Longo, 2000 Addiction: Part I. Benzodiazepines—Side Effects, Abuse Risk and Alternatives

[Altostrata]

Acknowledging prolonged benzo withdrawal syndrome, this paper appeared in American Family Physician.

 

Am Fam Physician. 2000 Apr 1;61(7):2121-8.

Addiction: Part I. Benzodiazepines--side effects, abuse risk and alternatives.

Longo LP, Johnson B.

Source

University of Wisconsin Medical School, Milwaukee, USA.

Abstract and free full text at http://www.ncbi.nlm.nih.gov/pubmed/10779253

Benzodiazepines are widely prescribed for a variety of conditions, particularly anxiety and insomnia. They are relatively safe and, with overdose, rarely result in death. However, used chronically, benzodiazepines can be addicting. These agents are often taken in combination with other drugs of abuse by patients with addiction disorders. In such patients, alternatives to benzodiazepines may be preferable and may include antidepressants, anticonvulsants, buspirone, antihypertensive agents and the newer neuroleptic medications. Caution must be used when prescribing benzodiazepines to patients with a current or remote history of substance abuse.

 

 

 

From free full text at http://www.aafp.org/afp/2000/0401/p2121.html

Addiction: Part I. Benzodiazepines—Side Effects, Abuse Risk and Alternatives

LANCE P. LONGO, M.D., University of Wisconsin Medical School, Milwaukee, WisconsinM.D.

BRIAN JOHNSON, Harvard Medical School, Boston, Massachusetts

Am Fam Physician. 2000 Apr 1;61(7):2121-2128.

 

....Benzodiazepines are widely prescribed for a variety of conditions, particularly anxiety and insomnia. They are relatively safe and, with overdose, rarely result in death. However, used chronically, benzodiazepines can be addicting. These agents are often taken in combination with other drugs of abuse by patients with addiction disorders. In such patients, alternatives to benzodiazepines may be preferable and may include antidepressants, anticonvulsants, buspirone, antihypertensive agents and the newer neuroleptic medications.

 

Caution must be used when prescribing benzodiazepines to patients with a current or remote history of substance abuse.

 

There is little doubt of the therapeutic efficacy of benzodiazepines in reducing anxiety, inducing sleep and quelling panic symptoms. As noted in a 1990 report by the American Psychiatric Association (APA) on benzodiazepine dependence, toxicity and abuse,1 the anxiolytic and hypnotic efficacy of benzodiazepines has been well established by numerous placebo-controlled studies.

 

Benzodiazepines are widely prescribed, with four of them—alprazolam (Xanax), clonazepam (Klonopin), diazepam (Valium) and lorazepam (Ativan)—listed among the top 100 most commonly prescribed medications.2 Benzodiazepines generally produce almost immediate effects, and thus may be prescribed for short-term, intermittent, “as-needed” use. Because many of the anxiety disorders wax and wane over time, patients with these disorders often prefer benzodiazepines because these agents can be taken intermittently, when patients feel the need to take them, and most patients can use benzodiazepines judiciously.1

 

Benzodiazepines are also widely prescribed for other reasons, such as muscle spasticity, convulsive disorders, presurgical sedation, involuntary movement disorders, detoxification from alcohol and other substances, and anxiety associated with cardiovascular or gastrointestinal conditions3  (Table 1).

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According to the APA report on benzodiazepines,1 11 to 15 percent of the adult population has taken a benzodiazepine one or more times during the preceding year, but only 1 to 2 percent have taken benzodiazepines daily for 12 months or longer. In psychiatric treatment settings and in substance-abuse populations, however, the prevalence of benzodiazepine use, abuse and dependence is substantially higher than that in the general population.4,5

 

Because benzodiazepines are controlled substances with abuse potential, special attention must be directed toward the patient's addiction history before these agents are prescribed. An understanding of the toxicity and side effects of benzodiazepines, abuse patterns and alternative anxiolytic and hypnotic agents may help clinicians maximize treatment outcomes and reduce medicolegal liability risks.

Neurochemistry

Benzodiazepine receptors are ubiquitous throughout the central nervous system. Benzodiazepine receptors are linked predominantly to γ amino butyric acid (GABA) receptors, which sensitize benzodiazepine receptors to the neurotransmitter GABA, the most prominent inhibitory neurotransmitter in the central nervous system.

