Drugs acting in Respiratory System

1. Drugs acting
in
Respiratory System
DR. SAROJ SUWAL

2. Drugs categories
 Anti Tussive and Expectorants
 Drugs used in Bronchial Asthma
 Drugs Used in Tuberculosis

3. COUGH
 is protective reflex,
 expulsion of respiratory
secretions or foreign particles
from the lungs & upper
airway passages.

4. why cough ?

5. Mechanism of Cough
 occurs due to stimulation of mechano- or
chemoreceptors in throat, respiratory passages or
stretch receptors in the lungs

6. Two types of Cough
Productive Cough
 Wet cough
 Useless, should be suppressed
 so cough suppressants
Non-Productive Cough
 Dry or tenacious Cough
 Useful , it serves to drain airway
 Suppression is not desirable
 Expectorants or mucolytics need
 May be harmful

7. Drugs Used for Cough
1. Pharyngeal demulcents
2. Expectorants (Mucokinetics)
3. Antitussives (Cough center suppressants)
4. Adjuvant antitussives

8. Pharyngeal demulcents
 Demulcent
a substance that relieves irritation of
the mucous membranes in the
mouth by forming a protective film.
 Lozenges, cough drops, linctuses
containing syrup, glycerine,
liquorice, Honey

9. Mechanism of Action
Demulcent
sooth the throat
reduce afferent impulses from the
inflamed/ irritated pharyngeal mucosa
provide symptomatic relief in dry
cough in throat.

10. Anti Tussive Drugs
Reduce the activity of the cough
center in the Brain
are used to relieve dry cough
suppress coughing
Used for Dry Cough

11. Anti tussive MOA
ACT on CNS
raise the
threshold of
cough center
or
act
peripherally in
the respiratory
tract
reduce tussal
impulses
Or
both these
actions.
Suppress
COUGH

12. Anti Tussive Drugs Classifications
 Centrally acting antitussives: →acts directly on medulla on cough
center
 Narcotics
Opioids(codeine, hydrocodone, morphine)
 Non Narcotics
 dextromethorphan
 Diphenhydramine
Locally acting antitussive
Anti Histamine
 demulcent ,throat lozenges, steam inhalant, Local anesthetic(benzonatate)
Antitussive of choice = Codeine
Mild to moderate cough = codeine and
pholcodine
Severe persistent cough of bronchial
cancer = Morphine and methadone

13. Not given to whom?
 contraindications
for those who have undergone thoracic and abdominal
surgery
precaution to pt with asthma, emphysema, COPD ( may
accumulation of secretions may occur

14. Codeine
 An opium alkaloid
 Suppress the cough center
 Has limited analgesic effect
 It is more selective for cough center and is treated as
the standard antitussive
 used for mild to moderate pain
hydrocodon are likely to be even stronger but they are
also accompanied by much greater risks (respiratory
depression, dependence).

15. ADR
 Abuse
 Retention of urine
 itching or hypersensitivity
 palpitations or bradycardia
 Most common →constipation,
 At higher doses→ respiratory depression and drowsiness
 it is contraindicated in asthmatics.
 Dose
 Tab. CODOPHOS 15mg PO TDS 5 days
 10 mg of phalcodine same as 15mg of codine

16. Dextromethorphan
 selective antitussive action ,Centrally acting
 raises threshold of cough centre
 dsesnt have analgesic property
 doesnot depress respiratory center
 effective as codeine, does not depress mucocilliary function of the airway mucosa
 is practically devoid of constipating and addicting actions.
 The antitussive action lasts for ~ 6 hours
 Side effect:
 Dizziness, nausea, drowsiness, ataxia. mental confusion
 Dose: 10 – 30 mg oral TDS

17. Antihistamines
 NON narcotic antitussive
 Many H1 antihistamines have been
conventionally added to antitussive
/expectorant
 They block the allergy mediators
 Chlorpheniramine (2–5 mg),
 Diphenhydramine(15–25 mg) and
 Promethazine (15–25 mg;)
 citrizine( 10 mg tds)
 levocitrizine 5 mg tds

18. Mechanism of Action of Anti Histamine Drugs
Anti histamine
Drugs
Blocks at H1
Receptor
Relaxation of
Smooth muscles in
Respiratory tract
• Also Decrease
Vascular
Permeability
• Reduction of
Puritus

19. Expectorant (Mucokinetics)
 agents given orally
 liquefy respiratory secretions and allow for their easier
removal
 Two types:
1. Mucokinetics : Bronchial secretion enhancers (
1. Sodium or Potassium citrate, Potassium iodide, Guaiphenesin
(Glyceryl guaiacolate), balsum of Tolu, Vasaka, Ammonium
chloride.
2. mucolytics
1. Bromhexine, Ambroxol, N-Acetyl cysteine, Carbocisteine

20. Bronchodilators
 Bronchospasm can induce or aggravate cough.
 Stimulation of pulmonary receptors can trigger both
cough and bronchoconstriction, especially in
individuals with bronchial hyperreactivity.
Bronchospasm
Stimulation of
Pulmonary receptor
Bronchoconstriction
and Cough

21. Bronchodilators
 Clear secretions by increasing surface velocity of
airflow during cough.
 relieve cough in such individuals
 improve the effectiveness of cough in
 Eg Salbutamol

22. Mucolytics
 are administered by inhalation
 to liquefy mucus in the respiratory tract.
 may be nebulized into a face mask or mouthpiece or instilled
directly into the respiratory tract through a tracheostomy.
 Sodium chloride solution and acetylcysteine (Mucomyst) the
agents recommended for use as mucolytics.