Class drugs used in cough

this class is in brief for under graduate understanding and examination purpose

1. Dr. RAGHU PRASADA M S
MBBS,MD
ASSISTANT PROFESSOR
DEPT. OF PHARMACOLOGY
SSIMS & RC.

2. Cough is a useful physiological mechanism that
serves to clear the respiratory passages of foreign
material and excess secretions.
Cough reflex is complex, involving the central and
peripheral nervous systems as well as the smooth
muscle of the bronchial tree.
It should not be suppressed discriminately.
Chronic cough can contribute to fatigue, especially in
elderly patients, in such situations the physicians
should use a drug that will reduce the frequency or
intensity of the coughing.

3. It has been suggested that irritation of the bronchial
mucosa causes bronchoconstriction, which in turn,
stimulates cough receptors (which probably
represent a specialized type of stretch receptor)
located in the tracheobronchial passages.

4. Stimulationofmechano-orchemoreceptors(throat,
respiratorypassagesorstretchreceptorsinlungs)
Afferent impulses to cough centre (medulla)
Efferent impulses via parasympathetic & motor
nerves to diaphragm, intercostal muscles & lung
Increased contraction of diaphragmatic, abdominal
& intercostal (ribs) muscles noisy expiration
(cough)

5. PRODUCTIVE COUGH
NON-PRODUCTIVE COUGH
Expectorants-increase the volume and decrease the
viscosity of secretions to enhance the propulsion of
these secretions upward and outward by ciliary
movement and coughing

6. Opioids –codeine, pholcodiene
Non-opioids-Dextromethorphan, noscapine and
pipazethate
Codeine –Semisynthetic opioid analgesic
-potent cough suppressant action
-10 BD/TDS-lesser addiction/constipation
Overdose-Resp. depression, convulsion, postural
hypotension, tachycardia

7. Structurally related to codeine
More potent, longer acting and better tolerated
than codeine
Causes lesser constipation and drowsiness than
codeine
Given orally 10-15mg BD

8. It is methyl ester of dextroisomer of levorphanol
MOA-NMDA receptor antagonist
It has least addiction, no analgesic action
(unlike levorphanol) least constipating effects and minimal
drowsiness
As potent as codeine -10mg TDS
Uses: Cough suppressant, used for temporary relief of
cough caused by minor throat & bronchial irritation
(accompanies with flu & cold), pain relief
Adverse Effects
Nausea, vomiting, drowsiness, dizziness, blurred vision

9. Naturally occurring opium alkaloid belonging to
benzylisoquinoline group
Devoid of analgesic activity, drowsiness and liability
Has minimal constipating effects and popular cough
suppressant
Given orally-15mg TDS-produce headache and tremors

10. Phenothiazine group of antitussive occasionally used
in cough mixtures
Negligible CNS depressants –orally 40mg-TDS
Morphine-powerful cough suppressant, but long term
use constipation

11. BENZONATATE
It is an antitussive structurally relatedto the local
anaesthetic tetracaine
Inhibits the afferent cough impulses to suppress the
central cough centre, but also inhibits the pulmonary
stretch receptorshas central as well as peripheral
mechanism of action
It possesses mild local anaesthetic action
Orally 100-200mg TDS
S/E-drowsiness, Nausea, Headache

12. Indirect peripherally acting cough suppressant
Provide protective coating over sensory receptors on
pharynx
Honey, liquorice, syp tolu, syp Vasaka
PRENOXDIAZINE
-acts by inhibiting pulmonary stretch receptors to
relieve bronchospasm
It has moderate antitussive action
Orally 100-200mg TDS

13. Local anaesthetic-
Xylocaine, Bupivaciane-applied on pharynx and larynx
and decrease sensitivity of receptors
Antitussive –not to be used in cough associated with
bronchial asthma or chronic bronchitis or
bronchiectasisharmful retention and thickening of
sputum

14. Drugs either increase or decrease the viscosity of
respiratory secretions and facilitate their removal by
ciliary action and coughing by mucolyticand mucokinetic
action
Mucolytic expectorants
They alter the chemical charecteristicsof mucous to
decrease its viscosity and to facilitate its removal by ciliary
action or coughing. Commonly used mucolytics-acetyl
cysteine, carbocysteine, Bromexine, Ambroxoland
Dornase-alfa

15. BROMHEXINE-Synthetic derivative of vasicine (alkaloid=
Adhatoda vasica)
MOA of Bromhexine
a) Thinning & fragmentation of mucopolysaccaride fibers
b) ↑ volume & ↓ viscosity of sputum
ACETLYL CYSTEINE
Mucolytic, that decreases viscosity of mucous by
splitting the disulfide (-S-S-) bonds of mucoproteins↓
viscosity
This action facilitated by Alkaline pH-7-9

16. Acetyl cysteine (cont..)
Nebulizn-3-5mlof20%soln
Onsetofactionquick---used2-8hourly
Uses
Cysticfibrosis(toviscosityofsputum)
Chronicbronchitis
Treatmentofparacetamolpoisoning
Unlabelleduseincludesthetreatmentofdryeyes
(keratoconjunctivitissiccaas5%acetylcysteinewith
hyperomellose
Adverseeffects
Nausea,vomiting,bronchospasminbronchialasthma

17. CARBOCYSTEINE-has protected –SH group therefore
cannot work through SH group and –S-S-interchange
It cannot split the disulphidebonds of mucus
AMBROXOL-metabolite of bromexine
-mechanism similar to bromexine
-more useful in mucus plugs
-30mg TDS

18. These expectorants stimulate the flow of respiratory
tract secretions by stimulating the bronchial
secretory cells (to increase the volume) and ciliary
movements (to facilitate their removal
Can also stimulate GI mucosaincrease resp. sectrn
Ammonium chloride, Sodium citrate Guaiacol,
Guiaifenesin

19. Essential oils-oil anize, oil eucalyptus
Provide mild exp. By directystimulating the
bronchial secretory cells
Ammonium chloride –cough expectorant in various
cough mixtures
-gastric irritantreflex bronchial sectrn
Sodium citrate-conventionally several cough mixtures.
after absorption, citrates get converted to
bicarbonates invivoand mucous becomes less viscous

20. Obtained from creosatewood
Safe expectorants with proven efficacy
GUAIFENESIN -Less irriatingderivative of guaiacol
After absorptn-secreted into bronchial glands-
increase airway secrtnand mucosal ciliary activity
Orall-100-200mg TDS