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Initially, methadone

may be given in 5-mg increments up to a total of 10 to 20 mg during the first 24

hours.

19 Larger methadone doses (i.e., a 20-mg starting dose) may be required for

patients with larger habits. If initial withdrawal symptoms persist 2 to 4 hours after

initial dose administration, the dose can be supplemented with an additional 5 to 10

mg. Federal regulations allow a maximum of 40 mg as an initial dose unless a

program physician documents that 40 mg was insufficient to suppress opioid

withdrawal symptoms.

20 Once a stabilizing dose has been reached (usually, 40–60

mg/day, but may be as high as 120 mg/day), methadone is tapered by 20% a day for

inpatients or 5% a day for outpatients.

15,19,20 Studies have suggested that slow tapers

are associated with better outcomes. The duration of the taper varies, but a period of

3 to 4 weeks is generally used. The gradual taper may last as long as 6 months. The

most common side effects of methadone are constipation, sweating, and sexual

dysfunction.

15,19 A Cochrane review of studies comparing methadone tapers with

other detoxification methods (adrenergic agonists and other opioid agonists) found

that programs vary widely in design, duration, and treatment objectives, but overall

the effectiveness of the treatments was similar.

21 A reasonable starting dose of

methadone would be 20 mg orally. An additional 5 to 10 mg could be administered

after 2 to 4 hours for persistent withdrawal symptoms. The daily dose should be

titrated upward every third day by 10 mg until stabilized on a methadone dose of 60

mg/day.

BUPRENORPHINE DETOXIFICATION

Buprenorphine, a synthetic partial opioid agonist, was approved by the FDA in

October 2002 for the treatment of opioid dependence. It is a partial agonist at mu

receptors, and in opioid-dependent patients, it prevents withdrawal symptoms.

Because of its partial effects, it produces maximal “ceiling” analgesia with

sublingual doses of 24 to 32 mg, a dosage equivalent to approximately 60 to 70 mg of

oral methadone. Buprenorphine is associated with a milder withdrawal syndrome

compared with full opioid agonists.

22

Because buprenorphine is a schedule III medication, it can be prescribed in an

office-based setting under the Drug Addiction Treatment Act of 2000. The film and

tablets contain buprenorphine hydrochloride alone or in combination with naloxone.

The naloxone is poorly absorbed orally, and its presence in the combination tablets

is to discourage the IV abuse of buprenorphine. Both forms can be used in an

inpatient setting, but the combination product is preferred in the outpatient setting to

decrease the risk of diversion. When initiating buprenorphine, the first dose should

not be given until more than 4 hours after the last dose of a short-acting opioid, such

as heroin, or 24 hours after a long-acting opioid, such as methadone. As previously

discussed, evaluation of objective opioid withdrawal signs may involve use of

standard rating scales. Induction dosing should begin with 2 or 4 mg on the first day,

which can be repeated every 2 to 4 hours if withdrawal symptoms subside and then

reappear, up to a maximum of 8 mg. The dose can then be titrated the second day in

2- to 4-mg increments to a dose of 12 to 16 mg.

22 Higher doses during induction may

precipitate withdrawal symptoms. In the inpatient setting, the patient may be

stabilized on a relatively low daily dose (e.g., 8 mg/day) and then tapered in

increments of 2 mg/day over the course of several days.

15

In the outpatient setting, the

patient should be initially stabilized on a daily dose (probably 8–32 mg/day) of

buprenorphine that suppresses withdrawal. The dose should then be gradually

tapered during a period of 10 to 14 days. Buprenorphine is not associated with any

significant adverse effects when used to manage opioid withdrawal. Buprenorphine

(and methadone) detoxification should be accompanied by psychosocial treatments

and support groups as mentioned.

3

A Cochrane review found that relative to clonidine, buprenorphine is more

effective in alleviating opioid withdrawal symptoms; patients treated with

buprenorphine stay in treatment longer, and are more likely to complete treatment.

23

The severity of withdrawal appears to be similar for withdrawal managed with

buprenorphine or methadone, but withdrawal symptoms may resolve more quickly

with buprenorphine. The authors of the meta-analysis concluded that although there is

limited evidence comparing buprenorphine with methadone, both agents have similar

effectiveness in the management of opioid withdrawal.

