This document summarizes various central nervous system agents including stimulants, depressants, and anesthetics. CNS stimulants increase mental and physical activity and include substances like caffeine and amphetamines. CNS depressants like barbiturates and benzodiazepines are classified as sedative-hypnotics and can induce sleep. General anesthetics cause unconsciousness during surgery by inhibiting nerve impulses while local anesthetics temporarily disrupt sensory nerve transmission in a specific body area. Nursing responsibilities involve monitoring for side effects and ensuring patient safety.

1. Central
Nervous
System
Agents
Ma. Tosca Cybil A. Torres, RN,
MAN

2. CNS
Stimulants

3. CNS stimulants are drugs
which increase the muscular
(motor) and the mental
(sensory) activities
 Their effects vary from the
increase in the alertness and
wakefulness (as with
caffeine) TO the production
of convulsion ( as with
strychnine) or death due to
over stimulation

4. Behavioral Manifestations of CNS
Stimulation
• mild elevation in alertness, decrease in
drowsiness and lessening of fatigue
(Analeptic Effect)
• increased nervousness and anxiety -
convulsions.

5. Molecular Basis of CNS
Stimulation
Imbalance between inhibitory and excitatory
processes as in the brain. This
hyperexcitability of neurons results from:
• potentiation or enhancement of excitatory
neurotransmission(e.g. amphetamine)
• depression or antagonism of inhibitory
transmission (e.g. Strychnine)
• presynaptic control of neurotransmitter
release (e.g. picrotoxin)

6. Classification of CNS
Stimulants
• Analeptic Stimulants
– Respiratory Stimulants
– Convulsants
• Psychomotor Stimulant
– Sympathomimetics or
Adrenergic CNS Stimulants
• Methylxanthines

7. Analeptic Stimulants
• diverse chemical class of agents
• majority can be absorbed orally
• have a short duration of action -
primary expression of
pharmacological effect is
convulsions (tonic-clonic)
uncoordinated
• pharmacological effect is
terminated through hepatic
metabolism
• Possible Common Mechanism of
Action -ability to alter movement of
chloride ions across neuronal
membranes

8. Respiratory CNS
Stimulants
• Doxapram - used to counteract postanesthetic
respiratory depression and for acute
hypercapnia in chronic pulmonary disease.
– Used with caution with neonatal apnea
– Administered IV
– Onset of action: within 20-40 secs
– SE: (overdose)
• Hypertension
• Tachycardia
• Trembling
• convulsions

9. Headaches: Migraine and
Cluster Migraine headaches-
characterized by a unilateral
throbbing head
pain, accompanied by N/V
and photophobia
Cluster headaches-
characterized by severe
unilateral nonthrobbing pain
usually located around the
eye. Usually not associated
with N/V

10. Preventive Treatment for
migraine
1. Beta adrenergic blockers
2. Anticonvulsants- Valproic
acid (Depakote)
3. Tricyclic antidepressants-
amitriptyline (Elavil)

11. Treatment or Cessation of
Attacks
• Ergotamine tartrate
– Nonspecific serotonin agonist and
vasoconstrictor
– Should be taken early during a
migraine attack
– May cause N and V

12. • Triptans
– The most common recently developed group of
drugs for tx of migraines and cluster headches
– Prototype: sumatriptan(Imitrex)
• Selective serotonin receptor agonist with a short
duration of action
• Considered more effective than ergotamine
• MOA: causes vasoconstriction of cranial carotid
arteries to relieve migraine attacks
• SE: dizziness, fainting, tingling, numbness, warm
sensation, drowsiness
• AR: hypotension, heart block, angina, MI, cardiac
arrest

13. • Amphetamines
– Stimulates the release of
norepinephrine and dopamine from the
brain and SNS.
– Can cause euphoria and alertness

14. CHARACTERISTICS
• all compounds are absorbed well orally
• large portion of untransformed amphetamine is
excreted unchanged in the urine.
Consequently, acidifying the urine with ammonium
chloride hastens its clearance, and thus reduces
its reabsorption in the renal tubules.
• Overdose: hyperreflexia, tremors, convulsions and
irritability
• CV problems: increased heart rate, increased
BP, palpitations and cardiac dysrythmias

15. • Therapeutic Uses:
– Narcolepsy
• Characterized by falling asleep during waking hours,
such as driving a car or talking with someone. Sleep
paralysis, a condition that is normal during sleep
usually accompanies narcolepsy which affects the
voluntary muscles making the person unable to move
and collapse

16. • Therapeutic uses:
– Attention Deficit/Hyperactivity Disorder
• May be caused by disregulation of
serotonin, norepinephrine, and dopamine.
• Occurs primarily in children, usually before
the age 7, but may continue through
teenage years.
• Characteristics involved include
inattentiveness, poor coordination, inability
to concentrate, restlessness, hyperactivity
(excessive and purposeless activity),
inability to complete tasks, and impulsivity.

