Histamine And Antihistamine

1. Presenter: Ajit Kumar Yadav
M.Pharm(Pharmacology)
Histamine and Antihistaminics

2. Introduction of Histamine
 Histamine is present mostly within storage
granules of mast cells. Histamine is distributed in
Mast Cells in all peripheral tissues of the body
and basophils, which circulate in the blood
 Tissues rich in histamine are skin, gastric and
intestinal mucosa, lungs, liver placenta.
 Histamine is also present in blood, most body
secretions, venoms and pathological fluids.
Synthesis, storage and destruction
 Histamine is β imidazolylethylamine. It is
synthesized locally from the amino acid histidine
and degraded rapidly by oxidation and
methylation.

3. Synthesis and degradation of histamine
MAO-Monoamine oxidase

4. ANTIHISTAMINE

5. Classification of Anti-Histamine
Drugs
1. HIGHLY SEDATIVE
 Diphenhydramine 25–50 mg oral BENADRYL 25,
50 mg cap., 12.5 mg/5ml syr.
 Dimenhydrinate 25–50 mg oral, DRAMAMINE 16
mg/5 ml syr, 50 mg tab
 Promethazine 25–50 mg oral, PHENERGAN 10,
25 mg tab., 5 mg/ml elixer,
 Hydroxyzine 25–50 mg

6. Conti…..
2. MODERATELY SEDATIVE
 Pheniramine 20–50 mg oral, AVIL 25 mg, 50 mg
tab, 15 mg/5 ml syr,
 Cyproheptadine 4 mg oral PRACTIN, CIPLACTIN
4 mg tab., 2 mg/5ml syrup,
 Meclozine (Meclizine) 25–50 mg oral In DILIGAN
12.5 mg + niacin 50 mg tab
 Cinnarizine 25–50 mg oral

7. Conti……
3. MILD SEDATIVE
 Chlorpheniramine 2–4 mg (0.1 mg/kg) PIRITON,
CADISTIN 4 mg tab,oral, i.m.
 Dexchlorpheniramine 2 mg oral POLARAMINE 2
mg tab, 0.5 mg/ 5 ml syr
 Triprolidine 2.5–5 mg oral ACTIDIL 2.5 mg tab.,
ACTIFED 2.5 mg
 Clemastine 1–2 mg oral

8. Cont……
4. SECOND GENERATION ANTIHISTAMINICS
 Fexofenadine 120–180 mg oral ALLEGRA, ALTIVA, FEXO
120, 180 mg tab
 Loratadine 10 mg oral LORFAST, LORIDIN, LORMEG, 10
mg tab,1 mg/ml susp.
 Desloratadine 5 mg oral DESLOR, LORDAY,
NEOLORIDIN 5 mg tab
 Cetirizine 10 mg oral ALERID, CETZINE, ZIRTIN, SIZON
10 mg tab,
5 mg/5 ml syr.
 Levocetirizine 5–10 mg oral LEVOSIZ, LEVORID,
TECZINE 5, 10 mg tab
LEVOCET 5 mg tab, 2.5mg/5 ml syr.
 Azelastine 4 mg oral AZEP NASAL SPRAY 0.14 mg
 Mizolastine 10 mg oral ELINA 10 mg tab
 Ebastine 10 mg oral EBAST 10 mg tab
 Rupatadine 10 mg oral RUPAHIST 10 mg tab

9.  CLINICAL USE OF ANTIHISTAMINE
 Allergic rhinitis (common cold)
 Allergic conjunctivitis (pink eye)
 Allergic dermatological conditions
 Urticaria (hives)
 Angioedema (swelling of the skin)
 Pruritus (atopic dermatitis, insect bites)
 Anaphylactic reactions (severe allergies)
 Nausea and vomiting (first generation H1-
antihistamines)
 Sedation (first generation H1-antihistamines)