Study Set Content:
At ordinary dosages, children occasionally (and adults
rarely) manifest (blank) rather than sedation.
excitation
At very high toxic dose levels, marked stimulation,
agitation, and even convulsions may precede
coma
have little or no
sedative or stimulant actions.
Second generation H1 antagonists
Several first-generation H1 antagonists have significant
activity in preventing
motion sickness
Certain H1 antagonists, notably (blank)), were used widely in the past in the treatment
of nausea and vomiting of pregnancy.
doxylamine (in Benedictin)
Some of the H1 antagonists, especially
(blank), have significant acute
suppressant effects on the extrapyramidal symptoms
associated with certain antipsychotic drugs
diphenhydramine
diphenhydramine This drug is given parenterally for to antipsychotics
acute dystonic
reactions
Many first-generation agents, especially those of the
ethanolamine and ethylenediamine subgroups, have
significant (blank) on peripheral
muscarinic receptors.
atropine-like effects
This action may be responsible for some of the (uncertain)
benefits reported for non-allergic rhinorrhea but may also
cause urinary retention and blurred vision.
atropine-like effects
Alpha-receptor blocking effects can be demonstrated for
many H1 antagonists, especially those in the
phenothiazine subgroup, eg, promethazine.
ADRENOCEPTOR-BLOCKING ACTIONS action may cause (blank) in
susceptible individuals.
orthostatic hypotension
is not
observed.
Beta-receptor blockade
Strong blocking effects at serotonin receptors have been
demonstrated for some first-generation H1 antagonists,
notably
cyproheptadine
cyproheptadine drug is promoted as an
antiserotonin agent
Nevertheless, its structure resembles that of the
phenothiazine antihistamines, and it is a potent
H1-
blocking agent.
Several first-generation H1 antagonists are potent (blank). anesthetics. They block sodium channels in excitable
membranes in the same fashion as procaine and lidocaine.
potent local
anesthetics.
are actually
more potent than procaine as local anesthetics.
They are occasionally used to produce local anesthesia in
patients allergic to conventional local anesthetic drugs.
Diphenhydramine and promethazine
Certain H1 antagonists, eg, (blank), inhibit mast cell
release of histamine and some other mediators of
inflammation.
cetirizine
This action is not due to H1-receptor blockade and may
reflect an
H4-receptor effect.
The mechanism is not fully understood but could play a
role in the beneficial effects of these drugs in the
treatment of allergies such as
rhinitis
