CNS stimulants act on the central nervous system to increase alertness, reduce fatigue, and elevate mood. They can stimulate the cerebral cortex, medulla, and spinal cord. Common stimulants include xanthine alkaloids like caffeine, which increase mental and physical performance, and amphetamines, which are used to treat narcolepsy and obesity but can cause side effects like palpitations and restlessness. Other stimulants like nikethamide act on the medulla to stimulate respiration, while strychnine acts on the spinal cord and is not used therapeutically but was historically studied for its convulsant properties.

1. CNS stimulants
SUJIT KARPE
PRINCIPAL,
SOJAR COLLEGE OF PHARMACY, KHANDVI

2. CNS STIMULANT - ANALEPTICS

3. • These drugs when administered, overcome narcolepsy by stimulating
central nervous system.
• They stimulate respiratory and other vital centers in the medulla.
CNS STIMULANT - ANALEPTICS

4. Overall effect of CNS stimulant
• Speed up the operation of the Central Nervous System
• Increase heartbeat, pulse, respiration, blood pressure,
and temperature
• Elevate Mood
• Increase Motor Activity
• Increase Alertness
• Decrease need for Sleep
• In case of overdose lead to convulsion and death.

5. CLASSIFICATION OF CNS STIMULANT
Depending upon Site of action
1. Cortical stimulants:
stimulate cerebral cortex by inhibiting Adenosine receptor
Eg: - Xanthine alkaloids, Amphetamine
2. Medullary stimulant:
stimulate medulla oblongata by inhibiting GABA receptor
Eg: - Nikethamide, Picrotoxin, Leptazol
3. Spinal stimulants:
Stimulate spinal cord (Competitive Antagonist of Glycine)
Eg: - Strychnine, lobeline, Nicotine

6. ModeofActionCNSSTIMULANT

7. https://www.youtube.com/watch?v=y7NhQYgeCkA

8. Xanthine Alkaloid – Caffeine, Theophylline, Theobromine
Pharmacological actions –
On CNS:
• Caffeine possess most significant activity.
• At high dose show medullary and spinal stimulation
• Cerebral cortex – stimulate mental activity and physical performance, cause
wakefulness, reduces rate of onset of fatigue, increase calculating power of brain,
increase motor activity for muscular work.
• Medulla – high dose stimulate respiratory, vagal and vasomotor centres which will
leads to increase in BP.
• Spinal cord – very large dose increases the reflex excitability of the spinal cord.

9. Xanthine Alkaloid – Caffeine, Theophylline, Theobromine
On CVS:
• Heart – have direct stimulant effect on heart and tend to increase heart rate,
force of contraction and thus cardiac output. Effect of vagal stimulation is
reduction in heart rate.
• Blood vessel – causes coronary and peripheral vasodilation and cerebral
blood vessel show constriction.
On smooth muscle:
• Relaxation of smooth muscle especially bronchial muscle. Theophylline is
useful in abolishing bronchospasm.

10. Xanthine Alkaloid – Caffeine, Theophylline, Theobromine
On Skeletal muscle:
• Strengthens the skeletal muscle contraction, increases muscular
metabolism and postpone the muscle fatigue, increase the ability of an
individual to do more muscular work.
On kidney:
• Produces increased urine output.
• Theophylline increases renal blood flow and GFR.
• Also by direct action on nephron it reduces the reabsorption of sodium,
chloride and water, thus act as diuretic.

11. Xanthine Alkaloid – Caffeine, Theophylline, Theobromine
Adverse effect:
• No serious toxicity. May produce confusion, tremor, excitement, headache and
hyperacidity.
• Development of tolerance.
Therapeutic uses:
• Stimulant for relief from fatigue and mild depression.
• In treatment of headache.
• Theophylline is used in bronchial asthma.
• Theophylline is used as diuretic.

12. Amphetamine
• It is sympathomimetic amine
• Have both central and peripheral action.
• Stimulate cerebral cortex, medulla and spinal cord.
• Cause wakefulness, alertness and improves the mental activity.
• Postpone fatigue and improves physical performance.
• Mood elevating action is responsible for its abuse.
• Repeated and excessive administration is usually followed by fatigue and
depression
• Peripherally, causes increase in both systolic and diastolic BP, reflex
bradycardia and at high dose cardiac arrhythmias.

13. Amphetamine
• Bronchial muscle relaxed while bladder and GI muscles shows constriction.
• Amphetamine by its action on feeding center and hypothalamus reduces
appetite which leads to weight loss.
Adverse effect:
• Palpitation, restlessness, insomnia, tremors, confusion and erratic behavior
are common.
• Psychological type drug dependence.

14. Amphetamine
Therapeutic uses:
• Used in treatment of Narcolepsy (attack of sleep in day time)
• Used in treatment of obesity.
Preparation:
Amphetamine (Amphetamine sulphate) 2.5 – 10mg.

15. Nikethamide
• Acts on chemoreceptors in carotid body and reflexly stimulate respiratory
center in medulla. This action is more powerful when respiration is already
depressed.
• Large dose may cause convulsion.
• Administered by subcutaneous, IM or IV route.
• It is often used in hospitals in the hope that it will restore the blood
pressure and strengthen the heart.

16. Strychnine
• Alkaloid obtained from dried seeds of Strychnos nuxvomica.
• No therapeutic value but has proved as useful tool in study of mode of
action of convulsant drugs.
• Acts mainly on spinal cord and abolishes the inhibitory post synaptic
potentiation, perhaps by acting as a competitive antagonist to an inhibitory
transmitter by preventing its release.
• Sensation of touch, smell hearing and vision are made more acute.
• Poisoning with strychnine may occur and is sometimes homicidal. (capable
of or tending towards murder)