Antitussive: Uses, Dosage, Side Effects and Interactions

Uses of Antitussive

Cough can be an irritating and sometimes debilitating symptom, often signaling underlying respiratory or systemic conditions. Antitussives—commonly known as cough suppressants—are medications or substances designed to reduce the urge to cough, either centrally (acting on the brain’s cough center) or peripherally (acting on nerves in the respiratory tract). Their primary goal is to improve comfort and quality of life, especially when cough serves no beneficial purpose, such as in dry, non-productive coughs. In this section, we’ll explore the main uses of antitussives, the types available, and the clinical scenarios in which they are most appropriate.

Indication	Description	Main Agents	Source(s)
Acute Cough	Short-term cough, often from colds or URTIs	Dextromethorphan, codeine, glaucine	1, 2, 12
Chronic Cough	Long-term cough (e.g., bronchitis, COPD)	Codeine, levocloperastine, DM	1, 10
Productive Cough	Cough with sputum	Guaifenesin (expectorant), bromhexine	2
Traditional/Herbal	Coughs of various etiologies	Fritillariae Thunbergii, Emblica officinalis	3, 5
Pediatric Cough	Cough in children (with caution)	Levocloperastine, non-opioid agents	10, 8

Table 1: Common Uses of Antitussives

Central vs. Peripheral Cough Suppression

Antitussives are generally divided into two main categories based on their mechanism of action:

• Centrally Acting Antitussives: These drugs suppress the cough reflex by acting directly on the cough center in the brainstem (medulla). Well-known examples include codeine, dextromethorphan, and certain non-opioid agents such as dimemorfan and glaucine. Centrally acting agents are generally preferred for dry, non-productive coughs 1 4 6 14.

• Peripherally Acting Antitussives: These target the nerves in the airways that trigger coughing, rather than the central nervous system. They are less commonly available but are preferred when central side effects are undesirable. Research is ongoing to develop safer, more effective peripherally acting agents 13.

Clinical Applications

Acute Cough

• Most frequently due to upper respiratory tract infections (URTIs) or the common cold.
• Antitussives may be used for short-term relief when cough is bothersome or disrupts sleep 1 2.
• Dextromethorphan and glaucine are commonly used for acute, non-productive coughs 2 12.

Chronic Cough

• Seen in chronic bronchitis, asthma, chronic obstructive pulmonary disease (COPD), and other long-lasting respiratory diseases.
• Centrally acting antitussives, especially codeine and newer agents like levocloperastine, are sometimes used for symptom control 1 10.
• Careful evaluation of underlying causes is essential before starting long-term suppressive therapy.

Productive Cough

• When cough is accompanied by sputum, expectorants such as guaifenesin or bromhexine are often used to help expel mucus rather than suppress cough 2.
• Suppressing productive cough is generally discouraged unless absolutely necessary for comfort or sleep.

Traditional and Herbal Uses

• Herbal remedies such as Fritillariae Thunbergii Bulbus and Emblica officinalis have been used in traditional medicine for their antitussive effects 3 5.
• These may be considered when conventional agents are not tolerated, but evidence is still emerging.

Pediatric Considerations

• Use of antitussives in children is controversial due to concerns about efficacy and safety, particularly with opioid-containing products like codeine 8 10.
• Non-opioid and newer agents with safer profiles (e.g., levocloperastine) are preferred.

Dosage of Antitussive

Dosing is critical for both efficacy and safety when using antitussives. The optimal dose depends on the specific agent, patient age, underlying health, and the nature of the cough. Misuse or overdose, particularly with opioid-containing antitussives, can lead to serious adverse events, especially in children. In this section, we summarize recommended dosages for common agents and highlight key dosing considerations.

Agent	Typical Adult Dose	Pediatric Dose*	Source(s)
Dextromethorphan	10–30 mg every 4–6 hours	2.5–15 mg every 4–6 hours	2, 18
Codeine	10–20 mg every 4–6 hours	0.5–1 mg/kg every 4–6 hours	1, 8
Glaucine	30 mg three times daily	Not well established	12
Levocloperastine	20 mg twice daily	1 mg/kg/day (divided doses)	10
Dimemorfan	20–30 mg three times daily	Not well established	14

*Always consult specific product labeling and local guidelines; pediatric dosing is agent-specific and requires caution.

Table 2: Common Dosages for Antitussives

Dosing Principles

Standard Adult Dosing

• Dextromethorphan: Widely used due to its safety profile and efficacy; standard dose is 10–30 mg every 4–6 hours, not exceeding 120 mg per day 2 18.
• Codeine: Typically 10–20 mg every 4–6 hours for adults; higher doses may increase risk of side effects and dependency 1 8.
• Glaucine: 30 mg three times daily has shown good efficacy with minimal side effects in studies 12.
• Levocloperastine: 20 mg twice daily in adults, offering rapid onset and good tolerability 10.
• Dimemorfan: 20–30 mg three times daily, comparable to dextromethorphan in efficacy 14.

Pediatric Dosing

• Dosing in children is more conservative and must be based on weight and age.
• Opioid antitussives (e.g., codeine) are not recommended in young children due to risks of overdose and respiratory depression, especially in those with ultra-rapid metabolism 8.
• Non-opioid agents such as levocloperastine may be safer alternatives, but dosing must be individualized 10.
• Always refer to local pediatric guidelines and never use adult formulations for children.

Dosing Errors and Overdose Risks

• Dosage miscalculations—such as using “drops” instead of milligrams—can lead to dangerous overdoses, especially with codeine 8.
• Overdose symptoms may include respiratory depression, somnolence, and, in severe cases, death (as tragically seen in pediatric case reports) 8.

