Such studies initiated by manufacturer are designed to promote product

EDITOR—The study by Ayres et al may have been selectively designed to promote a product as safe; they endorse it as conforming to unpublished guidelines for postmarketing surveillance studies under safety assessment of marketed medicines.1 Withdrawals from the study are mainly for reasons “not related to safety,” and the withdrawal rate of the product under evaluation is almost three times that of the salbutamol inhaler with conventional propellant.

I have several reservations about the study. Postmarketing surveillance studies initiated by the manufacturer are primarily designed to promote a product to the medical profession and the general public. One incentive for patients to enter such a study is the availability of a prescribed drug without charge. Participating general practitioners receive a generous fee—particularly attractive and effective in medical recruitment to this study since “neither the patient nor doctor had to undertake any procedures related to the study.” Criteria of drug safety in this study relate mainly to hospital admissions and perceived adverse effects.

One basic safety criterion—whether the hydrofluoralkane inhaler is reliable—has been omitted from this study. The manufacturer (3M), which sponsored the study, is certainly aware of the problem of failure of the inhaler caused by the nozzle becoming blocked. My practice prescribed and dispensed 356 hydrofluoralkane inhalers to 66 patients, but four fifths of the patients reported or returned the inhalers …