Nonopiate Symptomatic Therapy of Opioid Withdrawal

Although opiate replacement has shown to provide a safe withdrawal, treatment with

opiates is not always necessary. The ability of the α2

-adrenergic agonist, clonidine,

to ameliorate some of the opioid withdrawal symptoms, has led to its widespread use

as a nonopioid alternative. Other α2

-adrenergic agonists (lofexidine, guanfacine,

guanabenz acetate) have also been investigated.

2,3,24 Noradrenergic outflow from the

locus coeruleus is increased during opioid withdrawal and is blocked by

administration of mu agonist opioids. Symptoms of opioid withdrawal, therefore, are

partly caused by excessive sympathetic activity in the locus coeruleus. Central α2

-

adrenergic agonists inhibit locus coeruleus noradrenergic outflow opioid

withdrawal, thereby significantly reducing some of the symptoms.

Clonidine is therefore best used in a multidrug regimen. Contraindications to

clonidine use include diastolic blood pressure less than 70 mm Hg, concurrent

dependence on sedative-hypnotics, and clonidine hypersensitivity or previous

intolerance. The most common adverse effects are sedation and hypotension. A

Cochrane review examined studies comparing clonidine with methadone taper and

found no significant difference in efficacy between the two for the treatment of heroin

or methadone withdrawal.

24 A separate Cochrane review did find buprenorphine to

be more effective than clonidine in alleviating opioid withdrawal symptoms.

23

A sublingual or oral test dose of 0.1 mg (0.2 mg for patients >91 kg) of clonidine

is given: if diastolic blood pressure remains more than 70 mm Hg, additional doses

may be instituted. Oral clonidine can be used at a dose of 0.1 to 0.2 mg/dose 2 to 4

times daily to a maximum of approximately 1 mg/day for 2 to 4 days after cessation

of opioids, then tapered and discontinued by 7 to 10 days.

24 Because opiate

withdrawal consists of other effects such as musculoskeletal aches and pains,

anxiety, insomnia, and gastrointestinal disorders, it is common to use medications

such as dicyclomine, loperamide, and ibuprofen as adjuncts. This is particularly true

when the detox protocol does not contain opiates.

2,18

(Table 90-2)

p. 1878

p. 1879

Table 90-2

Symptomatic Therapy of Opiate Withdrawal

Symptom Medication

Bone, muscle, joint or other pain Ibuprofen, naproxen, other NSAID

Insomnia, anxiety Benzodiazepine

Gastrointestinal hyperactivity Loperamide, dicyclomine

Nausea Prochlorperazine, ondansetron

Sources: Schuckit MA. Treatment of opioid-use disorders. N Engl J Med. 2016;375:357–368 and ASAM Public

Policy Statement on Treatment for Alcohol and Other Drug Addiction, Adopted May 1, 1980, Revised: January 1,

2010. http://www.asam.org/quality-practice/definition-of-addiction.

D.J.’s blood pressure and drug history should be evaluated for clonidine therapy.

Provided his diastolic blood pressure is greater than 70 mm Hg after the clonidine

test dose, he can receive oral clonidine 0.1 mg with additional medications to treat

his withdrawal symptoms, along with psychosocial counseling.

Ultrarapid Opiate Detoxification

Ultrarapid opiate detoxification (UROD) is a method to shorten the opioid

detoxification period by precipitating withdrawal with an opioid antagonist. The

opioid antagonist causes rapid stripping of agonist from opioid receptors. UROD is

performed under heavy sedation or general anesthesia so the patient does not

consciously experience the acute withdrawal symptoms. The protocols for UROD

vary in terms of the setting of the procedure (inpatient or outpatient), opioid

antagonist (naloxone, nalmefene, or naltrexone), anesthetic agent, adjunctive

medications, and duration of anesthesia.

25

The UROD procedure includes risks, such as vomiting with aspiration;

cardiovascular complications, including cardiac arrest; pulmonary edema; and

death.

25 Some patients have reported residual withdrawal symptoms for several days.

Little information exists regarding referral to ongoing treatment or relapse rates after

UROD.

26 A review of five randomized, controlled trials found no benefit of UROD

compared with safer, less expensive treatments.

26 UROD has been criticized for

being simply a “quick fix” that fails to address the underlying behavior changes

necessary for recovery. Additionally, it subjects patients to possible morbidity and

mortality when safer, established procedures are available. The high cost of UROD

limits its accessibility. The American Society of Addiction Medicine recommends

against this method of treating opiate withdrawal due to cardiac complications and

anesthesia related events.

