A 50-year-old man returns for follow-up of hypertension. He is currently taking 20 mg of lisinopril. His blood pressure readings over the past month are 150/96, 155/98, 160/94, and 162/96. His renal function is normal, and he has been taking his lisinopril regularly.
What do you recommend?
A. Increase his lisinopril to 20 mg twice a day.
B. Switch to valsartan.
C. Add amlodipine.
Dr. Douglas S. Paauw
But is there much benefit in doubling the dose of antihypertensive medications?
H.J. Gomez and colleagues studied the dose response of lisinopril in essential hypertension.2 Patients received very-low-dose (1.25 mg or 5 mg), moderate-dose (20 mg), or high-dose (80 mg) lisinopril. The difference in blood pressure reduction between 20 mg and 80 mg was modest (5 mm/3 mm less in those receiving 80 mg, compared with 20 mg). There was no clinical effect at 1.25 mg of lisinopril, but a relatively flat dose response above 20 mg.
A similar finding was reported by J.R. Benz and colleagues in regard to escalating doses of valsartan.3 The study looked at blood pressure in response to valsartan at doses of 80 mg and 160 mg, and in combination with hydrochlorothiazide. The difference in blood pressure between valsartan 160 mg and 80 mg was 3 mm/0.8 mm. The difference in blood pressure between patients taking 80 mg of valsartan and 25 mg hydrochlorothiazide, compared with those taking 80 mg of valsartan, was 12/6.
In a meta-analysis of 354 randomized trials of fixed-dose blood pressure medications, M.R. Law and colleagues found that cutting the doses in half only reduced effectiveness of lowering BP by 20%.4 The average reduction in systolic BP was 9.1 mm Hg, and reduction in diastolic BP was 5.5mm Hg – which only was reduced to 7.1 mm Hg/4.4 mm Hg when the doses of medications were cut in half. Side effects attributed to beta-blockers, calcium channel blockers, and diuretics were very dose related, whereas the side effects attributed to ACE inhibitors were not.
In another meta-analysis comparing monotherapy vs. combination therapy for lowering blood pressure, adding another drug lowered blood pressure fivefold more than doubling the dose of the initial antihypertensive drug.5
I think the right answer in this case would be to add amlodipine instead of doubling the dose of lisinopril or switching to valsartan as a single agent. The data are striking on how little effect there is in increasing antihypertensive medication doses. Adding another antihypertensive medication should be the standard practice when the first medication started does not achieve the desired goal.
Dr. Paauw is professor of medicine in the division of general internal medicine at the University of Washington, Seattle, and he serves as third-year medical student clerkship director at the University of Washington. Contact Dr. Paauw at dpaauw@uw.edu.
References
1. JAMA. 2003 May 21;289(19):2560-72.
2. Br J Clin Pharm. 1989;28:415-20.
3. J Hum Hypertens. 1998 Dec;12(12):861-6.