Cough reflex
Cough reflex arc includes four links:
(1) Respiratory nerve terminal receptors, including mechanical receptors, chemoreceptors and lung stretch receptors.
(2) The afferent nerve is vagus nerve fiber.
(3) The cough center of the medulla oblongata is located in the dorsal part of the medulla oblongata, adjacent to the respiratory center.
(4) Efferent nerves, including vagal efferent fibers, superior laryngeal nerves and cranial nerves. They cooperated to complete the cough.
Cough is a reflex defense mechanism to remove foreign bodies and protect the lower respiratory tract. The essence of coughing is to inhale violently and forcefully, then the glottis are closed, and the intercostal muscle and diaphragm are forced to contract one after another, which can build up the intrapulmonary pressure of about 40 kPa. Then the glottis suddenly opened, and the diaphragm quickly contracted hard, so that the gas in the lungs rushed out of the respiratory tract at a high speed, and the substances attached to the respiratory mucosa were ejected, forming cough and expectoration. This complex and coordinated action is to stimulate the nerve terminal receptors, excite the respiratory center of the medulla oblongata through afferent nerves, and then send out impulses from the respiratory center, which act on the intercostal muscle, diaphragm and glottis through efferent nerves, thus producing cough and expectoration.
Mechanical receptors, chemoreceptors and lung stretch receptors are distributed on respiratory mucosa, so mechanical stimulation of mucus, dust or foreign bodies, chemical stimulation of smoke and toxic gases, and increased muscle tension caused by bronchospasm can all cause cough. The afferent impulse of receptors and the efferent excitement of cough center mainly pass through vagus nerve. Because vagus nerve endings are not only distributed in throat, trachea and bronchus, but also in pleura, lung and viscera, besides chest irritation, head and abdomen lesions can also cause cough. Any link of the above cough reflex arc changes or fails, which will cause cough disorder.
The function of antitussive drugs
Cough reflex can last for several days to months, and cough with acute respiratory infection can last for several days, and it can disappear after inflammation is controlled. Cough caused by chronic bronchitis, asthma, smoking, etc. It often lasts for more than 3 weeks and can be considered as a chronic cough. For cough, it is often necessary to use some drugs to stop it, so the use of antitussive drugs can easily be considered as an effective measure.
Application principle of antitussive drugs
(1) Make a clear diagnosis, determine the cause of cough, and actively take corresponding treatment measures. Firstly, control infection, take anti-infective drugs orally and eliminate inflammation; Or anti-allergens, combined with symptomatic treatment, can make cough-relieving and expectorant drugs receive good results.
(2) The treatment of common cough should be mainly expectorant, and antitussive drugs should not be used alone. Only when frequent severe cough is caused by irritation of pleura and pericardium, or when frequent irritating dry cough occurs due to insufficient sputum, which affects the rest and sleep of patients, can antitussive drugs be used for a short time in order to prevent complications caused by severe cough (such as pulmonary vascular rupture, emphysema, bronchiectasis and hemoptysis). For cough with excessive phlegm, it should be combined with expectorants (such as ammonium chloride, bromhexine, acetylcysteine, etc.) to facilitate the discharge of sputum and strengthen the antitussive effect.
(3) For wet cough with excessive sputum, such as lung abscess, medication should be used with caution to avoid retention of respiratory tract or aggravation of infection due to obstruction of sputum discharge.
(4) For those who have a persistent cough for more than 1 week, accompanied by repeated or persistent cough, fever, rash, asthma and lung abscess, they should go to the hospital for a definite diagnosis or consult a doctor in time.
(5) Besides medication, we should also pay attention to rest, keep warm, avoid smoking and avoid irritating food. Sedatives or sedatives can be used for people with poor sleep or emotional irritability.
benproperine
[drug action]
Benproperine is a powerful non-narcotic antitussive with rapid onset. Animal experiments show that the antitussive effect of this product is 2-4 times stronger than codeine. The antitussive effect of this product is twofold. In addition to blocking sensory nerve impulses from lung and pleural stretch receptors, it also has spasmolytic effect on bronchial smooth muscle and has certain inhibitory effect on cough center, but it does not inhibit breathing. The effect on smooth muscle is similar to papaverine, and it will not cause spasm or contraction of biliary tract and duodenum, constipation and addiction. Indications: Irritating dry cough and cough caused by other reasons, such as cold, acute and chronic bronchitis, upper respiratory tract inflammation (pharyngitis, rhinitis), etc.
