This combination product contains two substances: tamsulosin (ATC-code: G04CA02) and dutasteride (ATC-code: G04CB02). Both of them are safety classified as probably not porphyrinogenic. The classification of the combination is therefore safety classified as probably not porphyrinogenic. For more details please refer to the monographs of the two substances.

Tamsulosin is a sulphamoyl phenethylamine derivative Dutasteride is an oxosteroide derivative

Tamsulosin is an alpha-1-adrenoceptor antagonist and dutasteride is a testosterone 5-alpha-reductase inhibitor, and the combination is used in the treatment of moderate to severe symptoms of benign prostatic hyperplasia (BPH). It is administered orally.

Tamsulosin is metabolized by CYP3A4 and CYP2D6 (Kamimura 1998). Tamsulosin has not been found to be an inhibitor of CYP1A2 (Miyazawa 2002), CYP2C9 (Rolan 2003), or CYP2D6 and CYP3A4 (Modi 2008). In the literature tamsulosin is not reported to be an inducer or inhibitor of any of the quantitatively major CYP enzymes and the absence of such characteristics is also in accordance with review-papers (Hisaka 2010, Isoherranen 2009 and Pelkonen 2008). No drug-drug interaction with tamsulosin as a perpetrator has been reported in the literature (Lexi-Interact). Dutasteride is metabolized by CYP3A4/5 (SPC). Dutasteride and its metabolites are mainly excreted in the feaces (SPC). Dutasteride does not have an effect on warfarin or digoxin and is thus not an inhibitor or inducer of CYP2C9 (SPC). In vitro interaction studies report that it is not an inhibitor of CYP1A2, 2A6, 2E1, 2C8, 2D6, 2C9, 2C19, 2B6 or 3A4 (SPC). No drug-drug interactions with dutasteride as perpetrator have been reported in the literature (Lexi-Interact, Keam 2008).

For tamsulosin (ATC-code: G04CA02) there are 7 reports of uneventful use in patients with acute porphyria.