RITODRINE HYDROCHLORIDE IN DEXTROSE 5% IN PLASTIC CONTAINER
Clinical safety rating: caution
Comprehensive clinical and safety monograph for RITODRINE HYDROCHLORIDE IN DEXTROSE 5% IN PLASTIC CONTAINER (RITODRINE HYDROCHLORIDE IN DEXTROSE 5% IN PLASTIC CONTAINER).
Ritodrine is a beta-2 adrenergic receptor agonist that stimulates adenylate cyclase, increasing cyclic AMP levels, leading to relaxation of uterine smooth muscle. It also has some beta-1 activity.
| Metabolism | Hepatic metabolism via conjugation and oxidation; metabolites are excreted in urine and feces. |
| Excretion | Renal: >90% as unchanged drug and metabolites; biliary/fecal: minimal (<5%). |
| Half-life | Terminal elimination half-life: 15-26 hours (mean 20 hours) in adults; prolonged in renal impairment. |
| Protein binding | 32% bound to albumin; minimal binding to other proteins. |
| Volume of Distribution | 0.8-1.5 L/kg (mean 1.0 L/kg), indicating distribution into total body water and some tissue binding. |
| Bioavailability | Oral: 30-40% (first-pass metabolism); IV/IM: 100%. |
| Onset of Action | IV: 2-5 minutes; IM: 5-10 minutes; oral: 20-30 minutes. |
| Duration of Action | IV: 2-4 hours; IM: 3-6 hours; oral: 4-8 hours. Duration may be shorter with chronic dosing due to tachyphylaxis. |
Intravenous infusion: initial rate 0.05 mg/min (50 mcg/min), increase by 0.05 mg/min every 10 minutes until effective or maternal heart rate >130 bpm; maximum rate 0.35 mg/min (350 mcg/min). Maintenance: continue at lowest effective rate for 12-48 hours after contractions cease.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment guidelines; use with caution in renal impairment due to potential for reduced clearance. Monitor fluid balance and renal function. |
| Liver impairment | No specific dose adjustment guidelines; use with caution in hepatic impairment due to altered metabolism. Monitor liver function. |
| Pediatric use | Not approved for pediatric use; safety and efficacy not established. |
| Geriatric use | Not indicated for geriatric patients due to risk of adverse events; avoid use in elderly. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for RITODRINE HYDROCHLORIDE IN DEXTROSE 5% IN PLASTIC CONTAINER (RITODRINE HYDROCHLORIDE IN DEXTROSE 5% IN PLASTIC CONTAINER).
| Breastfeeding | It is not known whether ritodrine is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when administered to a nursing woman. No M/P ratio available. |
| Teratogenic Risk | FDA Pregnancy Category B. Animal studies have not revealed evidence of teratogenicity; however, no adequate and well-controlled studies in pregnant women. In first trimester, risk is theoretical; use only if clearly needed. In second and third trimesters, use for management of preterm labor may cause maternal and fetal tachycardia, maternal hyperglycemia, and fetal hyperinsulinemia. Neonatal effects include hypoglycemia, ileus, and hypocalcemia. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to ritodrine or any component","Pre-eclampsia, eclampsia, or severe hypertension","Maternal cardiac disease (e.g., tachyarrhythmias, myocardial infarction)","Placental abruption or hemorrhage in pregnancy","Intrauterine infection (chorioamnionitis)","Fetal distress or intrauterine fetal demise","Cervical dilation >4 cm or ruptured membranes (relative)"]
| Precautions | ["Maternal pulmonary edema, especially with multiple gestations, fluid overload, or concurrent corticosteroids.","Maternal cardiac effects including tachycardia, arrhythmias, myocardial ischemia, and hypotension.","Hypokalemia and hyperglycemia.","Fetal tachycardia and neonatal hypoglycemia.","Use for >48-72 hours not recommended due to limited benefit and increased risk."] |
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| Fetal Monitoring | Maternal: Heart rate and blood pressure, serum potassium, glucose, and lactate levels; pulmonary edema assessment (respiratory rate, auscultation). Fetal: Heart rate monitoring via electronic fetal monitoring; assess for tachycardia. During infusion, monitor maternal vital signs every 5-15 minutes and fetal heart rate continuously. |
| Fertility Effects | No adequate data on fertility effects in humans. Animal studies have not shown impaired fertility at clinically relevant doses. |