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  1. 1. DRUGS FOR MYASTHENIA GRAVIS Neostigmine Pyridostigmine Edrophonium 1
  2. 2. MYSTENIA GRAVIS• Chronic muscular disease caused by a defec in neuromuscular transmission characterize by gradual destruction of Ach receptors.• characterized by fatigue and severe weakness of skeletal muscles 2
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  5. 5. DRUGS FOR MYASTHENIA GRAVIS1. NEOSTIGMINEACTION: – Inhibit destruction of Ach facilitating transmission of impulse across myoneural junctionPHARMACOKINETICS:• Poorly absorbed orally• Can cross blood-brain barrier affect CNS• Duration of action 2-4hrs 5
  6. 6. DRUGS FOR MYASTHENIA GRAVIS1. NEOSTIGMINECONTRAINDICATION:• Obstruction of GI tract, urinary tract• Peptic ulcer disease• Asthma• Coronary insufficiency• Hyperthyroidism 6
  7. 7. DRUGS FOR MYASTHENIA GRAVIS1. NEOSTIGMINEADVERSE EFFECTS:• EXCESSIVE MUSCARINIC STIMULATION – Excessive salivation – Increased gastric secretion – Increased tone and motility of GI – Urinary urgency – Bradycardia – Sweating 7
  8. 8. DRUGS FOR MYASTHENIA GRAVIS1. NEOSTIGMINEADVERSE EFFECTS:• NEUROMUSCULAR BLOCKADE – Accumulation of Ach in amount sufficient to produce depolarizing neuromuscular blockade – Results in paralysis of respiratory muscles 8
  9. 9. DRUGS FOR MYASTHENIA GRAVIS2. PYRIDOSTIGMINE (Mestinon)• Inhibit destruction of Ach• Has longer duration than neostigmine• * adverse reaction: decreased HR, diarrhea and hypotension 9
  10. 10. DRUGS FOR MYASTHENIA GRAVIS3. EDROPHONIUM (Tensilon)• A drug with very short duration of action (10-20 min)• PRIMARILY USED AS A DIAGNOSTIC AGENT to differentiate myasthenic crisis from cholinergic crisis• If the drug alleviates symptoms = MYASTHENIC CRISIS• If the drug intensifies symptoms = CHOLINERGIC CRISIS 10
  11. 11. DRUGS FOR ALZHEIMERS DISEASE Cognex Aricept 11
  12. 12. ALZHEIMERS DISEASE• Progressive disorder involving neuronal degeneration in the cortex leading to loss of memory and inability to perform activities of daily living 12
  13. 13. DRUGS FOR ALZHEIMERS DISEASE1. COGNEX• 1st cholinesterase inhibitor approved for Alzheimer’s disease• Administered orally• Food decreases absorption• Blood levels peak in 2 hrs, with short half- life of 3hrs, must be administered 4x a day• Cause liver damage with high dose 13
  14. 14. DRUGS FOR ALZHEIMERS DISEASE2. ARICEPT• Current agent of choice• Well-absorbed orally• Eliminated mainly in urine and partly in bile• Has longer plasma half-life of 6hrs• Administered 1x a day 14
  15. 15. Alzheimer’s – Medical Management• Medication to treat symptoms – Memory:Cognex, Aricept – Agitation: Mellaril, Haldol• Supplements – Folic Acid & Vitamin B12 – Low fat diet – NSAIDS
  16. 16. MedicationsCholinesterase inhibitors used to treat mild to moderate dementia• Tacrine hydrochloride (Cognex)• Donepezil hydrochloride (Aricept)• Rivastigmine (Exelon)Medications to treat depressions• Tranquilizers for severe agitation• Thioridazine (Mellaril)• Haloperidol (Haldol)• Antioxidants: vitamin E, anti-inflammatory agents, estrogen replacement therapy in women
  17. 17. DRUGS FOR SEIZURES Hydantoins Succinimides 17
  18. 18. SEIZURES• Sudden and rapid firing of electrical impulse from neuron located in brain• Generalized seizures begin in 1 area and spread throughout the different areas of the brain• Partial seizures involve only 1 area of the brain and remain localized. 18