2

Pharmacotherapies for maintenance treatment of

Opioid Use Disorder

MAINTENANCE THERAPY

The ultimate goal of outpatient substance use disorder programs is to assist the

addicted patient into a drug-free healthy lifestyle. This results in reductions in

medical conditions for the patient and reduced crime and health care cost for societal

members. Methadone for maintenance treatment of opioid substance use disorder is

federally regulated and is only available through specially licensed opioid treatment

programs. The Drug Addiction Treatment Act of 2000 allows qualified physicians to

prescribe Schedule III, IV, and V medications approved for the treatment of opioid

dependence in an office-based setting.

27 Currently, only buprenorphine, a Schedule III

medication, is approved for this indication.

CASE 90-4

QUESTION 1: A.X., a 27-year-old man, has a severe opiate use disorder (addiction) to heroin for the last 3

years but is tired of the street scene and wants to “get clean” (complete abstinence). He can no longer afford

his growing daily habit but is not sure he can stop using opioids. He seems willing and determined to receive

treatment for his heroin dependence. What therapeutic options are available to him?

The goal of eliminating illicit opiate use is the gold standard; however, a more

realistic expectation is reduced use and subsequent harm reduction. Even temporary

reductions in heroin use are a benefit due to reduced risk of developing major health

(HIV, hepatitis C) and social (crime) issues.

2 Medical management of opioid

dependence should be accompanied by psychosocial treatments, such as cognitivebehavioral therapies, behavioral therapies, and self-help groups, such as Narcotics

Anonymous (NA).

Methadone maintenance is the most common form of pharmacologic treatment for

opioid dependence. During methadone maintenance, heroin-dependent patients are

stabilized on a dose of methadone that will be sufficient to suppress cravings for 12

to 24 hours without producing euphoria. Studies have shown that patients maintained

on methadone doses of 60 mg or more had better outcomes than those maintained on

lower doses.

28 Most patients do well on a dose range of 60 to 120 mg/day, although

some patients require more and some require less.

20 Because methadone is

metabolized via CYP450 3A4 drugs that induce, this pathway can precipitate

withdrawal in patients maintained on methadone. Drugs that inhibit this pathway

extend the duration of methadone’s effects. The half-life of methadone is typically 25

hours (15–60) but can extend up to 120 hours with frequent dosing.

29 The drug is

administered daily at the clinic in a single liquid oral dose. With the aid of daily

counseling and rehabilitation, the goal is to eventually taper the patient from

methadone as well. Patients who relapse repeatedly despite supportive treatment

will require long-term maintenance therapy. This may take years, and it is shown that

longer duration in treatment correlates with better outcomes. Methadone’s efficacy

comes from the fact that it reduces cravings without producing euphoria itself,

primarily due to its slow time to peak. This produces a high degree of crosstolerance to other opioids so that it is extremely difficult to obtain euphoria with IV

injection of other opioids. But, patients have been able to reach euphoric states

through the concomitant IV administration of other opioids. The higher purity heroin

available today has required even higher doses of methadone to achieve cross-

tolerance.

28

It is often cut (mixed) with fentanyl to increase the opiate effect.

Buprenorphine has the advantage of office-based availability, thus removing the

stigma associated with attending a methadone clinic and providing more places for

patients to receive treatment because methadone clinics are limited as to how many

patients can enroll and may be hundreds of miles away from the patient’s home.

Buprenorphine, and high-dose methadone (60–100 mg) therapies were compared

with low-dose methadone (20 mg), all three therapies were effective in treating

opioid dependence and were superior to low-dose methadone.

30 Trials comparing 12

to 16 mg/day of buprenorphine with moderate doses of methadone (50–60 mg/day)

have generally shown comparable outcomes, although higher doses of methadone

(>80 mg) appear to be superior to buprenorphine.

30 Low-dose buprenorphine seems

to have worse outcomes compared to low-dose methadone.

31 Buprenorphine patients

are more likely to be employed, have less medical comorbidity, and a shorter

duration of drug use compared to methadone clinic patients.

