Determination of the relative bioavailability of nedocromil sodium to the lung following inhalation using urinary excretion.
OBJECTIVE
To determine the relative lung deposition of nedocromil sodium following inhalation by comparing the amounts of nedocromil sodium excreted in the urine after oral and inhaled dosing.


METHODS
Ten healthy volunteers swallowed 8 mg of nedocromil and inhaled 4 x 2-mg doses on separate days. Urine was collected at 0.0, 0.5. 1.0, 2.0, 5.0, 24 h and 36 h after dosing. Urinary excretion of nedocromil was determined by high-performance liquid chromatography.


RESULTS
A significantly greater amount of nedocromil was excreted following inhalation than after oral dosing. The mean with (SD) amount excreted at 0.5, 1.0 h and 24 h following inhalation of 4 x 2-mg doses was 41.0 (19.5), 93.0 (39.1) and 319.9 (138.1) microg. Corresponding values after oral administration of 8 mg of nedocromil were 2.1 (2.2), 6.3 (4.7) microg and 74.4 (58.8) microg, respectively.


CONCLUSIONS
Nedocromil excreted in the urine at 0.5 h and 1.0 h after dosing is representative of the amount of drug delivered to the lungs. This method could be used to compare the relative bioavailability to the lungs following inhalation, and hence the performance of different inhaled products and inhalation techniques. The amount of nedocromil excreted in 24 h post-dose is representative of the emitted dose which was delivered to the body.
Postgraduate Studies in Pharmaceutical Technology, School of Pharmacy, University of Bradford, UK.
O A
OA
Aswania
S A
SA
Corlett
H
H
Chrystyn
D000280:Administration, Inhalation; D000284:Administration, Oral; D000328:Adult; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000652:urine; D001682:Biological Availability; D005260:Female; D006801:Humans; D008168:Lung / Q000378:metabolism*; D008297:Male; D017835:Nedocromil / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000652:urine; D012016:Reference Values
D018927:Anti-Asthmatic Agents; D017835:Nedocromil