Beta-blockers

Beta-blockers are substances that use competition mechanism to block all effects of adrenergic substances (catecholamines and drugs- adrenergic stimulators) that are done over adrenergic beta-receptors.

The most of beta-receptors are thought to be isoprenaline derivates. The most significant beta-blockers are: propranolol, sotalol, oksprenolon, alprenolon and pindolol.

The most significant pharmacological effects of beta-blockers are manifested on: cardiovascular system, bronchias and metabolism.

Cardiovascular system

Beta-blockers decrease frequency of heart rate, miocard contractility, and it comes to decrease in heart minute volume. Decrease in arterial blood pressure is caused by beta-blockers, which is the result of influence of these substances on beta-blockers of various organs.

Bronchias

Through blocking of beta-2 adrenergic receptors, these substances enable effect of parasympaticus that is manifested through bronchoconstriction. At healthy people this effect is very weakly manifested. Through use of selective beta-1 or beta-2 blockers only effects on specific organs would be given depending on receptor type.

Metabolism

Beta-blockers inhibit glicogenolysis, lypolysis and calorigenesis.

Therapy indications – Beta-blockers are used in healing cardiovascular system illnesses( angina pectoris, increased blood pressure and heart arrhythmia) and thyrotoxycosis(thyroid glandula hyperfunction).

Appliance in sport

Decrease of glycogenolysis, tonus and blood circulation in muscles, decrease of heart hitting/minute volume and blood pressure are the effect of beta-blockers, that are used in sports where fine neuro-muscular control is needed, preciseness and energy reserves keeping.

Use is not allowed in competitive period in soccer.

Harmful effects

The biggest harmful effects are:

• Bronchospasm
• Bradycardia
• Acute renal infarction

Other harmful effects are: circulatory shock, hypoglycemia, pulmonary edema, nausea, diarrhea and allergy reactions.

Detection

Beta-blockers can be detected in urine through appliance of gas chromatography-mass spectrometry methods. Concentration of phenylpropranolamine bigger than 25 µg/ml is thought to be illegal.

Non-allowed beta-blockers are:

Acetobutolol, alprenolol, atenolol, betaxolol, bisoprolol, bunolol, carteolol, carvedilol, celiprolol, esmolol, labetolol, levobunolol, metipranolol, nadolol, oxprenolol, pindolol, propranolol, sotalol and timolol.

“Doping in sport”, Marina Djordjevic Nikic