Asthma and Herbs
By - 12/03/2005
H.N. Shiva Prasad
Man’s existence on this earth has been made possible only because of vital
role played by the plant kingdom in sustaining his life. Herbs have been the
highly esteemed source of medicine throughout human history. They are widely
used today, is not a throwback to the Dark Ages but an indication that herbs
are a growing part of modern, high-tech medicine. About 25-30 percent of today's
prescription drugs contain chemicals derived from plants.
Unlike synthetic substances the natural drugs do not give symptomatic relief rather provide complete cure of many diseases. Due to these salient features the importance of herbal drugs has been realized seriously and they are becoming a preferred way of therapy throughout the globe.
World Health Organization has recognized the potential of traditional and folk medicines in the management and self-reliance of health care system and currently it is encouraging and promoting the traditional systems in “National Health Care Programmes” of various countries.
Herbal therapy provides rational means for the treatment of many diseases such as respiratory problems, gastro-intestinal disorders, cardio-vascular illness, metabolic and degenerative diseases/disorders associated with the aging. Research carried out on herbals in recent past has helped the society in the cure of certain cancers and search is continuing for finding remedies for AIDS and other diseases which so far are considered to be stubborn and incurable from any synthetic molecule.
PROLOGUE TO ASTHMA
The medical term "asthma" describes a chronic lung disease characterized by a decreased ability to breathe easily. In the disease, the flow of air in and out of the lungs is obstructed in the branching tubes (airways) that carry air to the air sacs deep inside the lung.
In asthma the lungs are over inflated due to the blockage of large and small air ways with the tenacious secretions, air is trapped within the lungs. The alveoli get affected due to impacted mucus or by the inflammation.
ASTHMA STATUS – GLOBAL SCENARIO
According to the WHO (January 2000) between 100 and 150 million people around the globe suffer from asthma and this number is rising. According to the UCB Institute of Allergy of Belgium, in Western Europe as a whole, asthma has doubled in last ten years. In the United States, the number of asthmatics has increased by over 60 per cent since the early 1980s and deaths have doubled to 5,000 a year. There are about 3 million asthmatics in Japan of whom 7 per cent have severe and 30 per cent have moderate level of asthma. In Australia, one child in every six under the age of 16 is affected with asthma. Although asthma sufferers have increased in every age group during the last decade, the largest increase of 73 per cent occurred among children and young adults under the age of 18 years. India has an estimated 15-20 million asthmatics. In view of the fact that air pollution is vital cause in the prevalence of asthma and thus asthma is believed to be a disease of civilization, much effort has been directed towards improving the quality of the air we breathe. These afore -mentioned figures are the concern of one and all. (2)
THE ASTHMA AND ASSOCIATED ECONOMIC BURDEN
Severity of the problem of asthma can be judged from the fact that mortality due to asthma is much more in number compared to day-to-day deaths due to other diseases. Although largely avoidable, asthma tends to occur as epidemics and affects young people as well. The human and economic burden associated with this condition is severe. The cost of asthma to society could be reduced largely through concerted international and national planning action.
Following figures are sufficient to reveal the gravity of the problem:
Ø Worldwide, the cost associated with asthma treatment is estimated to exceed those of TB and HIV/AIDS combined.
Ø In the United States annual asthma care cost exceed US $ 6 billion.
Ø Presently Britain looses about US $ 1.8 billion on health care for asthma and because of days lost through asthma and associated illness.
Ø In Australia, annual direct and indirect medical cost associated with asthma reaches almost US $ 460 million (3).
As per the Global Strategy for Asthma Management and Prevention Report (4) based on the pathology and its functional consequences, asthma can be defined as a chronic inflammatory disease of the air-ways in which many cell types, in particular mast cells, eosinophils and T-lymphocytes play an important role.
Theories explaining asthma mechanisms are:
According to the most popular theory asthma is a fundamentally ‘Allergic Sequence’ due to a wrongful response of the immune (defence) system to a challenge, e.g. by inhaled pollutants (5).
As per another theory based on the ‘Neurogenic Hypothesis’ the asthma attacks are precipitated by a sudden spasm of smooth muscles in the air passages due to imbalance within the nervous system, i.e. autonomous nervous system which regulates smooth muscles via adrenergic and cholinergic receptors.
According to the third theory nicknamed as ‘Myogenic Hypothesis’ white cells migrating to walls of air passages make the smooth muscles hyperactive and prone to sudden spasms leading to an asthma attack.
TYPES OF ASTHMA
Asthma is of two types, one is called Extrinsic or Atopic Asthma and the other is called Intrinsic or Non-atopic Asthma.
