Pharmacological Approaches in Pain Management

1
Pharmacological Approaches inPain Management
Ryan J. Bickel, Pharm.D., BCPS updated by David
G. Curry, PhD, APRN for NUR344, Fall, 2009 Used
with permission
2
Learning Objectives

• Review common non-opioid, opioid, and adjuvant
  analgesic medications
• Discuss and apply equianalgesic dosing concepts
  to selected case studies

3
WHO Pain Ladder
http//erlewinedesign.com/end-of-life-care/gfx/who
_ladder.gif
4
Non-Opioid Medications

• Ceiling effect to analgesia
• Do not produce tolerance or physical dependence
• Exhibit antipyretic properties

Ref. 1
5
Acetaminophen (APAP)

• Mechanism of action unclear
• No anti-inflammatory effects
• Causes liver toxicity at high doses
• Max dose 4 gm/day, if no liver disease
• Newest recommendation 2.6 gm/day
• Decreases opioid requirements

Ref. 1,2
6
Salicylates

• Aspirin (ASA)
• Effective as APAP for acute pain at similar doses
• Worse side effect profile than APAP

• Salicylate Salts
• Safer than ASA
• No platelet effects
• Examples
• Diflunisal (Dolobid)
• Magnesium salicylate (Doans)

Ref. 1,3
7
NSAIDs

• Efficacy is similar amongst NSAIDs
• Differences in potency, time of onset, duration
  of action
• Side effects
• GI bleeding
• renal dysfunction
• platelet dysfunction

Ref. 1,3
8
NSAIDs

• Ibuprofen (Motrin)
• initial choice for acute pain due to cost
  safety
• GI safety profile similar to placebo in doses of
  lt1200 mg/day
• Maximum daily dose 3200 mg/day
• Now available in IV form (Caldolor)
• Ketorolac (Toradol)
• first parenteral NSAID available in U.S.
• use limited to lt5 days due to side effects

Ref. 2,3
9
COX-2 Inhibitors

• Selectively inhibit cyclooxygenase-2
• less GI irritation less platelet effects
• other side effects similar to NSAIDs
• Celecoxib (Celebrex)
• Role patients with low cardiovascular risk who
  require NSAID therapy are at increased risk for
  GI toxicity

Ref. 4
10
Opioids

• Originally derived from poppies
• Body possesses endogenous opioids
• enkephalins
• endorphins
• Opiate Receptors
• mu (?)
• delta (?)
• kappa (?)
• sigma (?)

Papaver somniferum
Ref. 2,5
11
Pharmacology of Opioids

• ?1 inhibit transmission of pain
• ?2 respiratory depression, euphoria,
• constipation, physical dependence
• ? inhibit transmission of pain
• ? inhibit transmission of pain
• ? autonomic effects, dysphoria,
• hallucinations

Ref. 5
12
Common Side Effects of Opioids

• Constipation
• very common, tolerance is unlikely
• stool softeners stimulant /- metoclopramide
• Nausea/Vomiting
• tolerance usually develops
• pretreat with prochlorperazine

Ref. 6
13
Common Side Effects of Opioids

• Urticaria/Pruritis
• due to histamine release
• treat with antihistamine
• Sedation
• tolerance usually develops
• Delirium
• rare in patients with normal renal function

Ref. 6
14
Side Effects of Opioids

• Respiratory Depression
• preceded by somnolence
• tolerance develops
• use caution in patients with underlying pulmonary
  dysfunction
• if RR lt8 bpm, consider naloxone (Narcan)

Ref. 6
15
Morphine

• Gold standard of opioid therapy
• Half-life 1.5 -2 hrs
• Duration 3 - 5 hrs
• Metabolized to a renally excreted active
  metabolite
• dose adjustment may be needed in renal failure

Ref. 7
16
Morphine

• Multiple dosage forms available
• extended-release cap/tab
• Avinza once daily dosing
• Kadian daily or q12h dosing
• MSContin, Oramorph SR q8-12h dosing
• Immediate-release tab
• oral suspension (Roxanol)
• suppository (RMS)
• parenteral injection (Duramorph, Infumorph)

Ref. 7,8
17
Hydromorphone (Dilaudid)

• Alternative to morphine
• safe in renal failure
• more soluble than morphine
• Good choice when opioid volume is an issue
• opioid tolerant patients
• cachectic patients
• Forms parenteral, tab, suppository

Ref. 7,9
18
Oxymorphone (Opana)