32,33 There are multiple

formulations of buccal and sublingual buprenorphine and absorption rates are

different between some of them. All are compared to the original buprenorphine

sublingual tablet (Subutex and Suboxone) regarding pharmacokinetics, blood

p. 1879

p. 1880

levels and efficacy. There is also a buprenorphine implant available which was

found similarly effective to lower doses of buprenorphine sublingual.

34 For

maintenance treatment buprenorphine combined with naloxone is the standard of care

with pregnancy or allergy to naloxone the only two reasons not to use the

combination.

2

Buprenorphine has a long half-life of around 35 hours (24–60 hours) and it

produces a relatively mild withdrawal when discontinued.

35

It is believed to be a

safer alternative to methadone because life-threatening respiratory depression is

much less likely to occur than with a pure mu agonist, unless another CNS depressant

is taken concurrently. Most deaths involving buprenorphine have been caused by a

combination of the drug with benzodiazepines and through injection of the

monotherapy formulation.

22,36 Naloxone bolus doses often are ineffective in reversing

respiratory depression caused by buprenorphine because of its prolonged occupancy

on mu receptors. Continuous infusion of naloxone is necessary to overcome

buprenorphine-induced respiratory depression.

37 Another safety advantage compared

to methadone is the lower risk of prolonging QTc.

29 Similar to methadone,

buprenorphine is also metabolized by CYP450 3A4.

The narcotic antagonist naltrexone can block the euphoriant effects of heroin and

other opiates, prevent the development of physical dependence, and afford protection

from opioid overdose deaths. Although naloxone is similar to naltrexone, it is

impractical because of its short duration of action and its extremely poor absorption

when taken orally. Naltrexone is orally active and provides a dose-related duration

of opioid blockade. An oral dose of 100 mg of naltrexone will block opiate effects

for 2 days, and 150 mg for 3 days. Thus, dosing on Monday, Wednesday, and Friday

is possible; however, it is recommended to use 50 mg QAM because it is easier to

remember for the patient and will result in better adherence. Naltrexone is also

available in an injectable extended-release formulation for once-monthly use.

38

Patients selected for naltrexone therapy must be opioid free to avoid precipitation of

withdrawal. For heroin- or morphine-dependent patients, a 4- to 7-day wait is

recommended, whereas longer half-life opiates can require a 10- to 14-day wait.

Patients who are highly motivated to abstain have been most successfully treated with

this drug.

Because A.X. has had a short duration of opiate misuse, he is a good candidate for

outpatient buprenorphine/naloxone or naltrexone. Methadone is equally effective but

does require enrollment into a clinic, which may or may not be practical for him.

Methadone clinics are considered more effective than the other choices because the

addiction becomes more severe.

Research suggests that physicians consume more opioids, sedatives, and alcohol

than the general public, but less tobacco.

39 The risk is largely based on access to

drugs of abuse, and drug dependence is described as an occupational hazard for

healthcare providers. Fentanyl (injectable as well as transdermal formulations) and

meperidine are primarily, but not exclusively, drugs of abuse among health care

providers. Hospice workers and veterinarians also have access to high-potency

opioids. Studies have noted that substance use was highest in psychiatrists and

emergency medicine physicians and lowest in surgeons and pediatricians.

39 Fentanyl

is associated with rapid development of dependence, intense tolerance, and drugseeking behavior in addicted physicians for a period of months rather than years.

A comprehensive assessment of addicted health care providers is necessary to

determine whether professional impairment is present, and whether issues involving

public health and safety or violations of ethical standards, such as professional

boundary violations or improprieties, require that the heath care provider be reported

to his or her respective medical board. A physician’s registration with the federal

DEA may need to be suspended. It generally is accepted that health care providers

require longer durations of treatment because they are held to a higher standard of

recovery owing to concerns of public safety, and they may be clever at concealing

their illness.

39

Health care providers are often good candidates for naltrexone therapy

(particularly the long action injection) because of the need to remain drug-free

despite continued access to opioids at work.

Opiate Use Disorder Treatment in Pregnancy

CASE 90-5

QUESTION 1: J.R., a 28-year-old woman, has been maintained on 100 mg of methadone daily for the past

year. J.R.’s last menstrual period was 8 weeks ago, and she took a home pregnancy test yesterday, which was

positive. What is the recommend treatment for pregnant patients?

Methadone has been accepted since the late 1970s to treat opioid use disorder

during pregnancy.

20 Methadone maintenance was determined to be the standard of

care for pregnant women with opioid use disorder by a 1998 National Institutes of

Health (NIH) consensus panel.

