

• Common, but tolerance typically develops within a
  few days
• Sedation varies with opioid and dosing schedule
• Additive effects with other cerebral depressants
• Decrease or discontinue other cerebral
  depressants
• Concurrent use of Dextroamphetamine or
  Methylphenidate is helpful, but tachyphylaxis is
  common

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Hallucinations / Confusion

• Less common, but may occur especially in older
  patients
• Often an indication of excess dosing
• Try dose reduction or different opioid

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Nausea / Vomiting

• Occurs in 50 65 of patients on oral morphine
• Varies with drug and route
• Usually easy to control, occasionally severe and
  difficult to control

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Nausea / Vomiting Three mechanisms

• Stimulation of chemoreceptor trigger zone (area
  postrema) in medulla
• Increased vestibular sensitivity
• Delayed gastric emptying

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Nausea / Vomiting Treatment is with

• Conventional antiemetics
• Prochlorperazine (Compazine)
• Trimethobenzamide (Tigan)
• Promethazine (Phenergan)
• Ondansetron (Zofran - expensive)
• Unconventional antiemetics
• Haloperidol (Haldol)
• Lorazepam (Ativan)
• Diphenhydramine (Benadryl)
• Corticosteroids
• Cannabinoids
• Pro-Peristaltic agents
• Metaclopramide (Reglan)
• Cisapride (Propulsid)
• Anticholinergic agents
• Hyoscyamine (Levsin)
• Process alteration
• Parenteral - Oral
• Different opioid

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Urinary Retention

• Opioids increase smooth muscle tone (sphincter)
• May also cause bladder spasms
• Try changing opioids or insertion of catheter

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Myoclonus

• Can occur with all opioids
• Typically due to high doses and/or dehydration
• Long half-life metabolites are typically
  implicated
• Reduce dose, change opioids, change routes and/or
  hydrate patient

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Respiratory Depression

• Cause of death in opioid overdose
• Tolerance develops rapidly
• Rarely a concern with appropriate dose
  escalations
• If accidental overdose occurs in a patient
  chronically receiving opioids, dilute Naloxone
  110 and titrate very carefully to reverse
  respiratory depression without precipitating
  withdrawal or reversing analgesia

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Allergy
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Dependency / Addiction / Tolerance
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