EXTRINSIC ASTHMA
In extrinsic asthma an increased responsiveness of the air-ways is caused by exposure to environmental trigger factors. These initiating factors cause an allergic reaction in susceptible individuals (6).
INTRINSIC ASTHMA
Intrinsic asthma generally occurs in the adult-hood in which allergic factors may not be demonstrated, for example stimuli like emotional state, exposure to cold air or inert dusts are responsible for the episode of intrinsic asthma (7).
DIAGNOSIS AND TESTS FOR ASTHMA (8)
The diagnosis of asthma depends on a detailed and enlightened evaluation of history and other tests, measurement and appropriate follow-up. The important laboratory tests useful in diagnosis of asthma include:
SKIN TEST
To detect specific IgE antibody – a positive immediate skin test reaction is a
function of IgE antibody for specific allergen, the release of mast cell mediators
and the reactivity of patient’s skin to histamine.
EOSINOPHILIA
In asthma patients, there is increase in the eosinophil count. The degree of
eosinophilia correlates with the severity of asthma.Though these cells can increase
in number in other tissues but emphasis is placed on eosinophils in blood (9).
CHEST X-RAY
In asthma patients the markings on lungs are increased particularly in chronic
disease. Inspiratory and expiratory chest X-rays help to diagnose body aspiration
as a cause of wheezing. Leakage of cells in tracheobronchial air-way can also
be observed.
STATUS OF ASTHMA TREATMENT THROUGH SYNTHETIC DRUGS
The management of asthma involves use of broncho-dilators for treatment of acute symptoms and using anti-inflammatory drugs for treating chronic inflammation-induced exacerbations (10). At present, no drug is available to effect air-way wall remodelling. Steroids are potent anti-inflammatory agents used in maintenance therapy of asthma (11). The corticosteroids decrease the severity of bronchial reactivity and reduce air-way inflammation and oedema (12). They inhibit mast cell degranulation and release of associated inflammatory mediators, decrease synthesis of inflammatory mediators, suppress new antibody formation and reduce the activity of immune cells. Steroids have a large number of adverse effects, the major side effects being, salt and water retention leading to hypertension, arrythmias, cardiac arrest, menstrual disorders, impaired wound healing and osteoporosis (13).
The primary action of adrenergic β2 agonists is to cause bronchodilation. Salmeterol is a highly selective β2 agonist with a longer duration of action (in acute asthmatic attack, more than 12 hrs) as compared to 6 hrs or less for the shorter acting β2 agonist such as salbutamol. Adverse effects of β2 agonists include muscle tremors, palpitation and peripheral vasodilation causing hypotension (14).
Ipratropium bromide, a synthetic atropine like agent that is available in metered aerosol, has no anti-inflammatory action. It acts through blockade of muscarinic receptors in the tracheobronchial tree, diminishing the bronchoconstricting effects of the vagal reflexes. Dry mouth, pupil dilation and glaucoma are adverse effects of ipratropium bromide.
The methylxanthines act on the body by interacting with second messenger system associated with adrenergic stimulation. Cyclic adenosine monophosphate (cAMP) is a second messenger responsible for increased cellular activity. By preventing the degradation of cAMP by phosphodiesterases, these drugs produce broncho-dilation as a result of an increase in levels of cAMP. Adversely xanthine derivative causes over-stimulation of nervous system, insomnia, anxiety, distress, nausea, vomiting and tachycardia (15).
The 5-lipoxygenase inhibitor and cysteinyl leucotriene antagonists have been found to reduce air-way inflammation and along with medication, regular exercise of respiratory system seems to improve asthma status of a person (16).
According to National Heart, Lung and Blood Institute (NHLBI) and Global Initiative for Asthma (GINA, 1996) medication for asthma can be divided into-
I. Quick relief medication: For emergency/ crisis management
II. Long term preventive medication: For maintenance therapy
SHORT RELIEF MEDICATION
(I) SHORT ACTING ADRENERGICS Β2 AGONISTS :
e.g. Albuterol, Bitolterol, Fenoterol, Isoetharine, Metaproterenol, Pirbuterol, Salbutamol and Terbutaline.
(II) ANTICHOLINERGICS:
e.g. Ipratropium bromide, Axitropium bromide, Telenzepine.