40 Currently, methadone is the only opioid medication

approved by the FDA for medication-assisted treatment of opioid use disorder in

pregnant patients. Women maintained on methadone frequently have regular

menstrual periods, ovulate, conceive, and have normal pregnancies. Heroin-addicted

mothers, however, generally experience more complicated pregnancies because their

lifestyles often predispose them to a poor general state of health and precludes

adequate prenatal medical care.

22

Infants born to heroin-addicted mothers may also

be exposed to other substances (e.g., alcohol, cocaine, tobacco). These infants tend to

be smaller, to weigh less at birth, and to be born prematurely compared with the

children of women not using opiates.

22

WITHDRAWAL DURING PREGNANCY

J.R. should continue methadone maintenance to avoid precipitating a withdrawal

syndrome or a relapse to opiate addiction. Both relapse and withdrawal syndrome

could lead to a spontaneous abortion.

20 A structured methadone maintenance program

provides access to counseling and perinatal medical care which are additional

benefits. The dose of methadone should be titrated individually throughout the

pregnancy and may even need to be increased and switched from QD to BID dosing

due to changes in kinetics that occur during pregnancy.

2 The neonate can be managed

for either opioid-induced CNS depression or methadone withdrawal after delivery,

as needed.

Methadone continues to be the standard of care for the management of opioid

dependence in pregnancy; however, a growing body of evidence suggests

buprenorphine may be a reasonably safe alternative.

15 Also most evidence suggests

that infants born to buprenorphine-maintained women have a lower incidence of

neonatal abstinence syndrome and shorter hospital stays.

41–43

NEONATAL ABSTINENCE SYNDROME (NAS)

CASE 90-5, QUESTION 2: Because methadone crosses the placental barrier, will J.R.’s infant exhibit opioid

withdrawalsymptoms after birth, and if so, how should they be managed?

Methadone crosses the placental barrier and can cause CNS and respiratory

depression as well as opioid withdrawal in the newborn. In general, the most

common opioid NAS symptoms include restlessness, tremors, a high-pitched cry,

hypertonicity, increased reflexes, regurgitation, tachypnea, diarrhea, and sneezing.

Seizures are associated with, but not necessarily caused directly by, opioid

withdrawal in the neonate.

44

Management of the neonate’s opioid withdrawal syndrome entails careful attention

to hydration with demand feeding and

p. 1880

p. 1881

symptomatic care. Treatment of opioid NAS should begin when symptoms occur;

prophylactic therapy is not recommended. Mild withdrawal symptoms generally do

not need therapy, but moderate to severe symptoms may require 14 or more days of

treatment.

44

Symptoms of physiologic withdrawal are usually apparent within 48 hours of

birth. At this time, treatment can be initiated. Currently, NAS is treated with

morphine.

41,44–46 Morphine can be started at a dose of 50 mcg/kg given orally four

times daily and titrated to control symptoms. Once the NAS symptoms have

stabilized, the dose can be decreased daily by 20% until discontinuation of the drug.

Phenobarbital is preferred for the treatment of NAS in cases of combined

dependence or benzodiazepine dependence or if maximum doses of opiate have been

used.

41

If used, phenobarbital is instituted in doses of 5 to 10 mg/kg/day in the first 24

hours, then tapered symptomatically, usually about 20%/day.

If J.R.’s infant displays opioid withdrawal symptoms (e.g., feeds poorly, becomes

tremulous or agitated), morphine at a dosage of 50 mcg/kg orally given four times

daily would be an appropriate intervention. This dosage is given until symptoms

stabilize and then gradually tapered (e.g., 20% each day) during the next week.

Buprenorphine has also shown positive data supporting its use and is a potential

option if morphine is unacceptable.

44

BREAST-FEEDING

Methadone is excreted into the breast milk of methadone-maintained mothers. The

amount of methadone in the breast milk is unlikely, however, to have adverse effects

on the infant.

47 Furthermore, studies have found minimal transfer of methadone into

breast milk.

20 There are little data regarding the safety of buprenorphine in breastfeeding. One study found low levels of buprenorphine and its active metabolite,

nalbuphine, in infants’ urine.

48 Breast milk offers advantages clearly beneficial to

infants, and J.R. should be encouraged to breast-feed her infant.

