Pharmacology of antitussives


Antitussives are a class of medications used to suppress coughing, a common symptom associated with various respiratory conditions. These drugs work by acting on the central nervous system or peripheral receptors to inhibit the cough reflex. This article will discuss the pharmacology of antitussives, including their mechanism of action, therapeutic uses, adverse effects, and considerations for special populations.

Mechanism of Action

Antitussives can be classified into two main categories based on their mechanism of action: centrally acting and peripherally acting agents. Centrally acting antitussives, such as codeine and dextromethorphan, suppress the cough reflex by inhibiting the cough center in the medulla oblongata of the brain [1]. These drugs bind to specific receptors, such as opioid receptors (in the case of codeine) or sigma receptors (in the case of dextromethorphan), resulting in the suppression of the cough reflex [2].

Peripherally acting antitussives, such as levodropropizine and moguisteine, act on peripheral receptors in the airways to reduce the sensitivity of cough receptors [3]. These agents may also have additional effects, such as reducing airway inflammation or bronchodilation, which contribute to their antitussive properties [4].

Therapeutic Uses

Antitussives are primarily used to alleviate cough associated with various respiratory conditions, such as acute upper respiratory tract infections, chronic bronchitis, and postnasal drip [1]. They are particularly useful when the cough is non-productive, persistent, or interfering with sleep or daily activities.

Codeine, a centrally acting opioid antitussive, is often prescribed for short-term relief of cough due to its effectiveness and well-established safety profile [2]. However, its use is limited by the potential for adverse effects, such as drowsiness, constipation, and the risk of dependence with prolonged use [5].

Dextromethorphan, another centrally acting antitussive, is a common ingredient in many over-the-counter cough suppressants. It is considered safer than codeine due to its lack of opioid-related side effects and lower abuse potential [1]. Dextromethorphan is often combined with other medications, such as antihistamines or expectorants, to provide comprehensive relief from cough and associated symptoms [3].

Peripherally acting antitussives, such as levodropropizine and moguisteine, are gaining popularity due to their favorable safety profile and lack of central nervous system side effects [4]. These agents are particularly useful in patients who cannot tolerate the sedative effects of centrally acting antitussives or in those with a history of substance abuse [3].

Adverse Effects and Precautions

Antitussives, like all medications, can cause adverse effects. The most common side effects associated with centrally acting antitussives include drowsiness, dizziness, nausea, and constipation [2]. These effects are more pronounced with opioid antitussives, such as codeine, and may limit their use in certain populations, such as the elderly or those operating machinery [5].

Peripherally acting antitussives generally have a more favorable side effect profile, with fewer central nervous system-related adverse effects [4]. However, they may still cause gastrointestinal disturbances, such as nausea or diarrhea, in some patients [3].

Special Populations

The use of antitussives in special populations requires careful consideration. In children, particularly those under the age of 6, the use of codeine is not recommended due to the risk of severe respiratory depression and the potential for overdose [5]. Dextromethorphan is considered safer in this age group but should still be used with caution and under the guidance of a healthcare provider [1].

In pregnant and lactating women, the use of antitussives should be evaluated on a case-by-case basis, weighing the potential benefits against the risks to the fetus or infant [2]. Non-pharmacological measures, such as humidity and hydration, should be considered as first-line options in these populations [4].

Patients with underlying respiratory conditions, such as asthma or chronic obstructive pulmonary disease (COPD), may require special consideration when using antitussives. In some cases, suppressing the cough reflex may lead to the accumulation of secretions and increased risk of respiratory infections [3]. Therefore, the use of antitussives in these patients should be closely monitored and combined with other therapies, such as bronchodilators or mucolytics, as needed [5].

Drug Interactions

Antitussives can interact with other medications, leading to potential adverse effects or reduced efficacy. Centrally acting antitussives, particularly opioids like codeine, can interact with other central nervous system depressants, such as benzodiazepines or alcohol, resulting in increased sedation and respiratory depression [2].

Dextromethorphan can interact with certain antidepressants, such as monoamine oxidase inhibitors (MAOIs) and selective serotonin reuptake inhibitors (SSRIs), leading to a potentially life-threatening condition known as serotonin syndrome [1]. Therefore, patients taking these medications should consult their healthcare provider before using dextromethorphan-containing products.

Peripherally acting antitussives generally have fewer drug interactions compared to centrally acting agents. However, they may still interact with other medications that affect the respiratory system or gastrointestinal tract [4]. Patients should inform their healthcare provider about all medications they are taking before starting antitussive therapy.


Antitussives play a crucial role in the management of cough associated with various respiratory conditions. The choice of antitussive agent depends on the underlying cause of the cough, patient factors, and potential adverse effects. Centrally acting antitussives, such as codeine and dextromethorphan, are effective but may cause sedation and other central nervous system side effects. Peripherally acting antitussives, such as levodropropizine and moguisteine, offer a safer alternative with fewer central side effects.

Healthcare providers should consider the individual patient’s needs, medical history, and potential drug interactions when prescribing antitussives. Special populations, such as children, pregnant women, and those with underlying respiratory conditions, require careful evaluation and monitoring. By understanding the pharmacology of antitussives and tailoring therapy to the specific patient, healthcare providers can effectively manage cough while minimizing adverse effects and improving patient outcomes.


[1] Becker DE. Basic and clinical pharmacology of autonomic drugs. Anesth Prog. 2012;59(4):159-169.

[2] Bolser DC. Pharmacologic management of cough. Otolaryngol Clin North Am. 2010;43(1):147-155.

[3] Dicpinigaitis PV, Morice AH, Birring SS, et al. Antitussive drugs–past, present, and future. Pharmacol Rev. 2014;66(2):468-512.

[4] Zanasi A, Mazzolini M, Tursi F, Morselli-Labate AM, Paccapelo A, Lecchi M. Levodropropizine for treating cough in adult and children: a meta-analysis of published studies. Multidiscip Respir Med. 2015;10(1):19.

[5] Bolser DC, Davenport PW. Codeine and cough: an ineffective gold standard. Curr Opin Allergy Clin Immunol. 2007;7(1):32-36.

Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always seek the advice of a healthcare provider with any questions regarding a medical condition.

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