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Cns stimulants & cognition enhancers

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cns stimulants ppt for MBBS ug

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Cns stimulants & cognition enhancers

  1. 1. Little clinical use, except methylxanthines  Can be classified in to:  › Respiratory stimulants ( Analeptics). › Convulsants › Psychomotor stimulants › Psychomimetic drugs
  2. 2. Doxapram :  MOA not clear, may excite central neurons  Short acting, high margin of safety.  Low doses selective for respiratory centre  ↑ Tidal volume & rate of respiration Uses :  Post-anaesthetic resp. depression  COPD i.e. hypoxemic,hypercapnic res.fail  Apnoea in premature infants
  3. 3. Dose- 2-5mg/min(max 4mg/kg) slow i.v infusion. Contraindications:  Hypoxaemic, normocapnic resp.failureasthma  Resp.fail due to neurological & muscular diseases.  Epilepsy Side effect:  Restlessness  Tachycardia  High doses: convulsions & arrhythmias 
  4. 4. No clinical use  Used as research tools Strychnine:  Alkaloid, convulsant poison.  Spinal cord stimulant  MOA: Blocking the receptors for Glycine  In poisoning convulsion treated withDiazepam or clonazepam slow i.v 
  5. 5. Picrotoxin:  Blocks the Cl- ion channel of GABAA. Bicuculline:  Plant alkaloid, GABAA antagonist. Pentylenetetrazole (PTZ):  Direct depolarization of central neurons  Provides useful animal model for testing anticonvulsant drugs.
  6. 6. Amphetamine group:  Amphetamine  Dexamphetamine  Methamphetamine  Methylenedioxy Methampheta(MDMA)  Methylphenedate  Fenfluramine
  7. 7. Non-Amphetamine group  Modafinil  Atomoxetine  Sibutramine  Pemoline Cocaine Methylxanthines:  Caffeine  Theophylline  Theobromine
  8. 8. MOA: ↑DA conc. In synaptic cleft by  Enter N endings by active transport  Displace DA(also NE) from vesicles  Also inhibits MOA-B, ↓DA metabolism. Pharmacological effects: (central)  ↑ motor activity  Euphoria & excitement  Anorexia  Stereotyped & psychotic behaviour
  9. 9. ↑ BP, inhibition of GI motility  Fatigue both physical & mental reduced.  Amphetamine psychosis on repeated use- paranoid ideas, A & T hallucinations. PK:  Well absorbed orally  Freely penetrates BBB  Unmetabolised drug excreted in urine 
  10. 10. ADHD with minimal brain dysfunction:  Characterised by› Hyperactivity › Inability to concentrate › Impulsive behavior  Dexamphetamine,  Methylphenedate,  Atomoxetine quite effective.
  11. 11. Narcolepsy: Characterised by Sleep attacks during day time  Night mares in awakening state  Cataplexy-reversible  Methylphenedate is still used  Modafinil- devoid of abuse liability
  12. 12. Fenfluramine, dexfenfluramine used earlier to treat obesity  Discouraged due to: Tolerance  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. 
  13. 13. Use:  Severe obesity with risk factors like DM. Adverse effects:  Dry mouth  Headache  Insomnia  Constipation  ↑in HR & BP  CI in CVS diseases, withdrawn from market
  14. 14. Tolerance  Psychic dependence, rarely physical. Amphetamine overdose:  Euphoria, dizziness, tremors, HTN  Irritability, anorexia, insomnia  Higher doses- convulsions, psychotic manifestations, arrhythmias, coma  Rx –diazepam(slow i.v), haloperidol  Gastric lavage, acidification of urine  HTN-nifedipine/labetolol, arry-esmolol 
  15. 15. Sudden deaths occurred with MDMA.  Induces heat stroke like conditionrhabdomyolysis & renal failure  Inappropriate secretion of ADH Methylenedioxy amphetamine (love drug)  75mg- psychotomimetic effects  150 mg-LSD like effects  300mg- amphetamine like  SE: tachycardia, HTN, arrhythmias 
  16. 16. Only caffeine if used as CNS stimulant PK:  Oral- rapid but irregular absorption  PPB:<50%  Distributed all over the body  Met: in liver by demethylation & oxid.  Metabolites excreted in urine  T1/2: 3-6hrs 
  17. 17. AE:  Gastric irritation, N, V  Nervousness, insomnia, agitation  Muscule twitch, rigidity  ↑body temp,delirium, convulsions  Tachy, extra systoles at high doses Uses:  In Analgesic mixture for headache  Migraine  Apnoea in premature infants
  18. 18. Produce changes in sensory perceptions, thoughts, behaviour & mood.  Actions mimic psychoses- psychedelics  Lysergic acid diethylamide (LSD)  Mescaline  Phencyclidine  Cannabinoids 
  19. 19. Derived from cereal fungus ergot  Hofmann synthesized & experimented on himself.  Act as agonist at 5HT2 receptors.  Excitation threshold of retina ↓-visual hallucinations  Excitation threshold of RAS↓-hyper arousal state  Experiences may be bad or good trip. 
  20. 20. Extract of hemp plant-C.sativa, C.indica  Bhang- paste of powdered dried leaves, used as drink  Marijuana- dried leaves & flowering tops, smoked in pipes or rolled as cigarettes.  Charas or hashish- resinous exudates leaves & flowering tops, potent smoked inpipe.  THC content more in hashish 
  21. 21. Initial CNS stimulation later sedation.  Stimulatory phaseeuphoria, ↑talkativeness, ↑appetite  Felling of confidence, relaxation & well being  Other- analgesia, antiemetic  Peripheral effects- tachy, VD, reddening of conjunctiva 
  22. 22.         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 Smoking cessation
  23. 23. Indications:  AD, multi infarct dementia  Mild cognitive impairment  MR, learning defects, ADHD in children  TIA, CVA, Stroke  Organic psychosyndromes  Sequale of head injury  ECT, brain surgery
  24. 24. ↑ global/regional blood flow  Direct support of neuronal metabolism  Enhancement of neurotransmission  Improvement of discrete cerebral functions 
  25. 25. Main pathological features:  Amyloid plaque  Neurofibrillary tangles  Marked ↓ in choline acetyltransferase & loss of cholinergic neurons in brain. 
  26. 26. ACEs that cross BBB are preferred. Tacrine:  Longer acting, reversible ACE  Palliative for mild to moderate AD  Orally active  Improves memory, cognition, well being  Facilitates Ach release  AE: hepatotoxicity 
  27. 27. 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 2 wks 
  28. 28. Transdermal Rivastigmine patch – applied every 24hrs  SE:diarrhoe, N, V, ↑urination Acetyl-L-carnitine:  Structural analogue of Ach  ↓ signs & symptoms of dementia in AD  ↑ cholinergic transmission  Also have antioxidant properties, slows progression of AD 
  29. 29. 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. Miscellaneous :  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 AD. 
  30. 30. ¡gracias "thank you" in Spanish

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