  19. 19. DRUGS FOR SEIZURES1. HYDANTOINS• Stabilize nerve membranes and limit spread of excitability from the initiating focusDrugs:1. phenytoin (Dilantin) = prototype drug2. ethotoin3. fosphenytoin4. mephenytoin 19
  20. 20. DRUGS FOR SEIZURES1. HYDANTOINSINDICATION: – Tonic-clonic seizuresPHARMACOKINETICS:• Slowly absorbed in small intestine• Excreted in urine• Highly protein bound, thus, decrease in serum protein or albumin can increase free phenytoin serum level• Half-life is 22 hrs 20
  21. 21. DRUGS FOR SEIZURES1. HYDANTOINSCONTRAINDICATIONS:• Psyche conditions• Bradycardia• Hepatic failureCAUTION:• Pregnancy – can cause birth defects and bleeding tendencies 21
  22. 22. DRUGS FOR SEIZURES1. HYDANTOINSADVERSE EFFECTS:1. GINGIVAL HYPERPLASIA2. Neurologic and psyche SE like slurred speech, confusion, depression and thrombocytopenia3. Hyperglycemia = effect of drug inhibiting release of insulinLess severe AE:1. Alopecia2. Hirsutism3. Nystagmus4. N&V 22
  23. 23. DRUGS FOR SEIZURES1. HYDANTOINSSPECIAL NURSING CONSIDERATIONS:1. Administer IV infusion of phenytoin directly into a large vein. – Maybe diluted in NSS; dextrose solution should be avoided-cause drug precipitation2. Do not administer continuously – 50 mg can be administered in a period of 1min for adult and 25mg in elderly 23
  24. 24. DRUGS FOR SEIZURES1. HYDANTOINSSPECIAL NURSING CONSIDERATIONS:3. Monitor local irritation at injection site4. Monitor drug levels as ordered; therapeutic level 10-20mcg/ml5. Enteral feeding interfere oral absorption. Stop feeding for 2 hrs before and after administration 24
  25. 25. DRUGS FOR SEIZURES2. SUCCINIMIDESACTION: – Suppress the abnormal electrical activity in the brain associated in petit mal or absence seizureINDICATION: – Control of absence seizures 25
  26. 26. DRUGS FOR SEIZURES2. SUCCINIMIDES – Absorbed in GI tract – Peak levels of 1-7hrs – Metabolized in liver – Excreted in urine – Able to cross placenta and enter breast milk 26
  27. 27. DRUGS FOR SEIZURES2. SUCCINIMIDESCONTRAINDICATIONS: – Renal/hepatic disease – Pregnancy and lactation – Intermittent porphyria 27
  28. 28. DRUGS FOR SEIZURES2. SUCCINIMIDESADVERSE EFFECTS:• Depressing effects in CNS: – Depression, drowsiness, ataxia, insomnia, HA and blurred vision• Bone marrow suppression and dermatologic reaction: – Pruritus, urticaria, alopecia and Steven Johnson’s syndrome 28
  29. 29. DRUGS FOR SEIZURES2. SUCCINIMIDESGENERAL NURSING CONSIDERATIONS:1. Discontinue at any sign of hypersensitivity reaction, liver dysfunction or severe skin rash – to prevent potential fatal reaction.2. Administer with food – to alleviate GI upset3. Women of child-bearing age should be referred for counseling – may cause serious damage to fetus 29
  30. 30. DRUGS FOR SEIZURES2. SUCCINIMIDESGENERAL NURSING CONSIDERATIONS:4. Suggest wearing of MedicAlert bracelet – to alert emergency workers about the use of the drugs5. Monitor CBC before and periodically during therapy – to detect bone marrow suppression early and provide appropriate interventions 30
  31. 31. DRUGS FOR SEIZURES3. DRUGS FOR PARTIAL/FOCAL SEIZURES – Carbamazepine (Tegretol) – Clorazepate (Tranxene) – Felbamate (Felbatol) – Gabapentin (Neurontin) – Lamotrigine (Lamictal) – Levetiracetam (Keppra) 31
  32. 32. DRUGS FOR SEIZURES3. DRUGS FOR PARTIAL/FOCAL SEIZURESACTION: – Control partial or focal seizures either by acting on the sodium and calcium channels or increasing GABA activity 32
