Anti Tussives, Anti Cough, Cough suppressant Drugs, Expectorants , Mucolytics , Glycerhiza , Guifenesin , Hydrylin Corex D , Codeine , Pholcodeine , Noscapine , Dextromethorphan , Benzonatate ,

1. Anti-Tussives
(Pharmacology & Therapeutics-1)
Lecture By
Dr. Muhammad Baqir Raza Naqvi
Nazar College of Pharmacy,
DAKSON Institute of Health Sciences, Islamabad
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2. Pathophysiology of Cough
Cough
Cough is a protective reflux by which the body gets rid of foreign, irritant materials
& accumulated secretions such as sputum from the tracheo bronchial tree.
It is necessary for preventing mechanical obstruction to
breathing.
Cough is due to stimulation of cough centers present in in
medulla oblongata near the vomiting center.
So cough reflex is just like vomiting reflex.
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3. Pathophysiology of Cough
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Cough Reflex

5. Causes of cough
Lower and upper respiratory tract infections.
Drugs induced cough, such as captopril
Chronic pulmonary diseases like chronic bronchitis, tuberculosis & lung cancer.
Asthmatic cough.
Local irritation of throat, larynx, trachea or bronchi etc.
Seasonal changes, Allergies (Allergic rhinitis) and smoking.
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6. Types of Cough
Productive cough
• It results from the removal of undesirable sputum from
the respiratory tract.
Non-productive cough
• In this type nothing comes out from respiratory tract. It is
exhausting, painful and trouble some.
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7. ANTI TUSSIVES
“Those agents or medications which are used to reduce the frequency
and severity of cough are called anti tussives.”
• These are also called as “cough suppressants.”
• Anti tussive drugs are effective in the treatment of annoying, dry,
unproductive cough that may interfere with the normal body
activities like talking & sleeping etc.
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8. Opiates derivatives
• Dextromethorphan
• Noscapine
Non opiate
synthetic derivatives
• Benzonatate
• Diphenhydramine
Classification of Anti-tussives
Narcotic Anti tussives
1. Centrally Acting Antitussives
Relatively less
addicting
• Codeine
• Pholcodeine
More addicting
• Morphine
• Methadone
• Dihydromorphine
Non narcotic Anti tussives
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9. Demulcents Glycerhiza Lozenges
Steam
inhalations
Tincture
benzoin
Local
anesthetics
Benzonatate Dropropizine
2. Peripherally Acting Antitussives
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10. Pharmacology of drugs
1. Codeine
• It is an alkaloid obtained from opium poppy in a concentration ranging from 0.2% -
7.5%.
• Since the amount is too low to be of commercial importance so most of codeine is
produced synthetically from methylation of morphine. (MCQS)
Mode of Action
• Codeine is centrally acting narcotic anti tussive. It depress the cough reflex by
directly acting on the cough center, suppressing cough as a result.
• It decreases the sensitivity of cough centers in the central nervous system to
peripheral stimuli and decreases mucosal secretion.
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12. Clinical Uses
• Effective in the treatment of non productive cough.
• Commonly used in spasmodic cough.
• Also used as analgesic but less potent than morphine.
Adverse effects
• GIT: Dry mouth, constipation.
• CNS: Euphoria, weakness, headache, insomnia,
agitation, trauma, physiological dependence.
• CVS: Skin rashes, urticaria, pruritus, edema.
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Napadoc tab. contains;
• Paracetamol = 500 mg
• Caffeine = 30 mg
• Codeine phosphate=15 mg

13. 2. Pholcodiene
• It is also centrally acting narcotic cough suppressant.
• It is equipotent to codeine in the treatment of unproductive cough.
• It is less toxic than codeine.
• It does not cause constipation & is well tolerated by children.
Mode of Action
• As it is centrally acting narcotic anti tussive, it blocks the cough reflex by
directly acting on cough center that lies in medulla oblongata of brain.
Thus suppressing the cough.
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Clinical Uses
• Effective in the treatment of unproductive cough.
• Effectively used to alleviate dry spasmodic cough.
Adverse effects
This drug is comparatively safe but it may cause;
• Drowsiness, dizziness,
• Nausea, dry mouth,
• Unlike codeine it doesn't cause constipation.
Each 5 ml of DAYCOR contains;
• Paracetamol 200 mg
• Diphenhydramine 13.33 mg
• Pholcodiene 3.3 mg

15. 3. Noscapine
• It is benzyl Iso-quinolone alkaloid of opium.
• It has similar anti tussive effects as codeine. But is
almost devoid of analgesic, hypnotic & sedative
properties.
Mode of action
• It is centrally acting non narcotic anti tussive. It
depress the cough reflex by directly acting on cough
center, and thus reduces the frequency of coughing.
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Clinical uses
• It is effective in all classes
of un productive cough.
Side effects
• Produces slight nausea.
• Its toxicity is very low.

16. Comparison among various anti tussive drugs
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Pholocodeine Codeine Noscapine
It is powerful anti tussive,
directly suppress cough center.
It is also directly suppress cough
center.
It is also powerful cough
suppressant, bcz directly
suppress the cough center.
Less respiratory depressant
affects.
More effect as respiratory
depressant.
More effect as respiratory
depressant.
Less constipating effects. More constipating effects. More constipating effects.
Less gastric irritation, because it
is water soluble.
more gastric irritation, because it
is less water soluble.
Also causes gastric irritation.
It causes less addiction. It causes addiction. It also causes addiction.
It does not depress cardiac
smooth muscles.
It depress cardiac smooth
muscles in large doses.
It also depress cardiac smooth
muscles in large doses.

17. 4. Dextromethorphan
• It is a popular non-narcotic anti tussive & is commonly used for
unproductive cough. It is also equipotent to codeine but rarely produces
drowsiness and GIT disorders.
Mode of action
• It is centrally acting non narcotic anti tussive.
• It blocks the cough reflex by direct acting on the cough centers in medulla
oblongata of brain and thus suppressing the cough.
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18. Side effects
This drug is safe as compared to other anti
tussive drugs.
The rare side effects includes;
• Dry mouth, nausea.
• Respiratory depression.
• Ataxia (Imperfect control of movements).
• Slurred speech (Mixing of words).
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Dextromethorphan is usually
given in combination with
anti histamines.

19. 5. Benzonatate
Mode of action
• Unlike the opioids, benzonatate suppresses the cough reflex through
peripheral action.
• It anesthetizes the stretch receptors located in the respiratory passages,
lungs, and pleura.
Side effects
• Dizziness, numbness of the tongue, mouth and throat.
• These localized side effects may be particularly problematic if the capsules
are broken or chewed and the medication comes in direct contact with the
oral mucosa.
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20. Summary of Anti tussive agents
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Book reference: Lippincott's illustrated review of Pharmacology (6th edition) Page # 382+390

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