Cough center

Nonnarcotic Antitussives. The most centrally active, noimarcotic antitussive is dextromethorphan [125-71-3] (39). It is similar to codeine in terms of potency and mechanism of action, ie, it is a direct depressant of the cough center. It is unique in that even though it is stmcturaHy related to codeine, it is not addictive. 

Gough-suppression of the cough reflex (antitussive effective) by exerting a direct effect on the cough center in the medulla. Gbdeine has the most noticeable effect on the cough reflex. 

It is believed that it acts by two mechanisms selective anesthesia of irritated receptors in the lungs and simultaneous suppression of the cough center. Synonyms of this drug are tes-salon, ventussin, and others. 

Pharmacology Dextromethorphan is the d-isomer of the codeine analog of levorphanol. Its cough suppressant action is due to a central action on the cough center in the medulla. Dextromethorphan 15 to 30 mg equals 8 to 15 mg codeine as an antitussive. 

Dextromethorphan (Mediquell, Benylin DM, PediaCare 1, Delsym, Others) [OTC] [Antitussive] Uses Control nonproductive cough Action Suppresses medullary cough center Dose Adults. 10-30 mg PO q4h PRN (max 120 mg/24 h) Peds. 2-6 y 2.5-7.5 mg q4-8h (max 30 mg/24 h) 7-12 y 5-10 mg q4-8h (max 60 mg/24/h) Caution [C, /-] Not for persistent or chronic cough Contra < 2 y. Disp Caps, lozenges, syrup, Liq SE GI disturbances Interactions T Effects W/ amiodarone, fluoxetine, quinidine, terbinafme T risk of serotonin synd Wf sibutramine, MAOIs T CNS depression Wf antihistamines, antidepressants, sedative, opioids, EtOH EMS Will not affect cough caused by asthma,... 

Dextromethorphan hydrobromide is the D-isomer of levorphanol. It lacks CNS activity but acts at the cough center in the medulla to produce an antitussive effect. It is half as potent as codeine as an antitussive. Anecdotal reports of abuse exist, but studies of abuse potential are lacking. It has few side effects but does potentiate the activity of monoamine oxidase inhibitors, leading to hypotension and infrequently coma. Dextromethorphan is often combined in lozenges with the local anesthetic benzocaine, which blocks pain from throat irritation due to coughing. 

MecHanismofAction A chemical relative of morphine without the narcoticproperties that acts on the cough center in the medulla oblongata by elevating the threshold for coughing. Therapeutic Effect Suppresses cough. 

Chapter 3), but there may be a central nervous system component like the cough center in the brain that contributes to these effects as well. 

Codeine Many trade names Inhibits cough reflex by direct effect on brainstem cough center... 

Dextromethorphan produces effects centrally at the cough center to raise the threshold for coughing. Researchers have also proposed that dextromethorphan has important interactions with compounds in the brain that have excitatory effects. Some researchers believe that dextromethorphan may eventually be used as a drag to protect the brain against strokes and bacterial meningitis. However, the Food and Drug Administration (FDA) has not yet approved dextromethorphan for these uses. 

Codeine, hydrocodone, and hydromorphone decrease the sensitivity of CNS cough centers to peripheral stimuli, and decrease mucosal secretion. These actions occur at doses lower than required for analgesia (see p. 135 for a more complete discussion of the opiates). Dextromethorphan [dex troe meth OR fan], a synthetic derivative of morphine, suppresses the response of the cough center. It has no analgesic or addictive potential, and is less constipating than codeine. 

The principal OTC cough supprcssiint is a drug called dextromethorphan, a relative of codeine that quiets the cough center but does not produce euphoria, dependence, or the other characteristic effects of narcotics. Still, it may cause drowsiness and depression ot respiration. 

Antitussives suppress the cough center in the medulla. A cough from acute rhinitis is caused by nasal mucous draining into the respiratory tract. There are two types of antitussives, non-narcotic and narcotic. 

Non-narcotic antitussive suppresses the cough center in the medulla... 

Narcotic analgesics (narcotic agonists) such as opioids act on the central nervous system to treat moderate and severe pain, suppress respiration and coughing by acting on the respiratory and cough centers in the medulla of the brain stem. All narcotic analgesics relieve pain. All except meperidine (Demerol) are also antitussive (cough suppression) and antidiarrheal. 

Opioid agonists also have an antitussive effect attributed to the depression of the cough reflex. Thus some opioids, typically codeine or one of its derivatives, are used for their antitussive activity, predominantly in combination products. The antitussive effect is in part the result of the interaction with opioid receptors at the cough center in the brain (23). The dose required for antitussive activity, however, is lower than that required for analgesia the opioid receptors involved in blocking the cough reflex are less sensitive to naloxone than those responsible for analgesia (23). 

Dextromethorphan Suppresses cough by central action on the cough center in medulla. 

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