Candesartan: Mainly eliminated in unchanged form, in minor parts metabolised by CYP 2C9. One reference and some clinical observations point to non- porphyrinogenicity. Hydrochlorothiazide: Not metabolised. Probably no CYP-affinity. Clinical experience of non-porphyrinogenicity. Conflicting evidence.

(To be edited, initial data ST OCT 04) Candesartan: Angiotensin II receptor antagonist. Mainly eliminated in unchanged form, to a lesser extent metabolized in the liver by 2C9. Less potent inhibitor of CYP 2C9. Hydrochlortiazide:Tiazide diuretic, sulfonamide congener. Eliminated in urine in unchanged form. Probably no CYP-affinity. Candesartan: Thunell, patient reports (n=5): tolerated. Andersson, patient report (n=1): tolerated. French list: autorisé Hydrochlortiazide: South African list: use. French list: autorisé. Australian list: unsafe associated with attacks. Thunell, patient report (n=1): tolerated. Andersson, patient reports (n=10): tolerated. Martindale: Hydrochlortiazide has been associated with acute attacks of porphyria and is considred unsafe in porphyric patients. EPI-list: sulfonamides are on the unsafe list.

Uneventful use reported in 8 patients with acute porphyria.