Anti tussive agents- definition,’7’classification

Anti tussive agents

Cough suppressants, or anti-tussive medicines, are a family of drugs intended to reduce coughing. As a protective strategy to remove foreign objects, mucus, or irritants from the respiratory system, coughing is a reflex activity brought on by irritation or inflammation. Coughing too much or too often, though, can be upsetting, interfere with everyday tasks, and cause sleep disturbances.

By suppressing the cough reflex through a variety of methods, these medicines relieve symptoms. Opioids, including codeine and hydrocodone, are a popular class of antitussive agents. These drugs efficiently lessen the urge to cough by acting on the cough region of the brain. But because opioids may become addictive and have unpleasant side effects including constipation and tiredness, they are usually only used for severe coughs or under strict medical supervision.

Another common anti-tussive is dextromethorphan, which is a non-opioid central acting drug. Dextromethorphan does not have the same potential for addiction as opioids. In a similar manner, it relieves coughing by working on the brain’s cough control center. Many cough syrups and cold remedies are sold over-the-counter that include dextromethorphan.

Benzonatate and other local anesthetics function by numbing the throat and inhibiting the cough reflex. By lessening the sense of irritation in the throat and respiratory system, these drugs relieve symptoms. However, because of their strength and possible adverse effects, they are usually only accessible with a prescription.

Even though they are not specifically anti-tussive medicines, several expectorants, such as guaifenesin, are frequently used in cough treatments. Expectorants function by reducing mucus in the respiratory tract, facilitating

Diphenhydramine and other antihistamines have anti-tussive qualities as well since they lessen respiratory tract and throat irritation. Antihistamines aren’t primarily meant to suppress coughs, but they can help with some of the discomfort while one is coughing, especially if allergies or upper respiratory tract infections are to blame. Antihistamines aren’t usually used just to suppress coughs, however they can make you drowsy.

It’s crucial to understand that although antitussive medications will reduce coughing temporarily, the underlying cause of the cough is not addressed by them. Consequently, unless instructed differently, their usage should be supervised by medical specialists and restricted to providing temporary symptom alleviation. In order to determine and treat the underlying reason of persistent or severe coughing—which might be infections, allergies, asthma, or other respiratory conditions—further investigation is necessary. appropriate

Anti tussive agents classification:

Anti-tussive agents, also known as cough suppressants, can be classified based on their mechanism of action and chemical structure. Here’s a classification of anti-tussive agents:


Opioids belong to a class of drugs that primarily target opioid receptors in the brain and body, mainly used for pain relief but also effective in suppressing coughs. These drugs are either derived from the opium poppy plant or synthesized to mimic its effects.

Their mechanism of action involves binding to opioid receptors, particularly mu-opioid receptors, found throughout the central nervous system and peripheral tissues. By binding to these receptors, opioids inhibit the cough reflex, primarily located in the brainstem’s medulla oblongata. This inhibition leads to a reduction in coughing and can alleviate related symptoms. Moreover, opioids can reduce the sensitivity of the cough reflex to irritants in the respiratory tract.

Popular opioid medications used for cough suppression include:

  • Codeine: A natural opioid often combined with other drugs for cough relief, available in various forms such as syrups and tablets.
  • Hydrocodone: A semi-synthetic opioid derived from codeine, frequently used with acetaminophen or ibuprofen for pain and cough suppression.
  • Dihydrocodeine: Similar to codeine, this semi-synthetic opioid is utilized for both pain relief and cough suppression.

However, the use of opioids for cough suppression is limited due to concerns about addiction, tolerance, and adverse effects. Common side effects include drowsiness, constipation, nausea, and respiratory depression, especially at higher doses. Prolonged use can lead to physical dependence and withdrawal symptoms upon cessation.

As a result, opioids are typically reserved for severe or unmanageable cough cases and are administered for short-term relief under medical supervision. Non-opioid alternatives like dextromethorphan and benzonatate are preferred for mild to moderate coughs due to their lower addiction risk and fewer side effects.