【 Adverse Reactions and Precautions 】 (1) Occasionally dry mouth, thirst, lethargy, fatigue, dizziness, heartburn, loss of appetite, abdominal discomfort, drug eruption, etc. (2) This product needs to be swallowed whole, and cannot be chewed (it has anesthetic effect on oral mucosa, leading to numbness). (3) The safety of this product during pregnancy has not been determined, so pregnant women should use it with caution. (4) It is forbidden for people who are allergic to this product.
【 Usage and Dosage 】 Take orally. Adults 20 mg -40 mg once, three times a day, can also be decided according to the condition. Children over 8 years old: 20 mg once, 2-4 times a day.
[Restricted dosage form] Tablets, capsules and granules.
[Optional marketed preparation] Kefule: tablet, produced by Pfizer Pharmaceutical Co., Ltd., each tablet contains 20 mg of benproperine phosphate for oral administration, and the usage is the same as above. Stored in a closed place at room temperature, valid for 5 years.
Pentovitin
[drug action]
This product is an amino ester derivative and a non-addictive antitussive. It has a direct inhibitory effect on cough center, and the antitussive effect is codeine 1/3. It also has a local anesthetic effect on respiratory mucosa and a weak atropine-like effect. Large dose can relax spastic bronchus and reduce airway resistance, so it also has a certain terminal antitussive effect.
Indications: Used for dry cough, acute cough and pertussis caused by upper respiratory tract infection.
【 Adverse reactions and precautions 】 Occasionally, there are symptoms such as constipation, mild headache, dizziness, dry mouth, nausea and abdominal distension. Glaucoma, cough with blood stasis in lung, cardiac insufficiency, excessive phlegm, driving and operating machines, pregnant women and lactating women should be used with caution. Those with excessive phlegm should be combined with expectorants.
【 Usage and Dosage 】 Take orally. 25 mg once, 3-4 times a day. Children over 5 years old take 6.25- 12.5 mg orally once, 2-3 times a day. Kebiqing syrup, 10- 15 ml once, 3-4 times a day, halved in children. [Limited dosage form] Tablets, syrups and compound preparations.
[Optional marketed preparation] Kebiqing tablets: tablets, produced by Beijing Shuanghe Pharmaceutical Co., Ltd., each containing pentonin citrate 25 mg, for oral administration, with the same usage as above.
Kebiqing syrup: syrup, produced by Beijing Shuanghe Pharmaceutical Co., Ltd., each bottle 100 ml, containing pentonin citrate 200 mg and ammonium chloride 3 g. Oral, the usage is the same as above. Store in a closed and cool place.
Dextromethorphan
[Drug action] It is a central antitussive drug, which inhibits the cough center of medulla oblongata and produces antitussive effect. The antitussive effect is significant, which is roughly the same as or slightly stronger than the same dose of codeine, but it has no analgesic effect. Long-term use has no addiction and tolerance. Therapeutic dose will not inhibit breathing, and it is fast and safe.
Indications: Used for cough caused by cold, acute and chronic bronchitis and upper respiratory tract infection.
[Adverse Reactions and Precautions] Atropine-like effects such as dizziness, headache, belching, loss of appetite, constipation and nausea can be seen, but it does not affect the curative effect. The above reaction can disappear by itself after stopping the drug. (1) Use with caution in patients with asthma with excessive phlegm. Patients at risk of respiratory failure are prohibited. (2) For cough caused by infection, both antibacterial and anti-inflammatory drugs should be used. (3) No teratogenic effect was found in animal experiments, but pregnant women should still use it with caution. (4) People with a history of mental illness should not use it. (5) Excessive medication can cause respiratory depression. (6) Don't use it with monoamine oxidase inhibitors (commonly used drugs for mental depression) at the same time, otherwise high fever or death will occur.
【 Usage and Dosage 】 Take orally. Adults take 10-20mg once, 3-4 times a day. 6- 12-year-old children once every 5- 10 mg, 1 every 4 hours, or 15 mg every 6-8 hours. 2-6 years old, 2.5-5mg once every 4 hours/kloc-0 times, or 7.5mg once every 6-8 hours/kloc-0 times.
