Drug Interaction:
+ Ritodine
Atropine
Systemic hypertension exaggerated with parasympatholytics
Betablockers
Beta-adrenergic blockers inhibit the action of ritodrine , avoid
co-administration
Corticosteroids
Concomittant use lead to pulmonary edema
Diazoxide / Gen anesthetics/ Magnesium Sulfate / Meperidine
Cardiovascular effects of ritodrine (especially arrhythmias or
hypotension) potentiated by concomittant use
Sympatho - mimetics/ Ritodine
Effects of concomittant use additive or potentiated. A sufficient
time interval should elapse prior to administration of another
sympathomimetic drug
Indication:
Management of Preterm labour
Adverse Reaction:
Dose-related alterations in maternal and fetal heart rates and in maternal blood pressure Persistent tachycardia .
140 bpm may indicate impending pulmonary edema. Infusion is associated with transcient elevation of blood glucose and insulin which decreases to normal after 48 to 72 hours despite continued infusion.
Palpitations, tremor, nausea, vomiting, headache, eryhthema, nervousness, jitterness, restlessness, emotional upset,anxiety, malaise,cardiac symptoms Sinus bradycardia may occur upon drug wihdrawal
Miscellaneous- neonatal effects are infrequently reported are hypoglycemia and ileus. Hypocalcemia and hypotension have been reported in neonates whose mothers were treated with other betamimetic agents.
Contra-Indications:
Antepartum haemorrhage, eclampsia and severe pre-eclampsia, intrauterine foetal death,
chorioamnionitis, maternal conditions such as arrhythmias, uncontrolled hypertension
or diabetes, bronchial asthma treated with beta agonists, hyperthyroidism, hypersensitivity.
Special precautions:
Cardiovascular risk factors, concurrent steroids, premature repture of membranes, migraine, check plasma glucose and potassium.
Migrane headache- transcient cerebral ischemia associated with beta-sympthomimetic therapy has been reported
Chorioamnionitis- when used to manage preterm labor in a patient with premature rupture of membrane balance benefits of delaying delivery against the risk of developing chorioamniionitis.
Intrauterine growth retardation-IUGR consider IUGR in the differential diagnosis of preterm labor, especially when the gestational age is in doubt. The decison to contnue or reinitiate administration will depend on an assessment of fetal maturity.
Lab test abnormalities- administration of ritodrine Iv elevates plasma insulin and glucose and decreases plasma potassium concentrations. Monitor glucose and electrolyte levels during the protracted infusion.
Base line ECG- shuld be performed to rule out occult maternal heart disease.
Sulfites - may cause allergic type of reactions
Warnings-
Maternal pulminary edema- has been reported in patients treated with ritodrine, sometimes after delivery. Closely monitor patients and avoid fluid overload.
Mild to moderate preeclampsia,hypertension or diabetes- do not administer to patients with these disoreders until the benefits clearly outweigh the risks.
Advanced labor- safety and efficacy in advanced labor have not been established.
Cardiovascular effects- beta-adrenergic drugs decrease cardiac output and even in a healthy heart this added myocardial oxygen demand can sometimes lead to myocardial ischemia.
Cardiovascular responses- are common and more pronounced during IV administration.
Monitor these effects, including maternal pulse rate, blood pressure, fetal heart rate, and maternal signs and symptoms of pulmonary edema.
Pregnancy- do not use this drug before 20 weeks of pregnancy.
Dosages/ Overdosage Etc:
Indications:
Management of Preterm labour
Dosage:
Initial IV treatment is followed by oral administration.
Initial dose is 0.1 mg/min(0.33ml/min or 20 drops/min using a microdip chamber at the
recommended dilution) to be gradually increased by 0.05 mg/min(10 drops/min) every
10 minutes,until the desired results are obtained.
Storage: Do not use if the solution is discoloured or contains any precipitate or particulate
matter. Store at room temperature,below 30C.
Overdosage-
Symptoms
Excessive beta adrenergic stimulation including exagerration of pharmacologic effects, the most prominent being tachycardia( maternal and fetal) palpitations, cardiac arrhythmia , hypotension, dyspnea, nervousness, tremor, nausea, and vomiting.
Treatment
1. Includes usual supportive measures. When symptoms occur as a result of IV use.
2. Discontinue the drug.
3. Use an appropiate beta blocker as an antidote.
4. Ritodrine is dialyzable.
Missed dose-
1. If you miss an oral dose of this medicine, and remember within 1 hour or so of the missed dose, take it right away.
2. However, if you do not remember until later, skip the missed dose and go back to your regular dosing schedule.
3. Do not double doses.
Patient Information:
Ref - USP PDI Vol II 17th Edition (1997)
RITODRINE- SYSTEMIC
1.Allergies-
Tell your doctor if you have ever had any unusual or allergic reaction to
ritodrine or sulfites. Also tell your healthcare care professional if you are
allergic to any other substances such as foods. preservatives or dyes.
2. Other medicines-
Tell your doctor if you are using any of the following -
Beta-adrenergic blocking agents- Ritodrine may be less effective if it
is used with any of these medicines
Corticosteroids- these medicines are given together to the mother to help
her babys lung develop. If you taking corticosteroids your dose may need
to be changed. Sometimes a combination of these medicines increases the
chance of side effects occuring in the mother
Medicines for asthma or breathing problems- because these products have
some effects that are similar to those of ritodrine, the chance of side effects
developing is increased, when these medicines are used with ritodrine.
3. Other medical problems-
Make sure you tell your doctor if you have any other medical problems
especially-
Diabetes mellitus- ritodrine may make this condition worse
Heart or blood vessel disease or
Overactive thyroid, uncontrolled - use of ritodrine may cause serious effects
on the heart, including irregular heartbeat
High blood pressure uncontrolled or
Migraine headaches or history of - rotodrine may make these conditions worse.
Rarely use of ritodrine during a headache may cause problems with blood
circulation in the brain.
Pharmacology/ Pharmacokinetics:
Pharmacology:
Ritodrine is a Beta-receptor agonist which exerts a preferential effect on beta 2-adrenergic receptors such as those in the uterine smooth muscle. Ritodrine may directly affect the interaction between the action and myosin of muscle through inhibition of myosin light chain kinase.
Pharmacokinetics:
Following a 60 minutes infusion of IV ritodrine, bioavailability is 100% with peak levels of 32 to 52ng/ml. Half-life of the distribution phase is 6 to 9 minutes, 1.7 to 2.6 hours for the second phase and 15 to 17 hours for the eliminatin phase. At 24 hours 90% of the drug is eliminated in the urine as metabolites.
Interaction with Food:
Reports not available.
Pregnancy and lactation:
Pregnancy:
No adequate and well controlled studies of the drug's effect in pregnant women before 20 weeks gestation, therfore do not use the drug before 20th week of pregnancy.
