Histamine

• mast cell stabilizers

• H1 receptor antagonists

• H2 receptor antagonists

• H3 receptor agonist and antagonist

drugs that affects histamine

mast cell stabilizers

inhibitors of mast cell degranulation and histamine release

• cromolyn sodium

• nedocromyl

mast cell stabilizers use for prophylaxis fo asthma believed to inhibit calcium influx

lodoxamide tromethamide

• prevents antigen-induced calcium influx into mast cells that causes histamine release

  • used topically for inflammatory diseases of the eye

• ethanolamines

• ethylenediamine

• piperazine

• propylamine

• phenothiazene

first generation anti-histamines

ethanolamines

• blocks H1, a1, M1, D2, 5HT

• most sedating class of antihistamines

sedation

most common side effect of first generation histamines

diphenhydramine HCl

prototype ethanolamine drug

ethanolamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

carbinoxamine maleate

ethanolamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

dimenhydrinate

ethanolamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

diphenhydramine hcl

ethanolamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

diphenylpyraline HCl

ethanolamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

doxylamine succinate

ethanolamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

clemastine fumarate

ethylenediamine

derivatives of ethanolamines, less sedating

ethylenediamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

phenbenzamine

ethylenediamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

pyrilamine maleate

ethylenediamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

methapyriline HCl

ethylenediamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

tripelennamine HCl/citrate

ethylenediamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

thonyzylamine HCl

ethylenediamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

antazoline phosphate

piperazine

used to treat dizziness

piperazine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

cyclizine HCl/lactate

piperazine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

chlorcyclizine HCl

piperazine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

meclizine HCl

piperazine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

hydroxyzine HCl

piperazine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

buclizine HCl

propylamine

used for cough and col remedies

propylamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

pheniramine maleate

propylamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

brompheniramine maleate

propylamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

chlorpheniramine maleate

propylamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

pyrrobutamine phosphate

propylamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

triprolidine HCl

propylamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

dimethindene maleate

propylamine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

phenindamine tartrate

phenothiazine

anticholinergic, a1 antagonist (produce hypotension), dopamine antagonist, local anesthetic effect, antiarrythmic action, used as a sedative and an antiemetic

anti malarials

phenothiazine were first investigated as _______

phenothiazine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

promethazine HCl

phenothiazine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

trimeprazine tartrate

phenothiazine

identify the classification of the first generation histamine (ethanolamine, ethylenediamine, piperazine, propylamine, phenothiazine)

methdilazine HCl

second generation histamines

• have little affinity for muscarinic, adrenergic, or serotonergic receptors

• this compounds were developed as selective H1 receptor antagonists with relatively high potency

• they also produced prolonged antihistaminic effects

• piperidines

• piperazines

• pyrrolidine

second generation anti-histamines

piperidine

identify the classification of the second generation histamine (piperidine, piperazine, pyrrolidone)

terfenadine

piperidine

identify the classification of the second generation histamine (piperidine, piperazine, pyrrolidone)

fexofenadine HCl

piperidine

identify the classification of the second generation histamine (piperidine, piperazine, pyrrolidone)

aztemizolep

piperidine

identify the classification of the second generation histamine (piperidine, piperazine, pyrrolidone)

loratadine

piperidine

identify the classification of the second generation histamine (piperidine, piperazine, pyrrolidone)

levocarbastine

fexofenadine HCl

terfenadine metabolite but less cardiotoxic

levocarbastine

ophthalmic piperidine

cetirizine

• is the primary acid metabolite of hydroxyzine resulting from complete oxidation of the primary alcohol moiety

• relatively polar = does not cross BBB

• can be given once a day

• terfenadine

• aztemizole

first discovered second generation anti histamines but are cardiotoxic

pyrrolidine

identify the classification of the second generation histamine (piperidine, piperazine, pyrrolidone)

acrivastatine

acrivastatine

• potency and DOA comparable to triprolidine

• no significant anticholinergic activity at therapeutic concentrations

• enhanced polarity limiting BBB penetration

dual acting histamines

compounds that block the release of histamine from mast cells (MCS) and antagonize the actions of histamine at H1 receptors

• azelastine

• ketotifen

• permirolast

dual acting histamines

H2 receptor antagonist

• can inhibit responses to gastric secretagogues

• commonly used for:

  • GERD

  • peptic ulcer disease

  • nonulcer dyspepsia

  • prevention of bleeding from stress-related gastritis

cimetidine

interferes with several imporatant hepatic cytochrome P450 drug metabolism pathways

(CYP1A2, CYP2C9, CYP2D6, and CYP 3A4)

• cimetidine

• ranitidine

• famotidine

• nizatidine
  

H2 receptor antagonists

90

nizatine has __% bioavailability and is taken orally