ch 39 drugs for allergic rhinitis

What does the upper respiratory tract do?

warms, humidifies, cleans, incoming air

What is the upper respiratory tract controlled by

autonomic nervous system

What is allergic rhinitis

inflammation of nasal mucosa

What is allergic rhinitis characterized by

watery eyes, sneezing, nasal congestion

what does allergic rhinitis cause

histamine release

what are preventers of allergic rhinitis

antihistamines, intranasal corticosteroids, mast cell stabilizers

what are relievers of allergic rhinitis

oral and intranasal decongestants, usually sympathomimetic

what is histamine

chemical mediator of inflammatory response

where is histamine 1 (H1) receptors found

smooth muscle of vascular system and bronchial tree

what does histamine cause when it reacts with the H1 receptor

many symptoms of allergic rhinitis

where are histamine 2 (H2) receptors found

stomach

what does histamine cause when it reacts with H2 receptors

causes peptic ulcers

What is the H1 antagonist (Antihistamines)

diphenhydramine (Benadryl)

What is the mechanism of action of diphenhydramine

histamine receptor blocker (first gen)

adverse effects of diphenhydramine

drowsiness, paradoxical CNS stimulation and excitability, anticholinergic effects

administration alerts for diphenhydramine

increased risk of anaphylactic shock when administered parenterally

What is the drug of choice for treating allergic rhinitis that has high efficacy and a wide safety margin

Intranasal corticosteroids

What is the prototype drug for intranasal corticosteroids

fluticasone (Flonase)

what is the mechanism of action for fluticasone

decrease local inflammation in nasal passages, thus reducing nasal stuffiness

adverse effects of fluticasone

nasal irritation, epistaxis

contraindications of fluticasone

hypersensitivity to the drug, patients with known bacterial, viral, fungal, or parasitic infections

food interactions with fluticasone

caution with licorice, may potentiate the effects

How long should you use intranasal preparation decongestants (sympathomimetic)

only 3-5 days because of rebound congestion

What is the response time like and are there systemic effects for oral preparation decongestants

more systemic effects, slower response time, less effective at relieving severe congestion

what is the decongestant prototype drug

oxymetazoline (Afrin)

what is the mechanism of action for oxymetazoline

stimulated alpha-adrenergic receptors in sympathetic nervous system; causes arterioles in nasal passages to constrict; dries mucous membranes

adverse effects of oxymetazoline

rebound congestion when used for longer than 3-5 days; minor stinging and dryness in nasal mucosa may be experienced

contraindications for oxymetazoline

patients with thyroid disorders, hypertension, diabetes, or heart disease

prototype drug for antitussives

Dextromethorphan (Delsym)

what is the mechanism of action for dextromethorphan

acts in medulla to inhibit cough reflex

adverse effects of dextromethorphan

dizziness, drowsiness, GI upset

contraindications of dextromethorphan

treatment of chronic cough

herbal/food interactions for dextromethorphan

grapefruit juice

what do expectorants and mucolytics do?

help loosen thick bronchial secretions; directly break down mucous molecule; make mucous thinner for easier removal by coughing

what are expectorants and mucolytics used for

cystic fibrosis, chronic bronchitis, or other diseases producing thick mucus

What do respiratory trees end in

dilated sacs called alveoli

How does gas move in the lower respiratory tract

gases move between blood and inspired air

what do semipermeable membranes allow

oxygen to enter the blood; carbon dioxide and cellular waste products to leave the lungs

what do bronchioles consist of

muscular, elastic structures; diameter (lumen) varies with contraction or relaxation of smooth muscles (diameter controlled by ANS)

What is respiration

process of brining O2 into body and moving carbon dioxide out

What are the two main processes of respiration

ventilation: moves air into and out of the lungs

perfusion: flow of blood through the lungs

How does the sympathetic branch contribute to autonomic control of airways

- activates beta 2 adrenergic receptors and causes bronchiolar smooth muscles to relax

- the airway diameter increases (bronchodilation)

How does the parasympathetic branch contribute to autonomic control of airways

- causes bronchiolar smooth muscle to contract

- the airway diameter is narrowed: bronchoconstriction occurs

results in less airflow

Describe administration by inhalation

common route of admin for pulmonary drugs; rapid and efficient; rich blood supply allows for quick absorption and onset of action; delivers drugs directly to sites of action

describe oral therapy

longer duration of action; frequent side effects; tolerance may develop

what is aerosol therapy?

