Antitussives suppress the cough reflex, especially useful in dry, non-productive coughs. They are classified based on whether they act centrally or peripherally. 1. Centrally Acting Opioid Antitussives Example: Codeine, Hydrocodon 2. Centrally Acting Non-Opioid Antitussives Example: Dextromethorphan, Butamirate 3. Peripherally Acting Antitussives Example: Benzonatate 4. Mixed Central & Peripheral Action Example: Levodropropizine 5. Other Soothing Agents: Menthol, Honey

1. ANTITUSSIVES
P. Harshitha Reddy

2. ANTITUSSIVES
Antitussives suppress the cough reflex, especially useful in dry, non-
productive coughs. They are classified based on whether they act centrally
or peripherally.

3. Classification
1. Centrally Acting Opioid Antitussives
Example: Codeine, Hydrocodon
2. Centrally Acting Non-Opioid Antitussives
Example: Dextromethorphan, Butamirate
3. Peripherally Acting Antitussives
Example: Benzonatate
4. Mixed Central & Peripheral Action
Example: Levodropropizine
5. Other Soothing Agents: Menthol, Honey

4. 1. Centrally Acting Opioid Antitussives
Example: CODEINE
MOA:
–Binds to μ-opioid receptors in the medullary cough center, depressing the
cough reflex.
PK Parameters:
–Route: Oral
–Bioavailability: ~50%
–Half-life: ~3 hours
–Metabolism: Liver (CYP2D6 to morphine)
–Excretion: Renal

5. Example: CODEINE
Therapeutic use:
Used as opioid antitussives to suppress severe, non-
productive cough. They also provide mild analgesic effects in upper
respiratory infections.
ADRs:
–Drowsiness, dizziness
–Constipation
–Nausea, vomiting
–Respiratory depression (at high doses)
–Risk of dependence or abuse

6. Example: HYDDROCODON
• Similar to codeine but more potent.
• Same ADRs, with a higher potential for addiction.

7. 2. Centrally Acting Non-Opioid Antitussives
Example: DEXTROMETHORPHAN
MOA:
–Acts on the cough center in the medulla by antagonizing NMDA
receptors.
–Lacks analgesic or addictive effects.
PK Parameters:
–Bioavailability: ~11%
–Half-life: 3–6 hours
–Metabolism: CYP2D6 (to dextrorphan)
–Excretion: Renal

8. Example: DEXTROMETHORPHAN
Therapeutic use:
Non-opioid cough suppressants effective in dry, irritating
coughs without causing sedation or dependency. Butamirate also has mild
bronchodilatory effects.
ADRs:
–Dizziness, nausea
–CNS depression (in high doses)
–Euphoria, hallucinations (at abuse doses)
–Serotonin syndrome (when combined with SSRIs)

9. Example: BUTAMIRATE
MOA:
Non-opioid central suppressant; reduces cough reflex at medullary center.
Therapeutic use: Non-opioid cough suppressants effective in dry, irritating
coughs without causing sedation or dependency. Butamirate also has mild
bronchodilatory effects.
ADRs:
–Drowsiness
–GI discomfort
–Skin rash

10. 3. Peripherally Acting Antitussives
Example: BENZONATATE
MOA:
–Anesthetizes stretch receptors in lungs and pleura, dampening afferent
cough signals.
PK Parameters:
–Onset: 15–20 minutes
–Duration: 3–8 hours
–Metabolism: Hydrolyzed by plasma esterases
–Excretion: Renal

11. Example: BENZONATATE
Therapeutic use:
Benzonatate numbs the throat and lungs, reducing the
cough reflex. Menthol and honey soothe irritated throat mucosa and
provide symptomatic relief in mild cough.
ADRs:
–Numbness of throat/mouth (if chewed)
–Dizziness, sedation
–GI upset
–Rare: seizures or cardiac arrest (if overdosed)

12. 4. Mixed Central & Peripheral Action
Example: LEVODROPROPIZINE
MOA:
–Acts on peripheral sensory nerves (C-fibers) and reduces cough
sensitivity.
PK Parameters:
–Bioavailability: ~75%
–Half-life: ~2–4 hours
–Excretion: Renal (unchanged)

13. Example: LEVODROPROPIZINE
Therapeutic use:
A peripherally acting antitussive that reduces cough reflex
sensitivity without CNS depression. Often used in dry, non-productive
coughs, especially in pediatrics.
ADRs:
–Drowsiness
–GI upset
–Palpitations (rare)

14. Other Soothing agents
Soothing Agents: Menthol, Honey
MOA:
– Exerts local anesthetic and soothing effect on the throat.
Therapeutic use: Menthol and honey soothe irritated throat mucosa and
provide symptomatic relief in mild cough.
ADRs:
Minimal; well tolerated