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Management of Asthma and Treatment by Ventolin Inhalers
Due to a lack of consistency in the definition of asthma, estimates of the prevalence of asthma in the general population have yrelded disparate results. By most criteria, however, asthma is a major health problem affecting from 2-20 percent of the population. During the past two decades, considerable advances have been made in our understanding of the pathophysiology of asthma and in the pharmacologic agents available to treat the condition. Despite this, asthma is frequently underdiagnosed and this precludes adequate treatment. In addition, asthma remains a considerable source of morbidity and hospital admissions for asthma continue to rise. Although the mortality rate for asthma has remained stable during the past ten years in most Western countries, recent reports of a marked increase in deaths from asthma in New Zealand are disconcerting. Moreover, the findings of recent surveys from Britain, which attempted to ascertain the factors associated with death from asthma, allow no grounds for complacency in our approach to the management of asthma. Several areas of deficiency in the management of asthma were identified in these reports including: (1) failure to recognize the severity of asthma by patients, relatives and physicians which resulted in delay in the institution of appropriate therapy; (2) inadequate supervision of patients, particularly in respect to serial measurement of pulmonary function; and (3) underuse of prophylactic drugs, inhaled steroids and cromolyn sodium in particular. Are you ready to lock away your asthma? Due to ventolin inhalers it becomes possible. Such preparaions you may order via buy-asthma-inhalers-online.com.
The rational treatment of asthma depends on an accurate initial diagnosis and assessment of the severity of asthma. This initial evaluation should be based on a detailed history and physical examination, supplemented by allergy skin testing if indicated by history. The diagnosis of asthma should be confirmed by pulmonary function tests, as poor correlation exists between patients’ symptoms and objective measurements of airway obstruction. In an office setting, airway obstruction is simply measured by the use of a peak flow meter or alternatively by a spirometric device which measures peak expiratory flow rate (PEFR), forced expiratory vital capacity (FVC) and forced expiratory volume in one second (FEV). Finally, the reversibility of airway obstruction should be determined by measuring lung function before and after the inhalation of a selective beta.; agonist, eg, albuterol.
Many philosophies of asthma management exist, but from the outset, it is important to adopt a positive approach and establish a treatment plan which is tailored to meet the needs of the individual patient. The goals of treatment should be clearly defined (Table 1), and adequate supervision and repeated pulmonary function testing arranged in order to determine the response to ventolin inhalers therapy and long-term course of the disease. For successful management of asthma it is of paramount importance that the patient and family members have a clear understanding of the nature of asthma, possible inciting factors, and the mechanism of action, mode of administration and possible side effects of the medications used. Patients must be instructed in the early recognition and treatment of acute asthma attacks and must have clear guidelines as to when to seek help if home treatment is not effective.
Although drug therapy remains the cornerstone of treatment, modern management of asthma demands a balanced approach incorporating other forms of treatment such as environmental control and immunotherapy.
Specific allergic irritant factors which appear to aggravate a patients asthma, as indicated by a detailed history and confirmed by skin testing, should be eliminated or avoided if possible. Patients with asthma and their family members should be encouraged not to smoke. If possible, a change of employment is indicated for patients suffering from occupational asthma. For patients who are sensitive to house dust, simple anti-dust measures are justifiable but obsessional measures are likely to be disappointing. An animal pet should be removed from the household only if there is good evidence that it is a major aggravating factor. Unfortunately, certain allergens, such as pollens and fungal spores, are ubiquitous and difficult to avoid.
Food allergens, eg, cow’s milk, may cause diarrhea and eczema but are a rare cause of wheezing. Elaborate exclusion diets are, therefore, not warranted in the management of asthma.
Although immunotherapy is widely practiced, its place in the overall management of asthma remains controversial. Favorable results have been obtained in controlled trials of immunotherapy in the treatment of allergic rhinitis, but trials of immunotherapy in the management of asthma have yielded variable results. In general, immunotherapy should be considered for selected patients with asthma, who are sensitive to one or more specific allergens, and whose asthma is not adequately controlled despite environmental control and optimal pharmacologic therapy. Immunotherapy in this situation should be used in conjunction with and not in place of ventolin inhaler and drug therapy. Finally, bacterial vaccines have no role in the management of asthma as respiratory infections that induce wheezing in asthmatic patients are invariably viral rather than bacterial in nature.
Patients with asthma should remain as physically active as possible. Swimming and sports requiring short bursts of activity are less likely to result in exercise-induced bronchospasm. Patients should be instructed in the prophylactic use of either a beta2 agonist or cromolyn sodium before engaging in athletic activity. In addition, the mouth and nose should be covered with a scarf when exercising in cold weather.
