Beta blockers have also been in use in the treatment of hypertensioh for a long time. They are often the first choice of drugs for the treatment of high blood pressure. Beta blockers were first developed as drugs to treat coronary artery disease but later they have been used also in the treatment of glaucoma, migraines, tremors of certain kind and of course in the treatment of high blood pressure. They lower blood pressure by blocking the effects of hormone nor-epinephrine (noradrenaline) which causes our heart to beat faster and vasoconstriction of our blood vessels. They also slow the release of renin (an enzyme) from our kidneys. Renin is the important enzyme which aids in the production of angiotensin II, an important substance that causes vasoconstriction (narrowing of) our blood vessels increasing our blood pressure. Beta blockers are very effective in decreasing blood pressure in patients who have associated cardiovascular conditions such as angina (chest pain) and arrhythmia (abnormal or irregular heart rhythms). They are also helpful in decreasing the blood pressure in patients who have had a previous heart attack. They act as a cardioprotective agent, and by controlling the above mentioned conditions and keeping the blood pressure in check, reduces the risk for second heart attack.
Beta blockers are classified on the basis of whether they act primarily on heart or on the blood vessels and heart, that is:
- Non-cardio selective.
Cardio-selective beta blockers have lesser side effects but they are not used in patients with cardiomyopathy (weak cardiac muscle caused by failure of heart).
Beta blockers are also classified on the basis of the organ in which they are metabolised:
- Beta blockers metabolised in kidneys
- Beta blockers metabolised in liver
- Beta blockers metabolised in both kidneys and liver
The doctor has to be very selective and cautious in the choice of beta blockers and the patient he is prescribing it to a patient with kidney problems cannot be given a beta blocker that is metabolised in kidneys.
Beta blockers include:
- Acebutolol (Sectrol)
- Atenolol (Altol, Tensimin, Hyperten, Odinol)
- Betaxolol (Iobet)
- Bisoprolol (Concor)
- Carvedilol (Carca, Carvidac)
- Labetalol (C Beta, Normadate) (is and combination of α and β blocker)
- Metopvolol (Betalock, Metopvolol)
- Nadolol (Corgard)
- Pindolol (Visken)
- Propranolol (Beta Block, Indeqal, Ciplar, Betalong)
- Timolol (Iotim, Ocobar)
Beta blockers have frequent side effects compared to other blood pressure medications, but patients complain only minimally, since the side effects are only very minimal and pose only a little trouble. Two of the most important side effects are:
- Decreased capacity for strenuous physical activities. Some of the other less important side effects are cold extremities, disturbance in sleeping, decreased sexual drive, impotence, a very little increase in blood TGL (triglyceride) level, a very little decrease in good cholesterol (HDL-high density lipoproteins).
Beta blockers are contra indicated in
- Persons with blockage in the conducting system of heart (bundle branch blocks).
Beta blockers are not the drugs of choice in active productive young persons, athletes, sportsmen or women involved in active sports because these drugs limit the ability to be physically very active.