3. *
Basic Description of CNS_PNS.
Understanding of the
Classification of CNS
STIMULANT
The Cerebral- Stimulant agents
The Medullary or M.O - Stimulant agents
The Spinal Stimulant agents
4. *
*The nervous system can be classified into
*The Central Nervous System (CNS)
*Brain and spinal cord
*The Peripheral Nervous System (PNS (
*The nervous system outside of the brain and spinal cord
10. *
*Definition and introduction
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
11. *
General Signs & Symptoms of CNS Stimulation
•↑ Heart rate
•↑ Respiratory rate
•Instability
•Tremors
•Hair erection
•Convulsion
12. *
According to:
• Structural similarities
or
• Site of therapeutic action in the central nervous
system (CNS)
or
• Major therapeutic usages
13. *
*1- Block neurotransmitters reuptake (Most reuptake
inhibitors affect either NE or 5- HT(Serotonin) : Cocaine
*2- Promote neurotransmitters release : Amphetamine
*3- Block Metabolism - MAO inhibitors (monoamine
5tttttoxidase):ex. Phenelzine
*4. antagonize the effect of inhibitory neurotransmitter:
Picrotoxin & Strychnine
14. *
*They can be divided based on their site of action:
1.Cerebral stimulants or cortical stimulant (amphetamines)
2.Medullary stimulants (picrotoxin)
3.Spinal stimulants (strychnine)
15. 1)
*Cerebral, or psychic, stimulants act on the central nerv
ous system and provide a temporary
sense of alertness and well
being as well as relief from fatigue.
*They are further classified as
a. Psychomimetics
- Amphetamine and related drugs
- Cocaine
b. Methylxanthines
16. a.
*Psychomimetics includes following agents
i. Amphetamine
ii. Methylphenidate
iii. Methamphetamine
iv. Cocaine HCl
Mechanism of action of psychomimetics
They act primarily by releasing NA and DA in the brain. They block NA
reuptake, inhibits MAO and has direct effect on receptors.
17.
18. I. Amphetamine
*Amphetamines are chemically related to adrenaline.
They are sympathomimetic drugs which mimic the effect of
stimulation on the nervous system by increasing the levels of
dopamine.
uses
* Amphetamines were initially used to treat narcolepsy and in WW
II were used by soldiers to combat fatigue. to improve the
performance of soldiers, military pilots and others who need to
remain alert under extremely fatiguing conditions.
Adverse effect
*With prolonged use, they are neurotoxic, causing degeneration of
amine-containing nerve terminals and eventually cell death.
• Regular use can lead to both tolerance & dependence.
19. II. Methylphenidate
*Methylphenidate (MPH) is a prescription stimulant commonly used to treat
Attention-deficit hyperactivity disorder, or ADHD.
*It is also one of the primary drugs used to treat the daytime drowsiness
symptoms of narcolepsy and chronic fatigue syndrome.
*The drug is seeing early use to treat cancer-related fatigue
Indications
1- ADHD
2- Narcolepsy
3- Treatment-resistant depression
4- Appetite suppressant
5- Antidepressant augmentation
Contraindication
Use of tricyclic antidepressants: (e.g. desipramine), as
methylphenidate may dangerously increase their plasma
concentrations, leading to potential toxic reactions (mainly,
cardiovascular effects).
20. iii.Methamphetamine
*Methamphetamine , also known as methylamphetamine, N-
methylamphetamine or desoxyephedrine, is a psychostimulant and
sympathomimetic drug.
Clinical uses
*It is considered a second line of treatment, used when amphetamine
and methylphenidate cause the patient too many side effects. It is also
used illegally for weight loss and 11 to maintain alertness, focus,
motivation, and mental clarity for extended periods of time, and for
recreational purposes.
Side effects
*Methamphetamine has the potential to cause addiction.
*Methamphetamine is a potent neurotoxin, shown to cause
dopaminergic degeneration.
*Methamphetamine addicts may lose their teeth abnormally quickly, a
condition known as "meth mouth".
21. iv. Cocaine
*Cocaine increase, mental alertness & produce a feeling of wellbeing &
euphoria that is similar to that caused by amphetamine like
amphetamine cocaine can produce hallucinations, delusion & paranoia
cocaine increases motor activity & at high doses causes tremors,
convulsion & followed by respiratory & vesomotor depression.
Uses
*Cocaine has a local anesthetic action for the therapeutic use of cocaine,
cocaine is applied topically as a local anesthetic for eye, ear & nose &
throat surgery
Adverse effect
*cocaine stimulation of CNS is followed by a period of mental
depression.
