-
Respiratory Care Jul 2007In health, the airways are lined by a layer of protective mucus gel that sits atop a watery periciliary fluid. Mucus is an adhesive, viscoelastic gel, the biophysical...
In health, the airways are lined by a layer of protective mucus gel that sits atop a watery periciliary fluid. Mucus is an adhesive, viscoelastic gel, the biophysical properties of which are largely determined by entanglements of long polymeric gel-forming mucins, MUC5AC and MUC5B. This layer entraps and clears bacteria and inhibits bacterial growth and biofilm formation. It also protects the airway from inhaled irritants and from fluid loss. In diseases such as cystic fibrosis there is almost no mucin (and thus no mucus) in the airway; secretions consist of inflammatory-cell derived DNA and filamentous actin polymers, which is similar to pus. Retention of this airway pus leads to ongoing inflammation and airway damage. Mucoactive medications include expectorants, mucolytics, and mucokinetic drugs. Expectorants are meant to increase the volume of airway water or secretion in order to increase the effectiveness of cough. Although expectorants, such as guaifenesin (eg, Robatussin or Mucinex), are sold over the counter, there is no evidence that they are effective for the therapy of any form of lung disease, and when administered in combination with a cough suppressant such as dextromethorphan (the "DM" in some medication names) there is a potential risk of increased airway obstruction. Hyperosmolar saline and mannitol powder are now being used as expectorants in cystic fibrosis. Mucolytics that depolymerize mucin, such as N-acetylcysteine, have no proven benefit and carry a risk of epithelial damage when administered via aerosol. DNA-active medications such as dornase alfa (Pulmozyme) and potentially actin-depolymerizing drugs such as thymosin beta(4) may be of value in helping to break down airway pus. Mucokinetic agents can increase the effectiveness of cough, either by increasing expiratory cough airflow or by unsticking highly adhesive secretions from the airway walls. Aerosol surfactant is one of the most promising of this class of medications.
Topics: Expectorants; Humans; Treatment Outcome; United States
PubMed: 17594730
DOI: No ID Found -
The Cochrane Database of Systematic... Nov 2014Acute cough due to upper respiratory tract infection (URTI) is a common symptom. Non-prescription, over-the-counter (OTC) medicines are frequently recommended as a... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Acute cough due to upper respiratory tract infection (URTI) is a common symptom. Non-prescription, over-the-counter (OTC) medicines are frequently recommended as a first-line treatment, but there is little evidence as to whether these drugs are effective.
OBJECTIVES
To assess the effects of oral OTC cough preparations for acute cough in children and adults in community settings.
SEARCH METHODS
We searched CENTRAL (2014, Issue 1), MEDLINE (January 1966 to March week 3 2014), EMBASE (January 1974 to March 2014), CINAHL (January 2010 to March 2014), LILACS (January 2010 to March 2014), Web of Science (January 2010 to March 2014) and the UK Department of Health National Research Register (March 2010).
SELECTION CRITERIA
Randomised controlled trials (RCTs) comparing oral OTC cough preparations with placebo in children and adults suffering from acute cough in community settings. We considered all cough outcomes; secondary outcomes of interest were adverse effects.
DATA COLLECTION AND ANALYSIS
Two review authors independently screened potentially relevant citations, extracted data and assessed study quality. We performed quantitative analysis where appropriate.
MAIN RESULTS
Due to the small numbers of trials in each category, the limited quantitative data available and the marked differences between trials in terms of participants, interventions and outcome measurement, we felt that pooling of the results was inappropriate.We included 29 trials (19 in adults, 10 in children) involving 4835 people (3799 adults and 1036 children). All studies were placebo-controlled RCTs. However, assessment of the risk of bias of the included studies was limited by poor reporting, particularly for the earlier studies.In the adult studies, six trials compared antitussives with placebo and had variable results. Three trials compared the expectorant guaifenesin with placebo; one indicated significant benefit, whereas the other two did not. One trial found that a mucolytic reduced cough frequency and symptom scores. Two studies examined antihistamine-decongestant combinations and found conflicting results. Four studies compared other combinations of drugs with placebo and indicated some benefit in reducing cough symptoms. Three trials found that antihistamines were no more effective than placebo in relieving cough symptoms.In the child studies, antitussives (data from three studies), antihistamines (data from three studies), antihistamine-decongestants (two studies) and antitussive/bronchodilator combinations (one study) were no more effective than placebo. No studies using expectorants met our inclusion criteria. The results of one trial favoured active treatment with mucolytics over placebo. One trial tested two paediatric cough syrups and both preparations showed a 'satisfactory response' in 46% and 56% of children compared to 21% of children in the placebo group. One new trial indicated that three types of honey were more effective than placebo over a three-day period.Twenty-one studies reported adverse effects. There was a wide range across studies, with higher numbers of adverse effects in participants taking preparations containing antihistamines and dextromethorphan.
