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Wednesday, April 13, 2005
Drugs to combat hypertension
By Henrylito D. Tacio
Health 101
"HIGH blood pressure is not an illness in itself," explains Dr. Robert Buckman, author of What You Really Need to Know About High Blood Pressure.
"In fact, most people who have it feel perfectly well and do not experience any symptoms. However, it is important that it is treated, because if it stays raised for any length of time it can damage the blood vessels and lead to serious health problems including eye problems, hardening of the arteries, heart attack, stroke, heart failure, and kidney failure."
There is a wide range of drugs that your doctor can prescribe to bring the blood pressure down. The aim is to find the particular drug or combination of drugs that lower blood pressure to a safe level and prevent problems.
Dr. Willie Ong, medical consultant of the Makati Medical Center, says there are several classes of drugs to treat hypertension. "Once you have started treatment, you must return to your doctor for regular blood pressure checks," he reminds.
Diuretics are the oldest, least expensive drugs available in the antihypertension arsenal. And, according to a recent study, they are the best starting point for lowering blood pressure when a drug is needed.
The U.S.-based Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack followed more than 40,000 men and women 55 and older for eight years. The study found that diuretics lowered blood pressure as well as better than newer, more expensive drugs.
"Diuretics are drugs that act on the kidneys to increase urine flow," explains Dr. Tan Kok Soon, senior consultant cardiologist at The Heart Specialist Clinic in Singapore. (Reducing body fluid means that there is less for the heart to pump around the body.)
"Of the diuretics, the thiazides are the most commonly used. They are by themselves not very strong diuretics (promoters of urine) but are highly effective as hypertensive agents. They act in the short term by inducing the kidney to excrete more salt and by reducing blood vessel resistance in the longer term."
Examples of thiazides include hydrochlorothiazide, bendrofluazide and indapamide. Possible side effects of diuretics include loss of appetite, stomach upsets, dehydration, impotence, high cholesterol and calcium levels, allergic reactions, increased uric acid, raised blood sugar, and muscle weakness.
In certain cases, doctors prefer beta-blockers, which are also given to treat heart attack, angina, palpitations and migraine. Beta-blockers reduce the heart's workload by preventing the stimulating effects of stress, slowing the heartbeat, and reducing its force. This makes it easier for the heart to pump blood around the body.
Propanolol, atenolol, metoprolol, isoprolol, and carvidelol are some examples of beta-blockers. "In addition to having multiple benefits, they are also cheap and effective," says Dr. Ong.
The possible side effects are light-headedness, cold fingers and toes, upset stomach, depression, fatigue, nightmares, wheezing, drowsiness, weakness, visual disturbances, impotence, elevated blood sugar, and insomnia.
For hypertensive patients with diabetes or heart failure, the ACE-inhibitors are a must (ACE stands for angiotensin converting enzyme).
These drugs block the formation of the hormone angiotensin that causes the blood vessels to narrow.
Their generic names end with the common syllable "-pril," for example, enalapril or perindopril. A dry hackling cough is probably the most common side effect. Should one develop cough, then the angiotensin-II inhibitors are good alternatives. The A2's, as they are called, end with the syllable "-sartan," for example, losartan or telmisartan.
Calcium antagonists are the most powerful drugs at the doctor's disposal. They reduce the amount of calcium in the muscular artery walls, relax muscles and cause arteries to widen. This leads to a drop in blood pressure. It also reduces the workload of the heart and cuts down its oxygen needs.
"All drugs which lower blood pressure have almost similar effectiveness," explains Dr. Abdul Rashid Abdul Rahman, a clinical consultant and associate at the Science University of Malaysia. "The main benefits of calcium antagonists are that they lower blood pressure rather more quickly than others and they also do it in a more predictable manner than some others."
Calcium antagonists are drugs that usually end with the syllable "-pine" like felodipine, nicardipine and nisoldipine. But they are very expensive. A widely prescribed drug amlodipine costs P40.50 per 5-milligram tablet or P13,000 per year. Aside from being expensive, they have also some side effects like flushing, headache, swollen ankles, and wanting to urinate more frequently than usual. Rare side effects include fatigue, nausea, drowsiness, rashes, ringing in the ears, thickened gums, and constipation.
Combination therapy--taking two types of drugs in a single tablet--is often extremely successful and produces fewer side effects. For instance, ACE inhibitors and calcium antagonists taken in combination seem to have a protective effect on organs such as the kidneys.
"Before leaving the doctor's office, make sure you understand exactly what the drug has been prescribed for and what side effects you can expect," advises Dr. Buckman.
Meanwhile, "hypertension is truly a serious problem that requires more serious attention," points out Dr. Esperanza Cabral, president of the Philippine Society of Hypertension. "It's no longer acceptable that just any doctor can treat any patient with hypertension. Many cases of hypertension are more complicated than they seem.
For Bisaya stories from Davao. Click here. (April 13, 2005 issue)
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