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CNS STIMULANTS

CNS STIMULANTS. SAMUEL AGUAZIM. What is the definition of a CNS stimulant?. A CNS stimulant is a drug that increases motor activity, causes excitement and decreases feelings of fatigue. CNS stimulants include the methyxanthines, nicotine, and the amphetamines. CNS stimulant.

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CNS STIMULANTS

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  1. CNS STIMULANTS SAMUEL AGUAZIM

  2. What is the definition of a CNS stimulant? • A CNS stimulant is a drug that increases motor activity, causes excitement and decreases feelings of fatigue. • CNS stimulants include the methyxanthines, nicotine, and the amphetamines

  3. CNS stimulant • PSYCHOMOTOR STIMULANTS • CAUSE EXCITEMENT & EUPHORIA • INCREASE MOTOR ACTIVITY • PSYCHOTOMIMETIC DRUGS • PROFOUND CHANGES IN THOUGHT PATTERNS AND MOOD • FEW DRUGS USED CLINICALLY • IMPORTANT AS DRUGS OF ABUSE

  4. METHYLXANTHINES • What are methyxanthines? A group of psychomotor stimulants include: • Caffeine • Theophylline • Theobromine ( found in cocoa but of little interest)

  5. How do methyxanthines work? • Research indicates that methyxanthines increases cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) by inhibiting phosphodiesterase and blocking adenosine receptors.

  6. CAFFEINE • What are the physiologic effects of caffeine? • Caffeine effects a number of organ systems within the body: • CNS- caffeine increases motor activity and alertness • Cardiovascular- caffeine increases heart rate and contractility

  7. CAFFEINE • Smooth muscle- caffeine and its derivatives relax the smooth muscles of the bronchioles. • Genitourinary- caffeine can ac as weak diuretic and increase urinary output of Na+, CI- and K+ • Gastrointestinal – caffeine stimulates secretion from the gastric mucosa. Therefore, patients who have peptic ulcer disease should be counseled to avoid caffeine

  8. Adverse Effects of chronic caffeine use? • At low doses- insomnia and agitation can occur • At higher doses (8-10g)- Emesis, convulsion and even cardiac arrhythmias can occur. • Do methyxanthines cross the placenta? • Yes, and they are secreted into the mother’s milk. Patients should be advised to avoid them during pregnancy and while nursing

  9. THEOPHYLLINE • THERAPEUTIC ROLE OF THEOPHYLLINE: • It can be used in the treatment of asthma, but currently it is not being used frequently because it has a very narrow therapeutic index and is not effective as the new beta agonist

  10. NICOTINE • How are the physiological effects of nicotine related to the dose? • In low doses, nicotine causes ganglionic stimulation by depolarization. • At high doses it causes ganglionic blockade

  11. NICOTINE • What are the physiologic actions of nicotine on the central nervous system? • At low doses- arousal, relaxation and improved attention • At high doses- central respiratory paralysis caused by disruption of medullary function

  12. NICOTINE • How does nicotine affect the peripheral nervous system? • At low doses- increase in blood pressure and heart rate; constriction of blood vessels to the digits and impairment of flow • At high doses- decrease in blood pressure and in action of GI and GU tract due to ganglionic blockade • NOTE: NICOTINE HAS NO THERAPEUTIC USES

  13. NICOTINE • What is nicotine’s route of administration? • Absorption occurs through oral mucosa by inhalation and transdermally. • What are its adverse effects? • CNS- irritability and tremors • Peripheral- intestinal cramps, diarrhea, and increased heart rate and blood pressure

  14. NICOTINE • What withdrawal symptoms do nicotine addicts experience? • A craving for tobacco is accompanied by irritability, restlessness, anxiety and gastrointestinal pain.

  15. AMPHETAMINES • Name three examples of this drug class. • 1. methylphenidate ( ritalin) • 2. methamphetamine ( methedrine)-”speed” • 3. dextroamphetamine ( dexedrine)

  16. AMPHETAMINES • How do these drugs work? • Amphetamines work by releasing neuronal stores of catecholamines especially norepinephrine and dopamine

  17. AMPHETAMINES • What are the physiologic actions of these drugs? • Euphoria • Decrease in fatigue • Increase in blood pressure • Increase in rate of respiration • Decrease in appetite

  18. AMPHETAMINES • What is their clinical use? • Attention deficit hyperactivity disorder(ADHD)-METHYLPHENIDATE is used to alleviate this problem • Appetite control- amphetamines decrease appetite by blocking the receptors in the lateral hypothalamus • Narcolepsy

  19. AMPHETAMINES • What is the route of administration? Oral • Where are amphetamines metabolized? In the liver • Does physiologic and psychological dependence occur with amphetamine use? • Yes- amphetamines can be very addictive

  20. AMPHETAMINES • What are the adverse effects of these drugs? • Amphetamines like caffeine and nicotine affects multiple organ systems. • CNS-insomnia, irritability, convulsions; chronic use can lead to a psychotic state resembling schizophrenia • Gastrointestinal- anorexia, nausea, dry motuh • Cardiovascular- palpitations, angina, arrhythmias, hypertension

  21. AMPHETAMINES • Amphetamines are contraindicated with what group of drugs? • The monoamine Oxidase (MAO) inhibitors • How is amphetamine overdose managed? • Chlorpromazine is beneficial in amphetamine overdose because it blocks the alpha receptors which are responsible for the CNS disturbances and hypertension

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