HANDBOOK OF PSYCHIATRIC DRUGS - PART 10 potx

Medications for Opiate Dependence Agonist maintenance treatment for opiate dependence is apowerful treatment with a large effect size.. Furthermore, many of the bettermethadone clinics o

least a month) of these medications for patients with problemdrinking, and not be discouraged by the fact that some patientswill not benefit.

Medications for Cocaine Dependence

Given the high relapse rates with psychosocial treatment alone,there has been considerable interest in the development ofpharmacotherapies for cocaine dependence Case reports andopen pilot studies have suggested that a variety of agentsmay be effective but double-blind trials have provided disap-pointingly inconsistent results Surveys have demonstrated thatmany addiction medicine specialists are using medicines totreat cocaine dependence despite the lack of evidence of astandard sufficient for FDA approval

The most widely prescribed medicines for cocaine dence are antidepressants Depression occurs frequently incocaine addicts and it is possible that antidepressants maycorrect neurotransmitter deficiencies associated with cocaineuse The best evidence relates to desipramine but early reports

depen-of its effectiveness in preventing relapse were subsequentlycontradicted and its efficacy for more than 6–12 weeks wasquestioned Typical desipramine doses are the same as for thetreatment of depression Concurrent use of an antidepressantand cocaine increases the risk of additive cardiotoxicity andpatients who recommence cocaine use during treatment should

be assessed for this possibility

Although antipsychotic drugs have been proposed on thegrounds that blockade of dopamine receptors would attenuatethe euphoric response to cocaine, experience treating patientswith schizophrenia and cocaine dependence do not supportthis hypothesis Furthermore, cocaine use is associated withdopamine depletion and may therefore increase the risk ofextrapyramidal effects

Psychomotor stimulants have been suggested as an agonistmaintenance treatment strategy Although early clinicalreports suggested stimulants might exacerbate cocaine depen-dence, more recent placebo-controlled trials suggest oraldexedrine may have promise Patients with attention deficitdisorder, which commonly co-occurs with cocaine dependence,

may benefit from stimulants Similarly, the effectiveness oflithium in reducing cocaine use is confined to patients withcomorbid bipolar disorder The anticonvulsant carbamazepinehad disappointing effects in controlled trials after initiallypromising results in open studies However, more recently,some of the newer anticonvulsants with GABA-enhancing

or excitatory amino acid inhibiting effects (e.g., topiramate,gabapentin) have shown promise in small placebo-controlledtrials

Interestingly, perhaps the most consistent data so farrelate to disulfiram, which has shown promise in a series ofsmall placebo-controlled trials for cocaine dependence, andthe effect does not seem to depend on concurrent alcoholuse Since disulfiram inhibits dopamine a-hydroxylase, whichcatalyzes the conversion of dopamine to norepinephrine in thebrain, it may promote increased levels of brain dopamine andcombat the dopamine depletion engendered by cocaine.Another pharmacotherapeutic strategy for cocaine depen-dence is to treat comorbid psychopathology, most commonlyunipolar depression, bipolar disorder, attention deficit hyper-activity disorder, and anxiety disorders Such treatment is mostlikely to have a direct impact on the psychopathology, followed

by indirect effects of improved functioning and reduced druguse The benefits of drug treatment in the absence of comorbidpsychopathology is unclear An effective pharmacotherapy forcocaine dependence is urgently needed

Medications for Opiate Dependence

Agonist maintenance treatment for opiate dependence is apowerful treatment with a large effect size When properlyprescribed, methadone will rapidly induce a dramatic remis-sion in 50% or more of patients It prevents or reduces illicitopiate use, craving for illicit opiates, criminal behavior associ-ated with acquisition of illicit opiates, and diseases associatedwith illicit opiate use (such as illness related to infection withhuman immunodeficiency virus), and improves employmentand other aspects of social functioning Methadone has alsobeen shown to reduce mortality rates among opioid dependentpatients, in part by protecting against overdose Methadone

is also sometimes misunderstood as ‘substituting one drug foranother.’ In fact, methadone works by inducing marked toler-ance such that effects of other opiates are blocked, and noeuphoric effects of the methadone itself are experienced Whenprescribed with careful titration, methadone is neither intoxi-cating nor sedating, and it does not interfere with performance

of functions that are important for responsible adult roles (e.g.,studies have shown that methadone does not impair drivingability)

