To the Editor.—
Since I published my observation on diphenoxylate hydrochloride therapy for treatment of the more resistant psoriatic plaques on the knees and elbows in the December 1985 issue of the Archives1, I have received many requests for more information about formulating the drug for topical administration and dosage for oral use.I use a twice-daily application of either a 0.25% or a 0.50% diphenoxylate hydrochloride preparation. The commercially available tablets of diphenoxylate hydrochloride, 2.5 mg, and atropine sulfate, 0.025 mg, are incorporated in any suitable base. Placebo preparations have equivalent amounts of atropine sulfate added to the selected bases. Vanishing creams, ointments, lotions, and shampoos have been used in our studies.Systemic treatment is usually reserved for the more generalized conditions. One tablet of diphenoxylate hydrochloride combined with atropine sulfate is ingested three times daily.With topical application, local erythema does occur at the site of involvement