Hypnotics: Characteristics, Types And Their Effects

The hypnotics are drugs that are used to produce effects of sleepiness in people, allowing treat anxiety disorders and sleep disorders. The group of hypnotic drugs is closely related to the group of sedative drugs.

The main action of hypnotic drugs is to generate drowsiness. In contrast, sedative drugs have the main therapeutic objective of reducing anxiety, generating analgesic sensations and promoting calm. 

hypnotics

Currently, hypnotics are substances that are used mainly to induce sleep, which is why they are popularly known as sleeping pills.

Characteristics of hypnotics

Hypnotics are psychoactive psychotropic substances that induce drowsiness and sleep in the person who uses them.

The effects of these drugs occur through the decrease in the activity of the cerebral cortex. That is, hypnotics act as central nervous system depressants .

Although the main function of these substances is therapeutic, hypnotics can also be used as a drug of abuse, since many of them generate addiction if they are used regularly.

Today, hypnotics encompass a wide variety of substances. In fact, all drugs that have the action of inducing drowsiness can be classified as hypnotics.

Types of hypnotics

Hypnotics can be broadly classified into two broad categories: oral hypnotics and intravenous hypnotics.

Oral hypnotics are characterized by being administered orally. They are usually used for the treatment of severe insomnia and should always be consumed under medical prescription. It is advisable not to abuse these types of substances as they can generate addiction, so it is usually recommended to use hypnotic drugs with caution.

On the other hand, intravenous and inhalation hypnotics are substances that are used to perform the anesthetic act and during sedation in a hospital environment. They are drugs that are vital to allow induction and maintenance of anesthesia, and are often used in conjunction with morphic or opiate medications, as well as muscle relaxants.

The main hypnotic substances are reviewed below:

Barbiturates

The barbiturates are a family of drugs derived from barbituric acid. They act as depressants of the central nervous system and their intake generates a wide range of effects on brain function.

The effects of barbiturates can range from mild sedation to full anesthesia. Likewise, they act as anxiolytics and as anticonvulsants.

Barbiturates are also characterized by generating a powerful hypnotic effect at the brain level. Its consumption produces feelings of drowsiness and reduces the alertness of the person.

They are fat-soluble substances, so they dissolve easily in the body’s fat. Barbiturates easily cross the blood-brain barrier and enter brain regions.

At the brain level, barbiturates act by preventing the flow of sodium ions between neurons and favoring the flow of chloride ions. They bind to GABA receptors in the brain and increase the action of the neurotransmitter.

In this way, barbiturates increase the activity of the neurotransmitters GABA and increase the depressant effect that it produces in the brain.

Regular consumption of barbiturates tends to lead to addiction and dependence on the substance. Likewise, the intoxication produced by these drugs can cause death if very high doses are consumed or mixed with alcohol.

Propofol

Propofol is an intravenous anesthetic agent. The duration of its effects is short and it is currently licensed for the induction of general anesthesia for both adults and children over three years of age.

The main therapeutic use of this substance is to maintain the general anesthesia of patients. Likewise, it is used as a sedative in the context of intensive care units.

Propofol is applied through various formulas in order to increase its tolerance. Currently, it is often used in formulations based on soybean oil, propofol, egg phospholipid, glycerol and sodium hydroxide.

By consuming this substance, propofol binds to plasma proteins and is metabolized in the liver. The duration of its effects is short and it is characterized by its rapid action.

However, the use of this drug can cause side effects, such as cardiorespiratory depression, amnesia, myoclonus, pain in the body region of administration and allergic reactions in people sensitive to its components.

Etomidate

Etomidate is a hypnotic drug that is derived from imidazole carboxylate. It is a short-acting substance that generates significant anesthetic and amnesic effects. However, etomidate differs from many other hypnotic medications by not generating analgesic effects.

The effect of etomidate begins right after its administration. Specifically, it is argued that the drug begins to act between the first 30 and 60 seconds. The maximum effect is reached during the minute after its administration and the total duration of the drug is sustained for about 10 minutes.

It is a safe drug that is used routinely for induction of anesthesia and to obtain sedation in a hospital environment.

The cardiovascular effects of etomidate are minimal and as side effects it presents pain on intravenous administration and adrenal suppression. 

Ketamine

Ketamine is a dissociative drug that has significant hallucinogenic potential. It is a substance derived from phencyclidine that is used in therapeutic environments due to its sedative, analgesic and especially anesthetic properties.

The main characteristic of ketamine as a hypnotic drug is that its consumption induces dissociative anesthesia. That is, it generates a functional and electrophysiological dissociation between the thalamocortical system and the limbic system of the brain.

This fact makes the higher centers unable to perceive auditory, visual or painful stimuli without generating respiratory depression. With the consumption of ketamine the eyes remain open with a lost look.

In this sense, the clinical effect of ketamine is defined as “somesthetic sensory block with amnesia and analgesia.”

During the last years, the use of ketamine in the medicinal field has been significantly reduced due to its hallucinogenic power and the possibility that the substance possesses to induce post-anesthetic psychotic states.

In contrast, ketamine is a substance that is increasingly used for recreational purposes. In this sense, ketamine is marketed under the name ‘Powder K’.

Its use tends to generate addiction, which is why there are more and more cases of ketamine abuse. Likewise, in certain cases the consumption of this substance is usually combined with psychostimulants, such as cocaine or methamphetamine.

