Aminoglycosides are commonly used in the treatment of nosocomial pneumonia in association with beta-lactams. Unfortunately, penetration of intravenously administered aminoglycosides into the lung tissue remains low. In animal models, aerosolization of these drugs provides high lung concentrations and low serum levels. Three-hundred milligrams of tobramycin and 1 ml of 99mTc-DTPA were administered via a pneumatic nebulizer to five healthy volunteers and to five mechanically ventilated patients. Lung scintigraphy was then performed, and plasma and urine pharmacokinetics were studied. In a second group of patients undergoing thoracic surgery, 300 mg of tobramycin alone were administered in the same way; a fragment of healthy lung was then removed, and tobramycin was measured. In the first group, the scintigraphy showed radioactivity distribution in the whole lungs both in healthy volunteers and in ventilated patients. Urine samples contained 5.5% of the initial amount of tobramycin. The mean serum half-life of tobramycin was 8.96 h in healthy volunteers and 11.23 h in ventilated patients. In the second group, mean lung tissue concentrations were 5.5 and 3.61 micrograms/g, respectively, 4 and 12 h after nebulization, respectively. Aerosolization of tobramycin thus produced high lung concentrations and low serum levels.

Unilateral 131I-6 beta-iodomethylnorcholesterol tumour uptake is a frequent feature in benign adrenocortical adenomas. Hormonal data and scintigraphic profiles obtained after dexamethasone, as well as hormonoscintigraphic changes observed after surgery, provide evidence that unilateral uptake is related to functioning adenomas with various degrees of autononomy and suggest that the 131I-6 beta-iodomethylnorcholesterol scan could be a valuable tool for screening 'subclinical' Cushing's adenomas.

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Since 1980, immunoscintigraphy has been performed in thousands of patients, and its clinical value has been demonstrated for selective indications in malignant (early detection of recurrences of colorectal and ovarian carcinomas) and non-malignant (cardiovascular and inflammatory) pathology. However, many clinicians are not yet very convinced of its efficiency. Opinions range between favourable interest and marked scepticism. The causes of this inconclusive verdict include an often moderate target-to-background ratio in images, the immunogenicity of injected murine antibodies and the fact that a true benefit for the patient has not yet been clearly demonstrated in large series of patients. Future prospects could significantly improve this and involve the reduction of non-specific activity in normal tissues (to improve disease target contrast and thus make image interpretation easier) and the decreased immunogenicity of injected immunoconjugates (to permit repetition of examinations). Radioimmunotherapy, an innovative and promising approach, is still limited by numerous problems. The results of clinical studies are still inconclusive, being encouraging only for specific indications. In the future, pre-targetting techniques should allow the rapid elimination of radioactivity from normal tissues, resulting in a significant increase in tumour-to-normal tissue ratios. Progress is also required in the choice of radionuclides and labelling techniques and in methods for dosimetric estimations. The clinical indications of radioimmunotherapy after systemic injection will concern mainly radiosensitive tumours such as lymphomas, small-cell lung cancers and neuroblastomas. After endocavitary injection, radioimmunotherapy could prove efficient in the treatment of micrometastases of ovarian carcinomas. For all indications, this new approach should be combined with other therapeutic modalities.