Isoprenaline

• (±)- isoproterenol,
• DL -1-( 3,4- dihydroxyphenyl ) -2 - isopropylaminoethanol
• (RS ) -1 - ( 3,4- dihydroxyphenyl ) -2 - isopropylaminoethanol
• (±) -1 - (3,4 -dihydroxyphenyl ) -2 - isopropylaminoethanol
• Rac -1-( 3,4- dihydroxyphenyl ) -2 - isopropylaminoethanol

C01CA02 R03AB02 R03CB01

Sympathomimetic

β -adrenoceptor agonist

155.5 ° C

8.64

Template: Infobox chemical / molecular formula search available

Isoprenaline is a synthetic racemic norepinephrine derivative which is used as a sympathomimetic agent. The drug was patented in 1943 by Boehringer Ingelheim.

Pharmacology

Isoprenaline is an adrenaline- like substance that is exclusively activated β -adrenoceptors, while norepinephrine has a high affinity for α - adrenergic receptors. Of N-isopropyl- substituent is responsible for this selectivity, at the same time optimum β -adrenoceptor affinity is achieved.

It causes the relaxation of the bronchial and vascular musculature, as well as increase the force of contraction and beating rate of the heart and blood pressure reduction ( while the systolic blood pressure increased slightly, the diastolic pressure drops sharply, resulting in an overall reduction in mean arterial pressure may result). The effect on the heart is accomplished by stimulation of β1 - adrenergic receptors, there is also the release of renin from the renal cortex. Receptors on the enzyme adenylyl cyclase is activated, which catalyzes the synthesis of cyclic adenosine monophosphate (cAMP), which leads to an increased production of the same. Due to increased cAMP concentration occurs to activate the enzyme protein kinase A, which results in phosphorylation of voltage-gated calcium ion channels. They are responsible for an increase of the slow inward current of Ca2 during depolarization of the cell. The increased concentration of Ca2 results in the increased heartbeat strength. The heartbeat and the excitation line, especially in the AV node, accelerated, since by increasing the slow influx of Na - the spontaneous diastolic depolarization is accelerated in all heart sections and Ca2 ions.

In addition, isoprenaline slows the antigen-induced release of the neurotransmitter histamine, which the mediation of anaphylaxis is braked, and increases the production of lactate. Furthermore, it has a uterusrelaxierende effect ( tocolysis ).

It is compatible with almost all common solutions for intravenous injection, with the exception of sodium bicarbonate. In the treatment of bronchial asthma, the application is preferred locally in the form of an aerosol of the systemic administration, because of the onset of action occurs as before, and the systemic effect of the excitation of β1 - adrenergic receptors, is smaller.

The administration of isoprenaline is contraindicated in hyperthyroidism, coronary and atherosclerosis, as well as in heart failure, arrhythmias, tachycardia and arterial hypertension.

Stereochemistry

Isoprenaline is as a 1:1 mixture (racemate ) of (R) - used and (S )-enantiomer, although the significance of the enantiomeric purity of the active compounds synthetically produced is increasingly given attention, for the two enantiomers of a chiral drug almost always show a different Pharmacology and pharmacokinetics. This was previously often ignored due to ignorance of stereochemical relationships. Basic considerations, would prefer to use the better and have fewer side effects active enantiomer. (R) - and (S) isomers of isoprenaline bind significantly different to human serum proteins.

Pharmaceutical Market

In Germany no finished product with this ingredient are available.