SEDATIVE-HYPNOTICS (NON-ETOH)

The sedative-hypnotics are a diverse group of compounds with broad clinical uses,

including anesthesia, treatment of anxiety, and treatment of insomnia. Ethanol, also a

sedative-hypnotic agent, continues to be the most widely abused substance in the

United States and will be discussed later. Benzodiazepines have become the

prototypical sedative-hypnotic drugs of abuse. Other abused sedative-hypnotic drugs

include carisoprodol and γ-hydroxybutyric acid (GHB). Carisoprodol, a

nonscheduled skeletal muscle relaxant, has an active metabolite meprobamate, a

sedative-hypnotic agent with known abuse potential.

49 GHB is a putative

neurotransmitter abused for its euphoric and sedative-hypnotic effects. Although

sedative-hypnotics can be abused as monotherapy, they are more commonly used as

adjuncts to other chemicals such as opiates and EtOH.

Abstinence Syndromes Associated with SedativeHypnotic Dependence

CASE 90-6

QUESTION 1: During a year of therapy for anxiety, B.J. increased his dose of alprazolam to two 1-mg tablets

5 times a day. He has admitted to “doctor shopping” and buying alprazolam on the street. He states he uses the

benzodiazepine to get high but he also becomes extremely anxious if he doesn’t use any alprazolam for more

than an afternoon. Will he experience withdrawalsymptoms if he suddenly discontinues alprazolam?

Patients who have been on long-term courses of therapeutic doses of sedativehypnotics often experience withdrawal symptoms on abrupt discontinuation of

therapy. Withdrawal syndromes seen with sedative-hypnotics are similar to those

seen with alcohol withdrawal and can include insomnia, anxiety, tremors, headaches,

restlessness, nausea, vomiting, hypertension, tachycardia, hypersensitivity to light,

sound, and touch, and perceptual distortions.

50 Generalized tonic–clonic seizures can

occur as isolated seizures or as status epilepticus. The psychoses that develop

resemble the delirium tremens produced by alcohol withdrawal and are usually

characterized by disorientation, agitation, delusions, and hallucinations. During the

delirium, hyperthermia and agitation can lead to exhaustion, rhabdomyolysis,

cardiovascular collapse, and death. Abstinence from short-acting barbiturates and

meprobamate produces symptoms that peak within 1 to 5 days. Discontinuation of

short-acting benzodiazepines (e.g., lorazepam, oxazepam, alprazolam, temazepam)

results in the abrupt onset of withdrawal symptoms, usually within 12 to 24 hours

after the last dose. Long-acting agents, and those with active metabolites, have a

gradual onset of milder withdrawal symptoms compared with the short-acting agents.

Withdrawal symptoms after chronic use of long-acting benzodiazepines typically

occur within 5 days of cessation and peak at 1 to 9 days after the last dose.

50

B.J. has been abusing alprazolam, taking more than the recommended maximal

dose. Likely, he will experience withdrawal, possibly including seizures, if he were

to abruptly discontinue the alprazolam. His withdrawal from this medication should

be medically managed.

Treatment of Sedative Withdrawal

Three general medication strategies are used for withdrawing patients from sedativehypnotics: tapering; substituting (and gradual taper) of phenobarbital for the drug of

dependence; and the substituting (and gradual taper) of a long-acting benzodiazepine

for the drug of dependence.

51 Gradual tapering of the drug of dependence is

appropriate for patients with therapeutic dose dependence or those taking long-acting

sedative-hypnotics, who are not currently abusing alcohol or other substances. A

recent meta-analysis suggests that management of benzodiazepine mono-dependence

by gradual taper is preferable to abrupt discontinuation.

52 The patient who is abusing

sedative-hypnotics already has a strong association between the drug of choice and

certain desired effects. Therefore, to minimize exacerbating addictive disease,

substitution and taper with a long-acting therapeutic agent is preferred.

The phenobarbital method is used in some drug treatment programs. The

pharmacologic rationale for phenobarbital substitution is that it is long acting,

producing little changes in serum levels between doses, thereby preventing

breakthrough withdrawal symptoms. Lethal doses are many times higher than toxic

doses, and dysphoria occurs with elevated dose, rendering it less desirable for

abusers.

