Analysis of relationship between peak inspiratory flow rate and amount of drug delivered to lungs following inhalation of fluticasone propionate with a Diskhaler.

Haruko Yokoyama, Yoshikazu Yamamura, Takeshi Ozeki, Tatsuji Iga, Yasuhiko Yamada

School of Pharmacy, Tokyo University of Pharmacy and Life Science, Hachioji, Japan.

Biological & pharmaceutical bulletin 2007 Jan

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A Diskhaler is a dry powder type of inhaler that utilizes a breath controlled drug delivery system. The inspiratory flow rate of the patient would have a significant influence on the effects of drugs administered by a Diskhaler. Thus, we investigated the relationship between inspiratory flow rate and amount of drug delivered into the lungs when using a fluticasone propionate dry powder inhaler with a Diskhaler (FP-DH). To investigate the amount of drug inhaled, we used an inhalation simulator, which consisted of a flow recorder placed in a plastic air-tight box that covered the FP-DH equipped with a twin impinger and a vacuum pump. Drugs located in a plastic box, as well as the device, throat, and stage 1 and stage 2, were assayed by HPLC-UV, following in vitro inhalation at the various flow rates ranged from 18.7 to 77.3 l/min for 2 s. The relationship between peak inspiratory flow rate and amount of drug released from the device was analyzed. A positive linear correlation between the dose released from the device and amount of drug deposited in stage 2 was observed (r=0.899, p<0.001). The doses deposited in stage 2 were estimated to be 2.9 microg at a flow rate of 20 l/min, 6.6 microg at 30 l/min, 8.4 microg at 40 l/min, 10.1 microg at 60 l/min, and 11.3 microg at 90 l/min. It was suggested that the amount of drug in the lungs decreased along with a decrease in peak inspiratory flow rate when it was lower than 60 l/min. Our results were found to be very useful to estimate lung deposition by using peak inspiratory flow rate for administration planning, especially in patients with a flow rate of less than 60 l/min.

Citation

Haruko Yokoyama, Yoshikazu Yamamura, Takeshi Ozeki, Tatsuji Iga, Yasuhiko Yamada. Analysis of relationship between peak inspiratory flow rate and amount of drug delivered to lungs following inhalation of fluticasone propionate with a Diskhaler. Biological & pharmaceutical bulletin. 2007 Jan;30(1):162-4