Introduction:
Sedative hypnotics is a class of drugs acting on central nervous that is able to cause sedation and hypnosis (sleep). Use of sedative hypnosis may vary from prescription only to over the counter use.sedative drugs are one of the most commonly used drugs nowadays. Moreover anesthetics like local and general anesthetics are also chemically linked to sedative hypnotics.classification of sedative hypnotics is based on their chemical nature and their pharmacological mechanism.Following are the various classes of sedative hypnotics.Their Mechanism of action, uses, side effects etc will be described in this post.
Classification Of Sedative Hypnotics:
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| sedative hypnotics |
On chemical and pharmacological basis the classification of sedative hypnotics reveals the following classes.
- Benzodiazepines
- Benzodiazepines Antagonists
- Barbiturates
- Melatonin receptor antagonists
- 5-HT3 receptor Antagonists
- Newer hypnotics
moreover each class is further classified into long acting, intermediate & short acting drugs.
Benzodiazepines:
Following are the drugs included in benzodiazepines class of sedative hypnotics.
- Clorazepate
- Clonazepam
- Diazepam
- Estazolam
- Flurazepam
- Lorazepam
- Midazolam
- Alprazolam
- Chlordiazepoxide
- Oxazepam
- Quazepam
- Temazepam
- Triazolam
Benzodiazepines antagonist:
currently this class has only one member i.e
flumazenil.
as the name indicated they are used in benzodiazepines toxicity.However they have no effect on other sedative hypnotics drugs.they may give the side effects of confusion, anxiety, benzodiazepines withdrawal symptoms etc.
Barbiturates:
barbiturates comprise the following members;
- Pentobarbital
- Phenobarbital
- Amobarbital
- Secobarbital
- Butabarbital
- Mephobarbital
Melatonin Receptor Agonist:
Ramelteon is the only drug included in Melatonin receptor agonist.it is administered as oral.
5-Ht-receptor Agonist:
Buspirone is the only member so far in 5-HT-receptor agonists.it is available in orally administered forms.
Newer hypnotics:
Eszopiclone, Zaleplon, Zolpidem are the recently developed drugs in sedative hynotics.they work like benzodiazepines but with minimal side effects and interactions than benzodiazepines.
Mechanism Of Action Of sedative hypnotics:
The mechanism of different classes of sedative hypnotics are much like one another except with few anomalies. Let us discuss them one by one.
Benzodiazepines mechanism:
The target site of benzodiazepines are GABA receptors sub-units. the drug binds to specific sub-units of gaba at cns synapses enhancing gaba mediated chloride ion channel opening. Thus bring about frequent hyperpolarization.
Benzodiazepines antagonists:
the parmacological response of this is against the former one, which make it the only choice of drug class used in case of benzodiazepines toxicity or over dose. their pharmacological mechanism is a simple competitive inhibition.
Barbiturates And Newer hypnotics:
Both of these two classes have a mechanism similar to benzodiazepines except for the minor difference in case of barbiturates, i.e barbiturates increase the duration of chloride channel hyperpolarization while benzodiazepines increase the frequency of hyperpolarizations.
5-HT-receptor Agonists:
Their exact mechanism is uncertain however these drugs have partial agonistic effect on 5-HT-receptors with affinity for D2 receptors.
Melatonin receptor agonists:
they possess agonistic effect on MT1 and MT2 receptors in suprachiasmatic nuclei in the CNS.
They show minimal adverse effects of rebound insomnias that the rest.