Methadone is well-suited for use as maintenance treatment

It is effective after oral administration and has a long half-life

>24 h; it suppresses opiate withdrawal syndrome for up to

36 h and it blocks euphoria induced by other opiates Chronicadministration is associated with minimal side effects, the mostfrequent of which are constipation, excess sweating, reducedsexual interest, but these rarely result in discontinuation oftreatment

The initial dose of methadone maintenance lies in therange 20–40 mg and this is mainly to relieve symptoms due

to abstinence This is followed by an ’induction period’, inwhich the dose may be increased in increments of 5–10 mguntil a dose is achieved that prevents opiate craving and blocksthe euphoric effects of illicit opiates Measures for patientmonitoring include subjective reports, interval history, andregular frequent usine toxicology analysis Although a dose

of 40 mg/day may be sufficient for some patients, there isnow evidence from several trials that most require 80 mg/day.According to Federal regulations, doses of methadone greaterthan 120 mg/day require permission, although individual statescan specify lower ceiling doses As with many psychophar-macologic treatments, the most common reason for treat-ment failure in methadone maintenance is inadequte dose,and continued opiate use should prompt consideration of adosage increase Some evidence suggests that optimal treat-ment response requires trough methadone blood levels inthe range 200–400 ng/mL, and blood level monitoring may beuseful in nonresponders Some patients are rapid metabolizers,which can be assessed by comparing peak and trough bloodlevels Rapid metabolizers may benefit from a divided, twicedaily dose schedule

A pragmatic drawback of methadone maintenance is thatregulations stipulate that it can only be administered atspecially licensed clinics that require frequent attendance(daily at the outset) and that are not even available in manygeographic regions This can be a practical constraint or adisincentive for many patients On the other hand, it hasbeen shown that the effectiveness of methadone maintenancedepends upon regular counseling in conjunction with the medi-cation, which is a requirement of methadone clinics, and moreseverely dysfunctional patients probably benefit from the struc-ture imposed by clinic rules Furthermore, many of the bettermethadone clinics offer primary medical and psychiatric care,which is important since chronic opiate-dependent patientsoften have multiple medical problems (e.g., hepatitis B and C,HIV) and psychiatric problems (e.g., depression, PTSD).

A recent development is the approval and marketing of thelong-acting opiate partial agonist buprenorphine (see also thesection above on opiate withdrawal on page 233), which hasbeen shown in clinical trials to have effectiveness equivalent tothat of methadone for maintenance treatment A major differ-ence is that buprenorphine can be prescribed by any physicianwho has taken a brief training course and received certification,making it more widely available than methadone maintenance.The main regulatory restriction is that individual physicianspracticing in an office-based setting are restricted to treating

no more than 30 patients with maintenance buprenorphine atany one time

Buprenorphine has interesting pharmacologic properties

It is a partial agonist, meaning that it binds opiate tors but only partially activates them This may translate intolower abuse potential compared with full agonists, althoughbuprenorphine has been abused by intravenous injections inother countries where it was widely available The sublingualformulations marketed for treatment of opioid dependence doappear to have limited abuse potential by themselves, and theSuboxone formulation, which includes naloxone, discouragesattempts to extract and inject the contents, since intravenousnaloxone will precipitate withdrawal; the naloxone is poorlyabsorbed by the sublingual or oral routes Buprenorphine bindsalmost irreversibly to opiate receptors, and dissociates very

recep-slowly, accounting in part for its long duration of action Whenproperly dosed, similarly to methadone, it induces tolerance,blocks the effects of other opiates, and produces little or nosedating or intoxicating effects.

