Justified deception? The single blind placebo in drug research

"Run-in" and "washout" periods involving the withholding of medication are widely used in drug research trials in pursuit of both patient safety and scientific reliability. Such no-medication periods can be justified ethically provided that they are apparent to patients, who can thereby properly consent to undergoing them. Less widespread, but still common, is the practice of "single blinding" no-medication periods, concealing them from patients by means of placebo. Whilst all placebos involve a measure of concealment, their use is typically justified in drug research trials (i) by their preserving the uncertainty generated by the random allocation of different treatments within a drug trial; and (ii) by the researchers openly declaring both the randomisation process and the chances of receiving placebo. In the single blind placebo "run-in" or "washout", neither of these conditions is met. This paper considers three possible defences of the practice of using single blind placebo "run-ins" or "washouts" and finds them all to fail; the practice appears ethically unjustified.