Page 364 Guide to Pain Management in Low-Resource Settings

352 Barbara Schlisio

Nonopioid analgesics Th e standard dose of diclofenac is 50–75 mg
t.i.d. (three times a day), of ibuprofen 400–800 mg t.i.d.,
Nonsteroidal anti-infl ammatory drugs and of aspirin 500–1000 mg q.i.d. (four times a day).
(NSAIDs)
Acetaminophen (paracetamol)
Despite their chemically diff erences, NSAIDs have a
common mode of action, the inhibition of prostaglandin Th e exact mechanism of action is unclear. Acetamino-
synthesis by the cyclooxygenase isoenzymes COX-1–3. phen might inhibit a central cyclooxygenase isoenzyme
Remember that prostaglandins sensitize peripheral no- (COX-3) and act as a central and spinal substance P in-
ciceptor nerve endings to mechanically and other stim- hibitor. Even though acetaminophen is classifi ed as an
uli, thus provoking a decreased pain threshold. Cen- antipyretic drug, it has mild anti-infl ammatory prop-
trally active prostaglandins enhance the perception and erties. Acetaminophen is a safe alternative medication
transmission of peripheral pain signals. But NSAIDs do when NSAIDs are contraindicated or not well tolerated
interfere with a number of other physiological functions by the patient.
as well, which explains most of their side eff ects. Th ese Acetaminophen is well tolerated in therapeutic
unwanted eff ects include the release of gastric acid, the doses, but it is hepatotoxic at high doses (approximately
aggregation of platelets, the activity of vascular endo- 6–15 g per day), when its metabolites can produce fatal
thelium, the initiation of labor, and an infl uence on the liver necrosis. Alcohol-dependent and undernourished
ductus arteriosus of neonates. patients are at especially high risk. Renal tubular necro-
NSAIDs are usually indicated for the treat- sis may also occur. However, and rightly so, acetamin-
ment of acute or chronic pain conditions, espe- ophen is often used for minor to moderate pain post-
cially where inflammation is present. In pain of low operatively, as well as in headache and cancer patients,
to moderate intensity, they may give sufficient pain because it is free of any gastrointestinal and renal side
control as a single therapy, but in moderate to severe eff ects when the dose recommendations are observed.
pain they should only be used in combination with Note the contraindications: severe hepatic and
opioids. In the postoperative situation it makes espe- renal impairment, alcohol-dependent patients, under-
cially good sense to combine opioids and NSAIDs be- nourished patients, and patients with glucose 6-phos-
cause the reduction in the dose of opioids will reduce phate dehydrogenase defi ciency.
any opioid side effects. Different NSAIDs are avail- Th e standard dose of paracetamol is 500–1000
able in different countries. Diclofenac and ibuprofen mg t.i.d., and postoperatively the initial oral or rectal
are used most frequently, but other NSAIDs have dose should be 2000 mg.
been shown to be comparable. To avoid unintend-
Dipyrone (metamizol)
ed drug accumulation, certain long-acting NSAIDs
should be avoided (e.g., piroxicam), and to avoid Dipyrone is supposed to be a central cyclooxygenase
gastrointestinal and renal side-effects, all NSAIDs inhibitor. It acts as an antipyretic. It diff ers from other
should be used short-term only. Most NSAIDs cause nonsteroid drugs in respect to its spasmolytic eff ects,
ulcers and other upper gastric symptoms such as dys- since dipyrone inhibits the release of intracellular calci-
pepsia and epigastric pain or discomfort if used long- um. Th e benefi ts of dipyrone are that you do not have to
term (>7–10 days). A less common but serious side worry about renal function and gastrointestinal side ef-
effect is anaphylactic reaction with development of fects and that it is generally cheap. Like acetaminophen,
severe bronchospasm and/or cardiovascular depres- dipyrone may also be used for long-term treatment. Its
sion. Renal failure is a more frequent and serious indications are acute and chronic pain of mild to mod-
complication and is mostly associated with long-term erate intensity, as well as colicky pain.
use, especially in patients with a history of previous A number of patients will complain about sweat-
renal impairment and hypovolemia. ing, for which there is no tolerance. Th e topic of idio-
Note the contraindications: gastrointestinal ul- syncratic drug reactions has been reopened after some
ceration, hemophilia, hypersensitivity to aspirin, young Scandinavian publications, and a number of countries
children because of the possibility of developing Reye’s have therefore made dipyrone unavailable. But several
syndrome, pregnancy especially the last trimester, countries, including Germany, Spain, and most Latin
breastfeeding, and advanced renal impairment. American countries, consider the risk low, compared to