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Dr. UMER SUFYAN M
The CNS stimulants mostly produce a generalized
action which may, at high doses, result in
They 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) and sometimes lead to death in over
1. Convulsants: Strychnine,Picrotoxin,Bicuculline,
2. Analeptics: Doxapram
3. Psycho stimulants: Amphetamines,
Methylphenidate, Atomoxetine, Modafinil,
Armodafinil, Pemoline, Cocaine, Caffeine.
Many other drugs are capable of causing CNS
stimulation as side effect or at high doses.
1. Strychnine: It is an alkaloid from the seeds of
Strychnos nux-vomica, and a potent convulsant.
action Spinal cord.
Block the postsynaptic inhibitory
response to glycine by blocking glycine
receptors. Glycine is the main inhibitory
transmitter acting on motor neurons.
End point Tonic convulsion.
Opisthotonus Also seen in;
Obtained from ‘fish berries’ of East Indies
Anamirta cocculus. It is a potent convulsant—
convulsions are clonic, spontaneous and
asymmetrical. The convulsions are accompanied
by vomiting, respiratory and vasomotor
action Medulla oblongata.
1. It inhibits the presynaptic
2. Noncompetitive GABAA
blocker which is a chloride
hyperpolarization → excitation.End point Clonic convulsion.
This synthetic convulsant has picrotoxin like
It is a competitive GABA-A receptor (intrinsic Cl¯
channel receptor) antagonist.
It is only a research tool.
It is a powerful CNS stimulant
Low doses cause excitation, larger doses produce
Antagonism of PTZ induced convulsions is an
established method of testing anticonvulsant
drugs in laboratory animals
ANALEPTICS (Respiratory stimulants)
These are drugs which stimulate respiration and
can have resuscitative value in coma or fainting.
Mechanical support to respiration and other
measures to improve circulation are more
effective and safe.
Situations in which analeptics may be employed
(a) As an expedient measure in hypnotic drug
poisoning untill mechanical ventilation is
(b) Suffocation on drowning, acute respiratory
(c) Apnoea in premature infant.
(d) Failure to ventilate spontaneously after
It acts by promoting excitation of central
At low doses it is more selective for the
Respiration is stimulated through carotid and
aortic body chemoreceptors.
Continuous i.v. infusion of doxapram may abolish
episodes of apnoea in premature infant not
responding to theophylline.
Post-anaesthetic resp. depression
COPD i.e. hypoxemic,hypercapnic res.fail
Apnoea in premature infants
Dose- 2-5mg/min(max 4mg/kg) slow i.v infusion.
Resp.fail due to neurological & muscular
High doses: convulsions & arrhythmias
Drug enter N endings by active transport
Displace DA(also NE) from vesicles by altering pH
↑DA conc. In synaptic cleft
Also inhibits MOA-B, ↓DA metabolism & DA
Release to synaptic cleft
Amphetamine & Non- Amphetamine:
Narcolepsy: Characterised by-
Sleep attacks during day time
Night mares in awakening state
Methylphenedate is still used
Modafinil- devoid of abuse liability
Fenfluramine, dexfenfluramine used earlier to
Discouraged due to:-
Insomnia, Pul.HTN, Abuse potential.
Sibutramine new drug used now
Blocks neuronal uptake of mainly NE & 5HT
(also dopamine) at hypothalamic site that
regulates food intake.
Severe obesity with risk factors like DM.
↑in HR & BP
CI in CVS diseases, withdrawn from market
Induces heat stroke like condition-
rhabdomyolysis & renal failure
Methylenedioxy amphetamine (love drug)
75mg- psychotomimetic effects
150 mg-LSD like effects
300mg- amphetamine like
SE: tachycardia, HTN, arrhythmias
Only caffeine if used as CNS stimulant
Oral- rapid but irregular absorption
Distributed all over the body
Metabolism: in liver by demethylation & oxid.
Metabolites excreted in urine
Gastric irritation, Nause, Vomiting.
Nervousness, insomnia, agitation
Muscule twitch, rigidity
↑body temp, delirium, convulsions
Tachy, extra systoles at high doses
In Analgesic mixture for headache
Apnoea in premature infants
LYSERGIC ACID DIETHYLAMIDE
Derived from cereal fungus ergot
Hofmann synthesized & experimented on
Act as agonist at 5HT2 receptors.
Excitation threshold of retina ↓- visual
hallucinations, hyper arousal state
Experiences may be bad or good trip.
Extract of hemp plant-C.sativa, C.indica
Bhang- paste of powdered dried leaves, used as
Marijuana- dried leaves & flowering tops,
smoked in pipes or rolled as cigarettes.
Charas or hashish- resinous exudates leaves &
flowering tops, potent smoked
THC content more in hashish
Initial CNS stimulation later sedation.
Stimulatory phase- euphoria, ↑talkativeness,
Felling of confidence, relaxation & well being
Other- analgesia, antiemetic
Peripheral effects- tachycardia, reddening of
Two types CB 1& 2 receptors
CB1 in brain CB2 in periphery
Anandamide-endogenous ligand CB1.
Dronabinol, Nabilone- synt.analogues of THC
Use: CB1 Agonists- ↑appetite in AIDS pts.
Dronabinol-antiemetic in cancer chemo.
Rimonabant : CB1 antagonist, used for obesity,
dose-20mg OD before Breakfast
Cognition is "the mental action or process of
acquiring knowledge and understanding through
thought, experience, and the senses.“
It encompasses processes such
as knowledge, attention, memory and working
memory, judgment and evaluation, reasoning an
d "computation", problem solving and decision
making, comprehension and production
AD, multi infarct dementia
Mild cognitive impairment
learning defects, ADHD in children
Sequale of head injury
ECT, brain surgery
↑ global/regional blood flow
Direct support of neuronal metabolism
Enhancement of neurotransmission
Improvement of discrete cerebral functions
Main pathological features:
Marked ↓ in choline acetyltransferase & loss
of cholinergic neurons in brain.
ACEs that cross BBB are preferred.
Longer acting, reversible ACE
Palliative for mild to moderate AD
Improves memory, cognition, well being
Facilitates Ach release
DONEPEZIL, RIVASTIGMINE & GALANTAMINE
Newer reversible Anti cholinesterase
Better penetration in to CNS
Better tolerated & less toxic than tacrine
Clinical results modest & temporary
Donepezil: 5mg OD orally evening ↑ max
10mg after 4 wks
Rivastigmine:1.5 mg orally BD ↑ to 3mg BD
after 2 wks
Galantamine:4mg BD orally ↑to 8mg BD after
Transdermal Rivastigmine patch –applied
SE:diarrhoe, N, V, ↑urination
Structural analogue of Ach
↓ signs & symptoms of dementia in AD
↑ cholinergic transmission
Also have antioxidant properties, slows
progression of AD
Excitotoxicity due to enhanced Glutamate
transmission via NMDA recp.
Dose:5mg OD slowly ↑ to 10-20mg/day
Non-comp. antagonist of NMDA recp.
Better tolerated, less toxic.
Nootropics- piracetam, aniracetam
High doses of vit E(1000 IU B.D)
Antioxidants-vit C, A, Zn, Se, bioflavonoids or
spirulina ↓ progression even in middle stage