Sedative Hypnotic Drugs


Sedative-hypnotic decrease anxiety in a low dose and have a calming effect. However, they do cause drowsiness and limit the motor skills.


Barbiturates are the prototype for this drug. In a low dose, they give sedation and an antiepileptic effect. In an intermediate or medium dose, they cause a hypnotic effect, decreased motor coordination, amnesia, anti-convulsion and euphoria. In a higher dose, they give general anaesthesia and respiratory depression as a side effect. And in a very high dose, usually seen in drug overdoses or for suicide, there is a coma, severe respiratory and cardiovascular depression.

There are several types of Barbiturates. The tolerance to barbiturates has an unknown mechanism of action but usually is caused by respiratory depression. It has psychological and physical dependence. There are heavy withdrawal symptoms when it's taken in a very high dose, such as hypothermia, sweats and delirium

It is used in circulatory, respiratory and sleep therapy as a treatment. Phenobarbital, which has a slow onset and long action, decreases the REM sleep cycle and is excreted renaly.

Pentobarbital, secobarbital and amobarbital have a quick onset with short to intermediate action.

Hexobarbital, thiopental and methohexital, which are given P.O. IV and again IV respectively, have an approximate half-life of 12 hours with high-fat tissue accumulation. They have a quick onset of short-acting.


Chlordiazepoxide decreases the motor skills but it has less of a sleepy and drowsy effect than benzodiazepines.

Anxiolytics, however, don't cause respiratory depression. In a small dose, they cause an anxiolytics effect, sedation, central muscle relaxation. In medium or intermediate dose they cause a hypnotic effect, motor incoordination, amnesia, convulsions a euphoria.

When overdosing, they cause general anaesthesia. They can also cause severe coma, cardiovascular and respiratory depression, especially, when alcohol is mixed with these drugs.

Anxiolytics treat insomnia and anxiety because they're safer than sedative-hypnotics. They can be sometimes used in a combination with beta-blockers because hypnotics are no longer used for anxiety.

They can be used for premedication for anaesthesia in surgery, for symptomatic therapy, in psychiatric manifestations as mood stabilizers, and they can help with drug-induced anxiety or agitation. They are also used to treat convulsions when mixed with antiepileptic drugs.

The drugs are GABA receptor inhibitors, which are linked to the chloride channels. The ion channel opens and the chloride enters caution hyper-polarization of the cell. This decreases the neuronal excitability.

The short-acting drugs are midazolam, triazolam and zolpidem.

The side effects are confusion and anger.

Intermediate-acting drugs are alprazolam, which is an anxiolytic, and zopiclone, which is a benzodiazepine receptor agonist.

Long-acting drugs include diazepam, which is an anticonvulsive, nitrazepam, chlordiazepoxide and clonazepam, which is a mood stabilizer.

They are injected P.O. The side effects of all of these drugs include sleepiness, cardiovascular and respiratory depression.

In case of overdose, people may experience aggravated sleep apnea. Withdrawal symptoms include insomnia, restlessness and convulsions.

The therapy to treat an overdose is flumazenil.

It has two to three weeks for sedate hypnotics to come into effect. They treat general anxiety, but they have an unknown mode of action.