Guaifenesin

Uses

Dextromethorphan is used for Chronic dry cough or unproductive cough; Acute dry cough which is interfering with normal function or sleep.

Guaifenesin is an expectorant commonly found in OTC products for the symptomatic relief from congested chests and coughs associated with cold, bronchitis, and/or other breathing illnesses.

Guaifenesin is an expectorant that is indicated for providing temporary symptomatic relief from congested chests and coughs which may be due to a cold, bronchitis, and/or other breathing illnesses .

Pseudoephedrine is an alpha and beta adrenergic agonist used to treat nasal and sinus congestion, as well as allergic rhinitis.

Pseudoephedrine is a sympathomimetic amine used for its decongestant activity.

Guaifenesin is also used to associated treatment for these conditions: Allergic cough, Common Cold, Common Cold/Flu, Cough, Cough caused by Common Cold, Coughing caused by Allergies, Coughing caused by Bronchitis, Coughing caused by Flu caused by Influenza, Fever, Flu caused by Influenza, Headache, Irritative cough, Itching of the nose, Itching of the throat, Nasal Congestion, Pseudobulbar affect, Rhinorrhoea, Sneezing, Upper respiratory symptoms, Watery itchy eyes, Airway secretion clearance therapy, Bronchodilation, Oropharyngeal antisepsisAllergic Reaction, Asthma, Asthma, Allergic, Bronchial Asthma, Bronchitis, Bronchospasm, Chronic Bronchitis, Chronic Obstructive Respiratory Diseases, Common Cold, Cough, Cough caused by Common Cold, Coughing caused by Allergies, Coughing caused by Flu caused by Influenza, Drug Allergy, Emphysema, Fever, Flu caused by Influenza, Food Allergy, Headache, House dust allergy, Irritative cough, Laryngitis, Nasal Congestion, Nasal Congestion caused by Common Cold, Phlegm, Pollen Allergy, Productive cough, Rash, Rhinorrhoea, Sneezing, Sore Throat, Tracheitis, Urticaria, Whooping Cough, Acute Rhinitis, Chest congestion, Chills occurring with fever, Dry cough, Excess mucus or phlegm, Mild to moderate pain, Minor aches and pains, Airway secretion clearance therapy, ExpectorantAllergic Rhinitis (AR), Allergies, Common Cold, Common Cold Associated With Cough, Common Cold/Flu, Cough, Cough caused by Common Cold, Eye allergy, Fever, Flu caused by Influenza, Headache, Irritative cough, Nasal Allergies, Nasal Congestion, Nasal Congestion caused by Common Cold, Pain, Perennial Allergy, Priapism, Respiratory Allergy, Rhinorrhoea, Seasonal Allergic Rhinitis, Seasonal Allergies, Sinus Congestion, Sinusitis, Sneezing, Sore Throat, Symptoms of Acute Bronchitis Accompanied by Coughing, Throat irritation, Upper Respiratory Tract Infection, Upper respiratory tract congestion, Upper respiratory tract signs and symptoms, Dry cough, Minor aches and pains, Sinus pain, Watery itchy eyes, Airway secretion clearance therapy

How Guaifenesin works

Dextromethorphan is an agonist of NMDA and sigma-1 receptors. It is also an antagonist of α3/β4 nicotinic receptors.[A10589] However, the mechanism by which dextromethorphan's receptor agonism and antagonism translates to a clinical effect is not well understood.

Although the exact mechanism of action of guaifenesin may not yet be formally or totally elucidated, it is believed that expectorants like guaifenesin function by increasing mucus secretion . Moreover, it is also further proposed that such expectorants may also act as an irritant to gastric vagal receptors, and recruit efferent parasympathetic reflexes that can elicit glandular exocytosis that is comprised of a less viscous mucus mixture . Subsequently, these actions may provoke coughing that can ultimately flush difficult to access, congealed mucopurulent material from obstructed small airways to facilitate a temporary improvement for the individual .

Consequently, while it is generally proposed that guaifenesin functions as an expectorant by helping to loosen phlegm (mucus) and thin bronchial secretions to rid the bronchial passageways of bothersome mucus and make coughs more productive, there has also been research to suggest that guaifenesin possesses and is capable of demonstrating anticonvulsant and muscle relaxant effects to some degree possibly by acting as an NMDA receptor antagonist .

Pseudoephedrine acts mainly as an agonist of alpha adrenergic receptors and less strongly as an agonist of beta adrenergic receptors.[A10896] This agonism of adrenergic receptors produces vasoconstriction which is used as a decongestant and as a treatment of priapism. Pseudoephedrine is also an inhibitor of norepinephrine, dopamine, and serotonin transporters.

The sympathomimetic effects of pseudoephedrine include an increase in mean arterial pressure, heart rate, and chronotropic response of the right atria. Pseudoephedrine is also a partial agonist of the anococcygeal muscle. Pseudoephedrine also inhibits NF-kappa-B, NFAT, and AP-1.