 

Benzodiazepines enhance the affinity of the recognition site for GABA by inducing conformational changes that make GABA binding more efficacious. Activation of the benzodiazepine-GABA-chloride ionophor complex is responsible for producing the therapeutic anxiolytic effects of benzodiazepines and for mediating many of the side effects and, possibly, dependence and withdrawal from these drugs.6

 

Similarly, other sites for drug and neurotransmitter binding are associated with the GABA receptor complex, which serves as a primary site of action of benzodiazepines, barbiturates and other sedative-hypnotics, such as alcohol.6 Benzodiazepines and barbiturates act at separate binding sites on the receptor to potentiate the inhibitory action of GABA. They do so by allosterically altering the receptor (changing its conformation) so that it has a greater binding affinity for GABA. Ethanol modifies the receptor by altering the membrane environment so that it has increased affinity for GABA and the other sedative-hypnotic drugs. That benzodiazepines, barbiturates and ethanol all have related actions on a common receptor type, which explains their pharmacologic synergy and cross tolerance. Thus, benzodiazepines are used during alcohol detoxification.

With long-term high-dose use of benzodiazepines (or ethanol), there is an apparent decrease in the efficacy of GABA-A receptors, presumably a mechanism of tolerance.6,7 When high-dose benzodiazepines or ethanol are abruptly discontinued, this “down-regulated” state of inhibitory transmission is unmasked, leading to characteristic withdrawal symptoms such as anxiety, insomnia, autonomic hyperactivity and, possibly, seizures.

Toxicity and Side Effects

With the introduction of chlordiazepoxide (Librium) in 1960, and because of the relative safety of benzodiazepines, these agents rapidly replaced barbiturates as sedative-hypnotics. They cause significantly less respiratory depression than barbiturates and, consequently, are rarely lethal in an overdose.

As a class of drugs, benzodiazepines share many clinical properties, although the different agents in this class may display different pharmacokinetic and pharmacodynamic properties (Table 2). Pharmacologic properties such as potency, half-life and lipophilicity, the duration of treatment and the rate of a dosage increase or decrease have a bearing on the occurrence of side effects.1 The development of physiologic dependence is somewhat predictable and is proportional to the total benzodiazepine exposure (dose × duration of treatment), although significant variability may exist among patients...

 

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TOXICITY AND DRUG INTERACTIONS

When used alone, benzodiazepines carry an extremely low risk of acute toxicity. However, benzodiazepines often are used with other types of medications, including other drugs with abuse potential, and these drugs can enhance the toxic effects of benzodiazepines. The latter interact synergistically with other central nervous system depressants, including other hypnotics, sedating antidepressants, neuroleptics, anticonvulsants, antihistamines and alcohol.8 Fatal overdoses in addicted patients often involve the combination of benzodiazepines and alcohol, with or without opiates. In addition, pharmacokinetic drug interactions may occur. For instance, selective serotonin reuptake inhibitors (SSRIs) may increase diazepam blood levels,9 and nefazadone (Serzone) may increase alprazolam levels10 through hepatic enzyme inhibition, leading to increased sedative-hypnotic effects or side effects.

PSYCHOMOTOR RETARDATION

Psychomotor slowing may be especially profound following initial administration of a benzodiazepine or with a sudden dosage increase. It also may be noted in patients, such as the elderly, who have decreased rates of metabolism or greater susceptibility to central nervous system depression.8 Psychomotor symptoms include drowsiness, poor concentration, ataxia, dysarthria, motor incoordination, diplopia, muscle weakness, vertigo and mental confusion.11 Studies of the psychomotor effects suggest that benzodiazepines slow reaction time and impair driving skills, increasing the risk of motor vehicle crashes in patients who are taking these agents.12

MEMORY IMPAIRMENT

Benzodiazepines induce anterograde amnesia, which accounts for the beneficial effects of benzodiazepines such as midazolam (Versed) for presurgical medication. These specific amnestic effects appear to be separate from sedation.11 Episodic memory (the remembering of recent events and the circumstances in which they occurred and their time sequences) is particularly impaired and more markedly so in heavy alcohol drinkers who also use benzodiazepines. Specific deficits in visuospatial ability and sustained attention have also been described in patients who have taken therapeutic doses of benzodiazepines regularly for longer than one year.13

PARADOXICAL DISINHIBITION

Increased excitement, irritability, aggression, hostility and impulsivity may occur in some patients who take benzodiazepines. This paradoxical disinhibition may, in rare cases, result in attacks of rage or violence, or other indiscretionary or antisocial behaviors.14 Such reactions may be due to disinhibition of behavioral tendencies normally suppressed by social restraints (as can also be the case with alcohol). These reactions occur most commonly in children, in the elderly and in persons with developmental disabilities.

DEPRESSION AND EMOTIONAL BLUNTING

An association has been noted between benzodiazepine use and depressive symptoms and, in some cases, the emergence of suicidal ideation. Some evidence indicates that higher benzodiazepine dosages are associated with an increased risk of depression and that reducing the dosage or discontinuing therapy may resolve the depressive symptoms.15 Although the mechanism of this action is unclear, benzodiazepine-related depression might occur as a physiologic result of a reduction in central monoamine activity.

