Pharmacology of sedative hypnotics, school of clinical pharmacy.

1. Sedative Hypnotics

2. Anxiety
• Anxiety is unpleasant state of tension,
apprehension, uneasiness
• Normal fear to response threating stimuli
Includes several components
 Defensive behaviors
 Autonomic reflexes
 Arousal and alertness
 Corticosteroid secretion and negative
emotions

3. • The anxiety disorder could be
 Generalized anxiety disorder / with out clear reason/
 Panic disorder / fear occurs in association with
somatic symptoms (tachycardia, sweating palpitation,
etc )
 Obsessive-Compulsive disorder (OCD)
Eg. Fear for exposure to germs (obsession) and repetitive
action such as hand washing many times
(compulsions)
 Phobia /strong fear for specific things/
 Post–traumatic stress disorder /recalling past
stressful experiences/
Anxiety

4. • Treatment should involve psychological rather
than or in addition to drug treatment
• Drugs
 Sedative / hypnotics
 Some times
antipsychotic and antidepressant drugs
Anxiety

5. A. Effective sedative
– reduces anxiety with out inducing sleep
– some decrease motor activity
– CNS depression should be minimal
– quicker onset, shorter duration, steeper dose
response curve
Sedative Hypnotics

6. B. Effective Hypnotic
– more CNS depression , induce & maintain
sleep
– the sleep should resemble natural one
– Slow acting drugs with flatter dose response
curve
Sedative Hypnotics

7. • Hypnotics
at lower dose may act as sedative and
at higher dose can produce general
anesthesia but BZDs do not
Sedative Hypnotics
Sedation hypnosis general anesthesia
(increased grades of CNS depression)

8. Sedative Hypnotics
A= Barbiturates
B= BZD

9. Clinical Uses of Sedative-Hypnotics
• To relief anxiety
• For insomnia
• For sedation and amnesia before & during
medical and surgical procedures
• Treatment of epilepsy and seizure states
• As a component of balanced anesthesia

10. Classification of sedative-hypnotics
1. Barbiturates
2. Benzodiazepines
3. Older sedative/hypnotics
4. New sedative/hypnotics
5. Other drugs

11. 1.Barbiturates
Long acting: Phenobarbitone
Short acting: butobarbitone and pentobarbitone
Ultrashort: Thiopentone, methohexitone
All have CNS depressant activity
• Produce dose dependent effects
Sedation hypnosis general anesthesia comma

12. MoA
• Facilitate the actions of GABA
• At high concentrations, the barbiturates may
also be GABA-mimetic and inhibit excitatory
neurotransmission
benzodiazepines ↑ frequency and barbiturates
↑ duration of GABA mediated Cl- channel oppening
Barbiturates

13. 2.Benzodiazepines(BZDs)
 Hypnotics
Diazepam,Flurazepam,Nitrazepam,
Alprazolam,Temazepam,Triazolam
 Antianxiety
Diazepam,Chlordiazepoxide, Oxazepm, Lorazepam,
Alprazolam
 Anticonvulsant
Diazepam,Lorazepam,Clonazepam,Clobzam

14. MoA BZDs
 Act selectively on GABAA receptor
 Bind to regulatory site of the receptor (allosteric
binding site)
 Enhance the response to GABA and facilitate
the opening of GABA activated chloride channel

15. Pharmacological use
• Reduction of anxiety and aggression
• Sedation and induction of sleep
Decrease time to get sleep & increase total
duration of sleep
• Reduction of muscle tone and coordination
Increased muscle tone (common future of anxiety) may cause aches and pain

16. • Anticonvulsant effect
BZD are selective anticonvulsant against
GABAA mediated convulsion
• Anterograde amnesia
BZD erase memory of event while under their
influence…for minor surgical
Pharmacological use

17. Why BZDs are preferable to barbiturates ?
1. BZDs have high therapeutic index
2. Hypnotic doses do not affect respiration or CVS
3. Cause less distortion on sleep architecture
4. Do not affect disposition of other drugs
5. Have relatively low abuse liability
6. Presence of BZD antagonist (flumazenil) as
antidote

18. BZD antagonist / flumazenil
 Use
in case of BZD over dosage
(if only respiration severely depressed)
 also blocks effect of zolpidem (hypnotic acts
similarly to BZDs) but more dose is required
(5mg)
 to reverse BZD anaesthesia and allows early
discharge of patients and easy for post anesthetic
management

19.  Flumazenil has fast on set (secs) and short
duration of action (1-2 hrs)
 BZDs have longer duration of action
 Therefore, repeated administration of flumazenil
is needed
BZD antagonist / flumazenil

20. Side effects of BZDs
• Drowsiness, confusion, amnesia and impaired
coordination
• BZDs enhance depressant effect of other drugs
( eg alcohol) synergistically
• Long lasting hangover effects
• Withdrawal syndromes
• Development of dependence
☼ Sedative / hypnotics should not be used for
longer duration

21. Many BZDs have active metabolites

22. • Duration of action of BDZs varies as a function of the
metabolites they produce
Not produce metabolite (eg lorazepam)
 intermediate t½ (10-20hrs)- can be used for elderly
Longer acting BZDs (eg. Flurazepam,and Diazepam)
produce active metabolites with t½ 20-120hrs- avoid
in elderly patients

23. 3.Older sedative hypnotics
Alcohol,Chloral hydrates, Mebrobamate,
Glutethimide and Methyprylon
4. Newer sedative hypnotics
 non BZD sedatives: agonist for a subtype of
BZD receptor
Zopicolone Zolpidem & Zalepon
 Buspirone ( potent agonist for 5-HTA receptor)

24. -Also binds to brain dopamine receptor (D2 )
-Less effective in panic disorders /acute anxiety
states b/c of slow on set of action (effects take
days or weeks to develop)
-Relief anxiety without causing marked sedative,
hypnotic, or euphoric effects
- Minimal abuse liability & no anticonvulsant or
muscle relaxant properties (unlike BZDs)
-No rebound anxiety/withdrawal signs on abrupt
discontinuance
Buspirone

25. Side effects
• dizziness, nausea, headache, but not sedation
or loss of coordination
• less troublesome than with benzodiazepines
Buspirone

26. 5. Other drugs that induce sedation
 Antihistaminics (promethazine diphenhydramaine)
 Neuroleptics / antidepressant (chlorpromazine,amitryline)
 Opoids (morphine, pethidine)
They have significant sedation effect but not reliable for
treatment of insominia
 β-adrenoceptor antagonists (e.g. propranolol) to treat
some forms of anxiety (for physical symptoms such as
sweating, tremor and tachycardia)
 block of peripheral sympathetic responses
 ‘ ….actors and musicians to reduce the symptoms of stage fright’
 Propranolol produces insominia as a side effect