During the past two decades a number of qualitative changes in the pharmacologic management of asthma have occurred: 1) availability of more selective, longer acting sympathomimetic agents with fewer side effects; 2) introduction of prophylactic agents, notably cromolyn sodium and inhaled corticosteroids; 3) development of sustained-release theophylline preparations and reliable serum theophylline assays; 4) a trend towards inhalation as the preferred mode of administration.
Sympathomimetic Agents. The pharmacology of sympathomimetic agents has recently been reviewed. A number of sympathomimetic drugs have been developed in recent years which are predominantly beta2 agonists, ie, produce effective bron-chodilation with minimal cardiac effects. These agents have more prolonged bronchodilator activity than non-selective adrenergic agonists such as epinephrine. Betas agonists currently available include albuterol (salbutamol), fenoterol, terbutaline and meta-proterenol. Although minor pharmacologic differences exist between these individual drugs, no one drug is superior in all respects. These drugs are extremely useful in the management of acute asthma, in the prevention of exercise-induced bronchospasm, as well as for maintenance therapy for chronic asthma. Side effects (eg, tremor and occasionally tachycardia) are more common after oral or parenteral, rather than after inhalation therapy.
The selective beta2 agonists can be administered by inhaled, oral or parenteral routes. Suggested doses are shown in Table 2. Inhalation is the preferred route of administration, as the drug is delivered directly to its receptor sites within the bronchial tree. Consequently, smaller doses can be used, the onset of action is more rapid, and systemic absorption and adverse effects minimized. The drugs can be inhaled either from a metered-dose inhaler (MDI) or from an oxygen or air-driven compressor and nebulizer. The efficiency of MDIs requires “hand-lung” coordination, making them unsuitable for many young children and elderly patients, particularly during an acute asthma attack when respiratory distress impairs inhalation technique. Such patients may be helped by attaching a spacer (Aerochamber) to the MDI. Alternatively, a breath-activated system (Rotahaler) can be used to inhale the drug as a powder. The administration of beta2 agonists via nebulizers has now become the standard in-hospital treatment for acute severe asthma and has virtually replaced the use of subcutaneous epinephrine in this situation.
Theophylline. The pharmacologic properties of theophylline have been reviewed elsewhere. Sus-tained-release preparations, either as tablets or bead-filled capsules, are ideal for the chronic management of asthma. These preparations usually need to be administered in a ql2h schedule, but rapid metabolism in pediatric patients may necessitate more frequent administration. Intravenous aminophylline remains a useful drug in the management of acute severe asthma, although a sympathomimetic agent should be the “first line” drug in this situation.
Theophylline is metabolized by the liver, but the rate of hepatic bio-transformation varies markedly among individuals and with age. A suggested dosing regimen for various age groups is shown in Table 3. Therapy should, however, be guided by serum theophylline determinations to allow for the wide interindividual variation in the rate of metabolism. In addition, certain physiologic and disease-related variables affect theophylline clearance (Table 4), and must be taken into account when administering theophylline preparations.
Cromolyn Sodium. The pharmacology of cromolyn has recently been reviewed. Cromolyn is a purely prophylactic agent which has no intrinsic bronchodi-lator or anti-inflammatory action. A trial of cromolyn is indicated for any asthmatic patient who requires daily prophylactic medication. It is also beneficial in exercise- or cold-induced asthma. Response to therapy is unpredictable, but overall, about 65 percent of adult and pediatric patients benefit. Cromolyn should be given a trial of six-eight weeks, as a therapeutic effect may not be immediately apparent. As the effects of cromolyn are topical, the drug should be introduced only when the airways are patent. In the presence of airway obstruction, cromolyn therapy should be initiated after a short course of bronchodilator therapy, in order to maximize the effect of the drug on the airways.
Cromolyn is usually given by inhalation as a dry powder. A cromolyn solution is available for administration by nebulizer. The usual dose is 20 mg, four times daily and, when clinical response occurs, a maintenance dose of 20 mg, two or three times daily may be adequate. A metered dose inhaler, delivering 1 mg per inhalation, is now available, and seems to be just as effective: the recommended dose is 2 mg, four times daily.
The optimal duration of therapy with cromolyn is difficult to define, and depends on the response of the individual patient. If the patient becomes asymptomatic during the period of cromolyn therapy, the treatment can be withdrawn to see if symptoms recur. For the patient who improves but remains symptomatic during therapy, the long-term use of cromolyn appears to be safe and virtually free from side effects.
