Medical Pharmacology Chapter 13  Opioids, Pain Management and Organ System Effects

Opioid Analgesics: Efficacy; Oral/Parenteral Potency Ratio

Generic name	Trade name	Oral/ Parenteral Potency	Maximum Efficacy
Morphine	generic	Low	High
Hydromorphone	Dilaudid	Low	high
Oxymorphone	Numorphan	Low	High
Methadone	Dolophine	High	High
Meperidine	Demerol	Medium	High
Fentanyl	Sublimaze	parenteral only	High
Sufentanil	Sufenta	parenteral only	High
Alfentanil	Alfenta	parenteral only	High
Levorphanol	Levo-Dromoran	High	High
Codeine	generic	High	medium
Oxycodone	Percodan	Medium	medium
Dihydrocodeine	Drocode	Medium	medium
Propoxyphene	Darvon	oral only	Low
Pentazocine	Talwin	Medium	Low
Nalbuphine	Nubain	parenteral only	Low
Buprenorphine	Buprenex	parenteral only	Low

Adapted from Table 31-2: Way, W.L., Fields, H.L. and Way, E. L. Opioid Analgesics and Antagonists, in Basic and Clinical Pharmacology, (Katzung, B. G., ed) Appleton-Lange, 1998, p. 501; selection of an appropriate analgesic will depend on the severity and type of pain.

 

• Summary of Opioid Analgesic Toxic Effects

  • Dysphoria including behavioral restlessness and  hyperactivity

  • Respiratory depression

    • All opioid analgesics: significant respiratory depression (inhibiting brain stem respiratory centers)

    • Characterized by: reduced response to carbon dioxide challenge

    • Respiratory depression:

      • Dose-related

      • Influenced by extent to sensory input

      • Opioid induced:  slight respiratory depression: tolerated in patients with no prior respiratory difficulty

      • Opioid induced:  slight respiratory depression: poorly or not tolerated in patients with:

        • Asthma

        • Chronic obstructive pulmonary disease (COPD)

        • Cor pulmonale

        • Increased intracranial pressure

  • Nausea and vomiting

  • Increased intracranial pressure

    •  With respiratory depression (secondary to opioid administration), PCO₂ increases and is associated with:

      1. Cerebral vasodilation (decrease in cerebral vascular resistance)

      2. Increase in cerebral blood flow

      3. Increase in intracranial pressure

       

  • Hypotensive states are worsened by preexisting hypovolemia or by other medications given concurrently (e.g. nitroglycerin in acute management of myocardial infarction)

  • Constipation

  • Urinary retention

  • Urticaria, itching

1. Way, W.L., Fields, H.L. and Way, E. L. Opioid Analgesics and Antagonists, in Basic and Clinical Pharmacology, (Katzung, B. G., ed) Appleton-Lange, 1998, pp 496-515;

2. Schuckit, M.A. and Segal D.S., Opioid Drug Abuse and Dependence, In Harrison's Principles of Internal Medicine 14th edition, (Isselbacher, K.J., Braunwald, E., Wilson, J.D., Martin, J.B., Fauci, A.S. and Kasper, D.L., eds) McGraw-Hill, Inc (Health Professions Division), 1998, pp 2508-2512;

3. Coda, B.A. Opioids, In Clinical Anesthesia, 3rd Edition (Barash, P.G., Cullen, B.F. and Stoelting, R.K.,eds) Lippincott-Ravin Publishers, Philadelphia, New York, 1997, pp 329-358.

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