17. Pharmacological Actions
• The primary effects of an oral dose are
wakefulness, alertness, decrease fatigue; mood
elevation, increased ability to concentrate; an
increase in motor and speech activity.
Amphetamines also diminish the awareness of
fatigue; person may push exertion to the point of
severe damage or even death.

18. • Stimulate the respiratory center,
especially when respiration is
depressed by centrally acting drugs,
(barbiturates and alcohol).
• Amphetamine can reverse the marked
sedation and behavioral retardation
resulting from reserpine-like drug.
• Depresses appetite by their action on
the lateral hypothalamus rather than
an effect on metabolic rate.

19. Mechanisms of Action
• Releases monoamines at synapses
in the brain and spinal cord.
• Inhibits neuronal uptake of
monoamine
• Antagonist at certain
adrenoreceptors
• May inhibit monoamine oxidase.

20. Adverse Effects
• CNS:
Euphoria, dizziness, tremor, irritability
, insomnia, Convulsion (at higher
doses), hyperthermia and coma
• C.V. Cardiac stimulation leads to
headache, palpitations, cardiac
arrhythmias, anginal pain
• Other: Weight loss, Psychotic
Reaction which are often
misdiagnosed as schizophrenia.
• Addiction - including psychic
dependence, tolerance and physical
dependence.

21. • Drug Interactions:
– Tricyclic antidepressant
– Antihypertensive Agents
– Foods high in tyramine content

22. • Amphetamine-like Drugs or ADHD and
Narcolepsy
– Given to increase a child’s attention span and
cognitive performance and decrease
impulsiveness, hyperactivity and restlessness
Prototype:
– Methylphenidate(Ritalin)
– Dexmethypendate (Focalin)
– Pemoline (Cylert)
– Modafinil(Provigil)- drug for nacolepsy which
increases the amount of time that clients feel
awake

23. Side Effects:
anorexia, vomiting,
diarrhea, insomnia,
dizziness, nervousness,
restlessness, irritability
Adverse reaction:
tachycardia, growth
suppression,
palpitations, transient
loss of weight in
children, and increased
hyperactivity

24. Nursing
considerations:
• Monitor V/S. report
irregularities
• Record height, weight, and
growth of children
• Observe for withdrawal
symptoms (N and V,
weakness, and headache)
• Monitor for side effects

25. Nursing considerations
• Instruct client to take drug with meals
• Avoid alcohol consumption
• Encourage use of sugarless gum to relieve
dryness of mouth
• Monitor weight twice a week
• Advise not to drive and use hazardous
equipments when experiencing palpitation,
nervousness, tremors

26. Nursing
considerations
• Instruct client not to discontinue the drug
abruptly
• Advise not to eat foods with caffeine
• Instruct to eat nutritious food because
drug may cause anorexic effect
• Teach to report drug side effects such as
tachycardia and palpitations

27. CNS
Depressa
nts

28. CNS Depressants: Classification
They are classified
according to their
pharmacological action
into:
1- Sedative – hypnotics
2- Anaesthetics

29. e
-
Hypnoti
cs

30. • Sedation
–Mildest form of CNS depression
–Diminishes physical and mental
responses at lower dosages of
certain CNS depressants but
does not affect consciousness

31. ep
Definition:
Physiological depression of consciousness
Sleep cycle:
Starts with latency period → NREM → REM →
cycles of NREM alternate with REM (about 4
cycles)
NREM REM
- Non rapid eye movement - Rapid eye movement
- Lasts for 90 min. - Lasts for 20 min.
- Thinking - Dreaming

32. I- Sedative - Hypnotics
Definitions
Sedatives:
Drugs which calm the patient & cause sedation and in large
doses cause sleep
Hypnotics:
Drugs which induce sleep that resembles the natural sleep
Ex. Barbiturates

33. Sedative Hypnotics
Mechanism of Action
• The GABA receptor is a pentameric structure that
forms a Cl- channel.
• The receptor complex includes distinct binding
sites for benzodiazepines, barbiturates and
GABA-like substances.
• GABA transmission exerts an inhibitory effect on
norepinephrine (NE), dopamine (DA), serotonin
(5-HT), and acetylcholine (ACh) pathways.

