Antihistamines

Question 1

Cetrizine

Answer 1

2nd generation H1 blocker- longer acting with more sedating effect than other 2nd generation blockers

Question 2

Fexofenadine

Answer 2

2nd generation H1 blocker - lower incidence of sedation

Question 3

Desloratadine

Answer 3

2nd generation H1 blocker

Question 4

Loratadine

Answer 4

2nd generation H1 blocker - Long acting with little sedation

Question 5

Chloropheniramine

Answer 5

1st generation H1 blocker - slight sedation; common component of OTC “cold” medications

Question 6

diphenhydramine

Answer 6

1st generation H1 blocker
- used to suppress extrapyramidal, Parkinson’s-like acute dystonic reactions and sx associated with the use of antipsychotic medications

• safe cheap and effective

Question 7

promethazine

Answer 7

1st generation H1 blocker, used as an antiemic to prevent motion sickness

Question 8

azelastine hydrochloride

Answer 8

0. 1% nasal spray used for seasonal allergic rhinitis
   - second generation H1 blocker

AE’s: somnolence, bitter taste, nasal burnining, sore throat, dry mouth

Question 9

1st vs. 2nd generation H1 blockers?

Answer 9

2nd generation drugs do not cross BBB due to it being more hydrophilic

• Thus the muscarinic receptors in the CNS are not stimulated, and there is no drowsiness as a SE
• have longer elimination t1/2 than 1st generation, thus have longer duration of action
• lower incidence of antimuscarinic side effect: i.e. dry mouth, dysuria

Question 10

what are antihistamines effective for?

Answer 10

sneezing, nasal itching, nasal discharge (rinorrhea)

not that effective in tx of congestion (must add decongestant)

Question 11

SE’s of first generation agents?

Answer 11

sleepiness
interfere with learning
decrease work productivity
impair psychomotor performance
increases risk of injury

**SE’s may persist morning after taking the drug

Sedation *

CNS: dizziness, tinnitus, nervousness, insomnia, fatigue, blurred vision

GI:nausea, vomiting, loss of appetite

Dry Mouth

Urinary retention (due to antimuscarinic effect)

Question 12

SE’s of second generation?

Answer 12

primarily GI: nausea, vomiting, loss of appetite

Question 13

Decongestant drugs?

Answer 13

alpha agonists: cause vasoconstriction, reduce edema

• available as nasal spray or oral tablets
• pseudoephedrine, phenylephrine, naphozoline, oxymetazonline, tetrahydrozoline, xylometazoline
• Effective only for relief of nasal congestion and not sneezing, itching, or discharge (often thus combined with H1-antihistamine)

Overdose AE’s:
insomnia, excitability, headache, nervousness, palpitations, tachycardia, arrhythmia, hypertension, nausea, vomiting, and urinary retention.

• Should not be used more than 3 days in order to avoid rebound congestion and rhinitis medicamentosa -> congestion will get worse

Question 14

Codeine

Answer 14

antitussives - opioid class used for central suppression of cough reflex

Question 15

Dextromethorphan

Answer 15

antitussives - opioid class used for central suppression of cough reflex

Question 16

list of antitussives?

Answer 16

codeine, detromethorphan, benoxinate (local anesthetic), diphenhydramine (antihistamine)

Question 17

N-acetyl-cysteine

Answer 17

expectorant: Facilitate secretion or decrease viscosity of mucus to facilitate clearance of mucus secretions in airways.

breaks sulfhydryl bonds in mucus proteins; makes mucus less sticky

• also can be used for tyelonol OD

Question 18

Guaifenesin

Answer 18

expectorant: Facilitate secretion or decrease viscosity of mucus to facilitate clearance of mucus secretions in airways.
- facilitaes removal of viscous mucous

Question 19

recombinant DNAse

Answer 19

• useful in cystic fibrosis to break up mucus plugs

Question 20

chronic problems of rhinitis?

Answer 20

locally delivered corticosteroids... beclomethasone dipropionate
budesonide
flunisolide
fluticasone propionate
triamcinolone acetonide

Question 21

ipratropium bromide

Answer 21

quaternary muscarinic receptor antagonist that doesn’t get into the systemic system - thus no major systemic effects

used intranasally (Roxane) to reduce secretions in the upper and lower respiratory tract in allergic rhinitis and chronic postnasal drip syndrome.

Question 22

Cromolyn sodium

Answer 22

nasal spray - are anti-inflammatory agents that indirectly inhibit antigen-induced bronchospasm and directly inhibit the release of histamine and other autocoids from sensitized mast cells.

May suppress the activating effects of chemoattractant peptides on eosinophils, neutrophils, and monocytes.

Cromolyn compounds do not directly relax smooth muscle, therefore they are not useful for control of acute bronchospasm.

Cromolyn compounds are primarily prophylactic. When inhaled several times daily, they inhibit both the immediate and late asthmatic responses to antigenic challenge or exercise.

Question 23

intranasal corticosteroids

Answer 23

they are hydrophobic and can easily get into the cells - these are the most effective drugs available for relief of sx of allergic rhinitis through inhibition of inflammaiton

beclomethasone dipropionate, budesonide, flunisolide, mometasone furoate, triamcinolone acetonide

• they reduce sneezing, itching, discharge, and congestion and are available in pump/spray formulations
• have very little SE’s: dryness, irritation of nasal mucosa, sore throat, epistaxis, h/a

Question 24

Montelukast

Answer 24

“Singulair” - blocks leukotriene receptor

• Modestly beneficial for relief of sneezing, itching, discharge, and congestion

Question 25

tx of allergic conjunctivitis?

Answer 25

main sx. is itching, may be seasonal or perennial -

treatment:

1. oral antihistamines, 2nd generation
2. topical eyederops with antihistamine eye drops
3. Antihistamine/decongestant combinations:
   pheniramine/naphazoline (Visine A)
   antazoline/naphazoline (Vasocon-A): these are over the counter, but can cause rebound vasodilation with continued use

Question 26

prophylaxis of type A influenza?

Answer 26

Amantadine - these inhibit the uncoating of viral nucleic acid and are used for tx initiated within 48 hours after initial appearance of sx

Question 27

H1 receptor activation results in?

Answer 27

bronchoconstriction, exocrine excretion, increased capillary permeability, vasodilation, and increased intracellular Ca2+ due to IP3, DAG

Question 28

what does histamine do?

Answer 28

1. seen in allergies, anaphylaxis, inflammation
2. decreases blood pressure and increase HR
3. results in histamine h/a due to vasodilation
4. “triple response of Lewis”
5. causes constriction of bronchioles

Question 29

what are antihistamines used?

Answer 29

1. allergic conditions - i.e. rhinitis and urticaria; but ineffective against bronchial asthma
2. motion sickness- 1st generation
3. insomnia - 1st generation use