Metabolised by CYP 3A4. Inducer of CYP 3A4. Two references consider it safe. Clinical experience (Swedish) seems to point to non-porphyrinogenicity.

(To be edited, initial data ST OCT 04) Antihistamine without sedative effect used (10 mg/d p.o.) in allergic rhinitis/conjunctivitis and in histamine mediatid pruritus and urticaria. The same general structure as cyproheptadine (PSP). Metabolized by CYP 3A4. Main metabolite is decarboxyethoxyloratidine with an elimination half time of 19 hours. South African list: use with care French list: authorized Andersson, patient reports (N=13): tolerated. Thunell: occasionally observed to be tolerated. C.Andersson, patient reports: tolerated (n=4)

Uneventful use reported in 28 patients with acute porphyria.