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 Compounded medicines are custom-blended by pharmacists to give
patients a different dose or formulation than they can get with
mass-produced prescription drugs. The current study focused on pain
creams made from medicines that are often prescribed for pain in
pill form such as muscle relaxants, anticonvulsants and
non-steroidal anti-inflammatory (NSAID) drugs.
Researchers randomly assigned 399 patients with different types of
chronic pain to receive either a compounded cream containing an
analgesic or a placebo cream without any medicine.
After one month, 36 percent of patients who used pain creams and 28
percent who got placebo creams reported less pain than they had at
the start, a difference that was too small to rule out the
possibility that it was due to chance.
"We know from other studies that some of the agents (lidocaine,
non-steroidal anti-inflammatory drugs) may be effective for certain
types of acute and chronic pain, so it is surprising that the
difference here did not reach statistical significance in any of the
pain types," said senior study author Dr. Steven Cohen, a pain
researcher at Walter Reed National Military Medical Center in
Bethesda, Maryland, and Johns Hopkins Medicine in Baltimore.
"This matters because compounded pain creams are much more expensive
than prescribed (lidocaine, diclofenac) or over-the-counter
(capsaicin) pain creams, but they didn't provide meaningful benefit
compared to placebo cream," Cohen said by email.
All of the patients in the current study were treated at pain
clinics at Walter Reed and had one of three types of pain syndromes.
Within these three groups, patients were randomly chosen to receive
either a compounded cream or a placebo cream.
One third of the patients had neuropathic pain, which happens due to
nerve damage and includes phantom limb pain experienced by amputees.
Patients in this group who got compounded creams received
anticonvulsants.
Another third had so-called nociceptive pain, the most common kind
that is often due to an injury or infection, not nerve damage.
Patients in this group who got compounded creams received muscle
relaxants and NSAIDs.
And one third had "mixed" pain caused by a variety of things; many
of the compounded creams were similar to drugs provided for nerve
damage or nociceptive pain.
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None of the patients reported serious side effects from their
assigned treatment, but more of them experienced skin irritation,
rashes and redness with compounded pain creams than with placebo
creams: 7 percent compared with 2 percent.
When patients rated their pain levels on a 10-point scale, with 10
being the most painful, the average pain reductions reported by both
compounded-cream users and the placebo group after a month were
nearly identical. The difference between groups was 0.1 points for
neuropathic pain and 0.3 points for both nociceptive and mixed pain.
One limitation of the study is that many participants had already
tried conventional pain relievers without success, increasing the
likelihood that compounded pain creams would be ineffective too, the
researchers note in the Annals of Internal Medicine.
The study may also have had too few patients to detect subtle but
clinically meaningful differences between compounded and placebo
pain creams, the authors point out.
Still, the study tested the most frequently used combinations of
medicines in compounded pain creams and found them lacking in three
different types of pain, said Dr. Nebojsa Nick Knezevic, a pain
researcher at Advocate Illinois Masonic Medical Center in Chicago
who wasn't involved in the study.
"This does not mean that we should abandon the use of topical
analgesics for different types of localized pain, because it is
safer and easier to use than systemic drugs, especially in elderly
patients with other (complex chronic medical problems)," Knezevic
said by email.
"However, more randomized placebo-controlled trials are needed with
a different combination of medications prior to their use in
everyday practice," Knezevic added.
SOURCE: https://bit.ly/2G8fNud Annals of Internal Medicine, online
February 4, 2019.
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