Respiratory systemScopeApart from their use to provide non-specific support for recuperation and repair, specific phytotherapeutic strategiesinclude the following : Treatment of: inflammatory catarrhal conditions of the upper respiratory mucosa (e.g. common cold, rhinitis, sinusitis, otitis media) acute bronchial and tracheal infections allergic rhinitis nervous coughing patterns.Management of : chronic obstructive pulmonary diseases (chronic bronchitis, bronchiectasis, emphysema, silicosis) asthma chronic tracheitis coughing due to persistent local irritation.

Because of its use of secondary plant products, particular caution is necessary in applying phytotherapy in cases of known allergic reactions to specific medicinal plant products.

Rationale and orientation

To the Chinese, the lungs were the internal organs most in contact with the exterior. So as well as ascribing to them thesource of the bodys rhythm and the site of the catalysis of vital energies, they were seen to be the organs in charge of defences. In earlier times the role of the respiratory system was obvious in all cultures; the first cry was generally taken tobe the first sign of life, the bronchial gasp on the deathbed the last, and a consistent fear throughout history was the hacking, bloody cough of consumption or tuberculosis, the disease that once cast its baleful influence over the popular imagination like cancer and AIDS now do, the constant reminder of how fatal debility followed weakening of the lungs. It was obvious that the lungs, even more than the stomach, were susceptible to contagion, the conceptual medieval precursor to viruses and bacteria. In this imagery, the key to resistance lay not in attacking alien invaders but in strengthening innate resources. Traditional strategies for treating respiratory disease were notably founded on supportive and tonifying remedies. Given that the modern virus remains as elusive as it ever was, an emphasis on supporting defences may seem appropriate again.

Modern interpretations of respiratory illness have shifted in recent years to identifying underlying inflammatory processes,involving leukotrienes and cytokines. Given that most pathologies have a strong inflammatory element, this is a promising avenue of further research for phytotherapy.

This is, however, the one area where the divide between traditional and modern approaches is not very wide.Elsewhere, there are very few modern endorsements of early treatment strategies.2 Modern medical science, which at firstembraced such agents in the earlier part of this century, now sees no role for their use. For example, modern editions of Martindales Extra Pharmacopoeia claim that: There is little evidence to show that expectorants are effective. Some modern drugs may have expectorant activity, such as bromhexine, but they are usually referred to as mucolytic. The impact of traditional remedies on the respiratory system is relatively poorly researched. Reliable external measures of change in mucosal function are elusive; many respiratory diseases are either self-limiting or are among some of the most persistent conditions in the clinic. Even in asthma, where peak flow rates provide a simple measure of benefit, the complexity of the condition and the usual presence of confounding and violent influences make easy characterisation of the condition, and the measurement of all but the most powerful across-theboard remedies, unreliable.

A sense that traditional approaches should be relegated to history is possibly reinforced in the medical psyche by theknowledge that one of the most dramatic advances of modern drugs was in controlling at last the old scourge of tuberculosis. However, this dismissal is not as conclusive as once thought. Tuberculosis is making a serious come-back on the world stage, attacking first the very impoverished and malnourished as it always did. As modern drugs struggle with this new manifestation, there may once again be value in looking at the lessons from the past, that treatment should bebased on supportive remedies in a regime of convalescence. With the luxury of choice, with the option of taking moderndrugs where these are necessary, but also being able to select more supportive strategies at other times, there is real valuein reviewing the treatments forged out of desperate but not always unsuccessful battles with disease in earlier times. These lessons are fortunately quite well learnt.

The dominant feature of respiratory conditions is how readily changes in their behaviour are appreciated subjectively. Theoften immediate effects of eating and drinking different foods and drinks, of temperature and humidity changes and of the various treatments used through history have been the main guide in determining therapeutic strategy. From such experience has come the view of the respiratory mucosa and musculature as being particularly sensitive to reflex responses, notably from the upper digestive tract, from the pharynx to the stomach. There is a persistent tradition in many cultures that respiratory problems are extensions of digestive dysfunctions. Embryology supports such links, with the bronchial tree originating as a diverticulum of the pharyngeal zone of the alimentary duct and sharing common vagal innervation, and the association, for example, between asthma and histamine H2 receptors in the stomach3 add further support to such connections.

