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- Habit Forming - Amobarbital sodium may be habit forming. Tolerance, psychological and physical dependence may occur with continued use (see Drug Abuse and Dependence and Pharmacokinetics under CLINICAL PHARMACOLOGY). Patients who have psychological dependence on barbiturates may increase the dosage or decrease the dosage interval without consulting a physician and may subsequently develop a physical dependence on barbiturates. In order to minimize the possibility of overdosage or the development of dependence, the prescribing and dispensing of sedative-hypnotic barbiturates should be limited to the amount required for the interval until the next appointment. Abrupt cessation after prolonged use in a person who is dependent on the drug may result in withdrawal symptoms, including delirium, convulsions, and possibly death. Barbiturates should be withdrawn gradually from any patient known to be taking excessive doses over long periods of time (see Drug Abuse and Dependence).
- Intravenous Administration - Too rapid administration may cause respiratory depression, apnea, laryngospasm, or vasodilation with fall in blood pressure.
- Acute or Chronic Pain - Caution should be exercised when barbiturates are administered to patients with acute or chronic pain, because paradoxical excitement could be induced or important symptoms could be masked. However, the use of barbiturates as sedatives in the postoperative surgical period and as adjuncts to cancer chemotherapy is well established.
- Usage in Pregnancy - Barbiturates can cause fetal damage when
administered to a pregnant woman. Retrospective, case-controlled studies have
suggested a connection between the maternal consumption of barbiturates and
a higher than expected incidence of fetal abnormalities. Barbiturates readily
cross the placental barrier and are distributed throughout fetal tissues;
the highest concentrations are found in the placenta, fetal liver, and brain.
Fetal blood levels approach maternal blood levels following parenteral administration.
Withdrawal symptoms occur in infants born to women who receive barbiturates throughout the last trimester of pregnancy (see Drug Abuse and Dependence).
If amobarbital sodium is used during pregnancy or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.
- Synergistic Effects - The concomitant use of alcohol or other CNS depressants may produce additive CNS-depressant effects.
Barbiturates may be habit forming. Tolerance and psychological and physical dependence may occur with continuing use (see Drug Abuse and Dependence).
Barbiturates should be administered with caution, if at all, to patients who are mentally depressed, have suicidal tendencies, or have a history of drug abuse. Particular caution is also indicated before administering barbiturates to patients who have abused other classes of drugs (see WARNINGS).
Elderly or debilitated patients may react to barbiturates with marked excitement, depression, or confusion. In some persons, especially children, barbiturates repeatedly produce excitement rather than depression.
In patients with hepatic damage, barbiturates should be administered with caution and initially in reduced doses. Barbiturates should not be administered to patients showing the premonitory signs of hepatic coma.
Parenteral solutions of barbiturates are highly alkaline. Therefore, extreme care should be taken to avoid perivascular extravasation or intra-arterial injection. Extravascular injection may cause local tissue damage with subsequent necrosis; consequences of intra-arterial injection may vary from transient pain to gangrene of the limb. Any complaint of pain in the limb warrants stopping the injection.
The systemic effects of exogenous and endogenous corticosteroids may be diminished by amobarbital sodium. Thus, this product should be administered with caution to patients with borderline hypoadrenal function, regardless of whether it is of pituitary or of primary adrenal origin.
Prolonged therapy with barbiturates should be accompanied by periodic evaluation of organ systems, including hematopoietic, renal, and hepatic systems (see General under PRECAUTIONS and ADVERSE REACTIONS).
- Animal Data. Phenobarbital sodium is carcinogenic in mice and rats after lifetime administration. In mice, it produced benign and malignant liver cell tumors. In rats, benign liver cell tumors were observed very late in life.
- Human Data. In a 29-year epidemiologic study of 9,136 patients who were treated on an anticonvulsant protocol that included phenobarbital, results indicated a higher than normal incidence of hepatic carcinoma. Previously, some of these patients had been treated with thorotrast, a drug that is known to produce hepatic carcinomas. Thus, this study did not provide sufficient evidence that phenobarbital sodium is carcinogenic in humans.
A retrospective study of 84 children with brain tumors matched to 73 normal controls and 78 cancer controls (malignant disease other than brain tumors) suggested an association between exposure to barbiturates prenatally and an increased incidence of brain tumors.
Usage in Pregnancy
- Teratogenic Effects. Pregnancy Category D - See Usage in Pregnancy under WARNINGS.
- Nonteratogenic Effects - Reports of infants suffering from long-term barbiturate exposure in utero included the acute withdrawal syndrome of seizures and hyperirritability from birth to a delayed onset of up to 14 days [see Drug Abuse and Dependence).
Labor and Delivery
Hypnotic doses of barbiturates do not appear to impair uterine activity significantly during labor. Full anesthetic doses of barbiturates decrease the force and frequency of uterine contractions. Administration of sedative-hypnotic barbiturates to the mother during labor may result in respiratory depression in the newborn. Premature infants are particularly susceptible to the depressant effects of barbiturates. If barbiturates are used during labor and delivery, resuscitation equipment should be available.
Data are not available to evaluate the effect of barbiturates when forceps delivery or other intervention is necessary or to determine the effect of barbiturates on the later growth, development, and functional maturation of the child.
Caution should be exercised when amobarbital sodium is administered to a nursing woman because small amounts of barbiturates are excreted in the milk.
Usage in Children
Safety and effectiveness have not been established in children below the age of 6 years.
Last reviewed on RxList: 8/21/2009
This monograph has been modified to include the generic and brand name in many instances.
Additional Amytal Sodium Information
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