HISTAMINE AGONIST

Histamine - R-alpha methylhistamine

Betazole (aka. gastramine/histalog)

Impromidine

Methimepip

HISTAMINE AGONIST

• Blood clots, gastric acid secretion, blood vessels to dilate, bronchoconstriction, increase the permeability of the capillaries, adrenaline is released, swelling and inflammation, frequent heartbeat

THE BODY’S RESPONSE TO HISTAMINE RELEASE

H3-specific agonist

Histamine - R-alpha methylhistamine

gastramine/histalog

Betazole aka

H2-receptors

Betazole (aka. gastramine/histalog)

Betazole (aka. gastramine/histalog)

• Used as test Gastric stimulant function

Impromidine

investigational agent; its ratio of H2:H1 activity is about 10,000

H3 specific agonist

Methimepip

pentagastrin (Peptavlon)

• has an effect just like gastrin when given parenterally  which stimulates the secretion of gastric acids pepsin and intrinsic factor  and has been used as diagnostic agent 

(Peptavlon)

pentagastrin BN

• Flushing

• hypotension

• tachycardia

• headache

• wheals

• bronchoconstriction

• gastrointestinal 

ADVERSE EFFECTS OF HISTAMINE AGONIST

classical antihistamines

HISTAMINE (H1) RECEPTOR AGONIST aka

HISTAMINE (H1) RECEPTOR AGONISTAka: classical antihistamines

• Competitive inhibitors (reversible) at the H1-receptor.

• carbonoxamine,

• dimenhydrinate,

• diphenhydramine (trade name: Gravol/Dramami) (equimolar combination of diphenhydramine and 8-chlorotheophylline),

• doxylamine (BN: Unisom) (sleeping aid), Clemastine (Travist)

Ethanolamines

antiemetics (for vomiting)

Ethanolamines use

Gravol/Dramami

diphenhydramine Trade name

diphenhydramine (trade name: Gravol/Dramami

equimolar combination of diphenhydramine and 8-chlorotheophylline

Unisom

doxylamine BN

sleeping aid

doxylamine (BN: Unisom) use

Tavist

Clemastine BN

Pyrilamine,

Tripelennamine

Ethylaminediamines

1. Ethylaminediamines: 

• Pyrilamine, Tripelennamine

• Produce moderate sedation 

• Can cause GI upset

(Antiemetics, anti-motion sickness)

Piperazine use

• Hydroxyzine, Cyclizine, Meclizine (Bonamine)

Piperazine

Bonamine

Meclizine BN

• Brompheniramine, chlorpheniramine (present in Neozep)

Alkylamine

chlorpheniramine

present in Neozep

Promethazine

Phenothiazines

Anti emetics

Promethazine use

Promethazine

• Weak alpha-adrenoceptor antagonist

Cyproheptadine

Miscellaneous

Antihistamine, anticholinergic and antiserotonin activities

Cyproheptadine use

DOSING INTERVAL

Ideal antacid should be rapid in onset and provide a continuous buffering action

• Mg(OH)2, MgO, CaC03

Rapid onset

• Mg trisilicate and aluminum compounds

Slow onset

Buffering action

• capacity to resist pH changes upon addition of small amount of acid or base

• Soluble and readily absorbed

• Can cause electrolyte disturbance and alkalosis

• Side effects

Systemic antacid:Sodium bicarbonate

• Form insoluble compounds in the GIT (hard to excrete)

Side effects

• Non- systemic antacids: Al, Ca, Mg

Heart failure

Renal failure

• Patients with increased risk of antacid toxicity

magnesium

Renal failure = should not use

hypermagnesemia

Renal failure = should not use magnesium containing antacids (can cause