The advent of centralized pharmacies has resulted in increased delivery of medications by mail. The climate of the Southwest combined with mailbox drug deposition poses the unique situation of prolonged drug exposure to potentially damaging heat. Based on anecdotal reports of formoterol degradation in this setting, our study examines the effect of heat on the formoterol capsule as well as its effects on drug delivery via inhalation.
Formoterol capsules in original blister packaging were heated at 70° C (158° F) for four hours. Capsules were removed from packaging and a vacuum setup was then used to dispense the formoterol into a filter tube using the inhalation technique and device provided by the manufacturer. Weights of the filter tube pre- and post-dispensation were obtained to calculate simulated drug delivery. These measurements were compared with those obtained from capsules which had not been exposed to heating.
The change in filter weights from capsules that underwent heating were significantly less than those obtained from capsules that had not been heated (5.5 ± 2.7 mg vs 12.7 ± 1.5 mg, p<0.05). In addition, visual inspection of heated capsules revealed gross distortion of capsule as well as visible clumping of formoterol. Temperatures less than 70° C resulted in no clumping, whereas temperatures greater than 70° C resulted in increased clumping and capsule distortion.
There is a significant decline in the amount of formoterol obtained through inhalation following simulated conditions inside a mailbox in Arizona heat.
Current methods of medication delivery should be reexamined, and patients should be cautioned regarding other situations where medications may be exposed to temperatures equal to or greater than 70° C, such as car trunks and interiors.
G.T. Chu, None.