Phytotherapeutics

Part of the problem with expectorants probably arises from confusion over their definition. Another stems from the difficulties involved with measuring their efficacy.

Overview of expectorants

An expectorant is a substance that enhances those physiological mechanisms by which respiratory tract secretions are cleared from the lungs. In the course of doing this they often render the consistency of respiratory tract secretions more fluid and/or more demulcent. They do not necessarily increase the quantity of coughed-up phlegm, nor are they necessarily antitussive (see below). Since reflex and warming expectorants act by different mechanisms, and on different parts of the lung tissue, an effective herbal prescription can combine these two types of expectorants, but depending on the patients condition as noted above. The effect and mechanism of action of reflex expectorants have been demonstrated by scientific experiments. However, since their effect seems to involve vagal stimulation of secretory glands, there may also be vagal stimulation of smooth muscle tissue in the lungs. Hence they should be used with caution in asthma, and combined with bronchiolar spasmolytics (but not anticholinergics that can dry respiratory secretions). Many lower respiratory tract disorders will benefit from the action of expectorants, but particularly those where mucus is tenacious and difficult to cough up. However, it depends on the cause of a cough whether an expectorant action is also antitussive.

The four definitions of expectorants given below highlight the difficulties. The dictionary meaning is only concernedwith the actual oral production of phlegm or sputum. Since the majority of mucus produced from the lungs is swallowed,this definition is clearly unsatisfactory. Definitions from the pharmacologists Boyd and Lewis are more useful, but probably the best definition comes from Brunton, a 19th century pharmacologist. Bruntons functional definition bestexplains the various ways in which medicinal plants can act as expectorants.

Definitions of expectorants Oxford Dictionary Promoting the ejection of phlegm by coughing or spitting Boyd (1954) An expectorant may be pharmacologically defined as a substance which increases the output of demulcent respiratory tract fluid Lewis (1960) Expectorants increase the secretions of the respiratory tract and so reduce the viscosity of the mucus which can then act as a demulcent. By virtue of the presence of increased quantities of fluid mucus, expectorants produce a productive cough which is less exhausting and less painful to the patient. Brunton (1885) Remedies which facilitate the removal of secretions from the air passages. The secretion may be rendered easier of removal by an alteration in its character or by increased activity of the expulsive mechanism.Why expectorants?Many respiratory conditions are characterised by abnormal mucus (catarrh) that can narrow airways. This abnormal mucus may be thick and tenacious and hence very difficult to clear from the airways. If expectorants can render this catarrh more fluid and/ or assist in its expulsion, then a clinical benefit should be achieved.

Expectorants can help to relieve debilitating cough. The presence of an irritation in the airways (such as tenaciousabnormal mucus) invokes the cough reflex. (The cough reflex is most sensitive in the trachea and larger airways. The sensitivity progressively decreases in the finer airways and in the very fine airways there is no reflex at all. So in alveolitis, there is little stimulation of the cough reflex, whereas for tracheitis the stimulus is strong.) By clearing abnormal mucus or by changing its character and making it more demulcent, expectorants can allay cough and are therefore antitussive.

In spite of the incomplete scientific case and lack of a consensus orthodox view, traditional approaches to expectorationare strong and consistent across cultures and history. They include mechanisms that are rational and usually immediately apparent.

Stimulating (reflex) expectorants

These are remedies that provoke increased mucociliary activity by reflex stimulation of the upper digestive wall. The classic examples were originally used as emetics. It was noted that this drastic action was accompanied by a noticeableexpectoration. In fact, traditional practitioners in Britain used emesis as a technique to clear the lungs in asthma and chronic bronchitis until quite recent times. Application of these remedies in sub-emetic doses was thus a consistent feature in all major herbal traditions. Herbs such as ipecacuanha, squills and Lobelia have been standards in Western medicine. There is some limited modern investigation of mechanisms involved. For example, ipecac-induced emesis is thought to be mediated through both peripheral and central 5-HT3 receptors. Other plants have been used as stimulating expectorants,although not used as emetics; members of the Primula, Bellis, Saponaria and Polygala genera are often included in this category in Western traditions. High saponin levels seem to be a common feature of this group and saponins are certainly nauseating in high doses.