2.Non-opioid central acting agents:

Non-opioid central acting agents are medications primarily employed as cough suppressants, diverging from opioids by targeting the brain’s cough center without the risk of addiction or CNS depression. Dextromethorphan (DXM), the most common agent in this class, belongs to dissociative anesthetics, structurally resembling opioids but lacking their pain-relieving and addictive traits. DXM operates by dampening the cough reflex in the brainstem, achieved through N-methyl-D-aspartate (NMDA) receptor inhibition and potentially sigma-1 receptor interaction.

Easily accessible over-the-counter (OTC) in various forms like syrups, lozenges, and capsules, DXM aids in relieving coughs stemming from colds, flu, bronchitis, and similar respiratory conditions. It’s often blended with other active ingredients, such as expectorants or antihistamines, for comprehensive symptom relief.

While DXM is generally safe within recommended dosages, it can provoke side effects like dizziness, drowsiness, nausea, and gastrointestinal disturbances. Misuse or high doses can induce hallucinogenic and dissociative states, highlighting the importance of adhering to usage guidelines.

Other non-opioid central acting agents like levocloperastine and moguisteine exist, though less commonly used, with potentially different mechanisms compared to DXM.

In summary, non-opioid central acting agents like DXM offer an essential approach to managing cough symptoms, serving as an alternative to opioids. However, responsible usage and medical consultation for persistent or worsening symptoms are crucial.

3.Local Anesthetics:

Local anesthetics are medications used to temporarily numb specific areas of the body, commonly employed in medical procedures to alleviate pain. They function by blocking nerve impulses, preventing the sensation of pain. These anesthetics fall into two main categories based on their chemical structure.

The first category, esters, includes drugs like procaine, benzocaine, and tetracaine. Esters are broken down in the bloodstream by an enzyme called pseudocholinesterase. They tend to have shorter durations of action compared to the second category, amides.

Amides, on the other hand, comprise drugs like lidocaine, bupivacaine, and ropivacaine. They are metabolized in the liver by microsomal enzymes and generally have longer-lasting effects than ester local anesthetics.

Local anesthetics can be administered through various routes, including topical application, injection directly into tissue (infiltration), injection near a nerve to block its function (nerve block), or injection into the epidural or subarachnoid space (epidural or spinal anesthesia). The choice of anesthetic and administration method depends on factors such as the procedure type and duration, the location to be anesthetized, and the patient’s medical history.

While local anesthetics are considered safe when used correctly, they can lead to side effects and complications such as allergic reactions, systemic toxicity (especially with excessive doses or rapid absorption), and local tissue damage if improperly injected. Hence, healthcare professionals must carefully select the appropriate local anesthetic and dosage, closely monitor patients during administration, and promptly address any adverse effects that arise.


Expectorants are medications that assist in clearing mucus from the airways, aiding in easier breathing by thinning and loosening mucus. They primarily work by increasing mucus volume or reducing its viscosity, promoting mechanisms like coughing and mucociliary clearance. Guaifenesin is a widely used over-the-counter expectorant found in various cold medications, helping to thin mucus for easier expulsion.

They’re commonly used for conditions like colds, bronchitis, and respiratory infections, where excess mucus and coughing are prominent. While they can be effective, results vary, and they’re typically more useful when combined with hydration, rest, and proper treatment.

Side effects like nausea and dizziness are possible, though usually temporary. Certain groups, such as pregnant women or those with specific medical conditions, should use them cautiously or avoid them altogether. It’s crucial to follow dosage instructions and consult a healthcare professional if there are concerns. Overall, expectorants play a valuable role in managing respiratory symptoms, but their use should be tailored to individual needs and medical history.


Antihistamines represent a commonly utilized group of medications aimed at mitigating allergic reactions and their associated symptoms such as itching, sneezing, runny nose, and watery eyes. Their mode of action involves blocking histamine, a substance released during allergic responses, from binding to histamine receptors in the body. These receptors are mainly of two types: H1 and H2. While antihistamines predominantly target H1 receptors, some also affect H2 receptors.

Key points regarding antihistamines include:

Mechanism of Action: Antihistamines function by competitively inhibiting H1 receptors, thereby hindering histamine’s ability to bind and trigger allergic symptoms. This action helps alleviate various allergic manifestations.

