antihistamines and antitussives

Question 1

antihistamine and antitussive drug uses

Answer 1

• allergic rhinitis (reaction)
• cough
• cough and cold preparations

Question 2

histamine effects

Answer 2

• released by mast cells
• cause symptoms of allergic reactions
• blood vessel dilation (redness/warmth), leaky capillaries (swelling), nerve ending stimulation (itchy)

Question 3

antihistamines general info

Answer 3

histamine receptor antagonists
- drugs that compete with histamine for receptor site
- 2 histamine receptor types: H1, H2

H1: cause swelling and allergic rxn symptoms
H2 antagonists: reduce gastric acid in PUD

Question 4

antihistamine mechanism of action

Answer 4

block H1 receptors and prevent consequences of histamine receptor stimulation
- vasodilation
- increased GI and respiratory secretion
- increased capillary permeability

Question 5

histamine vs antihistamine effects

Answer 5

cardiovascular/small blood vessels:
- histamine: dilation and increased permeability (swelling)
- antihistamine: reduce dilation of blood vessels, reduce permeability of blood vessels

exocrine glands:
- histamine: stimulate salivary, lacrimal, bronchial secretions
- antihistamine: reduce salivary, lacrimal, bronchial secretions

Question 5

antihistamine other uses

Answer 5

skin: reduce capillary permeability, wheal and flare formation, and itching (pruritus)

Question 6

antihistamine indications

Answer 6

palliative treatment (not a cure, make comfortable)
- nasal allergies
- allergic reactions
- seasonal or perennial allergic rhinitis (hay fever)

• motion sickness
• sleep disorders

Question 7

main types of antihistamines

Answer 7

• traditional
• nonsedating/peripherally acting

Question 8

traditional antihistamines

Answer 8

• antagonists of H1 receptors
• peripherally: reduce respiratory/eye symptoms
• centrally: cause sedation - CNS
• have anticholinergic effects
• used in nighttime relief (causes drowsiness)

Question 9

traditional antihistamine example

Answer 9

diphenhydramine

Question 10

traditional antihistamines other effects

Answer 10

anticholinergic effect
- act on cholinergic receptors
- drying effect that reduces nasal, lacrimal gland and salivary secretions (runny nose, tearing)

Question 11

traditional antihistamines adverse effects

Answer 11

anticholinergic effects:
- dry mouth (reduce salivary secretions)
- difficulty urinating
- constipation
- changes in vision (dilated pupils, blurred vision - PNS affects lens shape for focus)
- high HR

Question 11

nonsedating/peripherally acting antihistamines

Answer 11

developed to eliminate unwanted adverse effects (sedation)
- work peripherally (fewer CNS adverse effects)
- longer duration of action (longer half life)

Question 12

nonsedating/peripherally acting antihistamines examples

Answer 12

• loratadine
• desloratadine
• fexofenadine
• cetirizine

Question 13

antihistamines nursing implications

Answer 13

traditional:
- report excessive sedation, confusion, hypotension
- avoid driving or operating heavy machinery
- do not consume alcohol or other CNS depressants

Question 14

antitussives

Answer 14

drugs to reduce cough
- opioids
- other agents
- used only for non productive coughs

Question 15

cough

Answer 15

respiratory secretions and foreign objects are naturally removed from by the cough reflex

cough reflex:
- induces coughing and expectoration
- initiated by irritation of sensory receptors in the respiratory tract
- reflex happens in the brain when info from the resp tract is sent to CNS then reflex sent back to body to cough
- controlled by medulla oblongata below the level of consciousness

Question 16

two basic types of cough

Answer 16

1) productive cough (congested, removes excessive secretions)
2) nonproductive cough (dry cough)
- can be harmful in situations like after hernia surgery

do not suppress productive cough (can be beneficial to remove excess secretions and harmful foreign substances)

Question 17

antitussives mechanism of action

Answer 17

opioids (lower dose than for analgesia):
- suppress cough reflex
- act in cough centre of medulla
ex: codeine, hydrocodone

Question 18

common OTC antitussive (nonopioid)

Answer 18

dextromethorphan (synthetic opioid like compound)

diphenhydramine (antihistamine)

Question 19

antitussives indications

Answer 19

used to stop cough reflex when the cough is unproductive and/or harmful

Question 20

antitussives adverse effects

Answer 20

codeine: sedation, nausea, vomiting, lightheadedness, constipation (typical opioid effects)

dextromethorphan: dizziness, drowsiness, nausea (less CNS effects)

Question 21

antitussive nursing implications

Answer 21

report:
- cough lasting over a week
- persistent headache
- fever
- rash

only use for nonproductive coughs