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11.8.2 CNS depressant drugs
Although not inevitable, abuse of CNS‐depressant drugs (eg opioids, alcohol) is often
associated with physical dependence and the development of tolerance (see Section 11.7).
Withdrawal from CNS‐depressant drugs produces symptoms of CNS and autonomic
hyperexcitability, the opposite of the effects of the CNS‐depressant drugs themselves.
Opioids
Opioid abuse not only involves the use of heroin but also legally prescribed opioids or
prescription opioids illegally obtained. The number of prescriptions for opioids continues to
increase in many countries and along with this the incidence of abuse of these drugs (Cicero et
al, 2007; Katz et al, 2007). Illicitly obtained prescription opioids now account for a large
proportion of all opioids used by patients with an addiction disorder (NDARC, 2009), in some
instances exceeding the use of heroin (Fischer et al, 2006; Katz et al, 2007).
Not all aberrant drug behaviours indicate opioid addiction. Those that may include
unsanctioned dose escalations, ‘lost’ or ‘stolen’ medications, obtaining the drugs from a
number of different prescribers, polysubstance abuse, use of opioids obtained illicitly, and
forging prescriptions (Turk et al, 2008), or other features listed under the definition of addiction
in Table 11.7 above. Other aberrant behaviours may indicate problematic opioid use caused by
a variety of factors other than addiction (Ballantyne & LaForge, 2007).
In general, when opioids are used in the short term to treat acute pain, they are usually
effective and the risk of abuse is considered to be very small, although there are no accurate
data and the exact incidence is unknown (Wasan et al, 2006). This may not be the case when
these drugs are used in the management of chronic non‐cancer pain, where long‐term use of
opioids may not provide as effective pain relief and the risk of abuse of the drugs may be
higher (Ballantyne & LaForge, 2007; Chou et al, 2009; RACP et al, 2009). Both patients with chronic
pain and those with an addiction disorder have a high rate of psychiatric comorbidities (such
as anxiety, depression and personality disorders) and patients with chronic pain may therefore
be more at risk of developing behavioural problems associated with opioid use (Ballantyne &
LaForge, 2007).
A large survey, to which over 9000 patients with chronic non‐cancer pain responded (a 64%
response rate), found that users of prescription opioids had higher rates of opioid and non‐
opioid illicit drug misuse and alcohol abuse compared with those not using prescription
opioids (Edlund et al, 2007 Level III‐2). However, it is difficult to get accurate information on the
rate of opioid addiction in chronic pain patients, especially as a variety of definitions are used
CHAPTER 11 LaForge, 2007). The prevalence of addiction in chronic pain patients prescribed opioids is
that may not differentiate between problematic drug use and true addiction (Ballantyne &
reported to range from 0% to 50% (Hojsted & Sjogren, 2007 Level IV). Others have reported that,
on the basis of urine toxicology, up to 30% to 40% of patients prescribed opioids for the
management of their chronic pain misuse those drugs (Turk et al, 2008 Level IV).
More recently, focus has turned to the use of ‘abuse deterrent’ formulations; strategies that
are being assessed include the use of technologies that prevent the release of active opioid
when tablets are crushed or attempts are made to extract the drugs by other means, and
combination of the opioid with an opioid antagonist such as naloxone (Katz et al, 2007).
Suboxone® is a trade name for a combination formulation of buprenorphine and naloxone,
now commonly used in opioid‐addiction treatment programs (see below).
430 Acute Pain Management: Scientific Evidence