Corticosteroids, Corticosteroids are not h-on-chodilators, yet they are valuable drugs in the treatment of severe chronic asthma. Chronic steroid therapy should be reserved for patients with asthma which is not adequately controlled despite the optimal use of nonsteroidal medications. In this situation, corticosteroids should ideally be administered by inhalation, but in some patients, oral steroid therapy will be necessary.
Inhaled steroids (beclomethasone dipropionate) provide effective control in the majority of patients with moderate to severe asthma and, in the case of steroid-depedent patients, may reduce or eliminate the need for oral steroids. Before initiating be-clomethasone therapy, it is essential that the patients asthma be brought under maximal control with aggressive bronchodilator therapy and, if necessary, a short course of oral steroids. The usual recommended dose of beclomethasone is 100-200 μg four times daily in adults (400 μg/day in children) and, if a clinical response occurs, this dose may be gradually tapered, ideally to a twice daily regimen. In adults, some investigators have achieved improved overall control of asthma by using high-dose inhaled beclomethasone (>1,600 μg/day), but at an increased risk of inducing adrenal suppression. The side effects associated with inhaled steroids appear to be minimal, the most common being oropharyngeal candidiasis and hoarseness.
The efficacy of corticosteroids in acute asthma remains controversial, as clinical trials to date have yielded conflicting results. Despite a lack of consensus, most physicians feel that steroids should be administered in severe acute asthma, especially when the response to aminophylline and sympathomimetic agents is suboptimal. In addition, any patient on inhaled or oral maintenance steroid therapy or who has received steroids in the preceding six months should be given corticosteroid replacement therapy during an acute episode.
Anticholinergic Agents. The discovery of ipratropium bromide, an atropine derivative, is an interesting new chapter in the pharmacologic management of asthma. It is currently available as a metered aerosol and as a solution for administration by nebulizer. As a bronchodilator, it has a slower onset of action but a more prolonged duration of action than betas stimulants. Recent trials have shown that ipratropium potentiates the bronchodilator effect of beta2 stimulants in acute asthma. Its exact role in the chronic management of asthma has not yet been defined. It may be a useful adjunct to betas agents in patients who require multiple drug regimens or may be an alternative for patients who suffer intolerable side effects from betaj agents.
Table 1—The Goals of Asthma Therapy
Maximum possible control of symptoms with minimum possible medications Decrease frequency and severity of acute attacks Maximal improvement in lung function Education of patients about their disease and its management Minimize school/work absenteeism Participation in sporting activities without restriction Normal growth
Table 2—Recommended Dosage Schedule for Betas Agonists
Drug OralAdministration AerosolAdministration Albuterol 2 mg per 5 ml syrup,2 mg or 4 mg tablets: 0.1 to 0.15 mg/kg/dose, 3-4 times daily 0.5% solution: 0.01 to 0.03 ml/kg to a maximum of 1 ml diluted with saline to 3 ml, up to 4 times daily In acute severe asthma,t may be used every 20 minutes in hospital, until a clinical response occurs. Fenoterol 2.5 mg tablets:0.1 mg/kg/dose, 3-4 times daily 0.1% solution: 0.01 to 0.03 ml/kg to a maximum of 1 ml diluted with saline to 3 ml, up to 4 times daily Metaproterenol 10 mg per 5 ml syrup, 20 mg tablets: 0.3 to 0.5 mg/kg/dose, 3-4 times daily 5% solution: 0,01 to 0.02 ml/kg to a maximum of 1 ml diluted with saline to 3 ml, up to 4 times daily Terbutaline 300 (jig/’ml syrup, 2.5 mg or 5 mg tablets: 0.075 mg/kg/dose, 3-4 times daily 1% solution: 0.03 ml/kg or to a maximum of 1 ml diluted with saline to 3 ml, up to 4 times daily
Table 3—Mean Age-Specific Dosage Requirements to Maintain Serum Theophylline Concentration within the Therapeutic Range
Age Total daily dose (ideal body weight) (mg/kg/24 hr) Infants 6-51 wk (0.3) x (age in weeks) + 8 Children 1-9 yr 24 Children 9-12 yr 20 Adolescents 12-16 yr 18 Adults 13 or 900 mg/day (whichever is less)
Table 4—Factors Reported to Alter Theophylline Clearance
Increased Clearance Decreased Clearance Age {increased in children) Age (decreased in infants) Low CHO, high protein diet High CHO, low protein diet Charcoal broiled meat Caffeine Cigarette smoking Macrolide antibiotics Marijuana smoking Cimetidine Chronic ethanol intake Viral infections Cystic fibrosis Cor pulmonale Congestive cardiac failure Cirrhosis
