All things histamine i think

Histamine on H1 (Location)

Smooth muscle

Endothelium

CNS

Histamine on H2 (Location)

Stomach (Parietal cells)

Heart

Histamine on H3 (Location)

CNS (Presynaptic)

Histamine on H4 (Location)

Bone marrow

Immune cells

Histamine on H1 Effect

Vasodilation, bronchoconstriction, and increased vascular permeability (edema), pain, itching

Histamine on H2 Effect

Increased gastric acid secretion, raises heart rate

Histamine on H3 Effect

Modulates neurotransmitter release (histamine, dopamine, serotonin)

Histamine on H4 Effect

Promotes inflammation and immune cell migration

Action of Histamine on Vascular system

Vasodilation

Action of Histamine on Respiratory system

Bronchoconstriction

Action of Histamine on GI

Increases gastric acid secretion

Action of Histamine on Nervous system

Stimulates sensory nerve endings (pain and itching)

Action of Histamine on the Heart

Increases heart rate and contractibility

Action of Histamine on Immune system

Attracts eosinophils and other immune cells

H1 Antihistamines (first generation) MOA:

Block histamine action at H1 receptors. Crosses the BBB and sedating.

H1 Antihistamines (second generation) MOA:

Blocks histamine action at H1 receptors. More selective, does not cross BBB and non-sedating.

H2 Blockers MOA:

Inhibit gastric acid secretion.

H3 Antagonist MOA:

Enhance CNS Neurotransmitter release.

H4 Antagonist MOA:

Reduce immune cell recruitment.

H1 Antihistamine (first generation) therapeutic use:

Allergies

Motion sickness

Nausea

Insomnia

H1 Antihistamine (second generation) therapeutic use

Long-term allergy relief

H2 Blockers therapeutic use:

GERD, Ulcers

H3 antagonists therapeutic use:

Potential treatment for cognitive disorders

H4 antagonists therapeutic uses

potential anti-inflammatory drugs