Antitussive Drugs | Can Antitussive Cure Cough?

Antitussive drugs act centrally by suppressing the neurons that are located in the brainstem's cough center. When the receptors of the airways send impulses to the brainstem and cause the contraction of muscles that need to cough, the cough reflex occurs. It is completely dependent on the location of stimulated receptors, the types of cough that may be produced, and whether mucus comes out with the cough or not, that is, whether the cough is productive or non-productive. So, in this article, I will give you the complete information about antitussive drugs.

Antitussive Drugs

Antitussives are generally used for tracheobronchitis and tracheitis. When inflammation is increased because of the coughing that is already present, and inflammation may also stimulate more coughing, it needs to be suppressed with the help of antitussive drugs.

Antitussives inhibit coughing's frequency and severity without interfering with the respiratory tract's natural ability to release excess secretions. They are divided into the following four subcategories:

(a) Centrally Acting Antitussives:

This class of drugs includes non-opioid derivatives like Dextromethorphan, Noscapine, and Pipazethate as well as opioid derivatives like Codeine, Pholcodeine, and Noscapine. These medications all have CNS antitussives and suppress the cough center, which controls the cough reflex.

Codeine

Codeine is a naturally occurring, semi-synthetic opioid analgesic and antidiarrheal with strong cough suppressant action. By binding to the opioid receptors at many sites within the central nervous system, codeine mimics the actions of endogenous opioids. Through codeine's action on the cough center in the medulla, the activity of the antitussive is mediated. It is administered orally. Overdose may result in convulsions, tachycardia, respiratory depression, and postural hypotension.

Pholcodine

Structurally, it is related to codeine, but it is slightly more potent, longer acting as well, and better tolerated than Codeine. It is more suitable for longer-term usage, and it may cause less constipation and drowsiness as compared to Codeine.

Dextromethorphan

It is the methyl ester of the dextroisomer of Levorphanol. It shows antitussive activity and does not have analgesic or addictive properties, less constipating effects, and minimal drowsiness. It inhibits the cough reflex by crossing the blood-brain barrier and activating sigma opioid receptors in the cough area of the central nervous system. As an antitussive, it is less strong than codeine.

It is among the most widely used suppressants for coughing. It is used in combination with other agents, such as bronchodilators in cough mixtures, as well as antihistamines.

Side effect:

Dizziness, nausea, drowsiness, and ataxia.

Noscapine

It is a naturally occurring opium alkaloid. It has no drowsiness as well as analgesic activity. It is a popular cough suppressant and has minimal constipating effects. A high dose of noscapine may produce nausea, headache, and tremors.

Pipazethate

It is a synthetic antitussive of the phenothiazine group, used in cough mixtures. It has very few CNS depressant effects.

Morphine is one of the most powerful cough suppressants, but it is generally not preferred because of its addiction potential. It is only used for terminally ill patients' coughs.

(b) Combined Central and Peripheral Antitussives:

There is only one drug present in this category.

Benzonatate

It is an antitussive, structurally it is related to Tetracaine, which is a local anesthetic. It not only inhibits the cough impulses to suppress the central cough center but also inhibits the pulmonary stretch receptors as well. Hence, it has both central and peripheral modes of action. It also has mild local anesthetic action.

The adverse reactions may include nausea, headache, drowsiness, and, in high doses, vertigo.

(c) Peripherally Acting Antitussives:

Prenoxdiazine

It acts by inhibiting the pulmonary stretch receptors to relieve bronchospasm. It has moderate antitussive action.

(d) Miscellaneous Drugs

Demulcents

These are peripherally acting cough suppressants. They offer a layer of defense over the pharynx's sensory receptors. It may include syrup tolu and syrup vasaka, honey, and liquorice.

Local anaesthetics

Local anesthetics such as Bupivacaine and lidocaine can be applied to the pharynx and larynx to minimize the sensitivity of sensory receptors for cough in this portion. These are generally used to treat cough that is associated with bronchoscopy and can also be used for patients those having other cough therapies.

Conclusion

In general, Antitussives should not be used for treating the cough that is associated with chronic bronchitis, asthma, or bronchiectasis, because they may cause thickening of sputum and may have harmful retention. I hope you have liked the article on the topic of antitussive drugs. Kindly use the comments section to ask any questions you may have.

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