Imaging techniques for assessing drug delivery in man

In vivo imaging technologies have a vital role to play in the pharmaceutica l development process. Gamma scintigraphy, comprising two-dimensional 'plan ar' imaging, is used widely to visualize and to quantify drug delivery, par ticularly by the oral and pulmonary routes. However, three-dimensional imag ing modalities - single photon emission computed tomography (SPECT), positr on emission tomography (PET) and magnetic resonance imaging (MRI) - may als o have applications within this area. Single photon emission computed tomog raphy and PET offer potential advantages over gamma scintigraphy in the ass essment of regional lung deposition from aerosol inhalers, but these advant ages are greatly outweighed by the practical problems associated with condu cting SPECT and PET studies. It is concluded that, for the foreseeable futu re, gamma scintigraphy is the imaging modality of choice in assessing the d elivery of new oral and pulmonary drug products.