[Drug overdose and treatment]
It is reported that 1 man abused dextromethorphan powder and inhaled it 2-3 times a day for 2-3 months. He felt euphoric after inhaling/kloc-0 for 5 minutes to 2 hours. However, the patient has no special symptoms after stopping the drug, only the feeling of craving for drugs.
[Drug Interaction] Drugs commonly used in combination with dextromethorphan to make compound preparations include antipyretic and analgesic drugs such as acetaminophen, antiasthmatic drugs such as aminophylline, expectorants such as ammonium chloride, guaiacol, antiallergic drugs such as chlorpheniramine, and sympathomimetic drugs such as phenylpropanolamine.
[Restricted dosage forms] Tablets, capsules, syrups, granules, oral liquids and compound preparations.
[Optional marketed preparation] Ke Mei: syrup, produced by Beijing Shengde Pharmaceutical Co., Ltd., each bottle contains dextromethorphan hydrobromide 90 mg and 180 mg, respectively 60 ml and 120 ml, pseudoephedrine 6 mg and 12 mg, chlorpheniramine 6 mg and 12 mg, and guaifenesin. Oral, adults once 5- 10 ml, three times a day; 0.5-2ml for 1 year-old children, 2-3ml for 1-3-year-old children, 3.5-4.5ml for 4-6-year-old children, 5-6ml for 7-9-year-old children, and 6.5-7.5ml for12-year-old children. Store in a sealed and cool place.
Pseudoephedrine hydrochloride tablets: tablets, each containing dextromethorphan hydrobromide 15 mg, pseudoephedrine hydrochloride 30 mg and pseudoglyceryl ether 100 mg. To relieve cough, take orally 1-2 tablets, three times a day. No more than 6 tablets per day, and the course of treatment does not exceed 7 days. Pregnant women, severe hypertension and people with a history of mental illness are prohibited.
Baijiahei Ganmao Tablets (Maxi Pseudoephedrine Tablets): Tablets, produced by Qidong Gaitianli Pharmaceutical Co., Ltd., have two kinds of tablets for daily use and night use. Each tablet contains acetaminophen 325mg, pseudoephedrine hydrochloride 30mg and dextromethorphan hydrobromide 15mg daily. In addition to the above ingredients, 25 mg of diphenhydramine hydrochloride is added to each night tablet. Oral, adults take one tablet a day, children and the elderly with wind above 12, once 1 tablet, once every 6 hours 1 time, twice a day; Take 1 tablet before going to bed, and the total daily dose shall not exceed 4 tablets. Patients with hypertension, heart disease, hyperthyroidism, glaucoma, asthma, emphysema and prostatic hypertrophy should not take it.
Puxilan tablets: tablets, produced by Thailand Atlantic Pharmaceutical Company. Each tablet contains dextromethorphan hydrobromide 15 mg for oral administration. Usage as above. Pregnant women and those with excessive phlegm are prohibited. Sealed storage at room temperature, valid for 3 years.
Livzon Leke: Tablets, produced by Livzon Pharmaceutical Factory of Livzon Pharmaceutical Group. Each tablet contains dextromethorphan hydrobromide15mg, pseudoephedrine hydrochloride 30mg and guaiacol glyceryl ether100mg. Used for coughing. Oral administration: adults should take 1-2 tablets once, three times a day, with no more than 8 tablets a day, and the course of treatment should not exceed 7 days.
Parque: Tablets, produced by Huanghe Liya Pharmaceutical Co., Ltd., each tablet contains dextromethorphan hydrobromide 10 mg, acetaminophen 325 mg, phenylpropanolamine hydrochloride 125 mg and chlorpheniramine 1 mg. Used for symptoms such as cold, fever, headache, stuffy nose, tears, cough, etc. Oral: adult 1-2 tablets, 6- 12-year-old children 0.5- 1 tablet, every 6 hours 1 time, no more than 12 tablets per day, and the course of treatment does not exceed 7 days.
Cough water for healthy children: syrup, produced by Lexin Pharmaceutical Co., Ltd., each bottle contains 120ml, and each 5ml contains 4.5mg of dextromethorphan hydrobromide, 2mg of chlorpheniramine, 30mg of ammonium chloride and 6mg of citric acid. Used for symptoms such as cold, fever, headache, stuffy nose, tears, cough, etc. Oral: 5- 10 children 10 ml, 3-5 children 5-7.5 ml, 1-3 children 5 ml, 6 months to/kloc-0 children 2.5-5 ml, 3-6 months children 2.5 ml, three times a day.
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