The buprenorphine/naloxone combination (Suboxone) ispreferred for both detoxification and maintenance treat-ment, although some patients may be more sensitive to thepresence of the antagonist (naloxone) and tolerate straightbuprenorphine (Subutex) better Because it is a partial agonist,buprenorphine will precipitate withdrawal in individuals whohave recently used any opioid drug; treatment should there-fore begin when there are clear signs of withdrawal (or at least

4 h after last use of a short-acting opioid) (see also the section

on buprenorphine for detoxification on page 234) There isless experience of induction with buprenorphine in individ-uals using long-acting agents such as methadone, but the risk

of precipitated withdrawal is greater The daily methadonedose should be below 40 mg per day before buprenorphineinduction is attempted, and a delay of around 48 h or more

is advisable to allow withdrawal symptoms from methadone

to manifest clearly Induction is completed over 2–4 days,depending on the target dose The recommended dose onday 1 is 16 mg, increasing to 16 mg on day 2 and there-after, and more gradual induction may be associated with ahigher risk of drop-out The dose should be adjusted in incre-ments of 2–4 mg to that which keeps the individual in thetreatment program and suppresses withdrawal symptoms; thetarget maintenance dose is 16 mg/day but may range from

4 to 32 mg/day Buprenorphine should be administered aspart of a psychosocial treatment program The relative ease

of withdrawing from buprenorphine may result in a greatertendency to leave the treatment program compared withmethadone

Owing to its long duration of action, buprenorphine can beadministered every other day (e.g., 32 mg every other day), oreven twice per week; this property can be useful for patientswhere there are concerns about compliance, since the medi-cation can be held at a clinic or by a significant other andadministered under observation on a less than daily basis

Buprenorphine can produce sedation However, emergence

of sedation should also raise suspicion of use of other drugs

or alcohol Unlike full opiate agonists (heroin, methadone,other narcotic analgesics), where respiratory depression is aserious risk, buprenorphine by itself produces less respiratorydepression The rate of deaths from drug overdose droppedsubstantially in France after buprenorphine was introduced fortreatment of drug dependence The one exception was over-doses of buprenorphine in combination with benzodiazepines,where deaths were observed This has led to an exaggeratedconcern that buprenorphine is contraindicated in patients whouse benzodiazepines For patients using benzodiazepines atregular, modest doses, which is the most common pattern evenamong opiate addicts, buprenorphine is safe Patients who takelarge doses or binges of benzodiazepines are at risk of over-dose in combination with a variety of other drugs, includingbuprenorphine, and alcohol It is likely that the risk of over-dose in such patients would be the same on either methadonemaintenance or buprenorphine maintenance

Naltrexone is a long-acting (24–48 h duration) opioid onist available in 50 mg tablets It is effective in blocking theeffects of opioids and can be used as a maintenance treat-ment, but its effectiveness has been limited by poor compli-ance Compliance can be improved with behavioral therapy,but rates of retention in treatment still remain well below whatcan be expected from agonist maintenance with methadone

antag-or buprenantag-orphine Furthermantag-ore, naltrexone does not protectagainst opiate overdose; patients who stop naltrexone are nottolerant and are therefore vulnerable to overdose Naltrexone

is also complicated to manage It cannot be started until apatient has been fully detoxified, in order not to precipitatewithdrawal Rapid induction methods using buprenorphine,clonidine, and clonazepam have been described, but gener-ally require 5–7 days to carry out Anesthesia-assisted rapiddetoxification and induction onto naltrexone has been shown

to involve the same level of discomfort, with increased risk

of serious adverse events, and is not recommended Once apatient is inducted onto naltrexone, if they stop taking thenaltrexone and relapse, naltrexone cannot be resumed withoutprecipitating withdrawal, and repeat detoxification is needed

In summary, although some patients benefit from naltrexone,

it is considered a second-line agent for patients who have failed

or refuse agonist treatment Patients maintained on naltrexoneshould be warned about the risk of fatal drug overdose ifnaltrexone is discontinued

