Sympathomimetic

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Sympathomimetics or sympathomimetics stimulate the neurotransmission of the adrenergic receptors in the sympathetic nervous system - part of the autonomic nervous system , which increases the outward action capacity under load ( " fight-or-flight "). This causes an increase in blood pressure and heart rate, an expansion of the airways, a general increase in performance and increased energy consumption. Also euphoria and an inhibition of the hunger center in the mid-brain and thus a reduction in appetite are other consequences.

Most preparations are subject to prescription requirements. In principle, they should only be taken under medical supervision, because they represent a considerable interference in the human organism. In addition to the desired effect, such as improving breathing, most sympathomimetics also have different side effects from the spectrum described above; for example an increase in blood pressure.

Development of synthetic sympathomimetics

Direct and indirect sympathomimetics

Direct sympathomimetics work by activating adrenoceptors by mimicking the effects of the physiological messengers (transmitters) adrenaline and noradrenaline . There are active substances that act preferentially on α-receptors, on β-receptors or on both types of receptors.

Indirect sympathomimetics are substances that increase the concentration of physiological transmitters in the synaptic cleft . This happens via an increased release from presynaptic nerve endings and an inhibition of resumption. Examples are ephedrine , which causes the bronchial tubes to expand and stimulates the circulation, as well as amphetamine and its derivatives such as methylphenidate and MDMA (“ ecstasy ”).

A distinction between a direct / indirect α-sympathomimetic effect or a pure α 1 / α 2 / β 1 / β 2 receptor effect is only possible as a tendency, since most active substances prefer neither strictly nor highly selective or even exclusively a single receptor type.

α-sympathomimetics

α-sympathomimetics bind selectively to α- adrenoceptors and activate them.

Direct α-sympathomimetics are predominantly used locally today to cause vasoconstriction (vasoconstriction). They are mainly used in nasal sprays with the aim of reducing the swelling of the nasal mucosa in rhinitis (cold). Active ingredients are naphazoline , tetryzoline , tramazoline , xylometazoline , oxymetazoline and phenylephrine . In oral therapy, the blood pressure stabilizing property is also in the foreground (CAVE: hypertensive patients).

Various active ingredients with an indirect α-sympathomimetic effect such as ephedrine or derivatives (amphetamines) or cocaine and derivatives are subject to prescription and the Narcotics Act in Germany .

α-Sympathomimetics must not be administered to the acres (extremities), i.e. to the tips of the body such as fingers, toes or ears, since the vasoconstriction can stop the blood flow in these regions. This can lead to necrosis and even amputation .

β-sympathomimetics

In pulmonary medicine , especially those sympathomimetics are used that attack the subgroup of β 2 receptors , such as fenoterol or salbutamol . In order to reduce a systemic effect, the β 2 sympathomimetics are usually administered there by inhalation. On the bronchial muscles, especially in asthmatics, they develop a bronchodilator (airway widening) effect. Long-acting sympathomimetics are mostly used in pulmonary medicine as controllers for asthma and COPD , while short- acting drugs are used as relievers (also on-demand medication).

One active ingredient that acts on both β 1 and β 2 receptors is orciprenaline .

Sympathomimetics that act on α and β receptors

Catecholamine derivatives are used therapeutically . The extent to which the adrenoceptor subtypes are activated is different for the individual substances, which enables differentiated applications. Important active ingredients are adrenaline , noradrenaline , amezinium metal sulfate , etilefrine , metaraminol , norephedrine , oxilofrin and dopamine and its derivatives dobutamine and dopexamine .

literature

  • Reinhard Larsen: Anesthesia and intensive medicine in cardiac, thoracic and vascular surgery. (1st edition 1986) 5th edition. Springer, Berlin / Heidelberg / New York et al. 1999, ISBN 3-540-65024-5 , pp. 42-50.

Individual evidence

  1. ^ Wolf-Dieter Müller-Jahncke , Christoph Friedrich , Ulrich Meyer: Medicinal history . 2., revised. and exp. Ed. Wiss. Verl.-Ges, Stuttgart 2005, ISBN 978-3-8047-2113-5 , pp. 167 f .