A low-dose, four-in-one blood pressure lowering pill taken just once daily controls blood pressure better than standard therapy at higher doses and improves adherence without any increase in side effects, conference delegates have heard.
Professor Clara Chow, director of the Cardiovascular Division at The George Institute in Sydney who presented findings from the small proof of concept study explained that previous studies had shown that quarter-strength doses reduced systolic blood pressure by about 5mmHg.
Professor Chow and her team wanted to find out whether combining low doses of four different types of blood pressure lowering agents in the one pill would have an accumulative effect, achieving much more effective blood pressure lowering than a standard dose.
Using a process called encapsulation the ‘quadpill’ combined quarter-strength doses of irbesartan, amlodipine, hydrochlorothiazide, and atenolol – the most commonly prescribed anti hypertensive drugs in Australia at the time of the study.
The study randomised 20 patients to the quadpill or placebo for 4 weeks, followed by a 2-week washout, after which the groups crossed over to the alternative intervention for another 4 weeks.
The study published earlier this year in the Lancet is the first placebo controlled trial to provide data on four quarter doses and has shown that the combination of drugs achieves an impressive blood pressure lowering effect of 22/13 mmHg.
Another appealing part of the single pill approach was that it improved adherence compared to standard therapy.
Professor Chow said that patients reported being more comfortable taking the quad pill over standard therapy knowing that it combined the lowest dose of each medication.
“Multiple doses are usually needed to control blood pressure but we’ve shown that very low doses still lower blood pressure and the effects are additive across classes, which we have been very excited to see.”
No side effects were seen in patients participating in the pilot study and Professor Chow also reported that a systematic review conducted by the quad pill investigators found no increased risk of side effects with a single, quarter-dose antihypertensive drug vs placebo, or of two combined quarter-doses compared to placebo.
However, she acknowledged that more data would be needed when it comes to combinations and adverse effects.
That information will come from a larger NHMRC funded trial, which Professor Chow said is just about to get underway.
She said the Quartet trial will randomise patients with a blood pressure greater than 140/90 mmHg who are either untreated or on monotherapy to the quad pill or to iberstartan. They will then be followed up at six and 12 weeks and again at six and 12 months [to assess blood pressure lowering effects].