*Physical dependence after only single use
22. b.
*Various beverages, particularly tea, coffee and cocoa, contain
methylxanthines, to which they owe their mild central stimulant
effects. (theophylline, caffeine, theobromine) are the drugs included
in metylxanthines
MOA
*methylxanthines (especially theophylline) inhibit
phosphodiesterase, which is responsible for the intracellular
metabolism of cAMP (Ch. 3). They thus increase intracellular
cAMP and produce effects that mimic those of mediators that
stimulate adenylyl cyclase. Methylxanthines also antagonise many
of the effects of adenosine, acting on both A1 and A2 receptors
23. *
Clinical use
*witH aspirin in some preparations for treating headaches and
other aches and pains,
*Theophylline (formulated as aminophylline) is used mainly as
a bronchodilator in treating severe asthmatic attacks
Side effects
*High doses of caffeine cause epileptiform type of convulsion
*Nervousness,insomnia, tremors
*withdrawa
24. 2)
*They are also called as analeptics Analeptics are general CNS
stimulants; they stimulate vitally important centers (respiratory
and vasomotor) of the brain. The primary medical use of these
drugs is as an anesthetic recovery tool or to treat
emergency respiratory depression.hense they are also called as
repiratory stimulant
*Medullary stimulant includes
a. Picrotoxin
b. Doxapram
c. Pentylenetetrazole or cardiazole
25. a.Picrotoxin
Picrotoxin is a toxin obtained from the seeds of the shrub Anamirta
cocculus. It is used as a central nervous system stimulant, antidote,
convulsant, and GABA (gamma aminobutyric acid) antagonist.
*MOA
Picrotoxin antagonizes the GABAA receptor channel directly, which is
a ligand-gated ion channel concerned chiefly with the passing of
chloride ions across the cell membrane. Therefore picrotoxin prevents
Cl- channel permeability and thus promtes an inhibitory influence on
the target neuron.
*Uses
it is most often used as a research tool, it has been used as a CNS
stimulant and an antidote in poisoning by CNS depressants, especially
barbiturates ,for relieving respiratory distress
26. b.Doxapram
Doxapram hydrochloride (marketed as Dopram, Stimulex or
Respiram) is a respiratory stimulant. Administered intravenously,
doxapram stimulates an increase in tidal volume, and respiratory rate.
MOA
Doxapram stimulates chemoreceptors in the carotid bodies of the
carotid arteries, which in turn, stimulates the respiratory centre in
the brain stem.
Uses
stimulate the respiratory rate in patients with respiratory failure. It
may be useful for treating respiratory depression in patients who have
taken excessive doses of drugs such as buprenorphin, also used for
recovery after anesthesia
27. c. Pentylenetetrazole or cardiazole
Pentylenetetrazol, also known as pentylenetetrazole,
metrazol, pentetrazol (INN), pentamethylenetetrazol,
Corazol, Cardiazol or PTZ, is a drug formerly used as a
circulatory and respiratory stimulant
MOA
It is specifically a GABA-a receptor antagonist it acts at the
picrotoxin (PTX) site of the gamma-aminobutyric acid type A
(GABA(A)) receptor
28. Side effects of medullary stimulant
In large doses they cause CLONIC CONVULSION
Characteristics of clonic convulsion:
1- Asymmetric
2- Coordinated
3- Intermittent
4- Spontaneous in origin
5- It starts as clonic then converted into tonic-clonic & finally to tonic
6- Removed by decapitation
29. Characteristic of chronic convulsions
1- Symmetric
2- Non-coordinated
3- Continuous
4- Reflex in origin
5- Characteristic arched back (Opisthatenous posture)
6- Removed by pithing
*Treatment of Strychnine Poisoning
(1) Remove/reduce external sensory stimuli
(2)Diazepam or Clonazepam I.V. or
(3) Nitrous oxide by inhalation to depress CNS and stop convulsions
which can be fatal
30. 3.
Spinal cord stimulant includes strychinne strychnine is a naturally
occurring alkaloid found in seeds from the plant Strychnos nox-
vumica
Site of action
*Spinal cord
Mecahnism of action
*Strychnine is an antagonist of glycine, Strychnine competitively and
reversibly the inhibitory neurotransmitter glycine at postsynaptic
neuronal sites in the spinal cord
*Side effects
In large doses strychnine causes TONIC CONVULSION and
causes strychine poisning
31. *
*Katzung Basic and clinical pharmacology
*Rang and Dales pharmacology 7th edition
*Good man and Gillman manual of
pharmacology
