Spring is here and it is the season of respiratory diseases. And when it comes to respiratory diseases, cough is inevitable.
Cough is a defense mechanism of the body and can be divided into acute, subacute and chronic coughs according to their duration and into dry and wet coughs according to their nature.
A cough without sputum or with very little sputum is called a dry cough. A dry cough may also turn into a wet cough: if the cough is accompanied by sputum, it is generally called a wet cough.
Cough can be caused by a variety of reasons, and the key to its treatment is etiologic treatment.
Mild and infrequent coughs generally do not need to be treated with cough suppressants, but a dry cough without sputum that is intense or a cough with sputum that is too frequent should be treated with appropriate cough suppressants to relieve the symptoms while targeting the cause.
The following is a summary of commonly used clinical cough medications.
Central cough suppressants
Central cough suppressants produce cough suppression by directly inhibiting the medullary cough center, and are divided into dependent and non-dependent cough suppressants according to whether they have addictive and narcotic effects.
Dependent cough suppressants
Codeine – addictive, dry cough
Directly inhibits the cough center of the medulla oblongata, with strong and rapid cough suppressing effects, and also has analgesic and sedative effects, and can be used for severe dry cough and irritating cough due to various causes, especially dry cough with chest pain.
Dosage: 15-30 mg orally or subcutaneously, up to a total of 30-90 mg daily.
Caution: Long-term application may produce tolerance and addiction; codeine can inhibit the secretion of bronchial glands, making sputum sticky and difficult to cough up, so it should not be used in patients with thick sputum.
Key points to remember
Addictive; used for dry cough with chest pain and severe dry cough without sputum where other cough suppressants are ineffective.
Non-dependent cough suppressants
Dextromethorphan – the most widely used
Currently the most widely used cough suppressant in clinical practice, similar to codeine, but without analgesic or hypnotic effects, no inhibitory effect on the respiratory center in therapeutic doses, and no addictive properties.
It is contained in a variety of over-the-counter cough suppressants.
It is indicated for coughing in cases of colds, acute or chronic bronchitis, bronchial asthma, pharyngitis, tuberculosis and other upper respiratory tract infections.
Dosage: Take 10-30 mg orally 3 times a day. The maximum dose is 120 mg a day.
Caution: Dextromethorphan may cause drowsiness; do not use when driving a car or working at height; contraindicated in women within 3 months of pregnancy and in those with a history of mental illness.
Key Points to Remember
Most widely used and contained in many over-the-counter compounded cough suppressants. Contraindicated during pregnancy.
Pentoxifylline – available for children
It has a selective inhibitory effect on the cough center, a mild atropine-like effect and local anesthetic effect, and an antispasmodic effect on bronchial smooth muscle at high doses, with both central and terminal cough suppressant effects.
It is a long-used cough suppressant in China, and its strength is 1/3 that of codeine, which is more effective in children than in adults.
Dosage: Take orally, 25 mg per dose for adults, 3-4 times a day.
Caution: Pentoxifylline should be used with caution in patients with glaucoma and cardiac insufficiency with pulmonary stasis.
Key Points to Remember
Better for children.
Peripheral cough suppressants
Suppress cough by inhibiting any of the receptors, afferent nerves, efferent nerves and effectors in the cough transmitter arc.
Narcotin – peripheral “codeine
It is an isovaline alkaloid contained in opioids, which produces peripheral cough suppression by inhibiting pulmonary twitch reflex and relieving bronchial smooth muscle spasm.
It has special therapeutic value for allergic cough, spasmodic cough, severe and episodic cough, and it can also inhibit inflammation caused by respiratory secretions.
Dosage: 15-30 mg orally, 2-3 times a day, up to 60 mg/dose for severe cough.
Key points to remember
The cough suppressant effect is equivalent to that of codeine, hence the name “peripheral codeine”.
Benpropirin – preferred for severe cough
It is a non-narcotic cough suppressant, 2 to 4 times more effective than codeine, and can inhibit peripheral afferent nerves as well as the cough center.
It is used for the treatment of acute and chronic bronchitis and coughs caused by various irritations, and is the drug of choice for severe coughs.
Dosage: Take 20-40 mg orally 3 times a day.
Precautions: Transient numbness of the mouth and pharynx may occur after taking the drug, and there are also adverse reactions such as weakness, dizziness and epigastric discomfort. Discontinue the drug if a rash appears during administration.
Key points to remember
It has a strong cough suppressant effect, equivalent to 2 to 4 times that of codeine, and is the drug of choice for severe coughs.
Do you remember it? Take a look at the following table and review it again.
Irritating dry cough – Benpropirin, pentoxifylline
Severe cough – Benpropirin is preferred, followed by dextromethorphan
Children’s cough – pentoxifylline
Women during pregnancy – dextromethorphan is contraindicated
Severe dry cough without sputum where other cough suppressants are not effective – codeine
Compounded preparations
In addition, coughs with a lot of sputum should be combined with expectorants such as ammonium chloride, bromhexine and acetylcysteine to facilitate sputum expulsion and cough suppressant effect.
There are also some compound preparations containing cough suppressants, expectorants and antihistamines, which have more clinical applications.
Compound methoxynamine capsule
Each capsule contains: methoxyphenamine hydrochloride 12.5 mg, noscapine 7 mg, aminophylline 25 mg, and chlorpheniramine maleate 2 mg.
The combination of several drugs, from different pharmacological effects, can not only reduce the cough caused by throat and bronchial inflammation, etc., but also relieve the cough during asthma attacks and facilitate the excretion of phlegm.
Dosage: 1~2 capsules 3 times a day, taken orally after meals. Forbidden for infants and children under 8 years of age.
Caution: Caution should be exercised when taking this medication if you have heart problems, high blood pressure or are of advanced age, if you have glaucoma, hyperthyroidism, difficulty urinating, or if you are undergoing treatment. Do not drive or operate machinery as this drug may cause drowsiness.
Cogonella Syrup
It contains codeine phosphate 20 mg and guaiacol glycerol ether 200 mg per 10 ml. It has obvious expectorant and cough suppressant effect.
Codeine is addictive when applied for a long time or in large doses, while guaiacol glycerol ether is a stimulating expectorant, which can dilute the sputum and make it easy to cough up.
Dosage: Children over 12 years of age and adults should take 10 ml three times a day, not more than 30 ml in 24 hours.
Children aged 6 to 12 years old should take 5 ml 3 times a day, not more than 15 ml in 24 hours.
Children 2-6 years old should take 2.5 ml 3 times a day, not to exceed 7.5 ml in 24 hours.