Albuterol effectiveness

Several genetic polymorphisms of P2-adrenergic receptors ( lAR) have been shown to modulate the P2-agonist (e.g., albuterol) effect in clinical practice [35, 36]. 

Figure 17.3 Drug effect (solid curve) versus time contrasted with drug concentration (dashed curve) versus time. Albuterol effect is measured by the forced expiratory volume in 1 s (FEVi).

Albuterol (also known as salbutamol outside the United States), the most commonly used inhaled short-acting 132-agonist, is a racemic mixture (50 50) of albuterol enantiomers. The R-enantiomer is the active component whereas the S-enantiomer is inactive or may be associated with unwanted effects. Levalbuterol, the pure R-enantiomer of albuterol, is available as a solution for nebulization and as an MDI dosage form. Comparative studies show similar efficacy and safety between levalbuterol and albuterol, but the acquisition cost of levalbuterol is substantially higher. 

Patients receiving these agents may notice improvement in 1 to 2 weeks, but maximal benefit may not be seen for 4 to 6 weeks. Cromolyn and nedocromil appear to be similar in efficacy to the leukotriene antagonists and theophylline for persistent asthma.18 Both agents are well tolerated with adverse effects limited to cough and wheezing. Bad taste and headache have also been reported with nedocromil. One dose of cromolyn or nedocromil prior to exercise or allergen exposure will provide effective prophylaxis for 1 to 2 hours. Cromolyn and nedocromil are not as effective as albuterol for prophylaxis of exercise-induced asthma. 

In patients with mild intermittent asthma, long-term control medications are not necessary, and patients should use a short-acting inhaled P2-agonist t° prevent or treat symptoms.2 This classification includes patients with exercise-induced asthma, seasonal asthma, or asthma symptoms associated with infrequent trigger exposure. Patients can pre-treat with two puffs of cromolyn or nedocromil prior to exposure to a known trigger. The treatment of choice for exercise-induced asthma is two inhalations of albuterol 5 minutes prior to exercise.1 Cromolyn and nedocromil are less effective than albuterol for prophylaxis of exercise-induced asthma. 

Albuterol is the preferred bronchodilator for treatment of acute exacerbations because of its rapid onset of action. Ipratropium can be added to allow for lower doses of albuterol, thus reducing dose-dependent adverse effects such as tachycardia and tremor. Delivery can be through metered-dose inhaler (MDI) and spacer or nebulizer. The nebulizer route is preferred in patients with severe dyspnea and/or cough that would limit delivery of medication through an MDI with spacer. If response is inadequate, theophylline can be considered however, clinical evidence supporting its use is lacking. 

Patients with acute hyperkalemia usually require other therapies to manage hyperkalemia until dialysis can be initiated. Patients who present with cardiac abnormalities caused by hyperkalemia should receive calcium gluconate or chloride (1 g intravenously) to reverse the cardiac effects. Temporary measures can be employed to shift extracellular potassium into the intracellular compartment to stabilize cellular membrane effects of excessive serum potassium levels. Such measures include the use of regular insulin (5 to 10 units intravenously) and dextrose (5% to 50% intravenously), or nebulized albuterol (10 to 20 mg). Sodium bicarbonate should not be used to shift extracellular potassium intracellularly in patients with CKD unless severe metabolic acidosis (pH less than 7.2) is present. These measures will decrease serum potassium levels within 30 to 60 minutes after treatment, but potassium must still be removed from the body. Shifting potassium to the intracellular compartment, however, decreases potassium removal by dialysis. Often, multiple dialysis sessions are required to remove potassium that is redistributed from the intracellular space back into the serum. 

Israel E, Drazen JM, Liggett SB et al. The effect of polymorphisms of the beta[2]-adrenergic receptor on the response to regular use of albuterol in asthma. Am J Respir Crit Care Med 2000 162 75-80. 

Ipratropium bromide has a slower onset of action than short-acting /J2-agonists (15 to 20 minutes vs. 5 minutes for albuterol). For this reason, it may be less suitable for as-needed use, but it is often prescribed in this manner. Ipratropium has a more prolonged bronchodilator effect than short-acting /l2-agonists. Its peak effect occurs in 1.5 to 2 hours and its duration is 4 to 6 hours. The recommended dose via MDI is two puffs four times a day with upward titration often to 24 puffs/day. It is also available as a solution for nebulization. The most frequent patient complaints are dry mouth, nausea, and, occasionally, metallic taste. Because it is poorly absorbed systemically, anticholinergic side effects are uncommon (e.g., blurred vision, urinary retention, nausea, and tachycardia). 

Inhalation solutions are designed to deliver a drug into the respiratory tree of a patient for a local or systemie effect. Examples of compounded inhalation solutions (Table 9) include individually and in combinations of albuterol, cromolyn, morphine sulfate, corticosteroids, ipratropium, metaproterenol, terbutaline, and others. 

Albuterol is a )32-adrenergic sympathomimetic amine with pharmacological similarities to terbutaline. It has almost no effect on jSj-adrenoreceptors of the heart. It has expressed broncholytic effects— prevention or relief of bronchi spasms, lowering respiratory tract resistance, and increasing the vital capacity of the lungs. 

Action Combo of P-adrenergic bronchodilator quaternary anticholinogic Dose 2 inhal qid neb 3 mL q6h Caution [C, +] Contra Peanut/soybean allergy Disp Met-dose inhaler soln for neb (DuoNeb) SE Palpitations, tach, nervousness, GI upset, dizziness, blurred vision Interactions T Effects Wf anticholinergics, including ophthalmic meds effects W/ herb jaborandi tree, pill-bearing spurge EMS See Albuterol may cause transient blurred vision/irritation... 

NAG, w/ or w/in 2 wk of D/C an MAOI Di p Caps SE t BP, tach, wt loss, sexual dysfxn EMS Use caution w/ albuterol can t CV effects monitor for liver injury (RUQ pain, h atomegaly, jaundice) t risk of suicidal thoughts OD Reports limited but may cause xCTostomia (dry mouth), anxiety, prolonged QT interval and Szs symptomatic and supportive... 

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