Butethal is a sedative and a hypnotic drug indicated for the treatment of severe intractable insomnia. It acts on receptors in the brain (GABA A receptors) causing the release of the chemical GABA. This chemical inhibits certain areas of the brain resulting in sleepiness. Common side effects are: drowsiness, sedation, unsteadiness, vertigo and inco- ordination. Also, hangover effect, paradoxical excitement, confusion, memory defects and skin rashes. Interactions may occur with the following: adrenocorticoids (cortisone-like medicine), anticoagulants (blood thinners), carbamazepine, corticotropin (barbiturates may decrease the effects of these medicines), central nervous system (CNS) depressants (using these medicines with barbiturates may result in increased CNS depressant effects), divalproex sodium, valproic acid (using these medicines with barbiturates may change the amount of either medicine that you need to take), and oral contraceptives containing estrogens (barbiturates may decrease the effectiveness of these oral contraceptives, and you may need to change to a different type of birth control).

Butethal:
https://drugs.ncats.io/drug/OHZ8QAW6YC

Butobarbital is a hypnotic drug which is a barbiturate derivative.

Used for severe, long-standing insomnia in people already taking barbiturate medicines. Butobarbital increases the activity of the neurotransmitter GABA in the brain, thereby increasing its calming effect and resulting in sleepiness. It remains active in the body for many hours and so may cause sleepiness that continues into the next day.

Butobarbital is used in the treatment of severe sleeping difficulties (insomnia). It is only prescribed to people who are already taking barbiturate medicines and will not be started in new patients. This is because it has a high potential for dependence and addiction and has more side effects and interactions with other medicines than other treatments for insomnia. It is also more dangerous if an overdose is taken.

Do not drink alcohol while taking this medicine. People quickly become tolerant to the sleep inducing effect of this medicine. If it is used continuously for longer than two weeks, it is likely to lose its effectiveness at causing and maintaining sleep. However, the medicine has a strong potential for making you become physically or psychologically dependent on it. This medicine is generally only suitable for short-term use.

It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine.

Excerpt from netdoctor.co.uk:
https://www.netdoctor.co.uk/medicines/brain-nervous-system/a7556/butobarbital/

Butobarbital Safety Data Sheet (PDF 6 pages):
https://fagron.com/sites/default/files/document/msds_coa/77-28-1_(GB).pdf

Butobarbital:

• A hypnotic drug
• A barbiturate derivative
• It was developed in 1921