Pharm- HEENT- antitussives

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Pharm- HEENT- antitussives
2013-05-26 18:56:49

Antitussives, decongestants, expectorants, H1 antagonists
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  1. Antitussives:
    inhibit cough thru either central or peripheral mech, or a combo of the 2.
  2. Antitussives.    
    Central acting drugs:
    • Guaifenesin and codeine (Cheratussin AC)- schedule V
    • dextromethorphan
  3. Dosing for Guaifenesin and codeine (Cheratussin AC):
    • Cough:  10 ml PO q 4-6h prn
    • Dosage forms: 10/100/ 5 mL
    • 10 codeine, 100 guaifenesin, in every 5 mL
    • Max daily dose (MDD) required on Rx
    • Dose should be decreased for renally impaired
    • Does have alcohol in it
  4. Antitussives.    
    Peripherally acting drugs:
    • Camphor
    • menthol
    • eucalyptus oil
    • Benzonatate (Tessalon)
  5. How does Benzonatate (Tessalon) act peripherally?
    by anesthetizing the stretch receptors located in the respiratory passages & lungs
  6. WARNINGS of Antitussives:
    • Severe hypersensitivity reactions (including bronchospasm, laryngospasm and       cardiovascular collapse) have been reported
    • Possibly related to local anesthesia from sucking or chewing the capsule instead of swallowing it
  7. MOA of centrally acting antitussives:
    • Inhibit the cough center in the brain
    • Exact mechanism not well understood
  8. MOA of peripherally acting antitussives:
    • Anesthetize local nerve endings
    • Act as demulcents (soothing agents)
  9. How does a cough occur? not sure this will be on exam...
    • Lower pharynx, larynx, trachea & small airways of respiratory system are       innervated by vagus & glossopharyngeal nerves
    • Stimulation of sensory receptors of these nerves leads to cough
    • Irritant leads to cough
    • Receptors relay info to cough center in brain (medulla)
    • A reflex motor response occurs; results in contraction of muscle to close glottis & muscles of expiration
    • Leads to an increase in intrathoracic pressure, followed by relaxation of the glottis
    • This results in rapid expulsion of air
  10. Indications of antitussives:
  11. kinetics of codeine (says FYI...?)
    • Onset occurs in 15–30 minutes. Peak antitussive effects within 1–4 hours.
    • Rapidly distributed into various body tissues.
    • Distributed into milk. Readily crosses the placenta.
    • Metabolized in liver, principally by CYP3A4, to O-demethylated morphine, the active       metabolite.
    • genetic differences in drug metabolism affect drug response
    • Excreted mainly in urine
    • Half-life: about 2.5–3 hours
  12. Kinetics of Dextromethorphan (FYI..?):
    • Onset of action is 15-30 minutes·
    • Duration is 3-6 hours
  13. kinetics of camphor or menthol (FYI...?):
    • Used topically  (vapors inhaled)
    • inhaled through a vaporizer
  14. SE of Dextromethorphan:
    • Drowsiness
    • nausea
    • dizziness
  15. SE of Benzonatate:
    • Sedation
    • HA
    • dizziness
    • Can numb mouth
    • Warn patients:  Do not chew or dissolve in the mouth when used as an antitussive
    • Why? temporary, potentially life-threatening local anesthesia of the oral mucosa, choking, or severe hypersensitivity reactions could occur.
  16. SE of Codeine; hydrocodone:
    • Lightheadedness
    • nausea
    • sedation
    • constipation
  17. CI of antitussives:
    • Dextromethorphan and MAOI inhibitors (selegiline, tranylcypromine, phenelzine,       isocarbozazid) use within 14 days;
    • Why? MAOI directly inhibit this enzyme, increases the amount in the synapse-increased  risk of serotonin syndrome- confusion, uncoordination, agitation
    • Ppl  are abusing unexpected OTC & rx meds
    • -dextromethorphan taken in high doses can create euphoria
    • OTC  cough & cold med in children:
    • -lifestyle modifications are 1st line of tx: humidifiers, saline, & nose suctioner
    • -encourage parents to avoid using vicks, can make it worse
  18. Expectorants:
    facilitate the removal of mucous from the respiratory tract
  19. expectorant drugs:
    Guaifenesin (Robitussin) (Mucinex)
  20. Indication for expectorants:
    chest congestion
  21. MOA of expectorants:
    Increases volume & decreases viscosity of respiratory secretions, resulting in increased flow & clearance of irritants  (“loosens” phlegm)
  22. kinetics of expectorants:
    half-life is 1 hr
  23. Dosing for Cheratussin AC (codeine/guaifenesin):
    • 10/100/5ml
    • contains alcohol
    • 20 mg codeine PO q4-6h prn.
    • Adjust dose amount in renal impairment
  24. 20 mg is =      ___ mL
    20 mg= 10 mL
  25. 2 categories of Decongestant drugs:
    • Direct alpha-1 agonists
    • Indirect alpha-1 agonists
  26. Direct alpha-1 agonists drugs:
    • Phenylephrine (Dimetapp)- not very effective be it is poorly absorbed
    • Oxymetazolone
    • Naphazoline
  27. Indirect alpha-1 agonist drugs:
    • Pseudoephedrine
    • Ephedrine
  28. MOA of decongestants:
    all nasal decongestants are vasoconstrictors
  29. Indication of decongestants:
    • nasal congestion; reduces "stuffiness"
    • ocular congestion
    • -temporary relief of conjunctival congestion, itching, & minor irritation
    • -used alone or in fixed combo c/ antihistamines &/or astringents
  30. Oxymetazoline is:
  31. Naphazoline is:
    Naphcon, Visine A
  32. Kinetics  of decongestants:
    • orally, topically, and ophthalmics
    • Pseudoephedrine: (oral) onset c/in 30 mins
    • Nasal decongestion may persist for 8 hours following oral administration of 60 mg and up to 12 hours following 120 mg of the drug in extended-release capsules.