(III) SHORT ACTING METHYL XANTHINES:
e.g. Aminophylline
(IV) ADRENALINE INJECTION
LONG TERM PREVENTIVE MEDICATION
(I) CORTICOSTEROIDS:
e.g. Adrenocorticosteroids, Glucocorticoids
Inhaler- Beclomethasone, Budesonide, Flunisolide, Fluticasone and Triamcinolone
Tablets /Syrups- Methylprednisolone, Prednisolone
(II) LONG ACTING Β2 AGONISTS:
Inhaler- Farmoterol, Salmeterol
Sustained release tablets – Salbutamol, Terbutaline
(III) ANTILEUCOTRIENES :
e.g. Montelucast, Zafirlucast and Zileuton
(IV) MAST CELL STABILIZERS :
e.g. Sodium cromoglycate, Ketotifen
(V) OTHER SUSTAINED RELEASE PREPARATIONS:
e.g. Aminophylline, Methyl xanthine.
HERBS REPORTED FOR TREATMENT OF ASTHMA AND ALLERGY
Ayurveda is a long-standing tradition that offers a unique insight into comprehensive approach to asthma management through proper care of the respiratory tract. This includes maintaining the nourishing functions of the lungs in providing oxygen to the body. In Ayurveda, respiratory tract functions are inter-related with those of other organs that supply nourishment to the body, viz., the stomach. It is believed that phlegm; humor or Kapha (which is one of the three basic humors in Ayurveda) is produced in the stomach and then accumulates in the lungs. Correcting imbalances in the basic humors is critical to health and can be achieved through proper digestion and metabolism. Ayurvedic formulations used in the management of asthma, therefore, judiciously combine herbs for breathing support with anti-oxidant herbs say Curcuma longa to support the digestive, cardiac and nerve functions and expectorant as well as soothing herbs. Ayurveda also recommends improving aeration to the lungs through Yogic breathing exercises for optimal aeration.
In addition to the attention paid to the daily care for the respiratory tract e.g. breathing exercises, Ayurveda offers herbs for successful prevention and treatment of respiratory tract conditions, some of which has been developed into semi synthetic compounds also. Some of these herbs and their active chemical constituents are briefly mentioned here and discussed in this review.
PIPER LONGUM
Piper longum traditionally known as Pippali in Sanskrit, has been used in Ayurveda and Unani medicines in the prevention and treatment of bronchial asthma (17). An Ayurvedic formulation containing P. longum, on clinical evaluation for the anti asthmatic activity, showed relief for the symptoms of asthma in a dose of 1-2 tea spoonful three times a day for four weeks.
ADATHODA VASICA
Adathoda vasica, known in Ayurveda by its Sanskrit name Vasaka, has been included in traditional preparations for the relief of cough, asthma and bronchitis (18 & 19).
TYLOPHORA ASTHMATICA
The therapeutic properties of Tylophora asthmatica (synonym – T. indica) known in Sanskrit as Anthrapachaka, are well documented in the treatment of bronchial asthma (20). Powder of dried leaves, root and decoction of its leaves are used traditionally in the treatment of respiratory hardship such as chronic bronchitis and asthma.
BOSWELLIA SERRATA
Boswellia serrata named in Sanskrit as Salai guggul having boswellic acid block the leukotriene biosynthesis by inhibiting enzyme 5-lipoxygenase. In addition, it decreases the activity of human leukocyte elastase (HLA) in vitro, which may further limit the expression of leukotrienes. Although there is no clinical documentation available on the usefulness of boswellic acid in asthma, the anti-leukotriene mechanism of this compound merits its inclusion in a new generation anti-asthmatic nutraceuticals.
COLEUS FORSKOHLII
Coleus forskohlii contains the diterpene derivative, forskolin, which may activate cyclic Adenosine Monophosphate (AMP). Forskolin has been successfully used in alleviation of experimentally induced asthma in human volunteers (21).
BENINCASA CERIFERA
Benincasa cerifera (Savi), (synonym – Benincasa hispida Thumb)
belonging to family Cucurbitaceae, is a large trailing or climbing gourd, with
softy hairy tendrils. Its fruits are large fleshy, oblong, pubescent and indehiscent.
The seeds are many, oblong, compressed and margined (22). Methanol extract of
B. cerifera seeds showed inhibitory activity on histamine release from
rat exudate cells induced by the antigen-antibody reaction and showed significant
anti-histaminic activity (23). Methanol extract of B. cerifera showed
excellent protection in guinea pigs against the histamine induced bronchospasm
at a dose of 50 mg/ kg (24).
CALOTROPIS GIGANTEA
Calotropis gigantea R. Br. belonging to family Asclepiadaceae is tall shrub reaching 2.4 – 3 m in height. Root barks are useful in treating enlargement of the abdominal viscera, intestinal worms and asthma (25).
