Chronic pain and prescription opioid misuse
Simon G Tordoff FRCA, FIPP
Praveen Ganty FRCA
Nociceptive and neuropathic pain responds to
opioids, and these are being increasingly pre-
scribed.1 – 3 The misuse of these prescribed
opioids presents a challenge to clinicians, and
the problem is compounded by easy availability
of medications containing codeine obtainable
over the counter, together with the associated
use of alcohol and recreational drugs.4 – 6
Definitions
Tolerance
Tolerance is the phenomenon where identical
doses of an opioid result in a decreasing effect;
higher doses are required to produce the same
effect. Tolerance can occur either to the drug’s
therapeutic effect or to its unwanted side-
effects. Pharmacological tolerance develops
because of a decrease in the number of opioid-
binding sites or an acute depletion of the neuro-
transmitter released by the drug or by a
decreased activity in intracellular second-
messenger systems. Behavioural tolerance
occurs when the patient learns to compensate
over time for the expected pharmacological
effects of the drug.
Withdrawal
Opioid withdrawal occurs when the opioid dose
is stopped or rapidly tapered, or when an
opioid antagonist is given. There may be
psychological effects which include craving
and agitation, and physical symptoms such as
diarrhoea, palpitations, or tachycardia.
Addiction
Addiction is a primary, chronic, neurobiologi-
cal disease, with genetic, psychosocial, and
environmental factors that influence its devel-
opment and manifestations. It is characterized
by behaviour that includes impaired control and
compulsive use of the drug, continued use
despite harm, and craving. There are consider-
able retrospective survey data that suggest that
addiction is rare after opioid prescription for
chronic pain.7, 8
Pseudoaddiction
Pseudoaddiction describes behaviour that may
occur when a patient’s pain is undertreated.9
This terminology is unfortunate because it
infers dishonesty on the patient’s behalf and
addiction to the medication; this is incorrect.
Patients might seek additional medications
either appropriately or inappropriately because
they have been prescribed an insufficient dose
of opioid. The common scenario is when
patients are converted from a parenteral dose of
opioid to an oral dose at what is thought to be
an equivalent dose but is in fact insufficient. If
patients request or seek an increased dose of
the opioid, they are then considered to be
showing signs of ‘addiction’. This leads to drug
hoarding, attempts to obtain extra supplies, and
requests for early prescriptions or an increased
dose; in fact, the underlying problem is that
their pain is undertreated or they are fearful of
the pain recurring. Some patients do resort to
illicit drug use, and such behaviours are often
mistaken as signs of addiction, but inappropri-
ate behaviour ceases when the pain is treated.
Dependence
Physical dependence refers to a state resulting
from the chronic use of an opioid that has pro-
duced tolerance and where physical withdrawal
symptoms result when the drug is abruptly dis-
continued or the dosage is reduced. There is
often confusion in both health carers and the
general public between the terms dependence
and addiction. Dependence describes the state
of requiring the drug to prevent physiological
withdrawal. Addiction describes the continued
use of the drug, despite it causing harm.
Opiophobia
Opiophobia describes the reluctance of prescri-
bers to use opioid medication for fear of
Key points
Opioids must only be
prescribed after careful
physical, psychosocial, and
vocational assessment.
Misuse of prescription
opioids can be reduced by
good prescribing practice.
Patients on prescription
opioids must be regularly
assessed.
Oral or transdermal route
of administration should be
used; parenteral, sublingual,
or transnasal routes should
be avoided.
Meperidine is particularly
unsuitable for patients with
persistent pain.
There are factors that might
predict whether a patient is
likely to misuse prescription
opioids.
Management of prescription
opioid misuse requires
prompt intervention and a
multidisciplinary approach.
Simon GTordoff FRCA, FIPP
Consultant in Anaesthesia and Pain
Management
University Hospitals of Leicester
NHS Trust
Leicester General Hospital
Leicester LE4 5PW
UK
Tel: þ44 0116 258 8253
Fax: þ44 0116 258 4727
E-mail: simon.tordoff@uhl-tr.nhs.uk
(for correspondence)
PraveenGanty FRCA
SpR in Anaesthesia and Fellow in Pain
Management
University Hospitals of Leicester
NHS Trust
Leicester General Hospital
Leicester LE4 5PW
UK
158
doi:10.1093/bjaceaccp/mkq030 Advance Access publication 23 July, 2010
Continuing Education in Anaesthesia, Critical Care & Pain | Volume 10 Number 5 2010
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causing addiction or toxicity. There are many factors involved, for
example, pressure from peers or patients or carers, regulatory
restrictions by government agencies, a lack of education and under-
standing of the use of opioids, or social and moral prejudice. Staff
might be fearful to prescribe or administer opioids for fear of
causing respiratory depression, addiction, or both.
