Respiratory: Inhaled Antihistamines Flashcards
Types of Respiratory Drugs:
Bronchodilators: Beta2-Receptor Agonists:
Basic Understanding:
Azelastine (Astelin, Astepro) and olopatadine (Patanase) are
the intranasal H1 blockers currently available in the United
States. They are used for the treatment of seasonal allergic
rhinitis and vasomotor rhinitis.
Types of Respiratory Drugs:
Bronchodilators: B2RAs:
Pharmacodynamics:
Azelastine is an H1 agonist and a potent inhibitor of histamine release from the mast cells. Azelastine and its metabolite
desmethylazelastine inhibit the effects of histamine by competing with histamine for H 1 binding sites. Azelastine may
also interfere with histamine- and leukotriene-induced bronchospasm. Olopatadine is a selective H1 receptor antagonist.
Types of Respiratory Drugs:
Bronchodilators: B2RAs:
Pharmacokinetics: Absorption and Distribution:
Azelastine, administered intranasally, has a systemic oral
bioavailability of 40%. Protein binding of azelastine is 88%
and for the active metabolite desmethylazelastine, it is 97%.
Peak serum concentrations are reached in 2 to 3 hours. Exact
absorption information is unknown. Distribution is unknown, but because somnolence is a reported adverse effect,
azelastine is assumed to enter the CNS. It is unknown whether
azelastine crosses the placenta or is distributed in breast milk.
Olopatadine is absorbed from nasal mucosa and peaks in
15 minutes to 2 hours after administration. The portion of
olopatadine absorbed is 55% protein bound.
Types of Respiratory Drugs:
Bronchodilators: B2RAs:
Pharmacokinetics: Metabolism and Excretion:
Azelastine is metabolized into the principal active metabolite
desmethylazelastine. Following intranasal dosing of azelastine to steady state, plasma concentration of desmethylazelastine is 20% to 30% of azelastine. Excretion of azelastine and
desmethylazelastine is via the feces. Olopatadine is not extensively metabolized and is eliminated in the urine.
Types of Respiratory Drugs:
Bronchodilators: B2RAs:
Pharmacotherapeutics: Precautions and Contraindications:
Some patients using intranasal azelastine may experience
somnolence and should be cautioned not to drive or operate
heavy equipment while using it. Patients should not use alcohol or other CNS depressants while using azelastine. Olopatadine is contraindicated only in patients with nasal diseases
other than allergies. Spraying into the eyes should be avoided.
It is unknown whether azelastine is excreted in breast
milk. Use during lactation with caution. Olopatadine has
been measured in the milk of nursing rats; no studies of use
in lactating women have been done. Because seasonal allergic
rhinitis is not generally a life-threatening disease, the benefits
do not outweigh the unknown risks to the infant.
Azelastine and olopatadine are Pregnancy Category C. It
should be used in pregnancy only if the potential benefits outweigh the risks to the fetus. There are no adequate studies in
pregnant women. In animals receiving more than 240 times
the normal dose, external and skeletal abnormalities have
been noted.
The safety of azelastine in children under age 5 years and
of olopatadine in children younger than age 12 years has not
been established.
Types of Respiratory Drugs:
Bronchodilators: B2RAs:
Pharmacotherapeutics: Adverse Drug Reactions:
There is an additive impairment of CNS function when azelastine is used with ethanol or other CNS depressants. When
azelastine is coadministered orally with cimetidine, the area
under the curve (AUC) and Cmax are increased by 65%. Data
regarding interactions with intranasal azelastine and cimetidine are not available. Azelastine should be used cautiously
with other antihistamines. There is theoretical additive CNS
depression when olopatadine is administered with other
CNS depressants or alcohol.
Types of Respiratory Drugs:
Bronchodilators: B2RAs:
Pharmacotherapeutics: Drug Interactions:
There are no clinically significant drug interactions with
cromolyn. Cromolyn solution for nebulizer use will form a
precipitate if mixed with ipratropium solution.
Types of Respiratory Drugs:
Bronchodilators: B2RAs:
Pharmacotherapeutics: Rational Drug Selection:
Oral Versus Intranasal Antihistamine
The provider may choose to use intranasal azelastine or
olopatadine rather than a systemic antihistamine because of
decreased adverse effects or fewer drug interactions noted
with the intranasal product.
Cost
The cost of azelastine (Astelin) is $146 for a 30 mL bottle,
with the generic costing $77 for a 30 mL bottle. Olopatadine
(Patanase) costs $175 for a 30.5 g bottle
Patient Variables
Azelastine should not be prescribed to children under age
5 years and olopatadine should not be prescribed to children
younger than age 12. Both drugs should be used with caution
in pregnant and lactating patients.
Types of Respiratory Drugs:
Bronchodilators: B2RAs:
Pharmacotherapeutics: Monitoring
There is no specific monitoring required with the use of azelastine or olopatadine other than symptoms of allergic rhinitis to determine efficacy.
Types of Respiratory Drugs:
Bronchodilators: B2RAs:
Pharmacotherapeutics:
Patient Education:
Administration
The patient should be instructed to prime the medication
unit before use by pumping the activator 4 times, or until a
fine mist appears. The patient should keep the sprayer
pointed away from the face, other people, and pets when
priming the medication. The patient should wipe the tip of
the sprayer with a clean tissue after using and replace the cap
between uses. To prevent the spread of infection, the sprayer
should be used by only one person.
Adverse Reactions
The patient should be instructed about the most common adverse reactions. Caution regarding driving or operating heavy
equipment while using azelastine should be stressed. The bitter
taste that some patients experience may be decreased by drinking water or another fluid after administration. The patient
should report any unusual adverse reactions to the provider.
The patient should be cautioned not to drink alcohol or take
any other CNS depressants while using intranasal azelastine.
The patient may not be aware that an intranasal medication
can have an interaction with an orally administered medication, and therefore, the provider must give careful instructions
before prescribing azelastine.
Lifestyle Management
Lifestyle management related to the disease process needs to
be discussed with the patient. Points to discuss often include
avoidance of known allergens and using environmental
methods to control dust mites and other common allergens.