Special Considerations

Two patient populations warrant particular comment: patients

on medical-surgical units who are methadone-maintained andpatients who are pregnant When patients are admitted tohospital their maintenance program should be contacted toverify their methadone dose This dose should be maintained,not reduced, during the stress of an illness and its treat-ment Maintenance methadone will prevent opiate withdrawalbut it will not provide analgesia Patients who are in severepain should therefore receive analgesia with a non-opiate or,bearing in mind that higher doses and shorter dose inter-vals may be needed, a short-acting opioid analgesic Opioidswith mixed agonist-antagonist properties, such as pentazocineand buprenorphine may precipitate withdrawal and should beavoided

Longitudinal studies have shown that in utero exposure

to methadone is not associated with abnormal development.Methadone maintenance should therefore be continued bywomen who become pregnant, though the dose may need to bereduced during the third trimester The neonate may developabstinence symptoms and this should be expected and treatedafter birth

Drug Treatments for Nicotine Dependence

Nicotine resembles other addictive drugs in that it inducessimilar addictive behavior patterns (such as inability to controlconsumption) and similar neuroadaptive changes (e.g., toler-ance) Nicotine intoxication and withdrawal are not associatedwith the acutely harmful behavior that other drugs of abusecause but the health consequences of nicotine make it themost important drug of abuse Withdrawal symptoms associ-ated with nicotine addiction include anxiety, restlessness, diffi-culty concentrating, and irritability Drug treatment to prevent

relapse in individuals with nicotine addiction must reduce thesesymptoms and in addition decrease craving for nicotine Thismust be achieved in an environment with multiple conditionalstimuli for nicotine use, such as the morning cup of coffee.Nicotine can be delivered safely and its use graduallyreduced using nicotine replacement therapy By contrast withmethadone maintenance, nicotine replacement therapy is not

an indefinite maintenance treatment but it is worthwhile ulating whether nicotine replacement reduces harm comparedwith cigarette smoking Nicotine replacement therapy iscurrently available as a transdermal patch and polacrilex ’gum’and both are effective in promoting abstinence

spec-The FDA recently approved a sustained-release lation of bupropion for the treatment of nicotine depen-dence It is as effective as nicotine replacement therapy Thesuggested dose is 150 mg twice daily, beginnning two weeksbefore smoking cessation is attempted In patients who derive

formu-no benefit from nicotine replacement or bupropion alone, acombination of the two therapies has been shown to be safeand more effective than monotherapy

Many patients who succeed in initiating abstinence fromcigarettes will relapse within 3–6 months Clinicians andpatients should not be discouraged by this The data suggestthat most patients who make repeated quit attempts eventuallysucceed in achieving sustained abstinence

PHARMACOTHERAPIES FOR SUBSTANCE ABUSERS WITH ADDITIONAL PSYCHIATRIC ILLNESS

There is consistent evidence that patients with psychiatricillness have higher than expected rates of substance abuse, andthat patients undergoing treatment for substance dependencehave higher than expected rates of psychiatric illness

In this challenging patient population, clinical experiencehas confirmed that:

• treatment should be administered by health sionals with expertise in general psychiatry and chemicaldependence

profes-• it is unrealistic to insist on abstinence as a condition fortreatment

• abstinence is not necessary for the safe and effective use ofmost psychotropic drugs

• symptom stability may be needed before a reduction insubstance use is apparent

• substance use disorder tends to persist unless it is treated as

an illness in itself, regardless of the effective management ofother psychopathology

This section summarizes the management of particularpsychiatric illnesses complicated by substance use and endswith a summary of important drug interactions in substanceuse disorders

