Beta Blockers - Different Types

Non-selective- Non selective beta blockers were the first type to ever be produced. They date all the way back to the 1960s. They were first developed as a treatment for certain heart conditions. Today they are prescribed mainly for performance anxiety, generalized anxiety, panic disorders, migraine prevention, tremors, atrial fibrillation, heart maintaince after a heart attack, and on rarer occasions high blood pressure. Some doctors may also prescribe them for certain issues with the adrenal gland and certain issues with the thyroid. The term “non-selective” stands for the fact that these drugs inhibit both Beta 1 and Beta 2 production. Inhibiting Beta 1 can cause a reduction in heart rate and a reduction in the velocity in which the heart beats. Inhibiting Beta 2 can cause a relaxation in the smooth muscles within the body. Beta 2 blockade can actually cause vasoconstriction in some areas of the body, although this effect is minimal compared to the vasodilation effect of Beta 1 inhibition. Beta 2 inhibition can have some unwanted side effects, like inflamed blood vessels in the lungs. This condition is called bronchoconstriction, and can cause breathing issues in some people. Patients who have underlying respiratory issues should not take non-selective beta blockers. It is thought today that overall cardiospecific beta blockers have less adverse side effects than non-selective. However when it comes to the treatment of anxiety non-selective beta blockers like propranolol are often thought to be more effective.

Cardioselective- Also known as cardiospecific, these are the most commonly prescribed type of beta blocker. They were first approved by the FDA in 1978. Technically they are considered second generation beta blockers. Cardioselective beta blockers are mostly prescribed for high blood pressure, supraventricular tachycardia, angina, and atrial fibrillation. Some doctors may also prescribe them for mitral valve prolapse, migraines, left ventricular dysfunction, and heart failure.  They work by targeting the restriction of only the Beta 1 receptor. This in turn lowers adrenaline. Lowering adrenaline decreases the resting heart rate. It also decreases the velocity in which the heart beats, and it does so more potently with cardioselective beta blockers than with non-selective beta blockers. Inhibiting Beta 1 also has another indirect blood pressure lowering effect, and that is lowering angiotensin ll production. This happens because Beta 1 sends signals to the body to produce renin. Patient studies have shown that systolic blood pressure drops can average 10 points, where as diastolic drops can average 8 points. The data from the studies tend to show better results than what is actually seen by patients in real life. It is important to note if taken in higher dosages, there selectiveness can fade. This means that a patient may experience some Beta 2 inhibition as well. In clinical trials this was only shown to happen when a patient was taking at least twice the minimum dosage. And the higher the dosage, the more the selectiveness would fade, linearly.

Third Generation- These are the newest kind of beta blockers to enter the pharmaceutical market. They are used to treat hypertension and heart failure only. Drug companies claim improvements have been made to the adverse side effects a lot of patients experience with first and second generation beta blockers. However it is important to note that real patient experiences have shown otherwise. In fact many patients have experienced the exact same side effects as the first two generations of these drugs. Withdrawal symptoms seem to be the same as well. Third generation beta blockers are considered to be highly cardioselective. Just like cardioselective beta blockers, they inhibit the production of only beta 1. These drugs further the effects of previous beta blockers. We will go over each one and there effects; there are three brand named third generation beta blockers. Labetalol, in addition to blocking beta 1 receptors, also blocks alpha receptors. Carvedilol, is an alpha blocker and beta blocker in one. And Nebivolol, works to increase nitric oxide production in the body in addition to inhibiting the beta 1 receptor. The added effects of these drugs is done mainly to further lower blood pressure, and improve longevity in patients with severe heart failure.