In a preliminary study the effect of tyramine, used as eye-drops, was assessed in two different ethnical groups composed of healthy volunteers: 6 Africans and 6 Caucasians.
Tyramine-induced mydriasis in the Caucasian group was 5 times greater than in the African group.
Similar differences had already been observed for indirect sympathominetic amines (ephedrine and cocaine) used as mydriatics, as well as for the effects of alpha 1 blocking drugs on the vascular system.
Very few data are available in the literature concerning the CNS effects of drugs modulating the alpha adrenergic receptors.