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There are eight major classes of blood pressure lowering medications, each of which has a different mechanism of action, and may include up to twenty individual drugs. So how does your doctor choose the right one for you? It would be very satisfying to be able to say that he or she can tell which one will work best and with the least side effects, but unfortunately this is not the case. There are some medications which cannot or should not be given to you if you have certain medical conditions: beta blockers, for example, make asthma worse. Beyond that, much of it is hit-or-miss.
There are some general guidelines, however. In the US, the official guideline, issued by the National High Blood Pressure Education Program, and updated every four or five years, is known as 'JNC VI' (it is the sixth such report), and it last appeared in 1997. Here are some of the recommendations.
If you are under the age of 65, the recommended drugs are:
The rationale for this is that they are 'tried and true', and the studies which have demonstrated that lowering blood pressure prevents strokes and heart attacks have mostly used these two classes of drugs. For the most part, we don’t yet know if the newer agents will be as good (or better?) in this respect, although there are several large-scale studies underway.
If you are over 65, the recommended drugs are:
- Diuretics
- Calcium Channel Blockers (of the dihydropyridine sub-class).
Diuretics have been shown to prevent strokes and heart attacks in the elderly in a large US study (called SHEP), and a European study called Syst-Eur showed the same thing using a calcium channel blocker (nitrendipine), which is not available in the US, but is closely related to Norvasc, Procardia, and Plendil.
If you have diabetes, the recommended drugs are:>
Several studies have shown that ACE inhibitors protect the kidney better than other classes of drugs (kidney disease is a complication of diabetes), and one Scandinavian study (CAPPP) has shown that heart attacks are less frequent than with beta blockers and diuretics.
If you have had a heart attack, the recommended drugs are:
Numerous studies have shown that beta blockers help to prevent second heart attacks.
In practice, many physicians do not follow these guidelines, and there is often no sound rationale why one drug is chosen over another. It’s important to realize that most drugs only lower blood pressure in about 60-70% of people to whom they are given, and we don’t have any good way of knowing who will respond to which drug. Another factor which influences your doctor’s choice of drugs is the marketing by the pharmaceutical industry: he or she may prescribe whichever drug of which samples were recently offered by a drug rep. Unlike drugs that lower cholesterol, drugs that lower blood pressure cannot be advertised directly to the consumer, because many of them cannot be taken by pregnant women, which places an automatic restriction on the advertisers.
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