Plant remedies traditionally used as stimulating (reflex) expectorantsCephaelis (ipecacuanha), Lobelia inflata (Lobelia), Urginea (squills), Primula veris (cowslip), Bellis (daisy), Saponaria(soapwort), Polygala senega (snakeroot)

Indications for stimulating expectorants Cough linked to bronchial congestion, especially where mucus is thick and tenacious or where there is unproductive cough Bronchitis, emphysema

Other traditional indications for stimulating expectorants In some cases as emetics in higher doses

Contraindications for stimulating expectorantsAlthough there is no firm evidence of unsuitability, as gastric irritants they can transiently upset some individuals (immediately relieved by withdrawing or changing the remedy). In addition, the use of stimulating expectorants should be kept under review in cases of dry and irritable conditions of the lungs asthma young children dyspeptic conditions

ApplicationStimulating expectorants are best taken in hot infusions or as tinctures or fluid extracts, before food.Long-term therapy with stimulating expectorants is appropriate in the management of chronic bronchial conditions aslong as digestive functions are not affected.

Advanced phytotherapeuticsStimulating expectorants may also be usefully applied in some cases (depending on other factors) of rheumatic and connective tissue diseases

Warming expectorants (mucolytics)Many of the spices were highly prized in the cold damp climates of northern Europe for their apparent ability to counteractassociated chest problems. In particular, ginger had an almost mythical reputation; where this or imported cinnamonand cloves were not available, Europeans resorted to fennel, aniseed, garlic, mustard and horseradish for the same ends.Later cayenne or chilli peppers were used for this purpose, although generally taken to be too drying in most cases. Theeffect of the pungent spices probably includes increased blood flow to the respiratory mucosa, a reflex irritation of the upper digestive mucosa (as with the stimulating expectorants) and, especially in the sulphur-containing garlic and mustard family, a decrease in the thickness of mucus by altering the structure of its mucopolysaccharide constituents; the sensation usually is of a clearing of catarrh and the shifting of congestion up from the lungs.5 A simple infusion of fresh ginger and cinnamon remains one of the most effective home treatments for the common cold.

Essential oils from various herbs (either administered as essential oils or contained in herbal extracts or tinctures) arethe most important agents that directly influence goblet cells to secrete more respiratory tract fluid and mucus. Boyd studied the effects of several essential oils in various experimental models (see Chapter 2). The most pronounced increaseof respiratory tract fluid was seen after ingestion of oil of anise. Interestingly ingestion of oil of eucalyptus had a moderateeffect that was not eliminated by cutting afferent gastric nerves. This finding supports the premise that essential oils do not generally act as reflex expectorants.

Plant remedies traditionally used as warming expectorantsPimpinella anisum (aniseed), Cinnamomum zeylanicum (cinnamon), Foeniculum (fennel), Zingiber (ginger), Alliumsativum (garlic), Angelica archangelica (angelica).

Indications for warming expectorants Productive cough associated with cold l Bronchitis, emphysema l Profuse catarrhal conditions l Dry cough, as per Boyd.

Other traditional indications for warming expectorants As aromatic digestives l Congestive chronic infections and inflammatory conditions.

Contraindications for warming expectorantsThe use of warming expectorants may be contraindicated or inappropriate in gastro-oesophageal reflux.

Traditional therapeutic insights into the use of warming expectorants

There is a close association in traditional medicine between catarrhal congestion and the digestive/assimilative functions.The warming remedies were seen to act seamlessly across both respiratory and digestive functions treating disturbancesin either or both together. Symptoms most often found with catarrhal conditions might include abdominal distension, lossof appetite and loose stools.

ApplicationsWarming expectorants are best taken immediately before meals. They are particularly effective taken in hot aqueous infusions. Long-term therapy with warming expectorants is usually acceptable.

Respiratory demulcentsThese herbs contain mucilage and have a soothing and anti-inflammatory action on the lower respiratory tract. Althoughthe mechanism is not clear, an opposite effect to that of the stimulating expectorants has been postulated; that is theeffect is a reflex one from the demulcent effect on the pharynx and upper digestive tract, again involving common embryonic origins and vagal innervation.

The major respiratory demulcent herbs are Althaea officinalis (marshmallow root or leaves) and other members ofthe Malvaceae (mallows), Ulmus spp. (slippery elm), members of the Plantago genus, Cetraria islandica (Iceland moss)and Chondrus crispus (Irish moss). Tussilago (coltsfoot) and Symphytum (comfrey) were very widely popular before concerns about pyrrolizidine alkaloids constrained their sale.