GLYCYRRHIZA GLABRA
Glycyrrhiza glabra Linn. is a perennial glandular herb with a sweet root
belongs to family Leguminosae. The plant is 50 cm – 1 m in height. Anti-metastatic
effect of glycyrrhizin in mice implanted with highly metastatic B16F10
melanoma cells was investigated where it was found that glycyrrhizin inhibits
the pulmonary metastasis of B16 melanoma through the regulation of
tumour associated Th-2 cells (26). Decoction of composite drug formulation containing
liquorice when tested for anti-asthma activity, all patients showed clinical improvement
in their symptoms of breathlessness, cough and wheezing at a dose of 30 ml t.i.d.
for 28 days (27). Glycyrrhizin at a dose of 10 mg/kg body weight significantly
inhibited early air-way response and late asthmatic response and ovalbumin specific
serum IgE levels were also reduced significantly by glycyrrhizin (28).
OCIMUM SANCTUM
Ocimum sanctum Linn – a small plant of family Labiatae is 30-60 cm in height. A dose of 500 mg of Tulsi extract when given thrice orally for one week to asthmatic patients relieved the breathlessness in patients along with the change in vital capacity of their lungs (29). Formulation consisting of O. sanctum, Inula recemosa, Terminalia belerica and Piper longum given for one month to one year proved beneficial for the patients suffering from the bronchial asthma as it stopped the attacks of bronchial asthma in 90 per cent cases (30).
CONCLUSION
Among many disease or disorders, asthma is a serious disorder effecting large population of the world. Asthma is a frightening condition, that can seriously impede one’s ability to breathe and suddenly rob the individual of its most important requirement i.e. oxygen.
Herbs are highly esteemed for millennia as a rich source of therapeutic agents for prevention and treatment of asthma and its ailments. Although the contribution of modern synthetic medicine for elevating the human sufferings cannot be under-estimated, equally true is the fact that most of them leave unwanted harmful side/toxic effects on the human system disturbing the basic physiology. During the last three decades or so there has been serious realization of these problems associated with synthetic drugs and as a result the world has started looking towards the herbs as agents of therapy which, apart from being comparatively cheap and easily available, are relatively free from the problems of side effects, toxicity and developing resistance towards causative organisms.
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ABOUT AUTHORS
M. Suresh Gupta is a lecturer in Pharmaceutics
at PES College of Pharmacy, Bangalore. He has worked as officer at Analytical
R & D in Dr. Reddy’s Lab, Hyderabad. He has developed many analytical methods
for natural drugs. He also worked as Research Associate at Glenmark Research
Centre, Mumbai.
H.N.Shivaprasad is a lecturer in Pharmacognosy
& Phytochemistry at PES College of Pharmacy, Bangalore. He has completed
his graduation and post-graduation from Rajiv Gandhi University of Health Sciences,
India. He is the university rank holder at graduate and postgraduate levels.
He has worked as Executive, R & D in Himalaya Drugs, Bangalore. He is doing
his Doctoral [Ph.D.] research at Dr. Hari Singh Gour Vishwavidyalaya, Sagar
[M.P].
He has several National and International publications to his credit. He has
written many health articles in Health and Fitness section of reputed daily
Vijay Times. He has also written many scientific articles to reputed herbal
websites. He has been awarded as Best presenter in 55th Indian Pharmaceutical
Congress, Chennai.
He is the Editor for “Continuing Health Awareness” a fortnightly bulletin
which is circulated among all the PES Group of institutions. He is the
reviewer for the prestigious PHARMACOGNOSY JOURNAL
Dr. S.Mohan is a Principal and Professor in Pharmaceutical chemistry
at PES College of Pharmacy, Bangalore. He has a vast teaching experience of
30 years. He has several National and International publications
to his credit. He has guided several M.Pharm and Ph.D. students till date. He
had the privilege to present scientific papers in International Conferences.
He has delivered invited lectures and chaired many scientific sessions in India
and abroad.
He was the President of the Association of Pharmaceutical teachers
of India, Karnataka State branch and is a life member of several reputed professional
and academic organizations.
He is the Editor-in-chief for “Continuing Health Awareness” a fortnightly bulletin which is circulated among all the PES Group of institutions.
Dr. M.D.Kharya is a professor of Pharmacognosy and Dean at Dept. of
Pharmaceutical Sciences, Dr. Hari singh Gour Vishwavidyalaya, Sagar [M.P], India.
He is a member of Senate and Chairman, board of studies, Dr. Hari singh
Gour Vishwavidyalaya, Sagar [M.P], India. He has several National and International
publications to his credit. He has more than thirty years of academic experience.
He has guided more than 50 M.Pharm and 10 Ph.D. students. He is a life member
of several reputed professional and academic organizations.
He is the President of the Association of Pharmaceutical teachers of India,
Madhya Pradesh. He is the Associate editor for Indian Journal of NaturalProducts.