Suspension of droplets or particles in a gas

Describe aerosol therapy

onset of action almost immediate

describe aerosol drugs administered for local effect

- immediate relief of bronchospasm

- loosens thick mucus

are there side effects for aerosol therapy

side effects are reduced, systemic effects can still occur

disadvantages of aerosol therapy

- Difficult to measure precise dose

- Usually, only 10 to 50% of drug is placed

- Instruction may be complicated for some patients

- Side effects occur if patient swallows drug or does not rinse mouth after inhalation

What kind of devices are used for aerosol therapy

nebulizer, metered dose inhaler (MDI), dry powder inhaler (DPI)

Describe action of nebulizer

- vaporizes liquid drug into fine mist

- uses small machine and face mask

describe action of metered-dose inhaler

- propellant delivers measured dose of drug

- patient times inhalation to puff of drug

describe action of dry powder inhaler

- patient inhales powdered drug

- device activated by inhalation

Describe asthma

a chronic disease

- has both inflammatory and bronchospasm components

when do symptoms of asthma occur

- from exposure to triggers

- upon exertion (exercise induced)

What are asthma drugs used for

- prevent asthma attacks

- terminate attack in progress

What are the twofold goals of asthma therapy

- to terminate acute bronchoconstriction component and inflammation component (short acting meds)

- to reduce the frequency of asthma attacks (long acting meds)

what are examples of quick-relief asthma meds

beta 2 adrenergic agonists, anticholinergics, systemic corticosteroids

what are examples of long-acting asthma meds

inhaled corticosteroids, mast cell stabilizers, leukotriene modifiers, long-acting beta 2 adrenergic agonists, methylxanthines, and immunomodulators

what are the most effective drugs for relieving acute bronchospasms

beta-adrenergic agonists

what do beta-adrenergic agonists do

activate beta 2 receptors in bronchial smooth muscle to cause bronchodilation

- fewer cardiac side effects than old drugs in this class

- range from ultrashort to long-acting

what is the prototype drug for Bronchodilators - Beta-adrenergic agonists

albuterol

what is the mechanism of action for albuterol

selectively binds to beta 2 adrenergic receptors in bronchial smooth muscle to cause bronchodilation

what are adverse effects for albuterol

headaches, throat irritation, nervousness, restlessness, tachycardia, chest pain w allergic rxn

administration alerts for albuterol

proper use of inhaler is essential

contraindications for albuterol

Hypersensitivity, caution in pts with cardiac dysrhythmias

drug interactions with albuterol

concurrent use with beta blockers will inhibit effect

describe anticholinergics

block parasympathetic nervous system with bronchodilator effect

- occasionally used as alternative to beta agonists in asthma therapy

- used in inhaled form

what is the prototype drug for anticholinergic - bronchodilators

ipratropium (atrovent)

what is the mechanism of action for ipratropium

causes broncho dilation by blocking cholinergic receptors in bronchial smooth muscle

adverse effects of ipratropium

cough, drying of nasal mucosa, hoarseness, bitter taste

admin alerts for ipratropium

proper use of MDI, 2-3 mins between doses

contraindications for ipratropium

other drugs in its class, antidiabetic drugs

What are methylxanthines?

group of bronchodilators related to caffeine

- once mainstay of asthma pharmacotherapy

- admin IV or oral

side effects of methylxanthines

common

- nausea, vomiting, CNS stimulation

- interacts with numerous drugs