Category:

• Hormonal

Description:

• Beta (b₂) receptor agonist

Indications:

• Management of preterm labor

Contraindications:

• Prior to the 20^th week of pregnancy

• In conditions where the continuation of pregnancy may be harmful to mother or fetus, such as:

  • antepartum hemorrhage that demands immediate delivery

  • eclampsia

  • severe preeclampsia

  • interuterine fetal death

  • chorioamnionitis

  • maternal cardiac disease

  • pulmonary hypertension

  • maternal hyperthyroidism

  • uncontrolled maternal diabetes mellitus

• Maternal conditions that would be adversely affected by ritodrine pharmacology, such as:

  • hypovolemia

  • cardiac arrythmias associated with tachycardia or digitalis intoxication

  • uncontrolled hypertension

  • pheochromocytoma

  • bronchial asthma already being treated with beta aganonists or steroids

Precautions:

• Pregnancy category B

• Transient cerebral ischemia has been associated in patients having migraine headaches

• Intrauterine growth retardation (IUGR) may occur, thereby decreasing birth weights for gestational age

• Be aware of cardiovascular effects if beta-agonists (decreased cardiac output, arrythmias, anginal pain)

• May cause maternal pulmonary edema.

• Lab abnormalities:

• Elevates plasma insulin and glucose levels

• Decreases plasma potassium levels

Adverse Reactions (Side Effects):

• Maternal:

  • palpitations (33%)

  • tremor, nausea, vomiting, headache, erythema (10-15%)

  • nervousness, restlessness, anxiety (5-6%)

• Fetal

  • hypoglycemia, ileus  

Dosage:

Administered by injection

• Initial dose: 

  • 0.05mg/min, gradually increased by 0.05mg/min every 10 minutes until desired result is obtained

• Effective dose generally between 0.15-0.35mg/min