Iota-carrageenan as an antiviral treatment for the common cold

Introduction: The common cold syndrome of acute upper respiratory tract viral infection is the most common disease among mankind and is an extremely common illness in children. There is a great need for a safe and effective antiviral treatment with minimal side effects. The challenge in developing a treatment is the numerous and varied respiratory viruses that cause this common illness and the need for a treatment with good tolerability and safety. Explanation: All respiratory viruses must reach the cell surface by passing through respiratory fluid and mucus, and this common feature may allow for the development of antivirals that capture viruses during this transit. This article discusses how large polyanionic molecules such as iota-carrageenan may trap positively charged respiratory viruses. Iota-carrageenan is a large polysaccharide molecule which is neither absorbed from the respiratory tract nor metabolised. It, therefore, does not have any pharmacological properties. Iota-carrageenan nasal spray has been shown to reduce the titres of respiratory viruses and to reduce the severity of symptoms in placebo-controlled clinical trials, including children and adults. The results of four clinical trials are presented. Conclusion: Iota-carrageenan is a good candidate as a safe and effective non-specific antiviral treatment for common cold, and more research is justified on polyanionic molecules like carrageenans as antivirals

Soothing properties of glycerol in cough syrups for acute cough due to common cold

The treatment and management of acute cough due to common cold costs billions of dollars of healthcare expenditure and there is a growing opinion that a simple linctus containing glycerol with flavourings such as honey and lemon is a safe and effective treatment for acute cough in children and adults. Glycerol is a component of most cough syrups, and although it is often thought of only as a solvent or thickening agent in cough syrups, it may be a major component for the efficacy of cough syrups due to its special properties of lubrication, demulcency, sweetness, and acting as a humectant. The major benefit of cough syrups in soothing cough is likely due to the properties of the syrup rather than the active ingredients and this review discusses the special properties of glycerol in relation to the treatment of acute cough

Common cold

The common cold is a unique human disease, as it is arguably the most common disease and because of the large number of respiratory viruses causing colds it is one of the most complex of human diseases. This review discusses the respiratory viruses and notes that all these viruses may cause the illness complex recognised as the common cold. The common cold is discussed as part of the “iceberg concept” of disease which ranges from asymptomatic infection to severe illness and death. The factors influencing the incidence of colds are discussed: crowding and sociability, stress, smoking and alcohol, immune status, sex, age, sleep, season, chilling, nutrition and exercise. The mechanism of symptoms related to the innate immune response is explained and symptomatic treatments are tabulated. Morbidity associated with common cold is discussed and possible vaccines

Placebo and side effects confound clinical trials on new antitussives

This review discusses how the placebo effect related to treatment side effects may confound clinical trials on antitussives and specifically looks at the implications for trials on ATP antagonists. These new antitussives have distinctive side effects on the sensation of taste, and investigators have expressed concerns that this may unblind the clinical trials. Blinding is an essential component of trial design, but the degree of blinding in trials is rarely assessed. The assumptions of additivity and balance in clinical trials are discussed as important factors that allow assessment of the pharmacological activity of an antitussive. How side effects unbalance a clinical trial by amplifying the placebo effect of active treatments is discussed. The point is made that unblinding of trials invalidates any assessment of efficacy but that there is little interest or discussion about this fundamental aspect of trials. Proposals are discussed which may improve the blinding of trials and control placebo effects by changes to participant information, trial design, patient selection and use of active placebos. The issue of unblinding of clinical trials is not a new issue, but if real progress is to be made in developing new antitussives, then it is an issue that needs to be urgently addressed

The powerful placebo effect in cough: Relevance to treatment and clinical trials

Interest in the placebo effect of medicines has developed from the use of placebo treatments as controls in clinical trials into a whole new area of research around how placebos fit into a psychosocial model of therapeutics. The large placebo effect associated with cough medicines is both a problem and an opportunity for researchers: a problem for clinical trials on new actives as the active must beat the large placebo effect, and an opportunity for harnessing the placebo effect to produce effective cough medicines without any pharmacologically active ingredient. This review discusses the mechanisms associated with the placebo effect of cough medicines and distinguishes between a ‘perceived placebo effect’ and a true ‘placebo effect’. The efficacy of sweeteners in cough syrups is discussed as well as viscosity, mucoadhesion, and flavoring. The complexity of modern cough medicines is demonstrated by an example of a medicine which contains one active ingredient, and eighteen excipients which provide a complex and intense sensory experience to enhance the placebo effect and complement the pharmacological activity of the medicine

What is the role of over 100 excipients in over the counter (OTC) cough medicines?

