The Use and Misuse of Demerol

INTRODUCTION

Meperidine (Demerol) has been a leading mu opioid analgesic for many years. There are many historical factors that led to meperidine being established as a standard agent for pain relief, but there are NO valid reasons for its continued status as a first line agent in analgesia and many reasons why it should not be used routinely.

DISADVANTAGES

Meperidine has several disadvantages:

1. A short duration of action

Meperidine has a duration of action of only 2-3 hours. Standard dosing (q 4-6 hours) leads to serum levels below the analgesic threshold for much of the dosing interval.

2. Strong local irritation

Meperidine is a strong local irritant. Because of this, meperidine should be given intramuscularly instead of subcutaneously. Injections can lead to irritation and fibrosis, which not only cause pain directly but also may decrease the analgesic effectiveness. Intravenous administration is superior.

3. Poor oral absorption

The oral absorption of meperidine is so poor and erratic that it is essentially useless as an oral agent (though still available).

4. Neurotoxicity

Neurotoxicity is the most important reason why meperidine is a poor choice for opioid analgesia. Normeperidine (6-N-desmethylmeperidine), an active metabolite of meperidine, is a strong CNS irritant and toxin. It can lead to dysphoria, tremor, myoclonus, and even generalized seizures.

Because of its long half-life, it accumulates in the system readily, even in otherwise healthy patients at standard doses. Patients with impaired renal function (the elderly and those with renal disease) are at increased risk for these side effects. Similarly, those exposed to higher or more frequent doses as well as those using the drug over longer periods of time are more likely to experience neurotoxicity. Finally, those with a pre-existing seizure disorder and those using concomitant drugs that lower the seizure threshold (e.g., MAO inhibitors, imipenem) have a higher risk.

MYTHS ABOUT ADVANTAGES

Meperidine is often purported to have advantages in pain control. Among the falsely claimed advantages are:

1. Meperidine does not have less addictive or abuse potential than other opioids.

2. Meperidine does not have specific benefit in patients with biliary colic or pancreatitis (that is, it has no unique properties re Sphincter of Oddi spasm).

3. There are no significant differences in opioid side effects with meperidine.

LIMITED INDICATIONS

Meperidine may be clinically useful in a few unusual clinical situations:

1. Analgesic use for rare patients with unmanageable adverse reactions to other first line opioids.

2. Prevention or treatment of rigors (chills) induced by blood products or drugs (e.g. Amphotericin B).

3. Treatment of post-anesthesia shivering (though considerable evidence suggests that warming is a preferred treatment).

4. Conscious sedation for procedures, when the rapid onset and short duration may be advantageous (however, intravenous fentanyl is even shorter-acting).

CONCLUSIONS

Meperidine has significant drawbacks as an analgesic agent. Clinical situations in which it is an appropriate choice are rare (see above). Many authorities have recommended that meperidine be eliminated from hospital formularies, and a number of leading hospitals have done so (San Francisco General and the City of Hope among them).

The Agency for Health Care Policy and Research (AHCPR) Guidelines for Acute Pain Management recommend that:

Meperidine should be reserved for very brief courses in otherwise healthy patients who have demonstrated an unusual reaction…or allergic response during treatment with other opioids.

The AHCPR Guidelines for Management of Cancer Pain suggest that:

Meperidine should not be used if continued opioid use is anticipated.

REFERENCES

University of Wisconsin Hospitals, Guidelines for Use of Meperidine, http://www.wisc.edu/wcpi/prof/mguide.htm

Jacox et al, Cancer Pain Guidelines, AHCPR, 1994

Carr et al, Acute Pain Guidelines, AHCPR, 1992

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