• Highly selective for mu receptor
• More potent than morphine
• Forms
• immediate release tab
• do not take with meals
• extended-release tab
• do not take with meals or alcohol
• parenteral

Ref. 8,9
19
Codeine

• Indicated for mild-moderate pain
• weak opioid activity itself
• usually combined with acetaminophen
• Metabolized to morphine by the liver (2D6)
• poor metabolizers (lack 2D6)
• ultra-rapid metabolizers (2D6 gene duplication)
• Side effects limit use
• Primarily nausea/vomiting or constipation

Ref. 2,10
20
Codeine Derivatives

• Used in moderate-severe pain
• Hydrocodone
• combined with acetaminophen (Lorcet, Lortab,
  Norco, Vicodin, Zydone)
• watch amount of acetaminophen (max 4 gm/day)
• Oxycodone
• extended-release tabs (OxyContin)
• immediate release caps/tabs (OxyIR, Roxicodone)
• oral solution (Oxyfast, Roxicodone)
• combination products (Percocet, Percodan, Tylox)

Ref. 1,2,8
21
Meperidine (Demerol)

• Not a first line agent!
• Variable oral bioavailability
• Short duration of action
• Relatively low potency
• Neurotoxic metabolites
• Normeperidine has very long half-life!
• Multiple drug interactions

Ref. 11,12
22
Meperidine

• Borgess Usage Guidelines
• Do not use for over 48 hrs
• Maximum dose 600 mg/24 hr period
• Avoid in patients with renal dysfunction or a
  history of seizures
• Oral use discouraged

23
Fentanyl

• Highly lipophilic
• Causes less histamine release than other opioids
• Unique dosage forms/delivery devices
• buccal tablet (Fentora)
• lozenge (Actiq)
• transmucosal film (Onsolis) restricted use in
  US at the present time
• transdermal patch (Duragesic)

Ref. 7-9
24
Fentanyl Transdermal Patch

• Advantages
• sustained-release opioid
• good in patients with poor compliance
• good choice if concerned about drug abuse
• Disadvantages
• delay in onset
• residual activity after patch removed must
  remove old patch!!
• expensive
• Note Heat increases rate of release from patch

Ref. 2,13
25
Methadone (Dolophine)

• Not a first-line opioid
• Non-opioid actions provide additional analgesia
• Half-life 22 hrs
• Duration 3-6 hrs (initial) 8-12 hrs (chronic)
• Pros cheap good for refractory pain
• Cons unpredictable difficult to dose drug
  interactions

Ref. 12,14
26
Propoxyphene (Darvon)

• Not a first line agent!
• Neurotoxic metabolite
• Long half-life
• Propoxyphene-APAP (Darvocet)
• not much more efficacious
• than APAP alone

Ref. 2,3
27
Mixed Agonist-Antagonists

• Not a first line agent
• causes withdrawal in patients on opioids
• ceiling effect on analgesia
• psychotomimetic adverse effects
• Lower abuse potential

• Examples
• Butorphanol (Stadol)
• Pentazocine (Talwin, Talwin NX)
• Buprenorphine (Buprenex)

Ref. 7
28
Tramadol (Ultram)

• Dual mechanism of action
• Used for moderate pain
• Less respiratory depression than opioids
• May enhance risk of seizures
• max dose 400 mg/24 hrs
• decrease dose in elderly renally impaired

Ref. 5,8
29
Adjuvant Pain Medications

• drugs that are used primarily for treating
  conditions other than pain, but may be analgesic
  in selected circumstances
• -AMA

Ref. 1
30
Common Adjuvant Medications

• Antidepressants
• Anticonvulsants
• Corticosteroids
• Topical Anesthetics
• Calcitonin
• Bisphosphonates

Ref. 1
31
Pharmacokinetics of Routes
Ref. 6
32
Equianalgesic Table
Opioid IM/IV (mg) Oral (mg)
Morphine 10 30
Oxycodone Not Available 20
Oxymorphone 1 10
Hydromorphone 1.5 7.5
Fentanyl 0.1 Not Available
Meperidine 75 300
Hydrocodone Not Available 20
Codeine 120 200
Ref. 8,15
33
Equianalgesic Dosing Methodology

• Total the 24-hour dose of current opioid usage
  including prn doses
• Convert for drug route using table
• Reduce calculated dosage 30-50
• Calculate breakthrough pain dose, if converting
  long-acting opioids
• 5 15 of total daily opioid dose

Ref. 15,16
34
Equianalgesic Case 1

• MJ is a 56 YOM with prostate cancer admitted
  to hospital for pain control. He was started on
  a morphine PCA. In the last 24 hours the patient
  has received 34 mg and his pain has been
  adequately control. The physician discontinued
  the PCA and started the patient on MSContin 30 mg
  PO BID. Is this an equivalent regimen?

