Treating Exacerbations of Chronic Pain

Wednesday, 09 March 2005 13:48


Exacerbations of chronic pain may cause patients to present to the emergency department with acute episodes, commonly of back or abdominal pain. Of course, there may also be acute conditions, which occur that are unrelated to the chronic condition, or post-operative analgesia is required.

In this situation, the usual medication is insufficient to provide analgesia but will interact with any treatment given for the acute condition. If the patient is on opiate medication, they will have developed tolerance to the effect not only of the medications they are taking, but also a degree of cross-tolerance to the effect of other opioid drugs.

This cannot necessarily be accurately predicted as it will vary between individuals. It is not within the scope of this article to address the complexities of prescribing under these conditions.

However, it is worth noting Mehl-Madrona's study published in 1999([1]). This looked at use of a combination of keterolac and chlorpromazine to replace the more usual meperidine/promethazine combination in the emergency room for exacerbations of chronic pain.

Keterolac is a potent Non-steroidal anti-inflammatory drug (NSAID) that is indicated for moderate to severe pain (NOT mild pain), chlorpromazine is a neuroleptic. Meperidine (pethidine) is a short-acting opiate given intramuscularly and promazine is given to prevent nausea and vomiting which may be induced by meperidine.

Patients were given either intramuscular doses of 60mg keterolac +50-75 mg chlorpromazine (KET-CHLOR) (depending on weight) or 50mg meperidine plus 25-50mg promethazine (MEP-PROM). (heavier patients were given 1.5 doses).

It was found that the pain relief of the 2 different protocols was comparable, but the KET-CHLOR patients had fewer side effects and this combination worked better for nausea (chlorpromazine is a more potent antiemetic than promazine).

The fluctuating course of arachnoiditis often involves periods of ?flare-up' for which at present there is no established treatment.

However, it may be appropriate to consider a course of anti-inflammatory measures such as NSAIDs or perhaps steroids in periods of increased inflammation, provided that this can be distinguished from ?mechanical' exacerbations comprising muscle spasm and/or joint pain etc. 

In any case, NSAID medication may well be helpful in analgesic terms aside from any anti-inflammatory activity. This aspect of the treatment of arachnoiditis requires further investigation.

[1] Mehl-Madrona LE J Am Board Fam Pract 1999; 12(3):188-194 Comparison of keterolac-chlorpromazine with meperidine-promethazine for treatment of exacerbations of chronic pain.