The standard method involves calculating a phenobarbital replacement dose for

the total daily dose of the sedative-hypnotic being abused. The calculation is based

on phenobarbital equivalents (Table 90-3). If multiple sedative-hypnotics are being

used, the totals for each drug and alcohol (amount of pure ethanol) are summated. The

total phenobarbital substitution dose should be given in divided doses, 3 or 4 times

daily (to avoid dysphoria). Because the calculated dosage is an estimate based on

patient history, which may be inaccurate, it is advisable to administer a test dose if

the calculated replacement dose is more than 180 mg/day. The test dose, generally

one-third the total dose, is given to the patient, who is then observed for 1 to 2 hours.

The patient is observed for mitigation of withdrawal symptoms as well as signs of

overmedication, such as somnolence or incoordination. Once an appropriate dose is

determined, the patient is usually stabilized on that dose for 1 to 2 weeks. After

stabilization, a gradual taper of phenobarbital is instituted, with dosages reduced by

15 mg weekly or every other week, or 10% of the current (starting) dose per week.

For the last 25% to 35% of the taper, the rate is slowed to keep the patient stabilized.

The taper should be held for a few days if withdrawal symptoms occur.

50

p. 1881

p. 1882

Table 90-3

Hypnotic Dose Equivalent to 30-mg Phenobarbital

Pure ethanol 30–60 mL Clonazepam 1–2 mg Pentobarbital 100 mg

Alprazolam 0.5–1 mg Diazepam 10 mg Secobarbital 100 mg

Butalbital 100 mg Flunitrazepam 1–2 mg

a Temazepam 15 mg

Carisoprodol 700 mg Lorazepam 2 mg Triazolam 0.25–0.5 mg

Chlordiazepoxide 25 mg Oxazepam 10–15 mg Zolpidem 5 mg

aNot approved for use in the United States.

Source: Dickinson WE, Eickelberg SJ. Management of sedative-hypnotic intoxication and withdrawal. In: Ries RK

et al. eds. Principles of Addiction Medicine, 4th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009:573.

B.J. has a substance use disorder to alprazolam. Tapering of alprazolam or

conversion to phenobarbital will both result in a safe withdrawal. His total dose of

alprazolam is 10 mg/day, so if phenobarbital is used he should receive 300 mg

divided 3 or 4 times a day. The total daily phenobarbital dose or alprazolam dose

should be tapered by 10% of the dose per week as tolerated.

γ-Hydroxybutyric Acid

γ-Hydroxybutyric acid (GHB), commonly referred to as “liquid ecstasy,” is a potent

“club drug.” Once available as an over-the-counter nutritional supplement, primarily

used by bodybuilders for its muscle building effect, the FDA removed it from the

retail market in 1990 because of widespread reports of poisoning. In 2000, it was

classified as a schedule I drug; however, a GHB-containing product, sodium oxybate,

is available as a schedule III prescription drug for the treatment of cataplexy

associated with narcolepsy. GHB is found in mammalian brain tissue, where it is

derived from conversion of its parent neurotransmitter, γ-aminobutyric acid

(GABA).

53

It is believed to be a neurotransmitter. Experimental evidence suggests

that the mechanism of action of exogenously administered GHB involves agonist

activity at the GABAB receptor.

53

γ-Hydroxybutyric acid has CNS depressant effects and is abused for its

euphorigenic properties, disinhibition, and enhanced sensuality. Its psychic effects

are similar to those of alcohol, and include increased libido, short-term anterograde

amnesia, and a dreamy, altered sensorium. It has a steep dose-response curve, and

common adverse effects include dizziness, nausea, weakness, agitation,

hallucinations, seizures, respiratory depression, and coma. Its effects are synergistic

with alcohol. GHB overdose may be fatal, and there is no antidote. Treatment for

GHB overdose is primarily supportive.

Highly addictive, tolerance and physical dependence can occur with regular use of

GHB, and a withdrawal syndrome has been seen in people who have taken high

doses of it (~18 g/day or more, although doses are variable in solution form) with

frequent dosing (every 1–3 hours).

53 Withdrawal symptoms can include muscle

cramps, nausea, vomiting, tremor, anxiety, insomnia, tachycardia, restlessness, and

delirium or frank psychosis. Death caused by pulmonary edema has been reported.

Treatment of withdrawal involves supportive care, including use of benzodiazepines

(e.g., lorazepam or diazepam) for sedation. Withdrawal can last up to 2 weeks.

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