Autocoids are the self treating substance and local hormones . which is create changes in body Phisiology on the situation of to admine poisonous as well as foreign substance.
in this ppt gives Physiology of 5HT , Prostaglandin, and Histamine with their clinical use and adverse effect.
Also discussed about anti histamine , 5 HT antagonist with suitable examples.
2. Autocoids
Definition
Autocoids are chemical substances produced by different cells of the body. They act as local
hormones at the site where they are synthesized and released, and change the function of the
other cells. e.g. histamines, Serotonin (5-HT), Prostaglandin (PG)
Autacoids
Polypeptides
Histamine
serotonin
Lipids
Amines
Kinins
angiotensin
Prostaglandins
Leukotriene's
Thromboxane
3. Histamines
Histamines are organic compound belonging to amine group . They are produced
in almost all the cell , But released in large amount when immune system is
defending against antigen. . They show their action when bine to their receptor
H1 receptor H2 receptor H3receptor H4 receptor
Smooth muscle
contraction
Increase gastric
acid secretion
Stimulates
sensory nerve
It make allergy
and
inflammation
worst
Increase
permeability of
capillaries
Increase
contractility of
heart muscle
Itching in skin
Histamines
4. 1) On CNS: Stimulates sensory neuron and give a feeling of itching
and other senses
2) On CVS:
• Dilation of blood vessels.
• Increases permeability of capillaries.
• Histamine shock: large amount of histamine causes too much vasodilation
and causes death.
• Increases contraction force of heart.
3) Inflammation and Allergic reaction: when antigen interacts with IGE
antibody present on the mast cell surface, the mast cell releases histamine
which causes inflammation and allergic reaction
4) Gastric Acid Secretion: H2 receptor present in gastric mucosa and when
histamine binds with it stimulates acid secretion
Pharmacology of Histamines
5. Definition
The Drugs prevent action of histamine are called anti-histamines or histamine antagonists.
Classification
1) H1 Antagonists: Diphenhydramine Hydrochloride, Cyclizine hydrochloride.
2) H2 Antagonists: Cimetidine, Rantidine.
3) H3 Antagonist: Thioperamide, Clobenpropit.
H1 Antagonists
H1 antagonist inhibit function of H1 receptor
First Generation H1 antagonist :
Diphenhydramine Hydrochloride, Cyclizine hydrochloride, Pyrilamine maleate, Promethazine hydrochloride etc.
They cross blood Brain Barrier easily and produce laziness
Second generation H1 antagonists : Cetirizine, Levocetirizine, acrivastine, Azelastine hydrochloride etc.
They don't cross blood Brain Barrier easily and produce laziness.
Anti-Histamines
6. Clinical Uses
1) Allergic disorders: H1 antihistamines are used to treat and prevent symptoms of allergic
reactions, like Dermatitis, Conjuctivitis, Pruritus (Itching), urticaria (skins rash ).
2) Common Cold: they are used to relief common cold symptoms.
3) Preanaesthetic Medication: it is used for its sedative and anticholinergic actions.
4) As anti- emetics : Promethzine, diphenhydramine etc. are used for prophylaxis of motion
sickness.
5) Parkinson's disease: it is used to treat Parkinson's disease .
6) Sedative and Hypnotics : it is used for sedative and hypnotic effects
Adverse Effects
1) feeling of sleep 2) Dryness of mouth and nose 3) blurred vision
Over dose : cause Central Excitation, Convulsion, respiratory and cardiac failure, and death
7. H2 -Antagonists
These drugs prevent the action of H2 receptors
Examples Cimetidine, Ranitidine, Famotidine.
Clinical Uses
They are used to prevent Gastric secretion in diseases like Hyperacidity, Gastric ulcer,
GRD etc.
Adverse Effects
1) Headache
2) Constipation
3) Vomiting
4) Gynacomastia (man boobs)
5) Impotency in males
H3 and H4 Antagonist
Thioperamide and Clobenpropit are H3 receptor antagonists but H3 and H4 antagonists are not used
usually, because their usefulness is still not clear
8. Definition
5 Hydroxy Tryptamine is an important neurotransmitter, it is synthenthesised by amine acid ,Tryptophan . It is
widely found in animal and plant, High concentration of 5HT is found in intestine, platelets and brain.
Physiological Roles
1) On CVS : It shows a complex action on CVS which depends on dose
a) On blood vessels: in starting induces vasoconstriction but later induces vasodilation.
b) On Heart It induces a positive chronotropic effect (Increases heart rate) and positive inotrope effect is also seen.
c) on blood pressure: its action on BP is complex. It may either cause hypotension or hypertension
2) Action on Smooth Muscles : It causes contraction of intestine bronchi, and uterus.
3) On Digestive System: It increases intestinal motility, and induce Emesis (vomiting)
4) On Lungs it causes contraction of bronchi.
5) Uterus: it increases contraction of Uterus.
6) On CNS:
a) It regulates the sleep, mood and appetite
b) Migraine contraction and relaxation of brain vessels sue to 5-HT causes a repeated and severe pain.
7) Allergic and Inflammatory actions: it involves in allergic and inflammatory reaction
5 Hydroxy Tryptamine ( Serotonine )
9. 5-HT Antagonists
Cyproheptadine, ketanserin, Ondansetron, Granisetron, Clozapine, olenzapine etc.
Clinical uses
1) Cyproheptadine
a. It is used in skin allergy like pruritus and urticaria.
b. It is used to treat Carcinoid tumor (slow growing tumor at any part of the body)
c. it is used to treat Migraine
2) Ketanserin: it is used as antihypertensive drug, it dilates blood vessels.
3) Ondansetron and Granisetron : these are used as anti-emetics
4) Clozapine, olenzapine, resperidone : these are used as antipsychotics.
Adverse effects
1. Dry mouth
2. Drowsiness
3. Weight gain
10. Definition
Prostaglandins (PGs) are lipid compounds. Arachidonic acid is the precusor for biosynthesis of
all PGs, and COX (Cyclooxygenase) enzyme involves in formation of PGs when phospholipid
membrane is damage due to any reason.
Physiological Roles
1) GI Tract: PGE2 and PGI2 reduce acid secretion and increase the secretion of mucus in the
stomach. Misoprostol, Rantidine are used to prevent ulcer due to NSAIDs.
2) Cardiovascular System: PGD2, PGE2 and PGI2 cause vasodilation, PGF2a Constricts
pulmonary veins and arteries. TXA 2 is a Vasoconstrictor
3) Platelets: PGI2 inhibits platelet aggregation. It is used during Haemodialysis to prevent
platelets aggregation.
4) Eye: PGF2a decreases the ocular pressure. Its analogues are used in glaucoma e.g.
Latanoprost, Bimatoprost etc
5) Uterus PGE2 (low concentration) and PGF2a Contract Pregnant Uterus, PGs are commonly
used for abortion. They can used for Induction of labour.
6) Male reproductive system: PGE, is useful in the treatment of erectile dysfunction. e.g.
alprostadil.
Prostaglandins
11. Clinical Uses
1) abortion
2) Induction of labour
3) PPH To treat postpartum hemorrhage ( excessive bleeding after childbirth)
e.g. Carboprost (i.m.) Misoprost (oral)
Adverse effects
nausea, Vomiting, diarrhoea, fever, flushing ( reddening of skin) hypotension etc
