antihistamines l.
Skip this Video
Loading SlideShow in 5 Seconds..
Antihistamines PowerPoint Presentation
Download Presentation

Loading in 2 Seconds...

play fullscreen
1 / 21

Antihistamines - PowerPoint PPT Presentation

  • Uploaded on

Antihistamines. Serotonin Agonists. H 1 receptors inhibit smooth muscle contraction decrease wheal, flare,and itch decrease secretions: salivary and lachrymal CNS: sedation. H 2 receptors inhibit gastric acid secretion decrease content and volume of gastric juice

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript


Serotonin Agonists

histamine antagonists
H 1 receptors

inhibit smooth muscle contraction

decrease wheal, flare,and itch

decrease secretions: salivary and lachrymal

CNS: sedation

H 2 receptors

inhibit gastric acid secretion

decrease content and volume of gastric juice

fasting, food stimulated and nocturnal

Histamine Antagonists
h 1 antagonists
H 1 antagonists
  • Relief of manifestations of immediate-type hypersensitivity reactions
    • allergic rhinitis
    • cold remedies
  • newer agents “selective” for peripheral H 1 receptors
    • less sedation (dose dependant)
antihistamine products

diphenhydramine (Benadryl)

chlorpheniramine (Chlor-Trimeton)


fexofenadine (Allegra)

loratadine (Claritin)

cetirizine (Zyrtec)*

* metabolite sedating

Antihistamine Products
  • dose related even for newer agents
  • most common ingredient in OTC sleep aids
children s formulations
Children’s Formulations
  • Most available as syrups
  • Allegra
    • 30 mg tab
  • Claritin
    • 10 mg Redi-tab (fast dissolve)
ucdhs adult allergic rhinoconjunctivitis guidelines

January 2001

UCDHS Adult Allergic Rhinoconjunctivitis Guidelines

HealthNet: Nasonex, Nasacort

Pacificare: Rhinocort, Nasonex, Nasarel

WHA: Rhinocort, Nasonex, Nasacort AQ

Approved UCDMG P&T Committee January 2001

Reviewed by: T. Albertson S. Teuber, M. E. Gershwin, R. Mowers, J. Fischer

other routes of administration
azelastine (Astelin)

nasal spray

allergic rhinitis

decrease side effect profile

Bitter amine taste

sedation (systemic absorption)

olopatadine (Patanol)

emedastine (Emadine)

ophthalmic antihistamine H 1

allergic conjuctivitis and itching

headache, taste perversion, abnormal dreams

other routes of administration
h 2 antagonists
H 2 Antagonists
  • Therapeutic Indications
    • duodenal and gastric ulcer
    • gastroesophageal reflux disease (GERD)
    • erosive esophagitis
    • hypersecratory conditions
    • heart burn, indigestion, sour stomach
    • multidrug regimen for the eradication of H.Pylori in peptic ulcer disease
uc davis primary care adult tx gerd
UC Davis Primary Care Adult Tx: GERD

Drug AWP/ea

Protonix® 40 mg 3.00

Aciphex® 20 mg 3.70

Prevacid® 30 mg 3.88

Nexium® 20 mg 3.99

Prilosec® 20 mg 4.15

Beck IT et al. The Second Canadian Consensus Conf. on Management of Patients with GERD. Can J Gastroenterol 1997;11 suppl B 7-20.

Katz PO. Treatment of GERD: Use of Algorithms. Am J Gastroenterol 1999;94(11)suppl:3-10.

Reviewed by; T. Albertson, J. Lee, J. Fischer, R. Mowers

UCDMC P&T Committee January 2002

June 2001

adverse reactions
Adverse Reactions
  • low incidence of side effects
  • headache and fatigue - 1%
  • cimetidine
    • highest incidence of gynecomastia (1- 4%)
    • P450 drug interactions
      • decrease digoxin levels
      • increase flecainide activity
serotonin 5 ht1 agonists
Serotonin 5-HT1 agonists
  • Treatment of Migraine with or without aura.
  • Acute treatment of Cluster headaches.
  • Drugs are combination of 5-HT (1A, 1B, 1D, 1E, 1F, 7)
  • No activity at 5HT 2-4 receptors, adrenergic, muscarinic, dopaminergic
mechanism of action
Mechanism of Action
  • Stimulation 5HT-1 receptors in extracerebral and intracranial blood vessels results in vasoconstriction. Also seen is an inhibition of neuropeptide release and decreased transmission in trigeminal pain pathways.
  • It is thought cranial vessel dilation induced by release of vasoactive peptides from sensory nerve endings in an active trigeminal system my be a root cause of Migraine.
prototype agents
Prototype agents
  • sumatriptan (Imitrex)
    • Tablets, nasal spray, injection
  • rizatriptan (Maxalt)
  • Several others
common adverse events
Common adverse events
  • Generally well tolerated
  • Events with 5% rate: paresthesia, nausea, dizzsiness, fatigue, dry mouth, headache, flushing
  • Rare but serious events: cardiac events with fatalities, cerebrovascular events with fatalities (hemorrhage, stroke, others)
rebound headache
Rebound headache
  • The risk of rebound headaches increases with the number of doses taken.
  • Patient information:
    • Take as soon as possible
    • Second dose may be taken if no response in 2 hours
    • Limit injections to 2 per 24 hours
    • Contact MD before taking additional doses if no response
Other drugs for Migraine Treatment

Ergot alkaloids such as dihydroergotamine (Migranal, DHE 45)

Migraine Prophylaxis

Beta blockers

Calcium channel blockers