Cough:

Protective reflex caused by stimulation of sensory nerves

in the mucosa of pharynx, larynx, trachea, bronchi induced

by infections, stimulus like smoke, dust etc.

Productive : Associated with sputum.

Nonproductive : Dry cough-No sputum.

Purpose : To expel respiratory secretions.

1. Pharyngeal Demulcents :

Glycerine and liquorice.

Drugs used for cough:

2. Expectorants (Bronchial secretion enhancers ) :

Sodium citrate, potassium citrate, potassium iodide,

Guaiphenesin, vasaka, ammonium chloride

4. Antitussives (cough suppressants) :

Codeine, pholcodeine, noscapine, dextromethorphan

3. Mucolytic :

Bromhexine, Ambroxol,

Acetylcysteine, carbocisteine.

Expectorants

Increase the tracheobronchial gland secretions,

Reduce the viscosity,

Facilitating the removal of sputum.

Used in chronic productive cough

Mucolytics

Break thick tenacious sputum

Lower sputum viscosity

Induce thin copious secretion

sputum comes out easily with less effort

Used in productive cough in chronic bronchitis

Antitussives/ Cough suppressants

In brain - raise the threshold of cough center,

↓cough reflex, suppress cough center in medulla.

In respiratory tract - reduces the tussal impulses.

Used in Dry unproductive cough, cough in allergic states

Severe productive cough – disturb sleep, in hernia/ piles/

cardiac disease/ocular surgery

Histamine :

A chemical present in mast cells, skin, gastric,

intestinal mucosa, lungs etc.

Antihistaminic drugs block H1 receptor and antagonize

the actions of histamine.

Classification

A) First generation antihistamines :

Diphenhydramine, Dimenhydrinate,

Hydroxyzine, Promethazine.

Pheniramine, Cyprohyptadine, Cinnarizine,

Meclizine, Buclizine, Chlopheniramine,

Dimethindene, Tripolidine, Clemastine, Cyclizine

A) Second generation antihistamines :

Cetirizine, Levocetrizine, Azelastine, Mizolastine,

Loratadine, Desloratadine, Rupatadine, Fexophenadine.

Advantages of 2nd generation:

Higher H1 selectivity

No anticholinergic side effects

Don’t cross BBB – no CNS depressant

Don’t impair psychomotor performance in driving

Additional anti-allergic mechanism - ↓↓ histamine release

Limitations of 2nd generation:

Relatively expensive

No anticholinergic – rhinorrhea in cold

No sedation – in severe cough, in child

Uses of antihistamines1.Allergic diseases :

Block the effects of released histamines (pruritus,

urticaria, dermatitis, rhinitis, conjunctivitis) by allergens,

blood transfusion, saline infusion reaction (chills, rigor),

anaphylaxis

2. Insect bite, ivy poisoning and abnormal dermographism

3. Skin: Allergy, Pruritides, urticaria, atopic dermatitis

4. Allergic rhinitis

5. Common cold

6. Cough

7. Seasonal asthma

8.Parkinsonism

9. Vomiting :

Motion sickness, Morning sickness, Postoperative,

Radiation & drug induced vomiting.

10. Vertigo

11.Preanesthetic medication

Adverse effects of antihistaminics:

CNS - Sedation, diminished alertness and concentration,

motor incoordination.

Anti Chol - Dry mouth, blurring vision, constipation,

urinary retention.

Topical application – contact dermatitis.