This document discusses various agents used to treat cough. It begins by describing the pathophysiology of cough and differentiating between acute, chronic, and subacute cough. It then categorizes cough medications as peripherally or centrally acting. Peripherally acting medications include demulcents, mucosal anesthetics, bronchodilators, expectorants, and miscellaneous agents. Centrally acting medications include opioid/narcotics and non-opioid/non-narcotics. Specific medications are discussed under each category along with their mechanisms of action, pharmacokinetics, indications, and side effects. The document provides detailed information on commonly used antitussive medications to treat cough.

1. SUMREEN KOUR
MVSc Scholar
Vety Medicine

2.  Agents used to relieve or
suppress coughing.
 Benificial in suppressing cough &
in decreasing morbidity in
respiratory disease.
 Indicated when cough is
painful,unproductive,distressing,
exhausting/exacebrate lung
damage.

3. PATHOPHYSIOLOGY
OF COUGH

4. Cough stimulus:pharynx
Larynx
Tracheobronchial tree
Cough centre located in medulla oblongata
Impulse(afferent
nerves): vagus
Glossopharyngeal
nerve
Effernet pathway
supplies nerve : abdomen
thoracic muscles
diaphragmic muscles
Forceful expulsion of air from lungs

5. COUGH
Duration
Acute
Chronic
Subacute
Dry/Produtive
Dry Productive

6. Peripherally
acting/locally
acting :
• Demulscents
• Mucosal
anaesthetics
• Bronchodilators
• Expectorants
• Miscellaneous
Centrally acting
• Opioid/narcotics
• Non-opioid/non –
narcoptics.

7.  Includes: honey
syrup
glycerine
liquorice
 They coat,protect & soothe throat directly &
promote salivation
reduce afferent
Impulse.
 Provide symptomatic relief in dry cough.

8.  BENZONATATE:
 Long chain polyglycol derivative local
anaesthetic.
 Related to procaine & tetracaine.
 Reduce coughing –
bronchitis,emphysema,influenza,pneumonia.
 Half life:3-8hrs.

9.  Act as local
anaesthetic.
 sensitivity to stretch
receptors in lower
airways & lungs
 Reduces drive to
cough.

10.  Drowsiness.
 Numbness of mouth & throat.
 Dysphagia.
 Allergic reactions.

11.  Drugs which causes an increase in calibre of
bronchus & bronchial tube.
 Used when there is:
- bronchial narrowing
- where improved alveolar ventillation
is required.
 Improve effectiveness of cough in clearing
secretions.
 Ephedrine.
 Theophylline.
 Isoprenaline.

12.  Mixed acting non-catecholamine which
stimulates alpha & beta receptors.
 Develop mild bronchodilation.
 Produces decongestion in bronchi which helps
to reduce mucosal swelling.

13.  No selective beta1 & beta2 adrenoceptor
agonist.
 Can be used parentrally.
 Marked brochodilation: 1-2hrs.

14.  Expectorants are agents which increase
volume or fluidity of secretion in respiratory
tract & fascilitate their removal by ciliary
action.
 Bromohexine
 Water aerosols

15.  Synthetic derivative of alkaloid vasicine
(adhatoda vasica).
 Useful if mucus plug present.
 Administered both oral & parentral routes.
 Used:
 Bronchitis
 Bronchopneumonia
 Chronic cough

16.  Mucus clearance.
 Fascilitate expectoration
 Allow animal to breathe freely.
Depolymerises mucopolysacchrides directly & liberate
lysosomal enzyme causing breakdown of network of fibres of
tenacious sputum
Increases Ig level in airways secretions enhancing membrane
permeability.
Active metabolite –stimulates & releases surfactant by type 2
pneumocytes –act as anti glue factor

17.  Used ocassionally to liquefy hyperviscous
mucus in repiratory tract.
 Aerosol/mist therapy only delivers few mm
of water to smaller pulmonary airways &
lungs.

18.  Dropizine
 Levodropropizine

19.  Opioid antitussive:
 Codeine
 Hydrocodone
 Butorphanol
 Hydromorphone.
 Non opioid antitussive:
 Dextromethorphan
 Noscapine
 phoicodine

20.  Potent inhibitors of medullary cough centre
at sub-analgesic dose -antitussive.
 Assoiated with:
 Sedation
 Constipation
 Depression of respiratory centre

21.  Opiate alkaloid
 Available both as base &
 phosphate & sulphate salts.
 ACTION:
 Causes direct suppression cough centre in
medulla.
 Action can be blocked by naloxane.
 Onset of action after oral-30min.

22.  Conversion of codiene to morphine occurs
inn liver & is catalysed by cytochrome
P450enzyme CYP2D6.
 Binds to M opioid receptors & exert effect.
 SIDE EFFECT:
 Anorexia
 Vomition
 Constipation
 Biliary & pancreatic duct spasm.
 Depression.

23.  Use with CNS depressants may increase CNS
/respiratory depressant action.
 Anticholinergic drug used with codiene may
increase chances of constipation.
 DOSE:
 Dogs:0,5-2 mg/kg PO

24.  Is synthetic opioid partial agonist
 Is potent analgesic and antitussive agent
 After oral administration it is completely
absorbed but undergoes a significant first
pass metabolism after oral administration
 DOSE –
DOG – 0.1-0.25 mg/kg bwt.

25.  Have been developed to increase safety of
centrally acting antitussive drugs.
 DEXTROMETHORPHAN:
 It’s a d-isomer of codiene aanalogue levorphanol.
 Occurs as odourless to whit yellow crystalline
powder.

26.  Mechanism of action:
 It acts as uncompetitive NMDA receptor
agonist & serotonin & norepinephrine
transporter blocker at different
concentrations.
 Pharmacokinetics:
 Absorbed by gastrointestinal tract
 enters blood stream & cross BBB.
 In liver it is metabolised by Cyt P450 enzyme
metabolite dextrorphan

27.  not used in allergic reactions
DRUG INTERACTIONS
Should not be administered along with MAOI or serotonin uptake
inhibitor due to potential for serotonin syndrome – life threatening
DOSE – 1-2 mg/kg bwt

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