  33. 33. DRUGS FOR SEIZURES3. DRUGS FOR PARTIAL/FOCAL SEIZURESCONTRAINDICATION:• Bone marrow suppression• Hepatic dysfunction• Pregnancy and lactation• Presence of renal stonesADVERSE EFFECTS:• CNS depression: drowsiness, fatigue, weakness, confusion and HA 33
  35. 35. NEUROMUSCULAR ABNORMALITIESMUSCLE SPASM• Result of musculoskeletal injury – Muscle stretches beyond capacity• Characterized by painful contraction of muscles• Spasms are felt when sensory impulses travel fro the spinal cord to the site of injury, passing the motor nerves to cause muscle contraction• Blood flow to the muscle is disrupted causing lactic acid accumulation and pain 35
  36. 36. MUSCLE SPASTICITY• Permanent condition caused by neuronal damage in the CNS• Hyperactive stimulation of the muscles resulting to loss of muscle coordination• Ex in MULTIPLE SCLEROSIS – Lesion in CNS interrupts nerve impulse resulting to progressive muscle weakness 36
  37. 37. CENTRALLY-ACTING MUSCLE RELAXANTS Prototype: Baclofen Baclofen Carisoprodol Chlorphenesin Chlorzoxasone Cyclobensapine Metaxalone Methocarbamol 37
  38. 38. CENTRALLY-ACTING MUSCLE RELAXANTSACTION:• Interfere with neuromuscular communication in CNS to cause muscle relaxationINDICATION:• Multiple Sclerosis• Cerebral palsy• Any trauma in spinal cord 38
  39. 39. CENTRALLY-ACTING MUSCLE RELAXANTS• Rapidly absorbed orally• Peak 2-3hrs• Can cross blood brain barrier and crosses the placentaCAUTION: – CNS depression – Cardiac dysfunction – Hepatic and renal dysfunction – Pregnancy and lactation 39
  40. 40. CENTRALLY-ACTING MUSCLE RELAXANTSNURSING CONSIDERATIONS:• Discontinue if + hypersensitivity or liver dysfunction. – If using baclofen, taper the drugs gradually within 1-2 weeks to prevent dev’t of psychoses• If receiving baclofen using IV pump, instruct client about the pump and the rationale for the need to monitor frequently• Report if client’s respiratory status deteriorates 40
  41. 41. DIRECT-ACTING MUSCLE RELAXANTS Prototype: Dantrolene 41
  42. 42. DIRECT-ACTING MUSCLE RELAXANTSACTION:• Relaxes muscles thru direct action on the skeletal muscle fibers• Dantrolene prevents muscular contraction by inhibiting the release of calcium from the muscle fibers 42
  43. 43. DIRECT-ACTING MUSCLE RELAXANTSINDICATION:• Tx of upper motor neuron disorders: MYASTHENIA GRAVIS & CEREBRAL PALSY• Acute tx of malignant hyperthermia (complication of general anesthesia=severe muscle contraction) 43
  44. 44. DIRECT-ACTING MUSCLE RELAXANTS• Only 30% of oral dose is absorbed, reaching peak plasma concentration in 5 hrs• Liver metabolizes the drug• Crosses the placenta and breastmilk 44
  45. 45. DIRECT-ACTING MUSCLE RELAXANTSADVERSE EFFECTS:• Muscle weakness : drooling, slurred speech, drowsiness, dizziness, malaise• GI effects: diarrhea, constipation, GI bleeding, dysphagia, n&v• Aplastic anemia and leucopenia 45
  46. 46. DIRECT-ACTING MUSCLE RELAXANTSNURSING CONSIDERATIONS:1. Assess for lactose intolerance before drug administration – Dantrolene capsules contain lactulose2. Administer with food or milk to avoid GI distress3. Advise to wear appropriate protective clothing sunscreen when exposed to direct sunlight 46
  47. 47. DIRECT-ACTING MUSCLE RELAXANTSNURSING CONSIDERATIONS:4. Provide safety precautions in cases of severe muscle weakness5. Provide frequent skin care to prevent skin breakdown6. Inform client that hepatitis is 1 of the dangerous adverse effects – Loss appetite, n&v, yellow skin or eyes and changes in urine and stool color. 47