34. Sedative – hypnotics:
Classification
Sedative-hypnotics
Barbiturates Non-barbiturates
1-Long acting (12-24 hr)
Ex. Phenobarbital
Benzodiazepines Non- benzodiazepine
2-Intermediate acting (8-12hr)
Ex. Amobarbital
3-Short acting (4-8 hr)
Ex. Pentobarbital
4-Ultrashort acting (0.5-1hr)
Ex. Thiopental

35. Barbiturates
MOA:
They have GABA like action → ↑ opening time
of chloride channels → ↑conductance of
chloride ions → hyperpolarization
Classification:
1-Long-acting
2-Intermediate-acting
3-Short acting
4-Ultrashort acting

36. • Barbiturates
– Prototype:
• Short acting: pentobarbital
sodium(Nembutal sodium) – for
sedation, sleep, or preanesthetic
• Intermediate acting: amobarbital
sodium(Amytal sodium)- sedative
and short term hypnotic, to control
acute convulsive episodes, and for
insomia
• Long acting: phenobarbital and
mephobarbital-used to control
seizures
• Ultrashort-acting: thiopental
sodium- used as a general
anesthetic

37. Nursing Responsibilities:
• Recognize that continued use of
barbiturate might result in drug abuse
• Monitor V/S, esp. RR and BP
• Raise side rails
• Check for rashes
• Administer phenobarbital IV at a rate of
less than 50mg/min. do not mix with other
medications. If to be given IM, use large
muscle such as the gluteus max

38. Client teaching
• Teach client the use on non pharmacological
ways to induce sleep----enjoying a warm bath,
listening to music, drinking warm fluids, and
avoiding drinks with caffeine 6hrs before
bedtime
• Instruct to avoid alcohol and antidepressants,
antipsychotics, and narcotic drugs----
respiratory depression
• Avoid taking herbs
• Advise not to drive or operate a machinery
• Instruct to take 30mins before bedtime

39. Benzodiazepines
• Can suppress stage 4 of NREM sleep, which may result
in vivid dreams or nightmares and can delay REM sleep.
• Effective for sleep disorders for several weeks longer
than other sedative-hypnotics but should not be longer
than 3-4 weeks as a hypnotic to prevent REM rebound
Prototype:
Alprazolam(Xanax)- for alleviating anxiety that may cause
sleeplessness
Estazolam(ProSom)- for treatment of insomia. Decreases
the frequency of nocturnal wakefulness
Lorazepam(Ativan)-used as a pre operative sedative and
to reduce anxiety

40. Nonbenzodiazepines
 used for short term treatment of insomia
 Well absorbed PO, onset 7-27 minutes
MOA: depression of the CNS, neurotransmitter
inhibition
Prototype:
zolpidem(Ambien)
S/E:
drowsiness, lethargy, hangover, irritability, dizzine
ss, anxiety
Adverse reactions:
tolerance, physiologic dependence

41. • Nursing responsibilities:
– Monitor V/S. check for respiratory depression
– Raise side rails
– Observe for side effects (hangover, light-
headedness, dizziness, or confusion)
– Teach non pharmacological ways to induce
sleep
– Suggest to urinate before taking sedative
hypnotics to prevent sleep disruption
– Instruct to avoid alcohol and antidepressants,
antipsychotics, and narcotic drugs----
respiratory depression

42. Anaesthetics
Definition:
Drugs which cause unconsciousness &
generalized loss of pain sensation, thus
allow surgical procedures to be carried out
Classified as general and local
Ex. thiopental (IV) , halothane (inhalation)
MOA:
Interfering with propagation of nerve impulses
by interfering with electrolytes movement
through the cell membrane

43. General anesthesia
• Is a reversible loss of consciousness induced by
inhibiting neuronal impulses in several areas of the
central nervous system
• General anesthetics are agents that block the pain
stimulus at the cortex
Produces a state of the ff:
 Analgesia
 Amnesia
 Unconsciousness characterized by loss of reflexes
and muscle tone

44. Local anesthesia
• Injection of a solution containing anesthetic
into the tissues at the planned incision site.
• Briefly disrupts sensory nerve impulse
transmission form a specific body area or
region.
Types of Local anesthesia
1. Topical anesthesia – topical agents are
applied directly to the area of skin or mucous
membrane surfaced to be anesthetized
2. Local infiltration – is the injection of an
anesthetic agent directly into the tissue
around an incision, wound, or lesion.

45. Purposes of Anesthesia
• To produce muscle relaxation
• To produce analgesia
• To produce artificial sleep or to cause loss
of consciousness
• To block transmission of nerve impulses
• To suppress reflexes

46. • Nursing responsibilities:
– Monitor client’s postoperative state of
sensorium.
– Check preoperative and postoperative urine
output
– Record V/S after induction of anesthesia----
may result to hypotension and respiratory
distress
– Administer an analgesic or a narcotic-
analgesic with caution until client fully
recovers from the anesthetic