Environmental Engineering Reference
In-Depth Information
products containing CFC propellants. 59 In a phased approach, these remaining products will be
removed from the market completely by December 31, 2013. Other countries may still allow mar-
keting of CFC products while alternatives are being developed and while conirmation of reliable
supplies of the alternatives is established.
1.3.1.2  HFC Systems
Several hydroluorocarbon (HFC) compounds were identiied as possible CFC propellant alter-
natives because of their non-ozone-depleting capacity and similar desirable characteristics in
common with CFC pMDI propellants (nonlammability, chemical stability, and similar vapor pres-
sures). These propellants currently include HFC 134a (1,1,1,2-tetraluoroethane) and HFC 227ea
(1,1,1,2,3,3,3-heptaluoropropane). 60 Extensive toxicological and safety testing demonstrated that
these propellants were at least as safe as the CFC propellants. 60-62 Subsequently, inhalers were
approved by regulatory agencies for medical use (Table 1.1). Despite apparent similarities with
CFCs, the HFC alternatives have required different formulation strategies and device designs. 57,63,64
In general, these challenges included overcoming different solvency properties, 64-66 designing
different materials and coatings for compatibility issues, 67 and identifying different atomization
TABLE 1.1
Common Marketed pMDIs and Their General Composition
Particle 
Size 
Estimate 
(Microns)
Therapeutic 
Group
Surfactants/
Excipients
Propellant 
System
Formulation 
Type
Drug
References
Bronchodilators
Atrovent
HFA
Ipratropium
bromide
Citric acid, water
HFA 134a,
ethanol
Suspension
Combivent
inhalation
aerosol
Ipratropium
bromide and
albuterol sulfate
Soya lecithin
CFC 11,
CFC 12,
CFC 114
Suspension
3, 2.4
[196]
Dulera
Mometasone furoate
and formoterol
fumarate dihydrate
Oleic acid
HFA 227,
anhydrous
alcohol
Suspension
[197]
Maxair
autohalor
Pirbuterol acetate
Sorbitan trioleate
CFC 11,
CFC 12
Suspension
3.1
[198]
Proventil
HFA
Albuterol sulfate
Oleic acid
HFA 134a,
ethanol
Suspension
1.96
2.21
[198]
Ventolin HFA
Albuterol sulfate
None
HFA 134a
Suspension
2.5
[199]
Xopenex
HFA
Levalbuterol
tartarate
Oleic acid
HFA 134a,
ethanol
Suspension
Corticosteroids
Azmacort
Triamcinolone
acetonide
CFC 12, 1%
w/w ethanol
Suspension
4.33
[200]
Flovent HFA
Fluticasone
propionate
HFA 134a
Suspension
QVAR
autohaler
Beclomethasone
dipropionate
HFA 134a,
ethanol
Solution
1.0
[201]
Symbicort
Budesonide and
formoterol
fumarate dihydrate
Povidone K25
USP, polyethylene
glycol 1000 NF
HFA 227
Suspension
 
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