Ritodrine 3-agonist

Adrenergic receptor agonists are also used to treat premature labour by causing uterine relaxation. Fenoterol and ritodrine are frequently used. The effectiveness of long-term tocolysis is controversial, since both desensitization of the receptors and the symptomatic nature of this treatment may limit their effects to 1-2 days according to one large study. 

The only drug that has been lieensed for the treatment of preterm labour in the US is ritodrine, a /1-2 adrenoceptor agonist. -2 Adrenoceptors are... 

The answer is e. (Hardman, p 215 J Ritodrine hydrochloride is a selective [ -adrenergic agonist that relaxes uterine smooth muscle. It also has the other effects attributable to J3-adrenergic receptor stimulants, such as b rone hod il at ion, cardiac stimulation, enhanced renin secretion, and hyperglycemia. 

It is P2 selective agonist with uterine relaxant property and preferred to suppress premature labour and delay delivery of fetus. But, use of ritodrine in suppressing labour has been found to increase maternal morbidity and neonate may develop hyperglycemia. So it... 

If labour begins prematurely, before 33 weeks gestation, myometrial relax-ants (tocolytic agents) can delay it for 48 hours. Beta-2-agonists, such as ritodrine hydrochloride, are given for up to 48 hours to elicit relaxation. Longer treatment is not recommended, because of risk of adverse effects on the mother. Nifedipine and the oxytocin receptor antagonist atosiban are also used to reduce premature uterine contractile activity. 

Salbutamol, fenoterol, rimiterol, reproterol, pir-buterol, salmeterol, ritodrine and terbutaline are P-adrenoceptor agonists that are relatively selective for p2-receptors, so that cardiac (chiefly p -receptor) effects are less prominent. Tachycardia still occurs because of atrial (sinus node) p -receptor stimulation the P2-adrenoceptors are less numerous in the ventricle and there is probably less risk of serious ventricular arrhythmias than with the use of nonselective catecholamines. The synthetic agonists are also longer-acting than isoprenaline because they are not substrates for catechol-O-methyltransferase, which methylates catecholamines in the liver. They are used principally in asthma, and to reduce uterine contractions in premature labour. 

Pj-adrenoceptor agonists relax the uterus and are given by i.v. infusion by obstetricians to inhibit premature labour, e.g. isoxsuprine, terbutaline, ritodrine, salbutamol. Their use is complicated by the expected cardiovascular effects, including tachycardia, hypotension. Less easy to explain, but more devastating on occasion to the patient, is severe left ventricular failure. Possibly the combination of fluid overload (due to the vehicle) and increased oxygen demand by the heart are factors. 

Ritodrine is a beta2-adrenoceptor agonist used in the treatment of premature labor. 

Beta-agonists ritodrine (IV, SQ, PO], terbutaline (SQ,PO) Magnesium sulfate (IV) Calcium channel blodcers(PO) NSAIDs indomethacin [PO. per vagina (PV), per rectum 0 R)] Oxytodn receptor antagonists... 

Ritodrine. Ritodrine (Yutopar) is a selective yS -rccep-tor agonist used to control premature labor and to reverse... 

The selective /32-adrenergic agonists terbutaUne and ritodrine have been reported to induce pulmonary edema when used as tocolytics. This disorder commonly occurs 48 to 72 hours after tocolytic therapy. This has never occurred with their use in asthma patients, even in inadvertent overdosage. This reaction may result from excess fluid administration used to prevent the hypotension from /32-mediated vasodilation or the particular hemodynamics of pregnancy. In a review of 330 patients who received tocolytic therapy and were monitored closely for their fluid status, no episode of pulmonary edema was reported. ... 

The responses of uterine muscle to Epi vary with phase of the sexual cycle, state of gestation, and dose. During the last month of pregnancy and at parturition, Epi inhibits uterine tone and contractions. fi -Selective agonists (e.g., ritodrine or terbutaline) can delay premature labor, although... 

The previously mentioned ritodrine is a selective p2-agonist that is used exclusively for relaxing uterine muscle and inhibiting the contractions of premature labor. Terbutallne, in addition to its use as a bronchodilator, also has been used for halting the contractions of premature labor. 

Ritodrine (Figure 6.2), a selective (32-adrenoceptor agonist used primarily in obstetrics, has been assayed following LLE into ethyl acetate at pH 9.4. 

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