Beta-2 sympathomimetics

β ₂ -sympathomimetics , also known as β ₂ -adrenoceptor agonists , are drugs which mimic the action of the catecholamines adrenaline and noradrenaline in the sympathetic system by activating β ₂ -adrenoceptors .

β ₂ sympathomimetics are mainly used in the therapy of bronchial asthma and COPD , as they have an expanding effect on the bronchial system. A distinction is made between rapid acting beta agonists (RABA) or short acting (short acting beta agonists, SABA) and long acting (long acting beta agonists, LABA) β ₂ sympathomimetics. The fast-acting substances (such as salbutamol , fenoterol and reproterol ) are mainly used as so-called "relievers" in the acute therapy of obstructive airways diseases, while the long-acting substances ( salmeterol and formoterol ) are used as "controllers" in long-term therapy and thus serve to prevent asthma attacks .

It is usually administered directly into the lungs via an inhaler system, but some substances can also be administered to muscles, blood vessels or under the skin. Alternatively, the active ingredient can be taken in capsules.

Unwanted side effects are, for example, sweating, restlessness, tremor and tachycardia , which also arise outside the lungs due to the activation of β ₁ receptors. An increase in oxygen consumption with an accelerated heartbeat can lead to an undersupply of the heart muscle cells, which under certain circumstances manifests itself in angina pectoris . Another undesirable effect can be a lowering of the potassium concentration in the serum, which in unfavorable cases leads to arrhythmias . The higher the dose used, the greater the side effects. In addition, inhalative use causes fewer side effects than in tablet form.

As uLABA ( u ltra L ong A cting B eta 2 A gonists) designated active ingredients of this type with more prolonged duration of action and only the need for once-daily dosing are available (eg. B. indacaterol )

During pregnancy, the active ingredient should only be used to a limited extent and according to medical advice, because on the one hand they have a labor-inhibiting function ( fenoterol ), and on the other hand the bronchodilators enter the child's organism through breast milk.

doping

β ₂ -sympathomimetics are used as doping agents due to their bronchodilating and partly anabolic effects, like the calf fattening agent Clenbuterol , which is actually banned in the EU for this purpose. It is a performance-enhancing drug, especially for endurance sports. In the past, any use of betamimetics was prohibited. However, there are now exceptions. B. For: Inhaled salbutamol: a maximum of 1600 micrograms over 24 hours in divided doses, whereby 800 micrograms must not be exceeded over 12 hours from any dose. Inhaled formoterol: Maximum delivered dose of 54 micrograms over 24 hours, Inhaled salmeterol: maximum 200 micrograms over 24 hours.

Individual evidence

1. ↑ J. Beier: Bronchodilator effects of indacaterol and formoterol in patients with COPD. In: Pulm Pharmacol Ther . 22 (6), Dec 2009, pp. 492-496.
2. ↑ ^{a b} G. A. Jacobson, M. Hostrup, CK Narkowicz, DS Nichols, EH Walters: Enantioselective disposition of (R, R) -formoterol, (S, S) -formoterol and their respective glucuronides in urine following single inhaled dosing and application to doping control. In: Drug testing and analysis. [Electronic publication before printing] March 2019, doi : 10.1002 / dta.2587 , PMID 30865387 .

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