Comparison: Terbutaline vs Salbutamol for Bronchospasm

• Both agents are beta 2 adrenergic receptor agonist, with no variability in terms if selectivity

Benefit of IV vs Inhaled Therapy

• no proven advantage of systemic (i.v. epinephrine, terbutaline, and salbutamol) over aerosol therapy in asthma
• large meta-analysis could find no benefit of systemic therapy in the papers reviewed. 
• intravenous beta2-agonists administered either by bolus or infusion did not lead to significant improvements in any of the outcome measures of clinical success
•  IV beta2-agonists was associated with an non-significant increase in risk of autonomic side effects (2- 12 times), and higher heart rates (4-10 beats per minute)
• The i.v. route for salbutamol in asthma is advocated by the Canadian Medical Association only if the response to nebulization is poor, the patient is coughing excessively, is moribund, or becomes so despite inhalation therapy.
• Inhalation is preferred to oral administration because it provides more rapid relief and causes fewer side–effects.

IV Terbutaline vs IV Salbutamol

• There is no evidence for any difference in efficacy between salbutamol or terbutaline 
• SC administration of epinephrine or terbutaline should be considered, in patients not responding adequately to continuous nebulised salbutamol, and in those patients unable to cooperate (depression of mental status, apnea, coma).
• acute salbutamol and terbutaline administration produce similar effects on heart rate variability and increase sympathetic modulation in the cardiac autonomic activity.
• no difference in efficacy between salbutamol and terbutaline; currently salbutamol is less expensive and available in a wider range of devices. 
• second line intravenous therapies considered for acute asthma in children above 2 years; salbutamol, aminophylline and magnesium sulphate. (based on SIGN UK)
• Most studies and paediatric guides recommend the use of IV Salbutamol over IV Terbutaline.
• Based on Sarawak Handbook of Medical Emergencies, both agents can be given as infusions in severe exacerbations of asthma (as alternative to aminophyline)  
• Based on Malaysian Paediatric Protocol, both agents are used in acute exacerbations of asthma (IV salbutamol in recommended to be initiated earlier, and only followed by IV terbutaline if no response)

References:

1. http://bja.oxfordjournals.org/content/early/2012/12/11/bja.aes444.full
2. http://www.ccforum.com/content/6/1/30
3. http://www.ncbi.nlm.nih.gov/pubmed/11488317
4. http://www.sign.ac.uk/pdf/sign101s62008
5. Travers AA, Jones AP, Kelly KD, Camargo CAJ, Barker SJ, Rowe BH. Intravenous beta2-agonists for acute asthma in the emergency department. Cochrane Database of Systematic Reviews 2001, Issue 1. 
6. http://www.ljf.scot.nhs.uk/LothianJointFormularies/Adult/3.0/3.1/Pages/default.aspx