PHOLEDRINE - A SUBSTITUTE FOR HYDROXYAMPHETAMINE AS A DIAGNOSTIC EYEDROP TEST IN HORNERS-SYNDROME

Mydriatic responses to eyedrops containing the indirect acting sympath omimetic amines tyramine, hydroxyamphetamine, and pholedrine have been compared in 10 healthy subjects. Pholedrine, the n-methyl derivative of hydroxyamphetamine, at a concentration of 1% had effects similar to those produced by 0.5% hydroxyamphetamine itself. Pretreatment with t opical guanethidine attenuated its responses and in 13 patients with u nilateral Horner's syndrome it distinguished clearly those five patien ts who had preganglionic from the eight with postganglionic lesions. I t is concluded that 1% pholedrine may be substituted for 0.5% hydroxya mphetamine, which is no longer available, as a diagnostic agent for us e in Horner's syndrome.