    • Presumed to cross the placenta
    • About 0.5% of an oral dose is distributed into milk over 24 hours.
    • Incompletely metabolized in the liver·
    • Excreted in urine·
    • Half-life is 9-16 hours; decreased excretion in alkaline urine
  33. SE of decongestants:    
    Imp SE of inhaled decongestants:
    • Inhaled: Rhinitis medicamentosa- rebound congestion
    • What can you do it pt has this? Taper them off it
    • CNS stimulation ; Anxiety, agitation, insomnia; take it during the day(Pseudophedrine)
    • Dizziness
    • Palpitations
    • increased blood pressure
    • urinary retention
    • Topical agents may cause stinging, burning & dryness
  34. CI of decongestants:
    • Severe HTN
    • CAD
    • MAOI use c/in 14 days (may lead to hypertensive crisis)
  35. What were the legal requirements put in place for Pseudoephedrine?
    • Combat Methamphetamine Epidemic Act of 2005
    • The act bans OTC sales of cold meds that contain the ingredient pseudoephedrine
  36. H1 antagonists (antihistamines):
    antagonize the allergic responses & other effects mediated by histamine
  37. H1 antagonists. First generation drugs:
    • Diphenhydramine (Benadryl)
    • Chlorpheniramine (Chlor-Trimeton)
    • Brompheniramine      
    • Promethazine (Phenergan)
    • Hydroxyzine (Vistaril)
    • Meclizine (Antivert) (Dramamine)
    • Clemastine (OTC & Rx) (Tavist Allergy)
    • Cyproheptadine (Rx) (Periactin)- DC'd
    • (Die C B Penis c/ Horrible and Mighty Condylomata & Chlamydia)
  38. H1 antagonists. Second generation drugs:
    • (Claritin)(Alavert) Loratadine - 10 mg·
    • (Zyrtec)Cetirizine
    • (Allegra) Fexofenadine
    • (Astelin) Azelastine (nasal)
    • (Optivar) Azelastine (ophthalmic)
    • (Clarinex) Desloratadine
    • (Xyzal) Levocetirizine
    • (Patanase) Olopatadine (nasal)
  39. Dosing and indication for Diphenhydramine (Benadryl)
    • Moderate to severe allergic rxns: 25-50 mg q 2-4 hrs.
    • not to exceed 400 mg/day
  40. Dosing for Loratadine (Claritin)
    10 mg
  41. Dosing for Cetirizine (Zyrtec)
    5-10 mg PO once daily
  42. Dosing for Fexofenadine (Allegra)
    • 60 mg PO 2x daily OR
    • 180 mg PO once daily
  43. Main indications for H1 histamine:
    allergic rxns
  44. Main indication for H2 histamine
    • to reduce gastric acid
    • Cimetidine (Tagamet)
    • Ranitidine (Zantac)
    • Famotidine (Pepcid)
  45. Histamine is primarily synthesized in
    mast cells
  46. An immune response mediated by histamine may lead to:
    • Bronchoconstriction
    • Vasodilation
    • Nerve sensitization
  47. MOA of H1 antagonists:
    • Antihistamines competitively antagonize histamine at the H1 receptor; altering the       immune response to an allergen:  (opposite of:)
    • -Bronchoconstriction
    • -Vasodilation
    • -Nerve sensitization
  48. Rhinitis:
    inflammation of the mucous membrane
  49. Allergic rhinitis:
    • Due to mucous membrane exposure to an inhaled allergen; results in a specific       response mediated by immunoglobulin E (IgE)
    • Response is characterized by sneezing, itchy, runny nose, & often nasal congestion & postnasal drip. Itchy eyes, ears and throat frequently accompany allergic rhinitis.
  50. Indications for H1 antagonists:
    • Allergic  symptoms
    • Allergic reactions
    • Urticaria
    • Motion sickness prevention
    • Nausea
  51. approaches for H1 antagonists:
    • allergen avoidance
    • pharmacotherapy to prevent or treat symptoms
    • specific immunotherapy
    • Antihistamines are more effective in preventing, rather than reversing, the actions of histamine.
    • Reversal of symptoms is probably due, in part, to the anticholinergic effects of the drugs.
  52. Symptoms that oral antihistamines control
    • Sneezing,runny nose, itching, conjunctivitis
    • For seasonal. Begin tx before allergen exposure
  53. Symptoms that ophthalmic antihistamines control:
  54. Symptoms that intranasal antihistamines control:
    Sneezing, runny nose, nasal itchiness
  55. Kinetics of H1 antagonists:
    • Well absorbed
    • Large volume of distribution
    • Metabolized by liver
    • Older agents are lipid soluble
  56. SE of H1 antagonists:
    • Anticholinergic (drying) effects: (first generation)
    • Dry mouth
    • Difficulty urinating
    • Constipation
    • Changes in vision
    • Drowsiness (less of a problem with second generation)
  57. Cautions of H1 antagonists:
    patients <6 and >65 years old, CNS depressant use, increased intraocular pressure, hepatic or renal disease, hypertension, asthma, COPD, peptic ulcer disease, BPH, hyperthyroidism