Antihistamine Drugs

Antihistamine Drugs

1. Anti histamines PREPARED BY: USHA RANI KANDULA, ASSISTANT PROFESSOR, DEPARTMENT OF ADULT HEALTH NURSING, ARSI UNIVERSITY,ASELLA,ETHIOPIA, SOUTH EAST AFRICA.

2. Anti histamines Histamine is an important chemical mediator that is stored in mast cell located in almost all body tissue.

3. Histamine is released in response to antigen for which a person has developed antibodies.

4. The effect of histamine include : Contraction of smooth muscle in the bronchi, GI tract and uterus Vasodilatation and increased capillary permeability ( edema)

5. Increased secretion of gastric juice, increased bronchial, intestinal and salivary secretion. Pain and itching caused by sensory nerve stimulation.

6. Antihistamine prevents the effect of histamine by occupying the histamine receptors.

7. The two types of histamine receptors are H 1 and H 2 receptors. H 1 receptors : are those associated with the smooth muscle of the blood vessels, bronchioles, GI tract.

8. H 2 receptors : are found on gastric parietal cells, the myocardium and certain blood vessels.

9. Mechanism of action

10. Antihistamines are H 1 antagonists and produce the following effects : 1. smooth muscles : H 1 anatagonist effectively inhibits the response of smooth muscles to histamine.

11. In the vascular smooth muscles, the H 1 antagonist inhibit the vasoconstrictor effect of histamine on the large blood vessels.

12. 2. capillary permeability : H 1 antagonist blocks the action of histamine, which leads to increase leakage of plasma.

13. 3. Nerve endings : H 1 antagonist effectively blocks the action of histamine on nerve endings, which cause itching and flare.

14. 4. Anaphylaxis and allergy : Many manifestations of type I (immediate ) hypersensitivity reaction like - urticaria - pruritis and angioedema are well controlled by H 1 antagonists.

15. Commonly used antihistamines - azatadine : 1-2 MG/oral - carbinoxamine : adults : 4-8 mg/oral children : 2-6 mg/oral

16. - pheniramine maleate ( chlorpheniramine ) : -4mg oral/IV

17. - dexchlor pheniramine ( polaramine ) : - adults 2 mg oral - dimenhydrinate : - adults 50-100mg -children 25-50 mg

18. - diphenhydramine ( benadryl ) adults : 25-50 mg children : 5mg/kg/day oral / iv / deep im

19. - phenindamine 25 mg oral - promethazine ( phenergan ) 12.5 – 50 mg oral / IM

20. - cetrizine ( levocetirizine ) 10 mg oral - loratadine 10-20 mg oral - fexofenadine 150-250 mg oral

21. Indications

22. INDICATIONS Allergic disorders Allergic rhinitis Common cold Insect bites Drug reactions Anaphylactic reactions

23. Allergic cough Urticaria Pruritis Nausea and vomiting

24. Uses

25. USES Allergic reactions to transfusion of blood or blood products.

26. Contraindications

27. Contraindications Narrow-angle glaucoma Prostatic hypertrophy Bladder neck obstruction Peptic ulcer disease

28. Asthma Pregnant women Dehydrated children Premature infants

29. Side effects

30. SIDE EFFECTS Sedation Dizziness Epigastric distress Dryness of mouth Thickened bronchial secretions

31. Nursing responsibilities

32. Nursing responsibilities Monitor for therapeutic and adverse effects. Administer IV slowly to prevent severe hypotension. Give antihistamines with food to decrease GI distress.

33. Assess client for drowsiness during first few days of therapy. Administer medications at bed time to help with the side effect of drowsiness.

34. Patient education

35. Patient education Take medications exact as prescribed. Avoid contact with allergens, responsible for the reaction. Do not take more than one medication at a time.

36. Do not operate heavy machinery or participate in other hazardous activities while taking this type of medications.

37. Thanking you