Today, four classes of active ingredients, each with several drugs, are the first choice for treating high blood pressure. In addition, there are four further drug classes for special cases, apart from rarely used drugs with an antihypertensive effect. On the one hand, this results in a pleasing variety of options for treating physicians and, on the other hand, the need to choose the right drug(s) for the individual patient. "Not every substance is equally suitable for every patient," explain Prof Dr Thomas Eschenhagen, Head of the Institute of Experimental Pharmacology and Toxicology at the University Medical Center Hamburg-Eppendorf, and colleagues in a recent article on antihypertensive drugs for the Heart Foundation's journal "HERZ heute". According to Eschenhagen, a member of the Scientific Advisory Board of the German Heart Foundation, there is no single drug or class of drugs that is superior to others. In other words, active substances have been developed in recent decades that are particularly suitable for certain hypertensive patients. They have different mechanisms of action. This is why the intelligent combination of substances promises a great effect with few undesirable effects. "In most patients, high blood pressure can be reduced to a healthy range simply and with few side effects by combining two first-choice active substances," Professor Eschenhagen and co-authors are convinced.
The drugs of first choice are:
- ACE (angiotensin converting enzyme) inhibitors,
- Angiotensin (AT) receptor blockers,
- calcium channel blockers,
- Diuretics ("water tablets")
ACE inhibitors (e.g. ramipril) and AT blockers (e.g. candesartan) prevent the vasoconstriction and therefore blood pressure-increasing effect of the endogenous hormone angiotensin II. Calcium channel blockers (e.g. amlodipine) relax the thin vascular muscle layer. Diuretics (e.g. HCT - hydrochlorothiazide) remove water and salt from the body, of which we are known to eat too much in western industrialised nations. It is very likely that the total amount of salt (NaCL) in the body is reduced "and this should contribute significantly to a long-lasting reduction in blood pressure", explains the Hamburg pharmacologist Professor Eschenhagen. Other important classes of active ingredients are beta-blockers, alpha-2 agonists, alpha-blockers and aldosterone receptor blockers. They are used specifically to slow down the effect of messenger substances that increase blood pressure.
How doctors choose the right antihypertensive drug
How do doctors decide in favour of or against a specific high blood pressure medication or a combination of active ingredients? Firstly, it is important to determine whether the patient "only" has high blood pressure (isolated hypertension) or whether other diseases are present. In the former case, a combination of a calcium channel blocker and an ACE inhibitor or AT blocker is often used today. If there are other illnesses, the choice depends on whether it is a heart or kidney disease, whether there is a risk of electrolyte imbalance in the blood, whether there are severely narrowed renal arteries or whether the patient is a pregnant woman. Has this person just survived a heart attack? Are there cardiac arrhythmias, diabetes mellitus or a vascular disease? Do pharmacological interactions with other medications need to be taken into account? All these considerations influence the choice and dosage of the active ingredients in question.
For example, beta blockers are no longer the first choice for isolated hypertension, Professor Eschenhagen and colleagues explain. "However, they are still an important part of standard therapy for patients with heart failure or after a heart attack." Some drugs also have additional effects that are useful in individual cases. For example, men with an enlarged prostate can benefit twice over from an alpha-blocker: blood pressure is lowered and emptying of the bladder is made easier. If active substances are combined, then those with different mechanisms of action. In this way, doses of the individual active ingredients can be kept low. Ideally, this results in an increased blood pressure-lowering effect with a reduced likelihood of side effects.
How undesirable effects can be prevented
Adverse effects are also an important decision criterion for the prescribing physician. The typical side effect profiles of the individual active ingredients are known from clinical studies and treatment practice. It is therefore possible to prevent such events, for example by regularly monitoring the electrolyte balance. Some side effects that occur initially subside over time, sometimes prompting a reduction in the dose or a change of active ingredient. "Side effects can be largely avoided if doctors choose a gradual dosage, i.e. start with very low doses and slowly increase to the target doses," emphasises the doctor. "This gives the body time to adjust to the medication."
According to the latest recommendations of the European Hypertension Society, every person with high blood pressure should be adjusted to a value below 140/90 mmHg. Even lower values are recommended for certain pre-existing conditions such as diabetes. Important: High blood pressure therapy is a lifelong therapy. And because other diseases can develop with age, the blood pressure setting must also be adjusted from time to time.
Injections for high blood pressure?
What is the case for a long-acting injection against high blood pressure as an alternative to swallowing tablets every day? Prof. Dr Heribert Schunkert, cardiologist at the German Heart Center Munich and Deputy Chairman of the German Heart Foundation, answered this question: "The research approach is very interesting and the initial results are promising." An RNA (ribonucleic acid) agent that specifically switches off the production of the endogenous hormone angiotensin II, which is involved in blood pressure regulation, is currently being tested. Initial clinical trials in patients with mild to moderate hypertension have been successful. "However, a substance can only be submitted for approval once this efficacy has been confirmed in a so-called phase 3 study involving a sufficiently large number of blood pressure patients," explains Professor Schunkert. However, this is likely to take several more years. More on the injection against high blood pressure here.
Scientific contact: Prof Dr Thomas Eschenhagen (t.eschenhagen(at)uke.de), Head of the Institute of Experimental Pharmacology and Toxicology at the University Medical Center Hamburg-Eppendorf (UKE)
Source: Press release German Heart Foundation e.V. (in German only)
