Ritonavir

Alfuzosin

Contraindicated.

No pharmaceutical opinion available for this interaction.

Mechanism

Ritonavir can inhibit the metabolism (CYP 3A4) and increase the plasma concentration of Alfuzosin.

Ritonavir

Pharmacodynamic effects

Recommendations

Alternative solution(s)

Alfuzosin

Pharmacodynamic effects

Increased risk of orthostatic hypotension.

Recommendations

Contraindicated. Use alternative.

Alternative solution(s)

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.*

Monitor

Side effects of alfuzosin: dizziness, orthostatic hypotension and headaches.

Tests

Pharmacokinetic parameters

Comment

* 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.

Reference
  • 2554
    Alfuzosin (Xatral), Sanofi-Aventis, Québec, Canada, 13 mars 2017.