Drugs for Rhinitis and allergies, Martin, Lec Flashcards
What are the H1 1st generation classic antihistamines
chloropheniramine
diphendydramine (benadryl)
promethazine (phenergan)
What are the H1 snd generation non-sedating antihistamines
cetirizine (zyrtec)
fexofenadine (generic Allegra)
desloratadine (clarinex)
loratadine (claritin)
What are the H2 blockers (gastric acid inhibitors)
cmietidine
famotidine
nizatidine
ranitidine
where is histamine natrually stored
mast cells
basophils
CNS and peripheral nerves as NT
Activation of H1 R results in what
bronchoconstriction exocrine excretion increase cpaillary permability contraction intestinal smooth m stimulation sensory nerve ending
how does H1 R signaling owrk
couples Gq and phospholipase C to increase hydrolysis, increase IP3 and DAG, increase intracel Ca
Where are H1 R found
smooth muscle
endothelial cells
brain
What are the effects of H2 stimulation
increase gastric H+ secretion!!!
cardiac effects
vasodilatory effects
mechanism of H2 R
inc adenyly cyclase so increase cAMP
where are H2 R found
gastric mucosa, heart, mast cells, brain
What are the CV effects of histamine
dec BP increase HR
increase force and rate of contraction
difference of low does histamine and higher dose on heart
low does activate H1 high dose activate H2 local edema and dilations histamine headache histamine shock
what is the triple response of lewis related to histamine release in skin
localized red spot- local dilation, seconda
flush or flare- axon reflex
wheal- local edema within 1-2 min
effects of histamine on non-vascular smooth muscle
bronchiolar constriction (asthmatics sensitive)
histamine affects on exocrine glands
gastric acid secretion via H2 R
effects of histamine on nervous system
pain, itching and lewis response in periphery
central is NT release
What leads to histamine release
IgE mediated (type I HS)
IgG or IgM mediated immune reactions
drug or chemical indued
physical release
what drugs can lead to release histamine
morphine, organinc bases (antibiotics)
why are the 2nd generation antihistamines non-drowsy
do not readily enter CNS
H1 blockers don’t work where?
H2 or preventing histmaine release
how do 1st generation H1 blockers lead to sedation effect
bing muscarinic cholinergic R and cross CNS
what type antihistamine is effective in preventing motion sickness
H1 1st generation, antiemesis and antinausea
which antihistamine is widely used as antiemetic
promethazine (phenergan)
indications for antihistamines
allergic conditions, motion sickness
insomnia
side effects antihistamines
sedation CNS nausea, vomiting antimuscarinint (dryness mouth, nasal passages, urinary retention) HS reactions
What are signs of overdose antihistamines
child- excitation, hallucination, ataxia, convulsions
fixed dilated pupils with flushed face and fever
can cause coma and cardiorespiratory collapse
why what terfenadine removed from market
caused torsades de pointes because mess with P 450 and CYP3A4
which H1 blokcer has antiserotonin activity
cyproheptadine
indications for H2 blokcer
peptic ulcer, gastric ulcer, zollinger-ellison syndrome
GERD
adverse effects H@ blockers
antiandrogenic, gynecomastia, galactorrhea
GI constipation, nausea, vomiting, diarrhea
CNS- HA dizzinesss hallucinations
hematologic- agranulocytosis, thrombocytopenia
liver toxicity
drug interactions cimetidine
inhibits CYP 450 oxidative drug metabolism system
so monitor when coadministered with P 450 metabolized drugs
