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Asthma, Justin Gillespie, Robyn Harris, & Lauren Van Rassel, Sealock,…
Asthma
Montelukast
Trade Name
Singulair
Indications
prevention and chronic treatment of asthma
management of seasonal allergic rhinitis
prevention of exercise-induced bronchoconstriction (EIB)
Mechanism of Action
Binds to LTD4 receptors
prevents smooth muscle contraction of bronchial airways
Pharmacokinetics
rapidly absorbed following oral administration (63-73%)
mostly metabolized by the liver, eliminated in feces, via bile with negligible renal excretion
distribution is unknown
peak onset is within 24 hours
oral (chewed) peak onset 2-2.5 hours, duration 24 hours
oral (swallowed) peak onset 3-4 hours, duration 24 hours
half-life is 2.7-5.5 hours
Contraindications/Precautions
do not use if allergic
use cautiously in acute attacks of asthma, reduction of corticosteroids, Phenylketonuria
use when pregnant/breastfeeding only if benefit to patient outweighs risk to infant
Adverse Reactions/Side Effects
headaches, nausea, diarrhea and nightmares, may cause liver dysfunction
Route/Dosage
Route: PO
Adult and children >15y/o dose: 10mg/day
Child 6-14 y/o: 5mg/day chew tab
Child 2-5 y/o: 4mg/day chew tab
Child 12-23mo: 4mg/day packet of granules
For exercise-induced bronchoconstriction
Adult/adolescent >15y/o: PO 10mg 2 hr prior to exercise. Do not take another dose w/i 24 hrs.
Nursing Implications
assessment: assess lung sounds prior to and periodically during therapy, assess for changes in behaviour related to suicidal thoughts or depression, assess for rash
implementation: may be gradually decreased with supervision, administer OD in the evening for asthma, or any time of day for allergic rhinitis; administer granules directly into mouth or mixed in soft foods (not fluids), administer dose within 15 minutes of opening, discard unused portion immediately. For EIB, take tablet 2+ hours before exercise, do not take within 24 hours of another dose
Patient & Family Teaching
this drug is for management of chronic symptoms, not to treat an acute attack
the medication is to help reduce the swelling of the lungs
should start seeing lessening symptoms in about a week
tablet needs to be chewed before swallowing
Avoid potentially hazardous activities, as dizziness may occur
fluid intake should be increased as possible
Do not use for acute asthma attacks
If also taking OTC meds with ephedrine, do not consume alcohol
Pathophysiology
Signs/Symptoms
Chest tightness
Cough
Shortness of breath
Airflow limitation on expiration
Wheezing
Etiology
Allergic Asthma
an acute immune response
early-phase response
immeiate and potent antigen-antibody reaction
reaction occurs on cells rich with histamines and leukotrienes (eg. mast cells)
triggers mucosal swelling and bronchoconstriction
late-phase response
Occurs 5-12 hours after initial response and can last several hours to days
airways become sensitized/hyper-responsive
further episodes may be triggered by factors other than allergens (eg. cold, dust, pollution)
neutrophils and eosinophils attract inflammatory mediators to create cycle of inflammation/obstruction
Chronic airway inflammation
Characterized by "attacks" - typically short and respond to medication
Can sensitize airways for future episodes of asthma attacks
Many possible triggers: allergens, exercise, viral respiratory infection, air pollutants, drugs
Age of onset ~50% before age 10, 80% before age 40
Treatment usually 2 types
Long-term symptom control
Taken on a regular schedule to help lessen and prevent symptoms
Rapid (acute) symptom control
Taken only when needed at the onset of an acute attack to alleviate symptoms
Justin Gillespie, Robyn Harris, & Lauren Van Rassel
Sealock, K., Lilley, L. L., Snyder, J. S., Collins, S. R., Seneviratne, C., & Lilley, L. L. (2021). Lilley's pharmacology for Canadian Health Care Practice. Elsevier.
Skidmore-Roth, L. (2011). Mosby's 2011 Nursing Drug Reference (24th ed.). Mosby.
Vallerand, A. H., & Sanoski, C. A. (2021). Davis's drug guide for Nurses. F.A. Davis Company.
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