Cns stimulants by Dr. Nadeem Korai
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Transcript of Cns stimulants by Dr. Nadeem Korai
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CNS Stimulants
Dr. Nadeem akhtar
MBBS.M.Phil
Asst. Professor Pharmacology
Amna Inayat Medical College
Shaikhupura
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CEREBRAL STIMULANTS
AND
HULLUCINOGENS
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Cerebrostimulants
1. Caffeine
2. Nicotine
3. Amphetamines
4. Cocaine
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Caffeine
• Caffeine is most widely consumed CNS stimulant.
• A cup of instant coffee or strong tea contains 50-70mg of caffeine
• Average daily consumption is about 200mg, in tea & coffee drinking countries
• Nuts of cola plant also contain caffeine• CNS stimulation & Diuresis are its
pharmacological actions• Main psychological effects are remove fatigue and
improve mental performance
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Mode of action
• Antagonize adenosine receptors
• Activates nor-adrenaline neurons
• Effect the local release of dopamine & glutamate
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Effects on different body function
• CVS: produce positive ionotrpic and chronotropic effects on heart.
• GIT: increase gastric secretions, therefore should be avoided in peptic or gastric ulcer
• Urinary system: produce mild diuretic action & increase urinary output of elctrolytes.
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Clinical uses
• Caffeine relax the smooth muscle of bronchioles therefore effective in asthma
• It is included with aspirin or paracetamol in some preparations to treat headaches or other aches
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Nicotine
• Nicotine is named after the tobacco plant Nicotiana tabacuma which acts as a nicotinic acetylcholine receptor agonist.
• Average 1 cigarette yields about 1 mg nicotine. As nicotine enters body it quickly distributed throughout blood stream and crosses BBB reaching brain within 10-20 seconds after inhalation.
• Eliminatin half life is 2 hrs
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• Metabolized in liver by cytochrome P450 enzyme system mostly by CY2A6 & CY2B6
• Major metabolite is cotinine
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• By binding to nicotinic acetylcholine receptors, it increases the level of several neurotransmitters in the brain.
• Tobacco smoke contains monamine oxidase inhibitors.
• Powerful interaction between MAOs and Nicotine are responsible for addictive effects of smoking
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Withdrawal
• Nicotine withdrawal is mild as compared to opiods and involves irritability with insomnia .
• Nicotine is among the most addictive drugs and relapse after attempted cessation is common
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Treatment
• Antidepressant BUPROPION is approved for nicotinic cessation therapy .
• It is most effective when combined with behavioral therapies
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Amphetamines
• Amphetamines are group of synthetic, indirect acting sympathomi metic drugs that cause the release of endogenous biogenic amines such as dopamine and noradrenaline.
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Mechanism of action
• It stimulate both alpha & beta adrenoreceptors through an indirect mechanism(by release of intracellular catecholamines and MAOs blockade)
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Pharmacological effects
• CNS: Psychic stimulation resulting in feeling of euphoria, self confidence, wakefulness, alertness with increase mental and physical activities.
• It has anti-fatigue & analeptic action
• It has mild analgesic properties, also increase analgesic effect of opiod and decrease effect of nitric oxide
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• It depress appetite by central action on hypothalamus feeding centers by reduction sense of smell and taste
• Chronic abuse leads to psychotic state with delusion and paranoia like schizophrenia.
• CVS: increase BP and reflex bradycardia with large doses may cause arythmias
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Clinical uses
Narcolepsy (its derivative methylphenidate is more better).
Hyperkinetic syndrome(attention deficit disorder)
Nocturnal enuresis
As nasal decongestant
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Adverse effects
• Dysphoria, confusion, headache, mental depressan, psychosis, confusion, , arythmia, anginal pain, dry mouth , anorexia, vomiting.
• Overdose is treated by CHLOROPROMAZINE
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Cocaine
• Cocaine is alkaloid found in the leaves of Erythroxylon coca.
• A shrub endogenous to the Andes.
• For more than 100 years it has been used in clinical medicine as a local anesthetic agent and to dilate the pupil in ophthalmology.
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Mechanism of action
• In CNS cocaine blocks the uptake of dopamine, noradrenaline, and serotonin through their respective transporters.
• The block of dopamine transporter by increasing dopamine concentration in the nucleolus accubens has been indicated in reward effect of cocaine.
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Adverse effects
• Loss of appetite
• Hyperactivity
• Intracranial hemorrhage
• Ischemic stroke
• Myocardial infarction
• Seizure
• Hyperthermia, coma &death on high doses
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HALLUCINOGENS
Hallucination: is a sense or perception(sight, touch, smell, sound or taste) that has no basis of external stimulation.
Hallucinogens are characterized as agents which produce hallucinations
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Cannabinoids
• 1)Endogenous cannabinoids: these
• include 2-arachidonyl (2-AG) &
anandamide, both bind to CB1 receptors where they inhibit release of either Glutamate or GABA receptors.
• Due to this backward signaling they are called retrograde Messengers'
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• Exogenous cannabinoids:
• These include Marijuna and other pharmacological active substances like Tetrahydrocannabinol (THC)
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Tetrahydrocannabinol (THC)
• This is a powerful psychoactive substance like opiods
• Causes release of Dopamine neurons mainly by pre-synaptic inhibition of GABA neuron in the VTA
• Half life of THC is about 4 hrs
• The onset of effect of THC after smoking marijuna occur within minute
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• The prominent effects are euphoria, relaxation , feelings of well being, grandiosity and altered perception of passage of time
• Dose dependant perceptual changes(vision distortion)
• Drowsiness, diminished coordination and memory impairment may occur
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• Rarely Cannabinoids create dysphoric state with higher doses
• Hashish ------ produce visional hallucination, depersonalization and frank psychotic episodes
• Increase appetite, nausea, decrease intraocular pressure and relief of chronic pain
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• Chronic use of marijuna produce dependency with mild withdrawal symptoms, like restlessness, irritability, mild agitation and insomnia.
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Lysergic acid diethylamide(LSD)
• Multiple sites in CNS are affected by LSD
• It shows agonistic activity at presynaptic 5HTI receptors in the midbrain and stimulates 5H2 receptors
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Physical effects
• LSD can cause pupil dilatation
• Reduce or increase appetite
• Increased wakefulness, numbness, hypo or hyperthermia, elevated blood sugar, increase heart rate, jaw clenching.
• LSD is not considered addictive drug
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Psychological effects
• Vary greatly from person to person
• Some users cite the LSD experience causing significant change in life pattern
• Some perceive radiant bright colors behind the closed eye lids(imagery) and altered sense of time & space
• This intuitive quality may play a role in spiritual and religeous aspects of LSD
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Clinical uses
• Alcoholism (diazepines are more better)
• Painful conditions
• Cluster headache
• End of life anxiety: study conducted in Switzerland (2008-2011)on patients who were in terminal illnesses and were counting their days. They were treated with LSD and showed promising results
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• LSD is taken orally from 100- 500 micrograms.
• Adverse effects: hyperreflexia, nausea, muscular weakness
• With high doses psychotic changes occur which are relieved by haloperidol
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Phencyclidine
• It is also called angel dust
• Inhibit the reuptake of dopamine, 5HT, and norepinephrine
• It causes dissociative anesthesia (insensitivity to pain without loss of consciousness)
• Tolerance often produce with continued use