Thiamylal is a barbiturate

Barbiturate

Barbiturates are drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia. They are also effective as anxiolytics, as hypnotics, and as anticonvulsants...

 derivative invented in the 1950s. It has sedative

Sedative

A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....

, anticonvulsant

Anticonvulsant

The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...

 and hypnotic

Hypnotic

Hypnotic drugs are a class of psychoactives whose primary function is to induce sleep and to be used in the treatment of insomnia and in surgical anesthesia...

 effects, and is used as a strong but short acting sedative. Thamylal is still in current use, primarily for induction in surgical anaesthesia  or as an anticonvulsant to counteract side effects from other anaesthetics. It is the Thiobarbiturate anologue of secobarbital

Secobarbital

Secobarbital sodium is a barbiturate derivative drug that was first synthesized in 1928 in Germany. It possesses anaesthetic, anticonvulsant, sedative and hypnotic properties...

.