35
Equianalgesic Case 1
Table IV dose
Table PO dose

Pt 24 hr IV dose
X amount of PO
36
Equianalgesic Case 1
Opioid IM/IV (mg) Oral (mg)
Morphine 10 30
Oxycodone Not Available 20
Oxymorphone 1 10
Hydromorphone 1.5 7.5
Fentanyl 0.1 Not Available
Meperidine 75 300
Hydrocodone Not Available 20
Codeine 120 200
Ref. 8,15
37
Equianalgesic Case 1

• Set up proportion
• Cross multiply

38
Equianalgesic Case 1

• 10X 1020
• Divide each side by the number in front of X
• 10X 1020
• 10 10
• Select Reasonable Regimen
• MS Contin 45 mg PO BID

X 102

39
Equianalgesic Case 1

• Calculate the oral morphine dose needed for
  breakthrough pain
• Answer Morphine 5 15 mg PO every 4 hours prn
  pain

40
Equinalagesic Case 2

• PJ is a 47 YO female who is receiving morphine
  2-6 mg IV q2h prn post-op. In the last 24
  hours, the patient has received 24 mg IV
  morphine. Surgery just dcd the morphine
  ordered Lortab 5/500 mg 1-2 tabs PO q6h PRN pain.
  What do you think of this regimen?

41
Equinalagesic Case 2

• Convert to oral morphine

10 mg IV
30 mg PO

24 mg IV
X
42
Equinalagesic Case 2

• Convert to hydrocodone

30 mg MS
20 mg HC

72 mg MS
X
43
Equinalagesic Case 2

• Dose Reduction
• Suggested daily hydrocodone dose for BR 24 36
  mg/day
• Assessment
• BRs current hydrocodone dose if given q6h
  scheduled 20 40 mg

44
Questions
45
References

• 1. Pain Management Part 1 Overview of
  Physiology, Assessment, and Treatment. Chicago,
  IL, American Medical Association, 2003.
• 2. Li JM. Pain management in the hospitalized
  patient. Med Clin N Am 2002 86 771-95.
• 3. Sachs CJ. Oral analgesics for acute
  nonspecific pain. Am Fam Physician 2005 71
  913-18.
• 4. Frampton JE, Keating GM. Celecoxib A review
  of its use in the management of arthritis and
  acute pain. Drugs 2007 67 2433-72.
• 5. Trescot AM, Datta S, Lee M, Hansen H. Opioid
  pharmacology. Pain Physician 2008 11 S133-53.
• 6. Emanuel LL, von Gunten CF, Ferris FD, eds. The
  Education for Physicians on End-of-life Care
  (EPEC) Curriculum. EPEC Project, The Robert Wood
  Johnson Foundation, 1999, Module 4.
• 7. Inturrisi CE. Clinical pharmacology of
  opioids for pain. Clin J Pain 2002 18 S3-S13.
• 8. Lexi-Drugs (Comp Specialty) computer
  program. Lexi-Comp. October 24, 2008.
• 9. Nickel EJ, Smith T. Analgesia in the intensive
  care unit pharmacologic and pharmacokinetic
  considerations.Crit Care Nurs Clin North America
  2001 13 207-17.
• 10. Gardner-Nix J. Principles of opioid use in
  chronic noncancer pain. Can Med Assoc J 2003
  169
• 38- 43.
• 11. Baker DE. Meperidine a drug past its prime.
  Hosp Pharmacy 2001 36 1131-32.
• 12. Auret K, Schug SA. Underutilization of
  opioids in elderly patients with chronic pain.
  Drugs Aging 2005 22 641-54.
• 13. Walsh D. Pharmacological management of cancer
  pain. Semin Oncol 2000 27 45-63.
• 14. Toombs JD, Kral LA. Methadone treatment for
  pain states. Am Fam Physician 2005 71 1353-8.
• 15. Rapp CJ, Gordon DB. Understanding
  equianalgesic dosing. Orthop Nurs 2000 19
  65-72.
• 16. Cleary JF. Pharmacokinetic and
  pharmacodynamic issues in the treatment of
  breakthrough pain. Semin Oncol 1997 24 S16-13
  S16-19.