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Samples of dust were collected from three articles of household bedding in twenty-two Sydney homes during a six-week period beginning in mid December, 1973. Mites, sometimes in large numbers, were found in all homes. The mean number of mites recovered from nursery sheepskins (all woollen) was thirteen times as high as the mean number from other forms of adult or infant bedding sampled. The high mean number in sheepskins is the result of massively high populations in seven of the eighteen skins sampled. Hospital sheepskins were almost almost uniformly mite free. Far fewer mites were collected from cot mattresses which were either vinyl topped or covered with a plastic coverslip than were collected from a cot mattress with a cotton top alone.

Twelve patients with chronic airways obstruction took part in a bioavailability study of a sustained-release preparation of theophylline (Nuelin SR). Each patient took a Nuelin SR (250 mg) tablet after an overnight fast and, next day, after a light breakfast. On the third day, six patients took two halves of a 250 mg Nuelin SR tablet after breakfast; six subjects took one-half of a 500 mg Nuelin SR tablet after an overnight fast. There were marked interindividual variations in the plasma theophylline concentrations on all study days. The effect of food was equally variable, and appeared to delay the peak plasma concentration in four subjects; in another four, the peak plasma theophylline concentration occurred earlier, and no change was observed in the remaining four. Overall, no significant differences either in the amount of theophylline absorbed, or in its bioavailability were observed. We suggest that patients should be instructed to take theophylline at the same time every day in relation to food intake; however, theophylline assay is essential for the appropriate use of the drug.

The Airflometer provides a useful index of expiratory flow rate and as such it is a worthwhile advance. It can provide an accurate index of FEV1 provided it is individually calibrated. Perhaps the only limitation is the lack of response of the instrument at low flow rates, for example, with an FEV1 of less than one litre. It is remarkably inexpensive.