RESPIRATORY

HISTAMINES

zNaturally occurring in human tissue

ySkin

yIntestinal Mucosa

yRespiratory tract

zStored in mast cells

HISTAMINE PHARMACOLOGY

zCARDIOVASCULAR (H1 effect)

yCerebral vessel dilation - causes histamine headache

yCapillary dilation

xIncreased vascular volume

xDecreased BP

yIncreased capillary permeability

xAllows free passage of plasma and protein

xLeads to edema

HISTAMINE PHARMACOLOGY (H1)

zBronchoconstriction

 

zSensory Nerve Ending - itch

HISTAMINE PHARMACOLOGY

zGastrointestinal (H2 Effect)

ySecretagogue

xIncreases gastric acid section

xDirect effect on parietal cells

MECHANISM OF ACTION

zStimulate histamine receptors

 

yH1 Receptor

xBlocked by antihistamines

yH2 Receptor

xBlocked by anti-ulcer H2 antagonists

FUNCTIONS OF HISTAMINES

zHypersensitivity Reaction

yAllergy

yAnaphylactic Shock

zNormal Physiology

yRegulate microcirculation

yTissue Growth and Repair

yGastric acid secretion

CLINICAL USE OF HISTAMINE

zDiagnostic Agent

yAchlorhydria

INHIBITION OF HISTAMINE RELEASE

zCromolyn

yProphylactic agent that inhibits histamine release from mast cells

yOral inhaler, nasal inhaler, and ophthalmic use

ANTIHISTAMINES

zBlocks H1 receptors so that histamines cannot bind and stimulate

zOnset of H1 blockade can be delayed 3 days if histamines have already been released

zOther properties

yanticholinergic

ANTIHISTAMINE PHARMACOLOGY

zVASCULAR

yBlocks permeabilty and vasodilation

zNERVOUS SYSTEM

yBlocks itch

zSMOOTH MUSCLE

yAntagonizes bronchoconstriction

yNot acute therapy

Side Effects

zSedation

 

zAnticholinergic

THERAPEUTIC USE

zSymptomatic relief of allergies

yExudative allergies

yAllergic dermatoses - hives, urticaria

yPruritis

ANTIHISTAMINES

zIneffective for:

yanaphylactic shock

yacute bronchial asthma

ycommon cold

xutilize anticholinergic properties

ANTIHISTAMINES

zDiphenhydramine, cetirizine - highly sedating

zBrompheniramine, chlorpheniramine - less sedating

zFexofenadine, loratidine - long acting, low incidence of drowsiness

THEOPHYLLINES

zPharmacology

yBronchodilation (smooth muscle effect)

yDiuretic effect (chemically related to caffeine)

yIncreases heart rate - at high doses

yInduces seizures - at toxic doses

LEUKOTRIENE RECEPTOR ANTAGONISTS

zRelaxes Bronchiole Smooth Muscle

ADRENERGICS

zBETA 2 property

yBronchodilation

yBeware of beta 1 spill over

CORTICOSTEROIDS

zInhaler is preferred route

yAvoid adrenal suppression

 

 

EXPECTORANT

zStimulates increased production of mucous

zDecreases viscosity of mucous

zFacilitates removal of mucous through ciliary action and cough

zControversial effectiveness

MUCOLYTIC

zAcetylcysteine

yAdministered via respiratory therapy

yBreaks up mucous in respiratory tract

yAlso utilized as an antidote to acetaminophen toxicity