Indications: Antihistamines find utility in treating allergic conditions such as hay fever, eye allergies, skin reactions, hives, and insect bite reactions. Additionally, they may address non-allergic issues like motion sickness, nausea, and sleep disturbances.

Types: Antihistamines come in diverse forms like tablets, capsules, liquids, nasal sprays, eye drops, and topical preparations. They are categorized into first-generation and second-generation variants.

  • First-generation antihistamines: Examples include diphenhydramine and chlorpheniramine, which tend to induce drowsiness due to their ability to cross the blood-brain barrier.
  • Second-generation antihistamines: Examples like loratadine and cetirizine cause less sedation as they penetrate the central nervous system to a lesser extent.

Side Effects: Common adverse effects include drowsiness, dry mouth, blurred vision, and constipation, more prominent with first-generation antihistamines. Second-generation ones are generally better tolerated.

Precautions: Caution is advised in individuals with specific medical conditions such as glaucoma, urinary issues, heart problems, and liver or kidney impairments. Antihistamines may also interact with other drugs and alcohol.

Duration of Use: Typically, antihistamines are used as needed for acute allergy relief. Prolonged usage necessitates medical supervision to monitor for side effects and explore alternative treatments if required.

Overall, antihistamines are effective tools for managing allergic symptoms, available in various forms to cater to individual needs. Proper usage, adherence to dosage instructions, and consultation with healthcare professionals regarding any concerns or medical conditions are essential.


Cannabinoids are a group of chemical compounds naturally occurring in the cannabis plant (Cannabis sativa). They affect the body by interacting with the endocannabinoid system, which is a complex network of receptors and neurotransmitters present throughout the body, including in the central and peripheral nervous systems.

The main cannabinoids of interest are:

  1. Tetrahydrocannabinol (THC): This is the component of cannabis responsible for its psychoactive effects, commonly known for inducing a “high” sensation. THC primarily interacts with cannabinoid receptors CB1 and CB2 in the brain and peripheral tissues, affecting mood, cognition, perception, and pain sensation.

  2. Cannabidiol (CBD): Unlike THC, CBD does not cause a psychoactive high. It has gained attention for its potential therapeutic effects, including anti-inflammatory, pain-relieving, anxiety-reducing, and neuroprotective properties. CBD interacts with various receptors in the endocannabinoid system and other neurotransmitter systems, such as serotonin and vanilloid receptors.

In terms of their potential as cough suppressants, cannabinoids, including THC and CBD, have shown promise in both preclinical and clinical studies. They have been explored for their ability to reduce cough reflex sensitivity and airway inflammation.

Research suggests that cannabinoids may achieve their anti-cough effects through several mechanisms:

  • Modulation of neurotransmitter release: Cannabinoids may influence the release of neurotransmitters involved in the cough reflex, such as substance P and glutamate.
  • Anti-inflammatory effects: CBD, in particular, has strong anti-inflammatory properties that could help alleviate airway inflammation and hyperreactivity associated with coughing.
  • Antioxidant effects: Cannabinoids possess antioxidant properties that may safeguard against oxidative stress and inflammation in the respiratory system.

However, it’s crucial to recognize that the exploration of cannabinoids as cough suppressants is still in its early stages, necessitating further studies to grasp their mechanisms of action and effectiveness fully. Moreover, the use of cannabinoids for cough relief may be restricted by regulatory measures, potential side effects, and concerns regarding abuse and dependence, especially with products containing THC.

As with any medication or therapeutic approach, individuals considering the use of cannabinoids for cough suppression should consult with healthcare professionals to evaluate the potential benefits and risks and ensure safe and appropriate usage.

7.Other Agents:

Certain other medications, such as anticholinergics like ipratropium bromide, may also have cough suppressant effects by blocking acetylcholine receptors in the airways, leading to reduced bronchial secretions and cough reflex sensitivity.

                          It’s crucial to remember that selecting an antitussive medication depends on a number of variables, such as the underlying reason of the cough, the intensity of the symptoms, the patient’s medical history, and the existence of any contraindications or concomitant diseases. As a result, seeking medical advice is crucial for accurately diagnosing and treating cough symptoms as well as choosing the best antitussive medication.

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