No pharmaceutical opinion available for this interaction.
Atazanavir / ritonavir can inhibit the metabolism (CYP 3A4) and increase the plasma concentration of Alfuzosin.
3A4, P-gp/3A4 > 2D6, P-gp
Ritonavir: 1A2, 2C9, 2C19, UGT, 2B6, 3A4 (auto-induction)
3A4, UGT1A1, P-gp E et 2C8/3A4 > 2D6 > 2A6, 2E1, P-gp, MRP2
Increased risk of orthostatic hypotension.
Contraindicated. Use alternative.
Tamsulosin 0.4 mg po QD or silodosin 4 mg po QD with close monitoring for signs of orthostatic hypotension. Terazosin, doxazosin and prazosin to start in small dose and adjust according to efficacy and patient tolerability.*
Side effects of alfuzosin: dizziness, orthostatic hypotension and headaches.
* Alternatives: flexibility of dosing with these agents and their metabolic pathways make safer choices. However, these alpha-blockers are not uroselective and may not be suitable for some patients.
Ref #2254 : The repeated administration of a 200 mg daily dose of ketoconazole, a potent CYP3A4 inhibitor, following a single dose of alfuzosin 10 mg not fasting for 7 days, increased alfuzosin Cmax and final AUC by 2.11 and 2.46-fold, respectively. No changes in other parameters, such as Tmax and T1/2, were observed. Repeated administration of ketoconazole 400 mg QD for 8 days increased the Cmax of alfuzosin by 2.3-fold, and the final AUC and the AUC by 3.2 and 3.0-fold, respectively.
If an anticholinergic medication is used as an adjunct in order to decrease symptoms of enlarged prostate, the clinician must be careful because interactions between protease inhibitors and these agents are noted.