Pronounced antitussive activity has been demonstrated experimentally with oral doses of 1000 mg/kg body weightof extract of Althaea officinalis (marshmallow), with comparable effects at 50 mg/kg of the isolated polysaccharides.6These animal studies might suggest enormous doses necessary for clinical effect but if, as implied, the effect is a mechanical one, it is likely that only marginal increases in dose would be necessary to have similar impact in larger animals like humans (see also Chapter 2 under Mucilages).

Respiratory demulcents were popular for childrens cough and generally for dry, irritable and ticklish coughing. Theywere seen as intrinsically contraindicated in wet, damp chest problems, although they can sometimes be quite well suitedto these if there is an irritable element.

Plant remedies traditionally used as respiratory demulcents l Althaea (marshmallow), Plantago spp. (ribwort and plantain), Verbascum (mullein, especially leaf), Chondrus (Irish moss), Cetraria (Iceland moss), Glycyrrhiza (licorice).

Indications for respiratory demulcents Dry, non-productive, irritable cough l Coughing in children l Asthmatic wheezing and tightness.

Other traditional indications for respiratory demulcents As mucilaginous digestive remedies l The effects of dryness on the respiratory system.

Contraindications for respiratory demulcentsThe use of respiratory demulcents may be inappropriate in profuse catarrhal or congestive conditions of the mucosa (butsee above).

Traditional therapeutic insights into the use of respiratory demulcentsAs with other respiratory remedies, there is a close association between effects here and on the digestive tract. Respiratorydemulcents are at their most appropriate if there are parallel indications in the gut: dry inflamed conditions such as gastritisand oesophagitis associated with hyperacidity, dry constipation and its various associated problems.

ApplicationRespiratory demulcents are best taken before meals. They are particularly effective taken in cold aqueous infusions.However, if gastro-oesophageal reflux is contributing to the pathology, as can be the case in asthma, they should be takenafter meals.

Long-term therapy with respiratory demulcents is usually well tolerated.

Respiratory spasmolyticsRespiratory spasmolytics relax the bronchioles of the lungs. Traditionally they included the solanaceous plants (the nightshade family) with powerful atropine-related antiparasympathetic constituents: Datura, Atropa and Solanum were the prominent antiasthmatics of early history. As could now be explained pharmacologically, these remedies tended alsoto dry up the mucosa and had other less desirable effects, so less powerful remedies were also popular. Ephedra sinica(ma huang) from Asia was popular when it reached Europe and works through a sympathomimetic action. Other gentleremedies include culinary herbs such as hyssop and especially thyme, horehound, the North American gumplant, Grindelia camporum and elecampane (Inula helenium).

Plant remedies traditionally used as respiratory spasmolytics

Ephedra (ma huang), Datura stramonium (jimson weed), Atropa belladonna (deadly nightshade), Solanumdulcamara (bittersweet), Hyssopus (hyssop), Thymus vulgaris (thyme), Lobelia inflata (lobelia), Marrubiumvulgare (horehound), Grindelia camporum (gumplant), Euphorbia hirta (pill-bearing spurge), Coleus forskohlii,Glycyrrhiza (licorice), Inula (elecampane).

Indications for respiratory spasmolytics Tight, breathless, non-productive coughing l Wheezing and other asthmatic symptoms.

Other traditional indications for respiratory spasmolytics Many of the gentler remedies were used as relaxants l The solanaceous plants have potent neuroactive properties.

Contraindications for respiratory spasmolyticsThe use of respiratory spasmolytics may be contraindicated or inappropriate in the following In the case of solanaceous plants: glaucoma, urinary retention, paralytic ileus, intestinal atony and obstruction l In the case of Ephedra: appetite disorders, glaucoma, prescription of monoamine oxidase (MAO) inhibitors.

ApplicationRespiratory spasmolytics may be taken at any time of the day as required for immediate effect.Long-term therapy with respiratory spasmolytics is acceptable in the case of the gentler examples, but not for the solanaceous plants or Ephedra, and in all cases there should be attention to treatment of underlying causes rather than relying on symptomatic relief.