AUTHORS' CONCLUSIONS
The results of this review have to be interpreted with caution because the number of studies in each category of cough preparations was small. Availability, dosing and duration of use of over-the-counter cough medicines vary significantly in different countries. Many studies were poorly reported making assessment of risk of bias difficult and studies were also very different from each other, making evaluation of overall efficacy difficult. There is no good evidence for or against the effectiveness of OTC medicines in acute cough. This should be taken into account when considering prescribing antihistamines and centrally active antitussive agents in children; drugs that are known to have the potential to cause serious harm.
Topics: Acute Disease; Administration, Oral; Adult; Ambulatory Care; Antitussive Agents; Child; Cough; Drug Therapy, Combination; Expectorants; Histamine H1 Antagonists; Humans; Nonprescription Drugs; Randomized Controlled Trials as Topic
PubMed: 25420096
DOI: 10.1002/14651858.CD001831.pub5 -
The Journal of International Medical... Aug 2014The authors would like to bring attention to the error published in 'Bioavailability of paracetamol, phenylephrine hydrochloride and guaifenesin in a fixed-combination...
The authors would like to bring attention to the error published in 'Bioavailability of paracetamol, phenylephrine hydrochloride and guaifenesin in a fixed-combination syrup versus an oral reference product' 'Annick Janin and Joelle Monnet' Journal of International Medical Research 42(2) pp. 347-359. DOI: 10.1177/0300060513503762.
PubMed: 24903555
DOI: 10.1177/0300060514533283 -
Molecules (Basel, Switzerland) May 2021Enzymes are highly specific biological catalysts that accelerate the rate of chemical reactions within the cell. Our knowledge of how enzymes work remains incomplete.... (Review)
Review
Enzymes are highly specific biological catalysts that accelerate the rate of chemical reactions within the cell. Our knowledge of how enzymes work remains incomplete. Computational methodologies such as molecular mechanics (MM) and quantum mechanical (QM) methods play an important role in elucidating the detailed mechanisms of enzymatic reactions where experimental research measurements are not possible. Theories invoked by a variety of scientists indicate that enzymes work as structural scaffolds that serve to bring together and orient the reactants so that the reaction can proceed with minimum energy. Enzyme models can be utilized for mimicking enzyme catalysis and the development of novel prodrugs. Prodrugs are used to enhance the pharmacokinetics of drugs; classical prodrug approaches focus on alternating the physicochemical properties, while chemical modern approaches are based on the knowledge gained from the chemistry of enzyme models and correlations between experimental and calculated rate values of intramolecular processes (enzyme models). A large number of prodrugs have been designed and developed to improve the effectiveness and pharmacokinetics of commonly used drugs, such as anti-Parkinson (dopamine), antiviral (acyclovir), antimalarial (atovaquone), anticancer (azanucleosides), antifibrinolytic (tranexamic acid), antihyperlipidemia (statins), vasoconstrictors (phenylephrine), antihypertension (atenolol), antibacterial agents (amoxicillin, cephalexin, and cefuroxime axetil), paracetamol, and guaifenesin. This article describes the works done on enzyme models and the computational methods used to understand enzyme catalysis and to help in the development of efficient prodrugs.
Topics: Acyclovir; Atenolol; Atovaquone; Catalysis; Chemistry, Pharmaceutical; Decitabine; Dopamine; Enzymes; Hydrogen-Ion Concentration; Hydrolysis; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Molecular Conformation; Nucleosides; Phenylephrine; Prodrugs; Protons; Quantum Theory; Software; Technology, Pharmaceutical; Temperature; Tranexamic Acid
PubMed: 34071328
DOI: 10.3390/molecules26113248 -
Chemical Science Aug 2022The development of chemoselective C(sp)-H deuteration is of particular interest in synthetic chemistry. We herein report the α-selective,...