Special Populations

• Elderly, those with liver or kidney dysfunction, and patients on multiple medications may require dose adjustments.
• Herbal and traditional agents vary in potency and dose; consult with a qualified practitioner if considering these options 3 5.

Side Effects of Antitussive

While antitussives offer welcome relief from persistent cough, they are not without adverse effects. The risk and severity of side effects depend on the agent used, dose, patient factors, and duration of therapy. Understanding potential side effects is critical to ensure safer, more effective use.

Agent/Group	Common Side Effects	Severe Risks	Source(s)
Opioids (e.g., codeine)	Constipation, drowsiness, nausea, dependency	Respiratory depression, overdose, addiction	1, 8, 11
Dextromethorphan	Drowsiness, nausea, dizziness	High-dose: hallucinations, serotonin syndrome	2, 18
Glaucine	Mild GI upset, appetite loss	Minimal; rare side effects	12
Dimemorfan	Loss of appetite, drowsiness, nausea	Very rare; no dependence	14
Levocloperastine	Minimal; no central adverse events	--	10
Herbal Agents	Variable (mainly GI upset)	Rare allergic reactions	3, 5

Table 3: Side Effects of Common Antitussives

Opioid Antitussives

• Codeine: Effective but carries risks of constipation, drowsiness, nausea, and, with excessive or prolonged use, dependence and addiction 1 11.
• Overdose: Particularly dangerous in children and ultra-rapid metabolizers—symptoms include respiratory depression, vomiting, and, in severe cases, death 8.
• Not recommended for pediatric use due to safety concerns 8.

Non-Opioid Synthetic Antitussives

• Dextromethorphan: Generally well tolerated, but high doses can cause CNS side effects (e.g., dizziness, confusion, hallucinations) and interact with serotonergic drugs, potentially leading to serotonin syndrome 2 18.
• Dimemorfan: Non-narcotic with low risk of dependence; minor side effects (<10%) include drowsiness and appetite loss 14.
• Glaucine: Well tolerated; gastrointestinal complaints are possible but rare, and fewer side effects than codeine 12.

Newer and Selective Agents

• Levocloperastine: Noted for lack of central nervous system side effects (e.g., no drowsiness), making it suitable for both adults and children 10.
• Benzodiazepines (e.g., clonazepam): Experimental use shows high potency but side effects and dependency risk limit clinical use 6 9.

Herbal and Traditional Agents

• Generally considered safe when used appropriately, but allergic reactions and gastrointestinal upset can occur, especially in high doses 3 5.
• Standardization and regulatory oversight may vary.

Interactions of Antitussive

Drug interactions can significantly impact the safety and efficacy of antitussive therapy. These interactions may be pharmacokinetic (affecting drug metabolism) or pharmacodynamic (affecting the drug’s action). Understanding potential interactions is vital, especially in patients taking multiple medications or with underlying health conditions.

Agent/Group	Key Interactions	Clinical Implications	Source(s)
Codeine, opioids	Other CNS depressants, CYP2D6 modulators	Enhanced sedation, respiratory depression	8, 11
Dextromethorphan	MAOIs, SSRIs, strong CYP2D6 inhibitors	Serotonin syndrome, toxicity	18
Benzodiazepines	Alcohol, other sedatives	Additive CNS depression	6, 9
Herbal agents	Variable (depends on product)	May interact with other drugs metabolized by liver enzymes	3, 5

Table 4: Key Antitussive Drug Interactions

Opioid Antitussives

• Codeine and Related Drugs:
  • Potentiation of sedation and respiratory depression when combined with alcohol, benzodiazepines, or other CNS depressants 8 11.
  • Metabolized by CYP2D6; genetic polymorphisms or inhibitors/inducers of this enzyme can alter effectiveness and risk of toxicity 8.
  • Risk of life-threatening respiratory depression in ultra-rapid metabolizers or those with liver impairment.

Dextromethorphan

• Serotonergic Drugs:
  • Combination with monoamine oxidase inhibitors (MAOIs) or selective serotonin reuptake inhibitors (SSRIs) can trigger serotonin syndrome—marked by agitation, confusion, fever, and, in severe cases, seizures 18.
  • CYP2D6 inhibitors can increase dextromethorphan levels, increasing risk of side effects.

Benzodiazepine Antitussives

• Clonazepam, Diazepam:
  • Additive CNS depression when used with alcohol or other sedatives; not commonly used as antitussives in clinical practice due to this risk 6 9.

Herbal and Traditional Agents

• Unpredictable Interactions:
  • May inhibit or induce liver enzymes, affecting the metabolism of other drugs 3 5.
  • Lack of standardization can lead to inconsistent potency and risk of unexpected interactions.

Practical Considerations

• Always review a patient’s full medication list before starting an antitussive, especially in high-risk groups (elderly, children, those with liver/kidney disease).
• Avoid combining multiple CNS depressants unless under medical supervision.
• Advise patients to report any unusual symptoms such as confusion, excessive drowsiness, or breathing difficulties promptly.

Conclusion

Antitussives play a vital role in managing troublesome coughs, but their use must be tailored to the individual’s needs and clinical context. Here’s a quick recap of the essential points:

• Common Uses: Antitussives are used for acute and chronic non-productive coughs, with special considerations for children and those with productive coughs.
• Dosing: Proper dosing is critical; opioid-containing agents require extra caution, especially in children.
• Side Effects: Side effects vary by agent, with opioids and centrally acting drugs carrying higher risks.
• Interactions: Drug interactions can be significant, particularly with CNS depressants and serotonergic medications.
• Patient Safety: Always weigh the benefits of cough suppression against potential risks, and consult healthcare professionals for individualized recommendations.

By understanding the uses, dosing, side effects, and interactions of antitussives, clinicians and patients can work together to safely and effectively manage cough, improving comfort and quality of life.