Withdrawal from Sedative–Hypnotics Symptoms of sedative–hypnotic withdrawal include:

Withdrawal from Sedative–Hypnotics Symptoms of sedative–hypnotic withdrawal include:

• tremor • anxiety • insomnia • anorexia • nausea and vomiting • postural hypotension • seizures

These symptoms are qualitatively similar to those of alcohol withdrawal and the Clinical Institute withdrawal assessment scale is therefore useful to document symptom progression and the response to treatment. Withdrawal from sedative–hypnotic drugs is a medical emergency: if untreated there is a risk of serious complications (such as hyperpyrexia) and death. The nature of withdrawal symptoms is similar for all sedative– hypnotics but the rate of onset and decline depends on the

231 half-life of individual drugs. For short-acting agents (e.g., seco-

DRUGS FOR TREATING SUBSTANCE ABUSE DISORDERS

barbital), withdrawal symptoms begin 12–24 h after the last dose. By contrast, symptoms develop more slowly for long- acting agents (e.g., diazepam) and may become maximal one week after the last dose.

Similar to the treatment for alcohol withdrawal, benzodi- azepine taper (as described above) is a good choice, particu- larly if the patient is dependent on benzodiazepines.

An excellent alternative for substitution therapy in sedative–hypnotic withdrawal is phenobarbital. This long- acting agent is associated with low between-dose fluctuation in blood levels; it has low potential for abuse and a wide margin between therapeutic and lethal blood levels. The symptoms of phenobarbital intoxication (ataxia, slurred speech, nystagmus) are readily apparent and easy to respond to in a detoxication protocol.

In detoxication of sedative–hypnotic dependency, the first step is to obtain a history of drug use. This enables the physi- cian to estimate the dose of phenobarbital equivalent to the total dose of sedative–hypnotic, as specified in Table 8-2.

The total phenobarbital equivalent dose is then summed and divided into a three-times daily dose regimen. The total daily dose of phenobarbital rarely exceeds 500 mg even for patients with extreme dependence.

In the event that acute withdrawal symptoms emerge before substitution therapy has begun, the first dose of phenobarbital may be administered by intramuscular injection. Withdrawal or intoxication symptoms should then be reassessed 1–2 h later to determine the next dose of phenobarbital.

The degree of dependence can be assessed by serial admin- istration of pentobarbital 200 mg but it is not clear whether this approach is superior to direct substitution with phenobarbital, which is speedy, simple, and safe.

There should be no signs of sedative–hypnotic withdrawal or phenobarbital toxicity 24–48 h after beginning substitution therapy with phenobarbital and the dose reduction phase may then begin. This involves a reduction in phenobarbital dose of 30 mg/day, maintaining the three times daily dose regimen. If phenobarbital toxicity occurs (slurred speech, nystagmus, ataxia), the next dose should be withheld and the total daily

232 HANDBOOK OF PSYCHIATRIC DRUGS

Phenobarbital Withdrawal Equivalents of Sedative– Hypnotics

CLASS/GENERIC NAME DOSE (mg) ∗

BENZODIAZEPINES Alprazolam

1 Chlordiazepoxide

25 Clonazepam

2 Clorazepate Diazepam

BARBITURATES Amobarbital

Chloral hydrate 500 Ethchlorvynol

5 ∗ Dose equivalent to 30 mg of phenobarbital for withdrawal.

Adapted from Wesson DR, Smith DE, Ling W, Seymour RB: Chapter 17: Sedative-Hypnotics. In: Lowinson JH, Ruiz P, Millman RB, Langrod JG, editors: Substance Abuse: A Comprehensive Textbook, 4th ed. Philadelphia: Lippincott Williams and Wilkins; 2005.

dose should be reduced. In the event of objective signs of withdrawal, the daily dose of phenobarbital is increased and the dose reduction phase is delayed until the patient is stabi- lized again.

DRUGS FOR TREATING SUBSTANCE ABUSE DISORDERS