Benzodiazepines

Benzodiazepines are psychotropic drugs that act on the central nervous system. Its consumption mainly produces sedative, hypnotic, anxiolytic, anticonvulsant, amnesic and muscle relaxant effects.

In this sense, benzodiazepines are one of the most widely used drugs in mental health, mainly to treat anxiety, insomnia, affective disorders, epilepsy, alcohol withdrawal and muscle spasms.

Likewise, they are used in certain invasive procedures such as endoscopy in order to reduce the anxious state of the person and induce sedation and anesthesia.

Today there are many types of benzodiazepines; all (except chlorazpete) are completely absorbed by the body. When they reach the brain regions, benzodiazepines act as nervous system depressants in a more selective way than barbiturates.

These drugs bind to specific receptors for benzodiazepines in the central nervous system, which are part of the gamma-aminobutyric acid (GABA) complex.

In this sense, benzodiazepines have an action similar to that of barbiturates but with more specific effects. For this reason, they are currently much safer drugs that generate fewer side effects and are used more frequently in medicine.

Regarding their hypnotic role, benzodiazepines may be useful for the short-term treatment of insomnia. Its administration is recommended only for a period of two to four weeks due to the risk that these drugs present of generating dependence.

Benzodiazepines are preferably taken intermittently and with the lowest possible dose to combat insomnia. These drugs have been shown to improve sleep-related problems by shortening the time it takes to fall asleep and prolonging the time you sleep.

Regarding anesthesia, the most used benzodiazepine is Midazolam due to its short half-life and its pharmacokinetic profile.

Benzodiazepine analogs

Benzodiazepine analogs are drugs that interact with the BZD / GABA / CL receptor. Its administration causes the entry of chlorine ions from the gamma-aminobutyric acid (GABA) complex, thus generating depressant effects on the central nervous system.

The most important benzodiazepine analogs are zolpidem, zopiclone, and zaleplon. Their function is similar to that of benzodiazepines and they have a high selectivity for benzodiazepine receptors in the brain.

Its main effects are characterized by generating a high conservation of sleep architecture and low muscle relaxant effects. Likewise, these substances have a high dependency potential if used long-term.

For the treatment of insomnia, there is currently some controversy as to whether benzodiazepine analogs are more or less effective than benzodiazepine drugs.

It is generally held that the efficacy of both drugs is similar. Benzodiazepines have the advantage of being more potent in short-term treatments, but benzodiazepine analogs can reduce side effects by almost half.

Melatonin

melatonin molecule

The melatonin is a hormone that is synthesized from the essential amino acid tryptophan. It is generated mainly in the pineal gland and participates in various cellular, neuroendocrine, and neurophysiological processes.

The main action of this hormone is to regulate the state of sleep and wakefulness. It is partly regulated by outdoor lighting and has low activity levels during the day and high at night.

The increased activity of this hormone indicates to the body the need to sleep and, therefore, it is the substance in charge of generating the sensations of sleep.

In its therapeutic use, melatonin has been approved as a drug for the short-term treatment of primary insomnia in people over 55 years of age. However, for many other types of sleep disorders, melatonin is not effective.

Antihistamine

Antihistamine drugs are substances that mainly serve to reduce or eliminate the effects of allergies. They act at the brain level by blocking the action of histamine through the inhibition of its receptors.

However, despite the fact that the main use of these drugs is the treatment of allergies, sedation is a side effect that is observed in almost all cases.

For this reason, these drugs are used today also for sedative purposes and some antihistamines such as diphenhydramine or doxylamine are used to treat insomnia.

Antidepressants and antipsychotics

Finally, antidepressants and antipsychotics are pharmacological groups that do not present drowsiness as the main therapeutic effect.

Antidepressants are medications that are used primarily to treat major depressive disorders and some eating disorders and anxiety disorders.

Antipsychotics are drugs that are commonly used to treat psychosis.

The therapeutic uses of both types of drugs are not exclusive. In this sense, certain antidepressants such as amitriptyline, doxepin, trozadone or mirtazapine, and certain antipsychotics such as clozapine, chlorpromazine, olanzapine, quetiapine or risperiadon, are used to treat insomnia.

References

  1. Brunton, Laurence L .; Lazo, John S .; Lasso Parker, Keith L. (2006). “17: Hypnotics and Sedatives”. Goodman & Gilman’s The Pharmacological Basis of Therapeutics  (11th ed.). The McGraw-Hill Companies, Inc. ISBN 0-07-146804-8. Retrieved 2014-02-06.
  2. Maiuro, Roland (13 December 2009). Handbook of Integrative Clinical Psychology, Psychiatry, and Behavioral Medicine: Perspectives, Practices, and Research . Springer Publishing Company. pp. 128–30. ISBN 0-8261-1094-0.
  3. Joint Formulary Committee (2013). British National Formulary (BNF)  (65 ed.). London, UK: Pharmaceutical Press. ISBN 978-0-85711-084-8.
  4. Nemeroff, CB (Ed) Essentials of clinical psychopharmacology American Psychiatric Press, Inc, 2001.
  5. Schatzberg AF, Nemeroff CB. The American Psychiatric Publishing Textbook of Psychopharmacology. American Psychiatric Publishing, Incorporated, 2003.
  6. Stahl, SM Essential psychopharmacology Barcelona: Ariel. 2002.

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