As part of an immune response to foreign pathogens,
histamine is produced
by basophils and by mast cells when
contacting the antigen.
Mast cells found at site of likely injury…nose,mouth,
feet, GI tract, respiratory,blood vessels.
Histamine will bind with certain receptors on cells to
give different results.
Histamine is also a brain neurotransmitter.
H1 receptor found in smooth muscle, endothelial cells.
histamine will cause increase of permeability of
vessel wall and brochoconstriction, runny nose.
H2 receptor found in stomach and vascular smooth
muscle cells histamine will cause gastric acid increase
H3 receptor found in CNS tissue. Histamine yields
H4 receptor found in basophils,bone marrow.
deals with chemotaxis.
Two main effects of anaphylactic shock on the body
are severe drops in blood pressure and impaired
The drastic drop in blood pressure
develops from the severe peripheral vasodilation
and the increased permeability of the capillaries.
The impaired breathing arises from
bronchoconstriction. The anaphylactic reaction
occurs very rapidly after the introduction of the
antigen into the patient.
Unless prompt action is taken by medically trained
personnel, the patient will die in a matter of minutes.
The drug used for anaphylactic shock is epinephrine.
Action- competes with histamine due to similar
structure. for treatment of allergies, insomnia, rash,
and prophylaxis for drug allergies
Adverse reactions- drying up body fluids, drowsiness,
and hyperactivity in some children
Considerations- these are the antidote for overdose in
anitpsychotic meds, and do not mix with alcoholsynergistic effect
action- supresses cough
Indicated for nonproductive coughs!
Opioid and non-opioid (narcotic and non-narcotic)
Mechanism of Action-Opioids---Suppress the cough reflex by direct action
on the cough center in the medulla
examples: codeine (Robitussin A-C, Dimetane- DC)
Onset: 15-30 min
Non-opioids/non-narcotic (less effective)
Suppress the cough reflex by anesthetizing the
stretch receptors in the respiratory tract and
preventing the cough reflex from being stimulated
by the medulla center in the brain
examples: benzonatate (Tessalon Perles)
dextromethrophan (Vicks Formula 44, Robitussin-DM)
Onset: 15-30 min
Reactions- depression, light-headedness
Considerations- dextromethorphan reacts with
due to the potential for seratonin syndrome, which is a potentially
condition that can occur rapidly, due to a buildup of an excessive
amount of serotonin
benzonatate must be swallowed not chewed. may cause
choking feeling, chest painn or numbness, hallucination, confusion.
Action- stimulates alpha adrenergic receptor to
constrict arteries within the nasal mucosa. many cells
have these receptors, to stimulate sympathetic NS.
Treats congestion from cold, sinusitis and infections
Reactions- increased blood pressure, increased heart
rate, insomnia, anxiety, tremors, rebound effect
Considerations- should be avoided by patient who
have DM, heart disease, enlarged prostate, tourette’s
Action- decrease thickness of mucus to remove or
cough out of the lungs. increase bronchial secretion
Reactions- vomiting and GI distress
Special considerations- drink plenty of water