Most medicines are white bitter powders that are formulated as tablets and capsules but cough medicines are an excep- tion 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 medi- cines 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 com- pendium (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, clini- cians 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 func- tions 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

Analgesic and decongestant efficacy of the combination of aspirin with pseudoephedrine in patients with symptoms of upper respiratory tract infection

The study investigated the efficacy and safety of a combination therapy of 1,000 mg aspirin (ASA) and 60 mg pseudoephedrine (PSE) on the symptoms of pain (combined score for headache and sore throat) and nasal congestion in 833 patients with acute upper respiratory tract viral infection (URTI), over 4 hours after a single dose in the clinic and over 3 days with multiple doses at home. The study demonstrated that over 4 hours in the clinic the combination ASA plus PSE was superior to PSE or placebo for relief of pain symptoms measured subjectively with pain scores, and was superior to ASA or placebo for relief of nasal congestion as measured objectively with rhinomanometry and subjectively with congestion scores. After 3 days of treatment, ASA plus PSE was superior to PSE but not to placebo or ASA for global pain assessments, and ASA plus PSE was superior to ASA and placebo but not to PSE for congestion assessments. No unexpected adverse events occurred and no serious adverse events were attributed to study medicines. This study demonstrates that a combination therapy of ASA plus PSE provides safe and effective relief of both common cold pain related symptoms and nasal congestion

Normal nasal patency: problems in obtaining standard reference values for the surgeon

This review examines why there is no normal range of nasal patency available to the surgeon when assessing nasal obstruction, and discusses the factors that influence nasal patency. Current normal ranges are examined and criticised because of the variability of normal values and the poor sampling methods used. Instability of physiological nasal patency is related to factors such as the nasal cycle and the nose’s direct exposure to the external environment. Decongestion of the nose is proposed as a way of stabilising anatomical nasal patency, and measurements of patency in this state may be more useful to the surgeon. Population studies are needed to establish a normal range, but these studies must control for factors such as age, height, sex, and nasal shape and size related to climatic adaptation. Rather than classify populations according to unscientific categories such as race, anthropometric measures such as the nasal index are proposed

Efficacy of inferior turbinate coblation for treatment of nasal obstruction

Objective: To determine the efficacy of inferior turbinate coblation for the treatment of nasal obstruction. Methods: Twenty patients awaiting submucosal diathermy to the inferior turbinates were recruited into the study. All underwent inferior turbinate coblation. Pre-operative and post-operative nasal function was investigated using posterior rhinomanometry and subjective symptom scales. Results: There was no significant increase in nasal conductance two weeks after inferior turbinate coblation (p = 0.159). However, three months after inferior turbinate coblation, median nasal conductance had increased significantly, from 203 to 324 cm3/s (p = 0.004). The median increase in nasal conductance was 73 cm3/s or 43.5 per cent. Post-operative visual analogue patients' reported post-operative visual analogue scales scores for nasal obstruction decreased significantly, both two weeks (p = 0.006) and three months after inferior turbinate coblation (p = 0.001) when compared to Pre-operative values. There was no change in the reported severity of rhinorrhoea, nasal itching or sneezing. There was a significant relationship (ρ = −0.57, p = 0.014) between pre-operative nasal conductance and change in nasal conductance after inferior turbinate coblation. Conclusions: This study confirms the short-term efficacy of inferior turbinate coblation for the treatment of nasal obstruction. The benefit was greatest in patients with lower pre-operative nasal conductance. Objective measures of nasal obstruction may be important when selecting patients for inferior turbinate coblation

Why is temperature sensitivity important for the success of common respiratory viruses?

This review explores the idea that temperature sensitivity is an important factor in determining the success of respiratory viruses as human parasites. The review discusses several questions. What is viral temperature sensitivity? At what range of temperatures are common respiratory viruses sensitive? What is the mechanism for their temperature sensitivity? What is the range of temperature along the human airway? What is it that makes respiratory viruses such successful parasites of the human airway? What is the role of temperature sensitivity in respiratory zoonoses? A definition of temperature sensitivity is proposed, as “the property of a virus to replicate poorly or not at all, at the normal body temperature of the host (restrictive temperature), but to replicate well at the lower temperatures found in the upper airway of the host (permissive temperature).” Temperature sensitivity may influence the success of a respiratory virus in several ways. Firstly; by restricting the infection to the upper airways and reducing the chance of systemic infection that may reduce host mobility and increase mortality, and thus limit the spread of the virus. Secondly; by causing a mild upper airway illness with a limited immune response compared to systemic infection, which means that persistent herd immunity does not develop to the same extent as with systemic infections, and re‐infection may occur later. Thirdly; infection of the upper airway triggers local reflex rhinorrhea, coughing and sneezing which aid the exit of the virus from the host and the spread of infection in the community