Pharmacotherapies
for Substance Abusers with Additional Types of Psychiatric Illness
Rates of
substance abuse are higher than expecte dmang patients with psychiatric
disorders, and psychiatric disorders are higher than expected among people with
substance abuse disorders.
Clinical
experience shows that:
·
treatment should be administered by professionals
with con-siderable experience in both general psychiatry and chemical
dependence;
·
it is unrealistic to insist on abstinence as a
precondition for treatment;
·
some symptom stability may be necessary before
reductions in substance use are evident;
·
abstinence is not a prerequisite for safe and
effective treatment with most psychotropic agents;
·
unless treated as a disorder in itself, a substance
abuse tends to persist after comorbid psychopathology is effectively treated.
This
section summarises the management of particular psychi-atric illnesses
complicated by substance use and some relevant drug interactions.
There is
controversy about the stage at which a mood disor-der iunduced by substance
abuse becomes a major depressive episode. Most specialists will diagnose a
second disorder in a patient who presents with a depressive syndrome only after
a 2 week period of sobriety. However, evidence from clinical trials shows that
antidepressants may be effective in patients who are not initially abstinent.
Clinical judgment is therefore important and, if a nonabstinent patient has
persistent depression, a trial of antidepressant therapy may be carried out.
Concurrent use of an antidepressant and a substance of abuse may increase the
risk of cardiotoxicity (arrhythmias), neurologic effects (seizures) or death
from intentional overdose. These risks are greatest with the tricyclic
antidepressants whereas the selective serononin reuptake inhibitors have a
safer pharmacologic profile. Patients should always be discouraged from
substance abuse but signifi-cant numbers of those taking antidepressants also
use alcohol and other potential drugs of abuse in moderation without harm.
Antidepressants seem to have a low risk of abuse, though abuse of amitriptyline
(for its sedative effects) and fluoxetine (for stimu-lant effects) has been
reported.
Substance
abuse or dependence is a common complication of schizophrenia and psychotic
symptoms occurring during drug intoxication or withdrawal also complicate the
diagnosis of schiz-ophrenia. An especially high degree of psychiatric
sophistication and patience is necessary for this group of patients. Long-term
studies (.one year) show that patients with schizophrenia and
substance abuse need an energetic treatment strategy to engage them in
treatment for psychosis, with an emphasis on compli-ance with antipsychotic
medication and the maladaptive effects of substance abuse. For most patients,
the problem of substance abuse diminishes after a year of compliance with
medication and treatment for addiction. In this setting, the use of long-acting
depot antipsychotic preparations is rational. Medication may also be combined with
contingency contracting for patients with schizophrenia, making the
unsupervised use of disability ben-efits contingent on negative urine
toxicology analysis.
Substance-induced
disorders (particularly stimulant in-toxication and alcohol or sedative-hypnotic
withdrawal) can re-semble generalized anxiety disorder or panic attacks, and
thus, as with depression, at least a two week period of abstinence is
preferable prior to initiating pharmacotherapy, although again there is room
for judgment. Other anxiety disorders, such as social phobia, agoraphobia, PTSD
or OCD have distinctive symptoms that do not overlap with symptoms of toxicity
or withdrawal. Behavioral approaches are effective for many anxi-ety disorders,
and should be considered, first alone and then as a supplement to
pharmacotherapy. Antidepressants are effective in the treatment of panic
disorder or generalized anxiety dis-order and have less abuse potential than
the benzodiazepines. Buspirone may be effective in generalized anxiety
disorder, especially at a dose of at least 45 mg/day. If a benzodiazepine is
prescribed, clinical opinion supported by experimental evi-dence suggests that
oxazepam and chlordiazepoxide are the saf-est alternatives because of their
gradual onset of action and a lower risk of euphoria. In general,
benzodiazepines should be avoided due to their abuse potential.
Substance
abuse occurs frequently in patients with bipo-lar disorder but there is a lack
of evidence of the effects of its treatment on substance abuse. Lithium does
not appear to have significant interactions with alcohol and cocaine but there
is little information about the safety of carbamazepine or valproic acid in
pateints with bipolar disorder and substance abuse.
Attention
deficithyperactivity disorder (ADHD) occurs more frequently than expected among
patients with sub-stance abuse disorders, and high rates of substance abuse
occur in children with both ADHD and conduct disorder. It is possible that such
patients may preferentially seek stimulants as self-medication of their
behavior disorder. The diagnosis of ADHD should be confirmed by evidence of
childhood illness and if possible verified by another informant. There is some
evidence that methylphenidate may be helpful in such cases and desipramine and
bupropion, both of which are used to treat ADHD in children, have also been
suggested. Studies are un-der way to improve our understanding of substance
abusers with ADHD.
Drug
interactions in patients with chemical dependency may be pharmacodynamic or
pharmacokinetic, and may occur be-tween drugs of abuse or between drugs of
abuse and prescribed medications.
The
combination of alcohol and cocaine has been associated with increased
hepatotoxicity and fatal cardiotoxicity. Alcohol together with opiates or
cannabis causes greater sedation and neurologic impairment than any of these
agents alone. Acute alcohol intoxication inhibits hepatic enzymes, increasing
blood levels of drugs metabolized by this system. By contrast, chronic alcohol
use induces hepatic enzymes and lowers blood levels of antipsychotic drugs,
tricyclic antidepressants, valproic acid, carbamazepine and certain
benzodiazepines. Griseofulvin, metronidazole, chloramphenical and oral
hypoglycemic agents cause a mild disulfiram-like reaction in combination with
alcohol. Chloral hydrate and alcohol are both metabolized by a pathway
dependent on alcohol dehydrogenase; taken simultaneously, competition for this
enzyme results in higher blood levels of both agents (this combination is known
as a “Mickey Finn”).
The
combination of cocaine and cannabis is associated with more tachycardia than
with either agent alone. Combining heroin and cocaine in a “speedball” more
readily produces respiratory de-pression than either alone. The use of cocaine
or amphetamine by someone taking a monoamine oxidase inhibitor may result in
hypertensive reactions.
Methadone
increases blood levels of tricyclic antidepressants and zidovudine. Conversely,
methadone levels may be reduced to the point where abstinence occurs by
rifampin, phenytoin, bar-biturates and carbamazepine. Meperidine taken during
treatment with a monoamine oxidase inhibitor may cause extreme reac-tions
ranging from collapse (hypotension and coma) to excitation (hypertension and
convulsions).
Smoking
cigarettes smoking lowers blood levels of caffeine; caffeine toxicity may be
therefore be misinterpreted as nicotine withdrawal in patients who stop
smoking. Smoking also lowers blood levels of antipsychotic drugs, tricyclic
antidepressants, theophylline and propranolol.
Hallucinogens
may act partly via serotonergic mechanisms and it is therefore unsurprising
that a serotonin reuptake inhibi-tor reportedly exacerbated
hallucinogen-persisting perception disorder (flashbacks) in adolescent LSD
users.
Related Topics
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.