Dosage

Guaifenesin dosage

Adults and Children over 12 years: 15 to 30 mg three to four times per day. However, 60 mg doses up to four times per day have been used without increased side effects.

Children between 6 and 12 years: 5-15 mg up to four times per day.

Children between 2 and 6 years: 2.5-5 mg up to four times per day.

Side Effects

Adverse effects with Dextromethorphan are rare, but nausea and dizziness sometimes occur. The drug produces no analgesia or addiction and little or no CNS depression. Excitation, confusion and respiratory depression may occur after overdosage.

Toxicity

A dextromethorphan overdose may present as nausea, vomiting, stupor, coma, respiratory depression, seizures, tachycardia, hyperexcitability, toxic psychosis, ataxia, nystagmus, dystonia, blurred vision, changes in muscle reflexes, and serotonin syndrome. Overdose should be managed through symptomatic and supportive measures.

The most prevalent signs and symptoms associated with an overdose of guaifenesin have been nausea and vomiting .

Although adequate and well-controlled studies in pregnant women have not been performed, the Collaborative Perinatal Project monitored 197 mother-child pairs exposed to guaifenesin during the first trimester . An increased occurrence of inguinal hernias was found in the neonates . However, congenital defects were not strongly associated with guaifenesin use during pregnancy in 2 large groups of mother-child pairs .

Moreover, guaifenesin is excreted in breast milk in small quantities . Subsequently, caution should be exercised by balancing the potential benefit of treatment against any possible risks .

Additionally, an LD₅₀ value of 1510 mg/kg (rat, oral) has been reported for guaifenesin .

The oral LD₅₀ of pseudoephedrine is 2206mg/kg in rats and 726mg/kg in mice.

Patients experiencing an overdose of pseudoephedrine may present with giddiness, headache, nausea, vomiting, sweating, thirst, tachycardia, precordial pain, palpitations, difficulty urinating, muscle weakness, muscle tension, anxiety, restlessness, insomnia, toxic psychosis, cardiac arrhythmias, circulatory collapse, convulsions, coma, and respiratory failure. Treat overdose with symptomatic and supportive treatment including removal of unabsorbed drug.

Precaution

Do not use Dextromethorphan to control a cough that is associated with smoking, asthma, or emphysema, or a cough that is productive (produces sputum or phlegm).

Interaction

The following medicines should be taken carefully while concomitantly use with Dextromethorphan: Amiodarone, Fluoexetine, Quinidine, CNS depressants and Monoamine oxidase (MAO) inhibitors.

Volume of Distribution

The volume of distribution of dextromethorphan is 5-6.7L/kg.

The geometric mean apparent volume of distribution of guaifenesin determined in healthy adult subjects is 116L (CV=45.7%) .

The apparent volume of distribution of pseudoephedrin is 2.6-3.3L/kg.

Elimination Route

A 30mg oral dose of dextromethorphan reaches a C_max of 2.9 ng/mL, with a T_max of 2.86 h, and an AUC of 17.8 ng*h/mL.

Studies have shown that guaifenesin is well absorbed from and along the gastrointestinal tract after oral administration .

A 240mg oral dose of pseudoephedrine reaches a C_max of 246.3±10.5ng/mL fed and 272.5±13.4ng/mL fasted, with a T_max of 6.60±1.38h fed and 11.87±0.72h fasted, with an AUC of 6862.0±334.1ng*h/mL fed and 7535.1±333.0ng*h/mL fasted.

Half Life

Dextromethorphan has a half life of 3-30 hours.

The half-life in plasma observed for guaifenesin is approximately one hour .

The mean elimination half life of pseudoephedrine is 6.0h.

Clearance

The mean clearance recorded for guaifenesin is about 94.8 L/hr (CV=51.4%) .

A 60mg oral dose of pseudoephedrine has a clearance of 5.9±1.7mL/min/kg.

Elimination Route

After administration, guaifenesin is metabolized and then largely excreted in the urine .

55-75% of an oral dose is detected in the urine as unchanged pseudoephedrine.

Pregnancy & Breastfeeding use

Pregnancy: Adequate and well-controlled studies in human have not been done. However, Dextromethorphan has not been reported to cause birth defects.

Lactation: It is not known whether dextromethorphan passes into breast milk. However, Dextromethorphan has not been reported to cause problems in nursing babies.

Contraindication

Hypersensitivity to Dextromethorphan or any other component.

Acute Overdose

Symptoms: In mild overdose, tachycardia, hypertension, vomiting, mydriasis, diaphoresis, nystagmus, euphoria, loss of motor coordination, and giggling; in moderate intoxication, in addition to those listed above, hallucinations and a plodding ataxic gait; in severely intoxication, agitation or somnolence.

Management: treatment is symptomatic and supportive. Naloxone may be useful in reversing toxicity.

Storage Condition

Store at 15-30° C

Innovators Monograph

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