Pharmacotherapy for Specific Psychiatric Disorders

It is difficult to be definitive about when a substance-inducedmood disorder becomes a major depressive episode According

to most experts, there should be a period of sobriety lastingtwo weeks before a second diagnosis can be made in apatient presenting with a depressive syndrome However, clin-ical trials have shown the benefit of antidepressant medica-tion in patients who are not abstinent to begin with Thus,there is room for clinical judgment, and, if significant depres-sion persists and the patient cannot achieve abstinence, trials

of antidepressant medications can be attempted In a patientvulnerable to substance abuse relapse, the most worryingeffects of antidepressant medication are cardiotoxicity (e.g.,arrhythmias), neurotoxicity (e.g., seizures) or death from inten-tional overdose These concerns are greatest with tricyclicantidepressants and the selective serotonin reuptake inhibitorshave a safer pharmacologic profile Although it is important todiscourage individuals from using drugs of abuse, a significantnumber of people taking an antidepressant use alcohol andother potential drugs of abuse in moderation without ill effects.There seems to be little abuse potential with antidepressantsthough abuse of amitriptyline for its sedative effects and, morerecently, fluoxetine for its stimulant effects, has been reported.Substance abuse or dependence are frequent complica-tions of schizophrenia; conversely, the psychotic symptoms thatoccur during drug intoxication and withdrawal complicate thediagnosis of schizophrenia These patients need a particularly

high degree of patience and sophisticated psychiatry services.Long-term follow-up (more than one year) of patients withschizophrenia and substance abuse suggests the need for ener-getic engagement in treatment for psychosis with an emphasis

on compliance with antipsychotic medication and the tive effects of substance misuse The problem of substanceabuse declines for most patients after a year of medicationcompliance and treatment for addiction Long-acting depotantipsychotics are a rational component of such a strategy Acombination of medication and contingency contracting hasalso been used for patients with schizophrenia, in which unsu-pervised use of disability benefits is contingent on negativeurine toxicology

maladap-Substance-induced disorders (particularly stimulant ication and alcohol or sedative–hypnotic withdrawal) canresemble generalized anxiety disorder or panic attacks, andthus, as with depression, at least a two week period ofabstinence is preferable prior to initiating pharmacotherapy,although again there is room for judgment Other anxietydisorders, such as social phobia, agoraphobia, PTSD, or OCD,have distinctive symptoms that do not overlap with symptoms

intox-of toxicity or withdrawal Behavioral approaches are tive for many anxiety disorders and should be considered, firstalone and then as a supplement to pharmacotherapy Antide-pressants are effective for panic disorder or generalized anxietydisorder and have less abuse potential than the benzodi-azepines Buspirone may be beneficial for generalized anxietydisorder at a dose of at least 45 mg/day If a benzodiazepine

effec-is still preferred, expert opinion (supported by some mental evidence) suggests that the safest agents are oxazepamand chlordiazepoxide because their onset of action is moregradual and they have a lesser tendency to produce euphoria

experi-In general, however, benzodiazepines should be avoided owing

to their abuse potential

Substance abuse and bipolar disorder (particularly in themanic phase) are frequently comorbid disorders but there islittle information about the effects of treatments for bipolardisorder on substance abuse Research in the treatment ofalcohol and cocaine dependence suggests that concurrent use

of lithium is relatively safe with regard to drug interactions but

little is known about the risk of interactions between mazepine and valproate and drugs of abuse in patients withbipolar disorder.

carba-Follow-up of children with attention deficit–hyperactivitydisorder (ADHD) and conduct disorder has revealed highrates of substance abuse, and ADHD may be over-represented

in substance abuse treatment settings It is possible thatpatients with ADHD may seek stimulants for self-medication.The diagnosis of ADHD requires evidence of illnessduring childhood, preferably with verification from anotherperson These patients have benefited from methylphenidate,according to some reports Desipramine and bupropion havebeen used successfully in treating children with ADHD andboth have been advocated in patients with comorbid substanceabuse

Drug Interactions in Chemical Dependency

Drug interactions in patients with chemical dependency may

be pharmacodynamic or pharmacokinetic, and may occurbetween drugs of abuse or between drugs of abuse andprescribed medications