The development of chemoselective C(sp)-H deuteration is of particular interest in synthetic chemistry. We herein report the α-selective, iridium(iii)-bipyridonate-catalyzed hydrogen(H)/deuterium(D) isotope exchange of alcohols using deuterium oxide (DO) as the primary deuterium source. This method enables the direct, chemoselective deuteration of primary and secondary alcohols under basic or neutral conditions without being affected by coordinative functional groups such as imidazole and tetrazole. Successful substrates for deuterium labelling include the pharmaceuticals losartan potassium, rapidosept, guaifenesin, and diprophylline. The deuterated losartan potassium shows higher stability towards the metabolism by CYP2C9 than the protiated analogue. Kinetic and DFT studies indicate that the direct deuteration proceeds through dehydrogenation of alcohol to the carbonyl intermediate, conversion of [Ir-H] to [Ir-D] with DO, and deuteration of the carbonyl intermediate to give the α-deuterated product.
PubMed: 35975159
DOI: 10.1039/d2sc01805e -
Multidisciplinary Respiratory Medicine 2017Guaifenesin, a mucoactive drug, acts by loosening mucus in the airways and making coughs more productive. It is used for relief of wet cough and chest congestion due to... (Review)
Review
Guaifenesin, a mucoactive drug, acts by loosening mucus in the airways and making coughs more productive. It is used for relief of wet cough and chest congestion due to the common cold, and remains the only legally marketed expectorant in the US (per OTC Monograph). An ingredient in numerous over-the-counter (OTC) cough/cold medications, guaifenesin has a secondary indication for use in stable chronic bronchitis (professional indication). Clinical pharmacology and patient studies support the clinical utility of guaifenesin in respiratory conditions where mucus hypersecretion is prevalent: acute upper respiratory tract infections (URTIs), stable chronic bronchitis, and possibly rhinosinusitis. Guaifenesin has a well-established and favorable safety and tolerability profile in adult and pediatric populations. Its dosing range (200-400 mg 4-hourly, up to 6× daily) allows flexible dose titration to allow an increase of plasma concentrations. Multiple daily doses are needed to maintain 24-h therapeutic effect with immediate-release formulations. Extended-release guaifenesin tablet formulations are available, providing convenience with 12-hourly dosing and portability compared to liquids. Guaifenesin is considered as a safe and effective expectorant for the treatment of mucus-related symptoms in acute URTIs and stable chronic bronchitis. Its clinical efficacy has been demonstrated most widely in chronic respiratory conditions, where excess mucus production and cough are more stable symptoms. Progress is being made to establish clinical models and measures that are more appropriate for studying symptomatic relief with guaifenesin in acute respiratory infections. This will help generate the up-to-date and high-quality data needed to optimize guaifenesin's effectiveness in established uses, and in new respiratory indications associated with mucus hypersecretion.
PubMed: 29238574
DOI: 10.1186/s40248-017-0113-4 -
Lung Oct 2020Most medicines are white bitter powders that are formulated as tablets and capsules but cough medicines are an exception where the taste and appearance of the medicine... (Review)
Review
Most medicines are white bitter powders that are formulated as tablets and capsules but cough medicines are an exception where the taste and appearance of the medicine are more important to the patient than the pharmacology of the active ingredient. Excipients are generally defined as any ingredient in a medicine other than the active ingredient. In most medicines excipients play a supportive role in delivering the medicine, but in the case of cough medicines, excipients have more important and complex roles and they can also be the main active ingredient of the cough medicine as menthol, glycerol, and sugars, which are declared as active ingredients. This review searched the United Kingdom electronic medicines compendium (emc) and found over 100 excipients in 60 different liquid formulations of over the counter cough medicines. The excipients were divided into functional groups: sweeteners, thickeners, flavors, colors, antimicrobials, and buffers, and the incidence and function of the different excipients is discussed. When considering the efficacy of a cough medicine, clinicians and pharmacists tend to think of the pharmacology of antitussives such as dextromethorphan or expectorants such as guaifenesin, and they rarely consider the role of excipients in the efficacy of the medicine. This review discusses the functions and importance of excipients in cough medicines and provides some new information for clinicians, pharmacists, and all interested in the treatment of cough when considering the composition and efficacy of a cough medicine.
Topics: Humans; Antitussive Agents; Cough; Drug Compounding; Excipients; Nonprescription Drugs; Pharmaceutical Solutions; Treatment Outcome
PubMed: 32889596
DOI: 10.1007/s00408-020-00390-x