Diversion
Diversion is the transfer of prescribed opioids for unlawful use.
Prescription opioids may be passed on or sold to persons other
than the patient for therapeutic or recreational use. Doctors have a
legal and ethical responsibility to uphold the law and to protect
society from drug misuse. Opioids must be responsibly prescribed
and they must be vigilant for and guard against misuse, while also
ensuring that patients have the required medication available.
Principles of good opioid prescribing
A multidisciplinary pain clinic will use a biopsychological model
to manage persistent non-cancer pain, and it is important to recog-
nize that opioids are only one aspect of the package of rehabilita-
tion that would include non-opioid pharmacotherapy, physical
therapies, cognitive behavioural/psychological therapies, and exer-
cise. The aim is to keep patients functional both physically and
mentally with an improved quality of life. The therapeutic goals of
prescribing opioids for chronic pain are analgesia and improvement
of function. There are many publications that describe the prin-
ciples of good opioid prescribing (Box 1).10 – 13
Box 1 Principles of good opioid prescribing
Thorough physical and psychological assessment.
Choose appropriate opioid and route of administration.
Establish therapeutic expectations.
Establish terms and long-term goals of opioid therapy.
Discuss side-effects.
Regular assessment and monitoring.
Assessment of the patient
A single practitioner should assess the patient and be responsible
for prescription of opioid. There should be regular follow-up to
monitor the clinical response, any adverse effects, and make dose
adjustments. There must be close liaison with other professionals
involved in the patient’s care. There are large differences in the
response to opioids between individuals and adverse effects are
common. Opioids are not effective in every patient, and clinical
trials have not identified criteria that might predict that any particu-
lar patient will respond favourably to opioids. There are no good-
quality randomized trials that have compared different opioids for
the management of chronic non-cancer pain.
Choice of opioid and route of administration
Opioids are usually prescribed by the oral route, and this allows
for easier dose titration. Lipid-soluble opioids such as meperidine
and fentanyl and short-acting preparations of morphine and
oxycodone are acknowledged to have greater misuse potential than
long-acting or sustained release preparations. These short-acting
preparations result in a rapid increase in opioid blood and central
venous system (CNS) concentrations. They may be used initially to
titrate the opioid dose, but must be converted to a sustained release
preparation as soon as possible. It is conventional to prescribe
short-acting medication for ‘breakthrough’ episodes in cancer-
related pain, but this should be kept to a minimum in patients with
pain which is not cancer-related. Prescriptions should be for slow-
release preparations only, and patients should be encouraged to use
alternative methods to cope with the variations in pain intensity
that might occur.
The transdermal route is another means of administering
opioids that has become popular with clinicians and patients. It
provides a constant rate of delivery and does not result in the rapid
increase in plasma concentrations that occur with short-acting for-
mulations, and this route should be considered in patients who
might be at risk of opioid prescription misuse.
Injectable opioids should not be used in the management of
patients with chronic non-cancer pain. It is a common misunder-
standing held by medical staff, patients, and carers that opioids by
the parenteral route provide better analgesia when compared with the
oral route. This is usually because the oral equivalent dosage pro-
vided by clinicians is much lower than the parenteral dose. Patients
are often admitted to hospital with an exacerbation of chronic pain
and commenced on parenteral opioids. The clinical goal in these cir-
cumstances must be to convert them to oral or transdermal delivery
at an appropriate equivalent dosage as soon as is practicable.
Clinical experience suggests that the synthetic opioid meperidine
is particularly unsuitable for patients with persistent pain because of
its high lipid solubility and a rapid onset. Many clinicians believe
that it causes less smooth muscle spasm than other opioids at equi-
potent doses, but there is no evidence to support this. Meperidine is
metabolized in the liver to normeperidine which is an active metab-
olite with half the analgesic efficacy but a longer half life (8–21 h)
than meperidine itself. It is a potent CNS stimulant and its accumu-
lation leads to irritability and nervousness, tremors, myoclonic
jerking, and eventually convulsions. Normeperidine accumulation is
likely to occur with high and frequent doses of the drug, and in
patients with either renal or hepatic impairment. Meperidine is con-
traindicated in patients who have received monoamine oxidase
inhibitors in the previous 14 days.
Establish therapeutic expectations
Patients must be given a realistic expectation about the extent of
analgesia that they might expect. Many patients consider that
opioids will relieve all their pain but this is rarely achieved.
Chronic pain and prescription opioid misuse
Continuing Education in Anaesthesia, Critical Care & Pain j Volume 10 Number 5 2010 159