Autacoids

Endogenous compounds (local hormones)

Play a role in the physiological and pathophysiological process.

Very short half life

Have a local action

Classifications

• Histamine

• Serotonin Amino acid

peptides

• PGs

• Leukotrienes

Fatty acid peptides

• Angiotensin

• Kinins (bradykinin)

• Endothelins

Vasoactive peptides

Histamine

Biosynthesis

Storage

Histamine Release

Allergic conditions

Release

Food poisoning from spoiled fish (Tuna)

Release

Drugs and peptides

Diseases

Distribution

Histamine receptors

Histamine receptors

Pharmacological effects of histamine

CVS (H1-H2)

V.D & Histamine shock

Capillary permeability (see)

Triple response (see)

Cardiac contractility and HR

Pharmacological effects of histamine

Smooth muscles (H2)

Bronchial and GIT

Peripheral nerve ending (H1)

Pharmacological effects of histamine

CNS

Histamine antagonism

Release inhibitors

• Mast cell stabilizers

• Glucocorticoids

Pharmacological antagonists

• H1 antagonists

• H2 antagonists

Physiological antagonism

Kinetics

Well absorbed from GIT.

Peak plasma level is achieved in 2-3 hours and effects usually lasts 4-6 hours (some have much long duration).

First generation drugs can pass BBB and placental barriers and some of them secreted in breast milk.

Metabolized by the liver and excreted in urine.

Pharmacological actions

Therapeutic uses

Allergic diseases

Motion sickness (Cyclizine- Meclizine-Promethzine)

Vertigo

Insomnia and anxiety associated diseases

Adverse effects