Quarter-dose combinations of blood pressure lowering medications appear to be effective in treating hypertension and result in fewer side effects for patients than a single dose of one drug, according to new research in the American Heart Association's journal Hypertension.
"Widespread control of blood pressure is generally low, even in high-income countries. The largest global survey of hypertension patients showed 88 percent of those aware of hypertension are treated with medications, but only one in three were able to gain control of their blood pressure," said Anthony Rodgers, M.B.Ch.B., Ph.D., study author and professor at The George Institute for Global Health, University of New South Wales in Sydney, Australia. "Because high blood pressure is so common and serious, even small improvements in management can have a large impact on public health."
In this first review to compare quarter-dose therapy to both standard dose and placebo, researchers analyzed and compared results from 42 trials, involving 20,284 people with high blood pressure on various doses of medications or taking no medication. The review included many different types of medications from the five main classes of drugs to treat hypertension, including ACE inhibitors, angiotensin receptor blockers, beta blockers, calcium channel blocker and thiazides.
- Two medications in combination, each at a quarter dose, was just as effective as one blood pressure lowering medication at standard dose.
- Four medications in combination, each at a quarter dose, was nearly twice as effective as taking one blood pressure lowering medication at the standard dose.
- The side effects from single and dual quarter-dose therapies were about the same as from placebo and much less than from a standard dose of a single antihypertensive medication. There was little information on side effects for the quadruple quarter dose therapy.
- While low-dose combinations for blood pressure control is promising, there still isn't enough research to warrant a change in how doctors prescribe blood pressure lowering therapies and there are also few low dose combinations currently available, researchers said.
"This new approach to treatment needs more research before it can be recommended more widely," Rodgers said. "The findings have not yet been tested in large long-term trials. People should not reduce the doses of their current medications."
Co-authors are Alexander Bennett, B.Med.Sc., M.Phil.; Clara Chow, M.B.B.S., Ph.D.; Michael Chou, M.B.B.S.; Hakim-Moulay Dehbi, Ph.D.; Ruth Webster, B.Med.Sc., Ph.D.; M. Abdul Salam, M.Pharm., Ph.D.; Anushka Patel, M.B.B.S., Ph.D.; Bruce Neal, M.B.Ch.B., Ph.D.; David Peiris, M.B.B.S., Ph.D.; Jay Thakkar, M.D.; John Chalmers, M.D., Ph.D.; Mark Nelson, M.B.B.S., Ph.D.; Christopher Reid, M.Sc., Ph.D.; Graham Hillis, M.B.Ch.B., Ph.D.; Mark Woodward, Ph.D.; Sarah Hilmer, M.B.B.S., Ph.D.; Tim Usherwood, M.D. and Simon Thom, M.D. Author disclosures are on the manuscript.
A grant from the National Health and Medical Research Council Program Grant supported the study.