Table 3.

Advantages and disadvantages of pharmacokinetic methods and gamma scintigraphy.

Advantages	Disadvantages
Pharmacokinetics methods
Good for comparison of	Need to differentiate
relative lung deposition	between the swallowed
relative systemic delivery	and inhaled doses
Identifies the effective lung	Does not identify dose deposition into different zones of the lungs
Original product used	Some assays do not have the sensitivity to measure the low concentrations
Simple crossover design for studies.
No washout period (can substitute another drug for continued management)
Can use urine samples
Shows a dose response relationship
Gamma scintigraphy
Widely used – good for comparisons	Reformulation of the product
Identifies the total lung dose	Long-term safety of radionuclide
Differentiates between deposition	In vitro validation of
into different zones of the lungs	reformulated product required and methods are not standardized
Striking visual images	Correction for tissue attenuation
Simple crossover design	Tissue attenuation
No wash-out period required	Does not identify systemic delivery
Demonstrates dose-response	Does not identify the
relationships	effective lung dose
	Expensive study to commission