 

“Emotional anesthesia” may also be seen in clinical practice. This effect may be sought by drug addicts who become progressively more incapable of tolerating their emotions and life stressors.

ADVERSE EFFECTS IN PREGNANCY

Benzodiazepines cross the placenta and are classified as class D teratogens. They may lead to the development of dependence and consequent withdrawal symptoms in the fetus.16 Benzodiazepines are excreted in breast milk and thus are usually contraindicated in breast-feeding mothers.

TOLERANCE

Tolerance to all of the actions of benzodiazepines can develop, although at variable rates and to different degrees. Tolerance to the hypnotic effects tends to develop rapidly, which may be beneficial in daytime anxiolysis but makes long-term management of insomnia difficult.17 Patients typically notice relief of insomnia initially, followed by a gradual loss of efficacy.18 Tolerance to the anxiolytic effect seems to develop more slowly than does tolerance to the hypnotic effects, but there is little evidence to indicate that benzodiazepines retain their efficacy after four to six months of regular use.19,20 Benzodiazepine therapy is often continued to suppress withdrawal states, which usually mimic symptoms of anxiety. Dosage escalation often maintains the cycle of tolerance and dependence, and patients may have difficulty discontinuing drug therapy.

DEPENDENCE

Benzodiazepine therapy can give rise to physiologic and psychologic dependence based on the drug's dosage, duration of therapy and potency.1 Thus, dependence will develop sooner (such as in one to two months) in a patient who is taking a high dosage of a high-potency agent such as alprazolam than in a patient who is receiving a relatively low dosage of a long-acting, low-potency agent such as chlordiazepoxide. As a result of physiologic dependence, withdrawal symptoms emerge with rapid dose reduction or abrupt discontinuation of the drug.

 

Psychologically, long-term use of benzodiazepines may lead to overreliance on the need for the agent, loss of self-confidence and varying degrees of drug-seeking behavior.8 Patients may be reluctant to discontinue the drug because of misplaced fears or anticipatory anxiety. Some patients combine alcohol with benzodiazepines when they are not able to acquire the desired or “needed” effects.

SHORT-TERM WITHDRAWAL SYMPTOMS

Withdrawal effects from therapeutic dosages of benzodiazepines are mainly anxiety symptoms.1,21 In addition, autonomic instability (i.e., increased heart rate and blood pressure level, tremulousness, diaphoresis), insomnia and sensory hypersensitivity are common. The most serious acute withdrawal symptoms are seizures and delirium tremens, which most commonly occur with abrupt discontinuation. The time frame for the emergence of acute withdrawal symptoms corresponds to the half-life of the particular agent being used.

 

Some elements of withdrawal are believed to occur in a majority of patients who have taken therapeutic dosages of benzodiazepines for more than a few months, although the severity of withdrawal symptoms generally depends on the amount of the original dosage, the rate at which the dosage is tapered, the selection of patients and the definition of withdrawal symptoms.1,18

PROTRACTED WITHDRAWAL

A protracted abstinence syndrome has been observed by addictionologists who are familiar with benzodiazepine addiction.22 Symptoms include prolonged (for several months) anxiety, depression and insomnia. In addition, physical symptoms related to gastrointestinal, neurologic and musculoskeletal effects may occur. This abstinence phenomenon may develop despite long, slow, judicious tapering of the dosage and is hypothesized to result from chronic neuroadaptation.

Effects in Elderly Patients

Among the elderly, the risk of drug interactions, psychomotor slowing, cognitive dysfunction and paradoxical disinhibition may be amplified. Benzodiazepine use in the elderly is associated with an increased rate of falls that cause hip and femur fractures and an increased likelihood of motor vehicle crashes.23,24 Cognitive impairment is common, although memory impairment may be reversible when benzodiazepines are discontinued.25

 

Cognitive deterioration associated with normal aging processes and dementia can be worsened by benzodiazepine side effects. Cortical suppression mechanisms may be disturbed in the elderly, and disinhibited behaviors may increase with benzodiazepine use. With less cognitive and social reserve in the elderly patient, the short- and long-term withdrawal symptoms and other benzodiazepine side effects may lead the patient to frequently visit or telephone the physician. The physician may feel “trapped”into arguing against the use of benzodiazepines and prescribing benzodiazepines to elderly patients. In one study,26 this impasse was broken by referring elderly patients to inpatient detoxification, which resulted in a dramatic decrease in annual physician visits.

Benzodiazepine Abuse....