Drugs:
Albuterol (proventil, ventolin)
Salmeterol (Serevent)
Terbutaline (Brethine)

Long-acting asthma inhaler

Long-acting asthma inhaler

Terbutaline SubQ injection

                                     
Terbutaline Acute-care use:
Onset: "Sub-Q: Measurable changes in expiratory flow rate occur within 5 minutes." (1)


(1): http://www.drugs.com/monograph/terbutaline-sulfate.html


Quoted from: http://www.medscape.com/viewarticle/568509_7

Although the results of a study by Appel et al.^[79] do not clearly define the role of systemic β-agonists in the treatment of life-threatening asthma, it suggests that subcutaneous administration of epinephrine or terbutaline should be considered in patients unresponsive to continuous nebulized β2-agonists, and in those patients unable to cooperate due to alteration of mental status or an inability to tolerate inhaled therapy. Epinephrine may also be delivered in intubated patients not responding to inhaled therapy during mechanical ventilation. Subcutaneously, 0.3-0.5 ml (1: 1000) of epinephrine can be administered every 20 min to a maximum of three doses. Terbutaline can be administered subcutaneously (0.25-0.5 mg) and is the preferred treatment in pregnant females. Subcutaneous administration of epinephrine or terbutaline should not be delayed since it is well tolerated even in older patients with no history of myocardialinfarction.^[80]Intravenous infusion of terbutaline starting at 0.05-0.10 μg/kg per min has been utilized predominantly in pediatric patients. It may be considered in the treatment of patients with no response to inhaled or subcutaneous treatment, and in whom respiratory arrest is imminent, or in patients not adequately ventilated despite optimal setting of the ventilator. A recent double blind, randomized controlled trial by Bogie et al.^[81] evaluated the benefit of intravenous terbutaline in 49 nonventilated children with acute severe asthma who were already on continuous high-dose nebulized albuterol. Although the use of intravenous terbutaline was associated with improvement in the clinical asthma severity score over the first 24 h, shorter use of continuous nebulized albuterol, and shorter ICU stay, the differences were not statistically significant.^[81]