Is Diovan HCT Safe to Take with Tadalafil?
Yes, it is safe to take Diovan HCT (valsartan/hydrochlorothiazide) with tadalafil, though mild blood pressure reductions may occur that are generally not clinically concerning. 1
Evidence for Safety
The most relevant clinical trial directly addressing this question demonstrated that tadalafil can be safely administered with antihypertensive medications, including combinations like Diovan HCT 1:
- In patients receiving ≥2 antihypertensive agents concurrently with tadalafil, no statistically significant differences in mean blood pressure changes from baseline were observed compared to placebo 1
- Tadalafil administration may result in mild blood pressure reductions in patients on antihypertensives, but these are generally not clinically concerning 1
- Cardiovascular event rates were comparable between tadalafil-treated patients with and without concomitant antihypertensive therapy 1
Important Safety Considerations
No hypotension or postural hypotension was reported in any tadalafil-treated patient in the phase 3 studies, compared with one report of each in placebo-treated patients 1:
- Syncope occurred in only 0.1% of tadalafil-treated patients (who was not on antihypertensives) versus 1.9% of placebo patients on antihypertensives 1
- The combination of valsartan with hydrochlorothiazide provides effective blood pressure control in approximately 70% of hypertensive patients 2
Clinical Algorithm for Safe Use
When prescribing tadalafil to patients on Diovan HCT:
- Ensure blood pressure is reasonably controlled before initiating tadalafil, as the combination may produce additive mild vasodilation 1
- Monitor for symptomatic hypotension during the first few doses, particularly dizziness or lightheadedness upon standing 1
- Advise patients to avoid volume depletion, as elderly or volume-depleted patients may be at increased risk for hypotension when combining vasodilators 3
- Continue routine blood pressure monitoring as you would for any patient on antihypertensive therapy 1
Critical Contraindication to Remember
The absolute contraindication is with nitrates, not with Diovan HCT 3:
- Patients who have used sildenafil (or other PDE5 inhibitors like tadalafil) within 24 hours should never receive nitroglycerin due to risk of profound hypotension 3
- This nitrate contraindication does not apply to the combination of tadalafil with ARBs or thiazide diuretics like Diovan HCT 1
Mechanism of Interaction
The mild blood pressure reduction seen with this combination occurs through complementary vasodilatory mechanisms 1:
- Valsartan blocks angiotensin II-mediated vasoconstriction 2, 4
- Hydrochlorothiazide reduces blood volume through diuresis 4
- Tadalafil causes vasodilation through phosphodiesterase 5 inhibition 1
These mechanisms are additive but not synergistic, resulting in generally mild and well-tolerated blood pressure effects 1