Second edition

21.qxd 3/10/08 9:58 AM Page 672
672 Substance use disorders
involuntary kicking movements, a phenomenon that gave
rise to another synonym for opioid withdrawal, namely
‘kicking the habit’. Insomnia may be severe. The pupils are
dilated and the temperature, pulse, and blood pressure are
all increased. Nausea, vomiting, intestinal cramping, and
diarrhea occur, and the resulting fluid loss may be so severe
that it causes circulatory collapse.
Withdrawal usually begins within the first day of abstinence,
peaks in a matter of days, and then generally subsides
over a week or so; in heavy users, however, a protracted
withdrawal syndrome may persist for weeks up to 6 months,
and is characterized by dysphoria, irritability, anhedonia,
insomnia, and drug craving (Martin and Jasinski 1969).
Other disorders may accompany opioid abuse or addiction.
Intravenous use brings the risk of bacteremia with
pulmonary abscess, endocarditis, cerebral abscess, cerebral
mycotic aneurysm, meningitis, osteomyelitis, and tetanus.
Parenteral users often share needles and are thus at risk for
acquired immune deficiency syndrome (AIDS), syphilis,
and hepatitis. Furthermore, the presence of particulates in
the injected fluid (as may occur when cigarette filters are
used) may lead to pulmonary fibrosis, pulmonary hypertension,
and cor pulmonale. Particulates may also collect
in regional lymph nodes causing a chronic lymphadenopathy
with edema, especially of the hands.
‘Skin popping’ may be followed by cellulitis or ulceration,
and those who inject heroin intramuscularly may
develop a myositis, with, in some cases, ossification.
Patients who ‘chase the dragon’ and inhale heroin vapor
may develop a leukoencephalopathy with dementia
accompanied by other signs such as ataxia, mutism, or
quadriparesis. (Kriegstein et al. 1999).
Illegally manufactured ‘street’ meperidine may be
contaminated with a by-product, methyl-phenyltetrahydropyridine
(MPTP), which in turn may cause a
chronic parkinsonian condition.
Course
Recreational use of opioids is uncommon and most patients
pass fairly rapidly to abuse and addiction. Although some
addicts, notably physicians who may have ready access to
opioids, are able to maintain their social positions, most
addicts quickly lose whatever gainful employ they may have
had and turn to crime to support their addiction. Those who
become deeply involved in the drug ‘subculture’ are liable to
have a violent death at the hands of others; suicide attempts
are also not uncommon, and those who do survive often end
up losing all in their pursuit of the drug.
Etiology
The intoxicant effects of opioids are mediated by their
binding to mu and, to a lesser extent, kappa receptors
within the central nervous system. Genetic factors appear
to increase the risk of addiction, as does the childhood
environment of most patients who become addicted,
whose parents are often themselves afflicted with opioid
addiction, alcoholism, or other substance use disorders.
Differential diagnosis
Opioid intoxication may be partially mimicked by intoxication
with alcohol, sedative–hypnotics or inhalants; however,
these intoxications generally lack the intense miosis
characteristic of most opioid intoxications; in doubtful
cases drug screening will resolve the issue. It must be borne
in mind, however, that many patients will use other substances
in addition to opioids: cocaine may be used to
reduce sedation, and alcohol or sedative–hypnotics may be
employed to ease the pain of withdrawal.
Treatment
Intoxication, if mild, may require only simple observation.
In severe intoxication, however, consideration should be
given to treatment with naloxone; however, care must be
taken to avoid ‘overshooting’ in addicts and producing a
hyperacute withdrawal syndrome.
Withdrawal should generally only be attempted on a
secure inpatient unit, and, given the intense drug craving
seen during withdrawal, patients should be confined to the
ward until the withdrawal has run its course; visitation, if
allowed at all, must be closely and continuously supervised.
Currently, there are three traditional approaches that
remain standard for withdrawal: ‘cold turkey’, withdrawal
with opioids, or treatment with clonidine. Recent work
also suggests effectiveness for buspirone.
Very few patients opt to go ‘cold turkey’; however, as
withdrawal is not life threatening, this may be appropriate
for some. Prochlorperazine may be given for nausea and
vomiting, diphenoxylate for diarrhea, and amitriptyline
(in a dose of approximately 50 mg at bedtime) for insomnia
(Srisurapanont and Jarusuraisin 1998), and these may
also be made available for those who undergo treatment
with either opioids or clonidine.
Withdrawal utilizing an opioid may be accomplished
with methadone, buprenorphine, or, if the patient had
been using another illicit substance (e.g., oxycodone), with
that agent. Treatment is generally commenced as withdrawal
symptoms appear. Methadone may be started in a
dose of 10–20 mg, with repeat doses every 4 hours as
needed to suppress symptoms. Most patients are stabilized
on a dose ranging from 20 to 40 mg daily, after which the
total daily dose may be reduced in decrements of 5–10 mg
daily. Buprenorphine may be given sublingually in an initial
dose of 4–6 mg, with repeat doses as needed every 2
hours until symptoms are suppressed, a process that generally
requires anywhere from 8 to 32 mg; once the patient is
stabilized, the dose may be gradually tapered in daily
decrements of 2–4 mg.