Products
Barbiturates are commercially available in many countries in tablet and injectable forms. Few drugs are still available because barbiturates have become less important after the introduction of benzodiazepines and other psychotropic drugs. Barbiturates were most commonly used in the first half of the 20th century. Barbiturates were synthesized as early as the 19th century. The first active ingredient was barbital launched by Bayer in 1904 (Veronal), which was developed by Emil Fischer and Joseph von Mering. Phenobarbital (Luminal) was launched in 1912, butobarbital (Neonal) in 1922 and amobarbital in 1923 (Amytal). Various other agents followed.
Structure and properties
Barbiturates are derivatives of barbituric acid, which is formally derived from urea and the malonic acid. In general, their active ingredient salts (e.g., sodium salt) are more water soluble.
Effects
Barbiturates (ATC N05CA) have depressant, sleep-inducing, antianxiety, narcotic, and anticonvulsant properties. The effects are due in part to binding to GABA-A receptors. Depending on the duration of action, a distinction is made between short- and long-acting barbiturates.
Indications
Medical indications include:
- Epilepsy, seizure disorders.
- Anesthesia, narcosis
- Withdrawal treatment, e.g. phenobarbital
- Short-term treatment of sleep disorders
- Restlessness and agitation
- Febrile convulsions
Other indications:
- Physician-assisted euthanasia (pentobarbital, secobarbital).
- To put animals to sleep
Dosage
According to the professional information. The dose is adjusted individually. Discontinuation should be gradual.
Abuse
Barbiturates can be abused as depressant intoxicants, for suicide, and for homicide. They are also used for executions in some countries. Overdose causes drowsiness, coma, life-threatening respiratory depression, hypotension, and shock, among other effects. It is life-threatening and can lead to death. Doses as low as 2 to 10 g can be fatal. Countless deaths have been reported in the past. The death of Marilyn Monroe has also been linked to a barbiturate overdose.
Active Ingredients
- Pentobarbital (euthanasia, pure sodium salt).
- Phenobarbital (aphenylbarbit)
- Primidone (Mysoline)
- Thiopental (generic, Pentothal is off-label) is a thiobarbiturate
Not or no longer commercially available in many countries (selection):
- Amobarbital (Amytal)
- Barbexaclone (Maliasin)
- Barbital (Veronal)
- Butalbital (e.g., Cafergot PB)
- Secobarbital (Seconal, USA).
Contraindications
Contraindications include (selection):
- Hypersensitivity
- Pregnancy and lactation
- Acute intoxication with centrally acting drugs or alcohol.
- Drug dependence
- Respiratory depression, respiratory disorders
- Simultaneous consumption of alcohol
- Hepatic porphyria
- Severe renal and hepatic dysfunction
- Diseases of the heart muscle
For complete precautions, see the drug label.
Interactions
Barbiturates are potent inducers of several CYP450 isozymes. Thus, they may reduce the effects of other drugs. The effects of centrally depressant drugs and alcohol may be enhanced.
Adverse effects
Possible adverse effects include:
- Central disturbances: Drowsiness, fatigue, drowsiness, slowed reaction time, dizziness,headache, nightmares, hallucinations.
- Paradoxical agitation, restlessness, aggressiveness and confusion.
- Bradycardia, hypotension, shock.
- Blood count disorders
- Respiratory depression
- Digestive disorders such as nausea, vomiting, constipation.
- Hypersensitivity reactions, photosensitization, skin disorders.
- Allergy
- Liver dysfunction
- Muscle and joint pain
- Bone disease due to an effect on vitamin D metabolism.
- Sleepwalking, driving while asleep
Barbiturates can lead to tolerance and psychological and physical dependence, and can cause withdrawal symptoms if abruptly discontinued.
