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Sedative-Hypnotic Drugs Cheat Sheet by

Introd­uction:

Sedation:
Reduction of anxiety
Hypnosis:
Induction of sleep
Sedative:
Synony­m=a­nxi­olytic, Reduces anxiety and has a calming effect
Hypnotic:
Produces drowzi­ness, Induces and maintains sleep

Dose-R­esp­onsive Curve for S-H Agents:

Clas­sif­ica­tion:

Benzod­iaz­epines:
>Short-­acting: Triazolam
>Interm­edi­ate­-ac­ting: alpraz­ola­m,l­ora­zep­am,­oxa­zep­am,­tem­azepam
>Long acting: pentob­arb­itone, phenob­arb­ito­ne,­sec­oba­rbitone

Mechanism of Action:

MOA: Benzod­iaz­epines

Receptors for BZ present = Thalamus, limbic struct­ures, cerebral cortex

BZ receptors =
> Part of GABAA receptor chloride ion channel macrom­ole­cular complex
> Major GABAA receptor isoform
>Five subunits: 2α1, 2β2, and 1Υ2
Benzod­iapines bind between α1 and Υ2 subunits

Increase the FREQUENCY of GABA-m­ediated chloride ion opening
 

MOA:Ba­rbi­tur­ates:

> Depress neural activity in midbrain reticular formation
>Bind to α and β subunits of the GABAA receptor
>Pr­olong the action of GABA and glycine
Increase the DURATION of GABA-m­ediated chloride ion channel opening
>may also block glutamate receptors and sodium channels at higher doses

MOA: Other Agents:

Zolpidem, Zaleplon, Eszopi­clone = not Benzao­dia­zepines

>Bind to benzod­iaz­epine receptor (BZ1 or ω1)

More selective to GABAA isoforms that contain α1 subunits
-Fewer adverse effects than benzod­iaz­epines
-Minimal effects on sleep patterns, less likely to cause dependence

>In­crease the FREQUENCY of GABA-m­ediated chloride ion opening

Effects:

Sedation
Antico­nvu­lsant actions
Tolerance
Hypnosis
Muscle relaxation
Psycho­logical dependence - Compulsive use
Anaest­hesia
Medullary depression
Physio­logical dependence - withdrawl symptoms if drug is discon­tinued

CNS Effects:

Clinical Uses:
> Anxiety states
> Sleep disorders
> Anesthesia
> Epilepsy
> Alcohol withdrawal state
 

Adverse Effects:

Psycho­motor Dysfun­ction:
Cognitive impair­ment, decreased psycho­motor skills, daytime sedation
Additive CNS Depres­sion:
Alcohol, antihi­sta­mines, antips­ychotic agents, opioids, tricyclic antide­pre­ssants
Overdose:
CVS and respir­atory depres­sion, Antidote: Flumazenil

Pharma­cok­ine­tics:

> Most are lipid soluble, absorbed well from GIT
> May cross the placental barrier during pregnancy - may depressed neonatal vital functions
> Detectable in breast milk - may exert depressant effects in nursing infant
> Metabolism by hepatic enzymes - renal function = no signif­icant effect on elimin­ation

Pharma­cok­ine­tics:

Benzod­iaz­epines:
-Converted to active metabo­lites with long half-lives
--Pote­ntial for accumu­lation
-Lorazepam and oxazepam do not form active metabo­lites
-Metab­olized mainly by CYP3A4

Barbit­urates:
-Exten­sively metabo­lized
--Except pentob­arbital
---Exc­reted partly unchanged in urine
Zolpidem: No active metabo­lites

Drug Intera­ctions:
-Induc­ers­/in­hib­itors of CYP3A4 interact with sedative hypnotics
--E.g. rifampicin (inducer), ketoco­nazole, cimetidine (inhib­itors)
-Barbi­turates induce metabolic enzymes

Atypical Sedati­ve-­Hyp­notics:

Buspirone:
>Pa­rtial agonist at 5-HT1A receptors
>Se­lective anxiolytic effects:
-Minimal CNS depressant effects = No antico­nvu­lsant or muscle relaxation effect
>Mi­nimal tolerance, depend­ence, and abuse potential
Ramelteon, Tasime­lteon:
> Melatonin receptor agonists
>Mi­nimal rebound or withdrawal symptoms
>Mi­nimal abuse potential
 

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