Adjuvant Analgesia for Management of Chronic Pain
by Bilal F. Shanti, MD, Gabriel Tan, PhD, Ihsan F. Shanti, MD, PhD
 To date, clinical pain practice relies on opioids as the primary
analgesics for the management of moderate to severe pain. Adjuvant analgesics use has
become increasingly important especially in the management of mild to moderate pain.
Adjuvants act on either the excitatory (e.g., substance P, and glutamate), inhibitory
neurotransmitters (e.g., GABA), or on neurotransmitters that modulate pain experience
(e.g., serotonin, norepinephrine).
Traditional Adjuvant Analgesics
Traditional adjuvant analgesics such as the NSAIDs, acetaminophen, and muscle relaxants
will be briefly described first before discussing the newer adjuvants.
• NSAIDs and Acetaminophen. Non-steroidal anti-inflammatory drugs (NSAIDs) are
widely used. It is important to note that Acetaminophen is not an anti-inflammatory
medication. Along with mild narcotics, NSAIDs remain the mainstay of treating mild pain.
They are usually well tolerated and are often used to address inflammatory processes, such
as muscle aches, strains, or sprains. NSAIDs, as a class, have analgesic, antipyretic, and
anti-inflammatory effects although not all of them are FDA-approved for analgesia use.
They have the advantage of a very low short-term side-effect profile that does not impact
the patient’s lifestyle. They are called non-steroidal because no steroid agent is
present in them. Aspirin, for decades now, remains the prototypical agent. Other examples
include ibuprofen (Advil, Motrin), naproxen (Naprosyn), and indomethacin (Indocin). NSAIDs
can be used synergistically with opioids and for pain not responsive to opioids
alone–especially in patients with bone pain and incidental pain. Unlike opioids,
NSAIDs do not cause ileus or sedation. Acetaminophen is recommended by the American
Geriatrics Society (AGS) as the drug of choice for mild to moderate musculoskeletal pain.
It has an excellent safety profile at therapeutic doses that can be up to 4000 mg/day.
Toradol (Ketorolac) is an injectable NSAID that is a potent analgesic (30 mg is roughly
equivalent to 7-10 mg of morphine) but has the potential for gastric irritation and
possible bleeding.1
• COX-2 Inhibitors. Celecoxib (Celebrex) and rofecoxib (Vioxx) mainly inhibit the
enzyme cyclo-oxygenase-2 (COX-2) and thereby result in anti-inflammatory effects with no,
or much less, gastric and renal side effects. They reportedly have fewer drug interactions
and have no effect on platelet aggregation or bleeding time commonly found with
traditional NSAIDs. COX-2 inhibitors are not free of side effects and package inserts
should be read thoroughly before prescribing these drugs. Both rofecoxib and valdecoxib
(Bextra) have been taken off the market because of concerns of potential side effects.
Meloxicam (Mobic) is not a typical COX-2 inhibitor although some have called for
re-classifying it as such.
Please refer to the April 2006 issue for the complete text. In the event you need to order a back issue, please click here.
— April 2006
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