1. Clinical Overview
Dinoprostone is a synthetic prostaglandin E2 (PGE2) used primarily in obstetrics and gynecology for cervical ripening and induction of labor. It mimics the natural prostaglandins produced by the body to prepare the cervix for delivery. In the Indian context, it is a critical drug for managing post-term pregnancies and other indications requiring labor induction, available primarily as a vaginal gel or pessary.
| Onset | Duration | Bioavailability |
|---|---|---|
| Cervical ripening effects begin within 10-30 minutes of vaginal administration. Uterine contractions typically begin within 1-4 hours. | The pharmacodynamic effects persist for several hours. The gel formulation's effect on cervical ripening can last up to 12 hours, while the pessary provides a sustained release over 12-24 hours. | Approximately 10-20% following vaginal administration due to extensive first-pass metabolism if absorbed systemically. Local cervical action is primary. |
2. Mechanism of Action
Dinoprostone acts locally on the cervix and uterus. It promotes cervical ripening by breaking down collagen fibers and increasing the water content and distensibility of the cervical stroma. It directly stimulates the myometrium, increasing the frequency, duration, and amplitude of uterine contractions, mimicking the natural process of labor.
3. Indications & Uses
- Cervical ripening for induction of labor in women at or near term with a medical or obstetric indication
- Induction of labor in cases of intrauterine fetal death (IUFD) or missed abortion (in the second trimester)
4. Dosage & Administration
Adult Dosage: For cervical ripening/labor induction: 0.5 mg (1 gel applicator) inserted high into the posterior vaginal fornix. A second dose of 0.5 mg may be repeated after 6 hours if needed, provided there is no evidence of uterine hyperstimulation and membranes are intact. Maximum cumulative dose: 1.5 mg (3 doses) within a 24-hour period.
Administration: For vaginal gel: Administer with patient in dorsal position. Insert applicator high into the posterior vaginal fornix. Patient should remain supine for at least 30 minutes post-administration. MUST be administered in a hospital setting with continuous electronic fetal heart rate and uterine activity monitoring for at least 2 hours post-dose and until regular contractions are established. Do not administer above the recommended dose or frequency. Oxytocin should not be initiated for at least 6-12 hours after the last dinoprostone dose.
5. Side Effects
Common side effects may include:
- Uterine hyperstimulation (with or without fetal distress)
- Nausea
- Vomiting
- Diarrhea
- Abdominal pain/cramping
- Back pain
- Fever/pyrexia (maternal)
- Fetal heart rate abnormalities (tachycardia, bradycardia, decelerations)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other Oxytocics (Oxytocin, Misoprostol, Carboprost) | Potentiates uterine stimulant effect, increasing risk of uterine hyperstimulation, tetany, or rupture. | Major |
| Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) e.g., Aspirin, Ibuprofen, Diclofenac | May antagonize the uterine effect of dinoprostone by inhibiting prostaglandin synthesis. | Moderate |
| Corticosteroids | Theoretical risk of enhanced anti-inflammatory effect; clinical significance unknown. | Minor |
| Antihypertensives | Dinoprostone may have vasoactive effects; monitor blood pressure. | Moderate |
7. Patient Counselling
- Do: Remain in the hospital for the entire duration of induction and labor.
- Do: Report immediately any severe, continuous abdominal pain, vaginal bleeding, dizziness, or difficulty breathing.
- Don't: Attempt to self-administer or take home.
- Don't: Get out of bed for at least 30 minutes after the gel is inserted as advised by the nurse/doctor.
8. Toxicology & Storage
Overdose: Manifests as uterine hyperstimulation (tetanic contractions lasting >2 minutes, increased basal tone), which can lead to fetal distress, uterine rupture, and amniotic fluid embolism. Systemic symptoms include severe nausea, vomiting, diarrhea, fever, chills, and bronchospasm.
Storage: Store in a refrigerator between 2°C to 8°C. Do not freeze. Keep in the original package to protect from light. The gel/pessary should be allowed to reach room temperature for about 30 minutes before use. Do not use if the seal is broken or the product is discolored. Keep out of reach of children.