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Sedatives & Hypnotics, Treatment of Insomnia, Other Drugs Causing…
Sedatives & Hypnotics
Barbiturates
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- Long acting – Phenobarbitone
- Short acting – Pentobarbitone, Butobarbitone
- Ultra-Short acting – Thiopentone, Methohexitone
- Pharmacological Actions - dose dependent CNS depression
- sedation
- amnesia
- anticonvulsant
- hyperalgesia
- PK - Induce CYP enzymes
- Termination of action – redistribution (thiopentone)
- Uses - Phenobarbitone – epilepsy
- Thiopentone – IV - induction of anesthesia
- Enzyme inducing property – phenobarbitone – congenital nonhemolytic jaundice
- ADRs - lethal in overdose
- sedation & hangover
- automatism
- tolerance, Psychological & physical dependence
- Absolutely C/I – ac. intermittent porphyria
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Benzodiazepines
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- Pharmacological Actions - Anxiolysis
- sedation
- anterograde amnesia
- anti-convulsant
- centrally acting skeletal muscle relaxant
- respiratory & CVS depression
Tolerance & dependence
- Partial cross tolerance with barbiturates & alcohol
- Tolerance to hypnotic & anticonvulsant actions alone
- Physical dependence – more for drugs with short t½
- Withdrawal symptoms – restlessness, anxiety, weakness, orthostatic hypotension, hyperactive reflexes, seizures.
- Uses - treatment of insomnia - short acting drugs preferred- diazepam, lorazepam, traizolam, alprazolam - not for > 7-10 days
- preanesthetic medication - anxiolysis & anterograde amnesia
- acute control of seizures & status epilepticus- Diazepam, Lorazepam
- anti epileptic drug - Cloazepam, Clobazam
- centrally acting skeletal muscle relaxant - Diazepam
- alcohol withdrawal - maintenance therapy - Chlordiazepoxide, Diazepam
- balanced anesthesia
- acute control of anxiety - Situational anxiety, panic attacks, phobias, PTSD - Alprazolam, Diazepam, Chlordiazepoxide
- Hypnotic - Diazepam, Lorazepam, Flurazepam, Nitrazepam, Temazepam, Triazolam
- Anti-anxiety - Chlordiazepoxide, Oxazepam, Alprazolam
- Anti-convulsant - Clonazepam, Clobazam
- ADRs - safe in overdose - lethal dose 1000 times therapeutic dose
- Drowsiness, impaired judgment, diminished motor skills
- Anterograde amnesia - impairs ability to learn new information, date rape drug
- ADRs worse in elderly, hepatic impairment, CVS disease
- C/I in COPD & obstructive sleep apnoea
Antidote - Flumazenil
- Disadvantages - Antagonism of respiratory depression not complete, Very short t½
- Antagonizes zolpidem, zaleplon & eszopiclone also
But DOES NOT antagonize barbiturates
Z compounds
Zolpidem, Zaleplon, Eszopiclone
- Quick onset (15-20 minutes), short duration (<6 hrs)
- Advantages – can be given late at night on SOS basis, No daytime hangover
- Preferred for sleep onset insomnia
Melatonin agonists
Ramelteon, Tasimelteon
- no addiction liability
- less effective than BZDs
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Orexin antagonist
Suvorexant, Almorexant
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Poisoning
Benzodiazepines
- aspiration of gastric contents
- monitor for respiratory & CVS depression
- enquire about polypharmacy - added alcohol, antidepressants - lethal
- Treatment - supportive + Flumazenil if required
Barbiturates
- Symptoms - Flabby, comatose, shallow breathing, fall in BP, renal shutdown, bullous eruptions
- Treatment - gastric lavage, activated charcoal
- Forced alkaline diuresis - NaHCO3, mannitol
- Hemodialysis/ hemoperfusion