Antihistamines action
- Inhibit smooth muscle constriction in blood vessels, and the respiratory and GI tracts
- Decrease capillary permeability
- Decrease smooth muscle constriction in airways
- Decrease salivation and tear formation
- Act by binding with histamine receptor
First generation antihistamines
Cross blood brain barrier
Sedative
Diphenhydramine (Benadryl)
Dimenhydrinate (Dramamine)
Pyrilamine
Hydroxyzine
Chloropheniramine
Promethazine
Terfenadine
Danny Drives Past homelles californians periodically
Second generation antihistamines
- Longer half lives
- No antimuscarinic effects
- Dont cros blood brain barrier
- Non sedative
- Fexofenadine (Allegra)
- Loratadine (Claritin)
- Desloratadine (Clarinex)
- Cetirizine (Zyrtec)
- Acrivastine (Semprex-D)
Actions of 1st generation antagonists
Local anesthetic effect (creams)
Reduce motion sickness (Dramamine)
Promote sleep
Risks of second generation
Greater risk of cardiac arrhythmias
Adverse effects of antihistamines
Mucous mebranes dryness
Cardiac stimulation
Blurred vision
Urinary retention
Nasal decongestants
Adrenergic
Afrin SUdafed (psedoephedrine)
WHen are nasal decongestants contraindicated
Hypertension
CAD
Narrow angle glucoma
TCA
MAOI
Antitussives
Depresses cough center in medulla, increases saliva flow
Codeine, hydrocodone
Dextromethorphan
Cold remedies contain
examples
Antihistamine, decongestant, analgesic
Chloropheniramine
Pseudoephedrine
Acetaminophine
Dextromethorpan
Guiafenesin
