Anxiolytic-Hypnotic-Sedative Drugs
Introduction
- Antianxiety or anxiolytic (anxiolytic-sedative, minor-tranquillizer) is drug used for treatment of anxiety and phobic states.
- Hypnotic is a drug that induces and/ or maintains sleep, similar to normal arousable sleep. Hypnosis meaning a trans-like state in which the subject becomes passive and highly suggestible.
- Sedative is a drug that subdues excitement and calms the subject without inducing sleep, though drowsiness may be produced. Sedation refers to decreased responsiveness to any level of stimulation; is associated with some decrease in motor activity and ideation.
- The sedatives and hypnotics are more or less general CNS depressants with somewhat differing time-action and dose-action relationships. Those with quicker onset, shorter duration and steeper dose-response curves are preferred as hypnotics while more slowly acting drugs with flatter dose-response curves are employed as sedatives. However, there is considerable overlap; a hypnotic at lower dose may act as sedative. Thus, sedation-hypnosis-general anaesthesia may be regarded as increasing grades of CNS depression.
Classification
Anxiolytic-Hypnotic-Sedative Drugs are classified as follows :
1. Benzodiazepines
- Benzodiazepines are widely used anxiolytic drugs.
- They have largely replaced barbiturates and meprobamate in the treatment of anxiety and insomnia, because benzodiazepines are generally considered to be safer and more effective
- Though benzodiazepines are commonly used, they are not necessarily the best choice for anxiety or insomnia. Certain antidepressants with anxiolytic action, such as the selective serotonin reuptake inhibitors, are preferred in many cases, and nonbenzodiazepine hypnotics and antihistamines may be preferable for insomnia.
- The targets for benzodiazepine actions are the γ-aminobutyric acid (GABAA) receptors. The GABAA receptors are composed of a combination of five α, β, and γ subunits that span the postsynaptic membrane.
- Benzodiazepines modulate GABA effects by binding to a specific, high-affinity site (distinct from the GABA-binding site) located at the interface of the α subunit and the γ subunit on the GABAA receptor. These binding sites are sometimes labeled “benzodiazepine (BZ) receptors.”
- E.g.
[wpsm_comparison_table id=”58″ class=””] - Benzodiazepines antagonist like- Flumazenil is used to reverse the effects of benzodiazepines.
2. Babiturates
- The barbiturates were formerly the mainstay of treatment to sedate patients or to induce and maintain sleep.
- Today, they have been largely replaced by the benzodiazepines, primarily because barbiturates induce tolerance and physical dependence and are associated with very severe withdrawal symptoms.
- All barbiturates are controlled substances.
- Certain barbiturates, such as the very short-acting thiopental, have been used to induce anesthesia but are infrequently used today due to the advent of newer agents with fewer adverse effects.
- E.g.
[wpsm_comparison_table id=”59″ class=””]
3. New / Non-Benzodiazepines
- E.g.
[wpsm_comparison_table id=”60″ class=””]
4. Azapirones
- E.g.
[wpsm_comparison_table id=”61″ class=””]
5. Sedative Anti-histaminic
- Some antihistamines with sedating properties, such as diphenhydramine, hydroxyzine, and doxylamine, are effective in treating mild types of situational insomnia.
- However, they have undesirable side effects (such as anticholinergic effects) that make them less useful than the benzodiazepines and the nonbenzodiazepines.
- Some sedative antihistamines are marketed in numerous over-the-counter products.
- E.g.
[wpsm_comparison_table id=”62″ class=””]
6. β- Blockers
- E.g.
[wpsm_comparison_table id=”63″ class=””]
Therapeutic uses
Anxiolytic-Hypnotic-Sedative Drugs have following clinical uses :
- Used as anxiolytic drug (antianxiety drug) effective for the treatment of the anxiety disorder symptoms secondary to panic disorder, generalized anxiety disorder (GAD), social anxiety disorder, performance anxiety, posttraumatic stress disorder, obsessive–compulsive disorder, and extreme anxiety associated with phobias, such as fear of flying.
- Useful in treating anxiety related to depression and schizophrenia.
- Used as hypnotic agent to treat Sleep disorders (insomnia).
- Used as anticonvulsant drug for epilepsy or seizures.
- Useful in the acute treatment of alcohol withdrawal and reduce the risk of withdrawal-related seizures.
- Used as centrally acting muscle relaxant in the treatment of skeletal muscle spasms, such as occur in muscle strain, and in treating spasticity from degenerative disorders, such as multiple sclerosis and cerebral palsy.
- Used for preanaesthetic medication, i.v. anaesthesia and conscious sedation.
