Independent market analyst Datamonitor estimates that over one in four people globally suffer from hypertension, yet some doctors (especially those in the UK) have yet to come to appreciate the importance of using multiple drugs to control the condition in their patients. However, according to a new report from Datamonitor, the majority of patients are not fully controlled on a single antihypertensive therapy, with many requiring a combination of two or three drugs from different classes to adequately lower their blood pressure.

Small difference, big effect

Clinical trials on hypertension patients continue to show that even small differences in blood pressure can have a significant effect on mortality outcome, says Datamonitor healthcare analyst and report author Peter Lahoud. Doctors have been accused of being slow to appreciate this fact, with too many patients still being inadequately treated with a single drug in combination with lifestyle modifications such as reduced salt intake and weight loss.

Now more physicians are starting to appreciate the importance of treating hypertension all the way to target blood pressure, and patients are increasingly taking drugs from more than one class.

It is estimated that there are currently more than 70 million Americans with hypertension (high blood pressure), a chronic disease that if not treated, may lead to other cardiovascular disorders like heart attacks and strokes, Lahoud says. The prevalence of hypertension will continue to increase due to the aging nature of the worlds population. However Datamonitor believes that the rising incidence of type II diabetes and the obesity epidemic will continue to drive up treatment rates even within age groups.

US among leaders

The UK has trailed the US, Japan and other European nations in the use of fixed-dose combination treatments, where more than one active ingredient is combined in a single pill or capsule, Lahoud says. Doctors in the UK have traditionally been very averse to using fixed-dose combinations, generally due to the teaching in medical schools that they prevent the ability of the physician to accurately adjust the doses of individual components or detect problems caused by a single component of a combination.

This attitude may be set to change in the near future however, as teaching methods are brought more in line with those around the world, which acknowledge the increased compliance and efficacy of combined treatments. This change will make the UK a fast-growing market for combination products over the next 10 years, as a newer generation of physicians educated on the importance of blood pressure control but without the aversion to fixed-dose combinations join the prescribing ranks.

There is currently no consensus gold-standard antihypertensive treatment, and no single drug has displayed significantly superior overall efficacy compared to other classes. Drugs from a number of different classes with distinct methods of action are used in lowering blood pressure, including: angiotensin II receptor blockers (ARB), angiotensin converting enzyme (ACE) inhinitors and calcium channel blockers (CCB). These three largest antihypertensive drug classes now account for over three quarters of the total market value, Lahoud says. The fastest growing class of antihypertensive drug are the ARBs, which have rapidly drawn level with the second highest selling class of antihypertensive, the ACE inhibitors. However both currently trail the CCB class.

Growing market

The antihypertensive market was worth $30 billion in 2003 (an increase of $3.5b on the previous year) and as a result of the increasing market size and the continuing switch from the use of older drugs to more costly newer versions, Datamonitor predicts the antihypertensives market will increase in value by $6.5b over the next 10 years, Lahoud says.

More patients are also being treated along new guidelines, which focus on overall cardiovascular risk, and thus the prescribing of a number of classes of drugs for each patient, which obviously also increases sales.

Although the sales of antihypertensive treatments continue to grow, the market is set for a period of consolidation as patent expiries and the emergence of cheaper generic versions drive down costs of the biggest selling branded drugs.

The US market accounts for 48% of the global value and is the largest and most mature market, showing the lowest market growth rate of 4.5% year on year during the period 20002003, compared to a global average of 7.5%.

Norvasc, a CCB from Pfizer (also known as amlodipine) is the worlds biggest selling antihypertensive and the fourth highest value pharmaceutical in the world. It alone accounts for almost 15% of the antihypertensive sales market, with over $4.3b in global sales in 2003, Lahoud says. However Norvasc looks set to lose the market leading position it has held for over five years as it suffers patent expiry throughout the main markets over the coming years, culminating with the patent expiry in the US during 2007.

Uptake of the newest class, the ARBs, has been slowed somewhat by their expense, with cost-conscious prescribers preferring the ACE inhibitors which are available generically and act on the same pathway but have a greater incidence of side effects. However in 2009- when the first ARB loses patent protection- a mass switch to the well tolerated ARB class from the ACE inhibitor class is expected as cheaper generic versions become available.