RITODRINE

Toxicity

LD50=64mg/kg (mice, IV); LD50=540 mg/kg (mice, oral); LD50=85 mg/kg (rat, IV)

Description

Ritodrine, 4-hydroxy-α-[1-[(4′-hydroxyphenethyl)amino]ethyl]benzylic alcohol (11.1.19), differs slightly from epinephrine, and in the given example only one hydroxyl group has been added to the aromatic ring of the phenylethylamino region of classic sympathomimetics. The second major difference between the examined series is the replacement of the traditionally terminal iso-propyl or tert-butylamine region with a p-hydroxyphenylethylamine. Finally, the third difference is the presence of a methyl group at the α-atom of the phenylethylamine region of sympathomimetics, which makes it similar to isoetharine.

The Uses of RITODRINE

Ritodrine is a selective β2-adrenoreceptor stimulant, predominantly of the urino-genital system. It is used as a tocolytic agent for problems associated with premature miscarriages, and only in specialized medical facilities.

The Uses of RITODRINE

Relaxant (smooth muscle).

Background

Adrenergic beta-agonist used to control premature labor.

Indications

For the treatment and prophylaxis of premature labour

Definition

ChEBI: (1S,2R)-ritodrine is a 4-[2-[[1-hydroxy-1-(4-hydroxyphenyl)propan-2-yl]amino]ethyl]phenol that has (1S,2R)-configuration. It is an enantiomer of a (1R,2S)-ritodrine.

General Description

Ritodrine is a selective β2-agonist that wasdeveloped specifically for use as a uterine relaxant. Its uterineinhibitory effects are more sustained than its effects onthe cardiovascular system, which are minimal comparedwith those caused by nonselective β-agonists. The cardiovasculareffects usually associated with its administrationare mild tachycardia and slight diastolic pressure decrease.Usually, it is administered initially by intravenous infusionto stop premature labor and subsequently it may be givenorally.

Pharmacokinetics

Beta-2 adrenergic receptors are located at sympathetic neuroeffector junctions of many organs, including uterus. Ritodrine is beta-2 adrenergic agonist. It stimulates beta-2 adrenergic receptor, increases cAMP level and decreases intracellular calcium concentration. The decrease of calcium concentration leads to a relaxation of uterine smooth muscle and, therefore, a decrease in premature uterine contractions.

Clinical Use

Ritodrine is a selective β2-agonist that is used exclusively for relaxing uterine muscle and inhibiting the contractions of premature labor. Terbutaline, in addition to its use as a bronchodilator, also has been used for halting the contractions of premature labor.

Synthesis

Ritodrine is synthesized from 4-benzyloxypropiophenone, which undergoes bromination into 4-benzyloxy-|á-bromopropiophenone (11.1.17). This is reacted with 2-(4-benzyloxyphenyl)ethylamine, forming an intermediate product (11.1.18), which undergoes further debenzylation by hydrogen using a palladium catalyst, giving ritodrine (11.1.19) [24,25].

Metabolism

Hepatic, by both the mother and fetus