No

Beta₂ Agonist

Inhibits uterine contraction in preterm labor

B (contraindicated before 20th week)

Do not use before 20th week of pregnancy, cardiac arrhythmias, pheochromocytoma

Monitor hydration status and blood glucose concentrations; fatal maternal pulmonary edema has been reported, sometimes after delivery; fluid overload must be avoided, hydration levels should be monitored closely; if pulmonary edema occurs, the drug should be discontinued; use with caution in patients with moderate pre-eclampsia, diabetes, or migraine; some products may contain sulfites; maternal deaths have been reported in patients treated with ritodrine and concurrent corticosteroids (pulmonary edema)

>10%:

Cardiovascular: Increases in maternal and fetal heart rates and maternal hypertension, palpitations

Endocrine & metabolic: Temporary hyperglycemia

Gastrointestinal: Nausea, vomiting

Neuromuscular & skeletal: Tremor

1% to 10%:

Cardiovascular: Chest pain

Central nervous system: Nervousness, anxiety, restlessness

<1%: Ketoacidosis, impaired LFTs, anaphylactic shock

Symptoms of overdose include tachycardia, palpitations, hypotension, nervousness, nausea, vomiting, tremor

Use an appropriate beta-blocker as an antidote

Decreased effect with beta-blockers

Increased effect/toxicity with meperidine, sympathomimetics, diazoxide, magnesium, betamethasone (pulmonary edema), potassium-depleting diuretics, general anesthetics

Stable for 48 hours at room temperature after dilution in 500 mL of NS, D₅W, or LR I.V. solutions

Tocolysis due to its uterine beta₂-adrenergic receptor stimulating effects; this agent's beta₂ effects can also cause bronchial relaxation and vascular smooth muscle stimulation

Absorption: Oral: Rapid

Distribution: Crosses the placenta

Protein binding: 32%

Metabolism: In the liver

Half-life: 15 hours

Time to peak serum concentration: Within 0.5-1 hour

Elimination: In urine as unchanged drug and inactive conjugates

Adults: I.V.: 50-100 mcg/minute; increase by 50 mcg/minute every 10 minutes; continue for 12 hours after contractions have stopped

Hematocrit, serum potassium, glucose, colloidal osmotic pressure, heart rate, and uterine contractions

May cause nervousness, restlessness, or anxiety

None reported

No information available to require special precautions

No effects or complications reported

I.V.: Remain in left lateral position during infusion; do not get out of bed. Report rapid heartbeat, dizziness, difficulty breathing, nervousness or restlessness, skin itching or rash.

Oral: Take as directed and follow instruction of prescriber for physical activity. Report palpitations or chest pain, acute nausea or vomiting, difficulty breathing, skin irritation or rash, abdominal cramping, vaginal discharge, or other signs of labor.

Infusion, in D₅W: 0.3 mL (500 mL)

Injection, as hydrochloride: 10 mg/mL (5 mL); 15 mg/mL (10 mL)

Bracero LA, Leikin E, Kirshenbaum N, et al, "Comparison of Nifedipine and Ritodrine for the Treatment of Preterm Labor," Am J Perinatol, 1991, 8(6):365-9.

Pisani RJ and Rosenow EC 3d, "Pulmonary Edema Associated With Tocolytic Therapy," Ann Intern Med, 1989, 110(9):714-8.