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H1 receptor antagonist (antihistamine)
Indications:
1) treatment of allergic rhinitis
2) treatment of pruritus & urticaria
Adverse effects:
1) sedation
2) sleepiness
3) decreased motor skills
4) anticholinergic effects
- hyperthermia, dry skin & mucous membranes*, tachypnea, hypertension, mydriasis
- somnolence & coma to agitation & seizures
- hallucinations, delirium
5) sinus tachycardia
* distinguish from sympathomimetic amines -> diaphoresis
Laboratory:
- antihistamines in body fluid
- antihistamines in blood
- antihistamines in gastric fluid
- antihistamines in serum/plasma
- antihistamines in urine
Mechanism of action:
1) controls sneezing, itching, rhinorrhea
2) does not benefit nasal congestion
3) inhibits mast-cell activation
4) non-sedating antihistamines do not cross blood-brain barrier
Interactions
drug interactions
drug adverse effects (more general classes)
Specific
acepromazine; acetylpromazine (Atravet, Acezine 2)
acrivastine
alcaftadine (LASTACAFT)
antazoline (Vasocon-A)
astemizole (Hismanal)
azatadine (Optimine)
azelastine (Astelin, Optivar, Azeptin, Azelastinum, Astepro)
bepotastine (Bepreve)
brompheniramine (Dimetane)
carbinoxamine; rotaxamine (Allergefon, Lergefin, Ciberon, Clistin, Rotoxamina)
cetirizine (Zyrtec, Alertisin, Reactine, Zerviate)
chlorcyclizine
chlorpheniramine (Chlor-Trimeton)
clemastine (Tavist)
cyclizine (Marezine, Nautazine)
cyproheptadine (Periactin)
desloratadine (Clarinex)
dimenhydrinate (Dramamine)
diphenhydramine (Benadryl, Alledryl, Allergival)
doxylamine (UniSom)
emedastine (Emadine, Rapimine, Daren)
epinastine (Elestat, Alesion)
fexofenadine (Allegra)
hydroxyzine (Atarax, Vistaril)
ketotifen (Zaditor, Zaditen, Alaway, Claritin Eye, Zyrtec Itchy Eye Drops)
laropiprant
latrepirdine (Dimebon, dimeboline, dimebolin)
loratadine (Claritin)
methapyrilene (Paradormalene)
olopatadine (Patanol, Pataday)
orphenadrine (Norflex)
phenindamine (Nolahist)
pheniramine (Tripoton)
phentoloxamine; phenoxadrine
phenyltoloxamine
promethazine (Phenergan, Farganesse)
pyrilamine (Mepyramine)
terfenadine (Seldane)
tripelennamine (PBZ, Pyribenzamine, Pyrinamine, Stanzamine)
triprolidine (Actidil)
General
histamine receptor antagonist (antihistamine)
parasympatholytic (anticholinergic, antimuscarinic agent)
References
- Medical Knowledge Self Assessment Program (MKSAP) 11, 16 20.
American College of Physicians, Philadelphia 1998, 2012, 2025
- Prescriber's Letter 15(7): 2008
Comparison of Antihistamines
Detail-Document#: 240707
(subscription needed) http://www.prescribersletter.com
- O'Donoghue M, Tharp MD.
Antihistamines and their role as antipruritics.
Dermatol Ther. 2005 Jul-Aug;18(4):333-40.
PMID: 16297006
- McCoy CE, Honda R.
Anticholinergic Toxicity in the Emergency Department.
J Educ Teach Emerg Med. 2023 Jan 31;8(1):S25-S47.
PMID: 37465041 PMCID: PMC10332772 Free PMC article