This medicine is used for termination of pregnancy between 13 and 20 weeks of gestation. It is indicated in second trimester abortion in situations such as failure of fetal expulsion with other methods, premature rupture of membranes with inadequate uterine activity, need for repeated intrauterine administration for expulsion, and rupture of membranes in the presence of a viable fetus without sufficient uterine contractions. It is also used for the treatment of postpartum hemorrhage when the uterus fails to contract adequately and does not respond to standard treatments.

Carboprost is a synthetic analogue of prostaglandin PGF2α that stimulates uterine contractions. It helps in inducing abortion and is also effective in controlling excessive bleeding after childbirth by promoting uterine contraction.

Carboprost tromethamine, when administered intramuscularly, stimulates strong uterine contractions similar to those occurring during labor at term pregnancy. Although the exact mechanism on the myometrium is not fully established, these contractions usually result in expulsion of uterine contents. After delivery, these contractions help achieve hemostasis at the placental site. It also stimulates smooth muscle in the gastrointestinal tract, which may lead to nausea, vomiting, or diarrhea. An increase in body temperature may occur in some patients. At higher doses, it may raise blood pressure due to vascular smooth muscle contraction, though this effect is generally not clinically significant at recommended doses. In some cases, transient bronchoconstriction may also occur.

Abortion: An initial dose of 1 ml of Carbestop (containing the equivalent of 250 mcg of Carboprost) is to be administered intramuscularly. Subsequent doses of 250 mcg should be administered at 1½ to 3½ hour intervals depending on uterine response. An optional test dose of 100 mcg (0.4 ml) may be administered initially. The dose may be increased to 500 micrograms (2 ml) if uterine contractility is judged to be inadequate after several doses of 250 mcg (1 ml). The total dose administered of Carbestop should not exceed 12 mg and continuous administration of the drug for more than 2 days is not recommended.

For Refractory Postpartum Uterine Bleeding: An initial dose of 250 mcg of Carbestop (1 ml) is to be given deep, intramuscularly (IM). If needed the dose of 1 ml may be repeated between 15 to 90 minutes. The total dose of Carbestop should not exceed 2 mg (8 doses).

Carboprost may enhance the effects of other oxytocic drugs; therefore, concurrent use with other oxytocic agents is not recommended.

This medication is contraindicated in patients with hypersensitivity to carboprost and in those with acute pelvic inflammatory disease.

The most common adverse effects are related to smooth muscle contraction, particularly gastrointestinal symptoms such as nausea, vomiting, diarrhea, and fever. Other complications following abortion may include endometritis, retained placental tissue, and excessive uterine bleeding.

Carboprost is classified as pregnancy category C. Animal studies have not shown teratogenic effects, but embryotoxicity has been observed in some cases. Any dose that increases uterine tone may pose a risk to the fetus.

Carboprost should be administered only by trained medical professionals in a hospital setting where emergency and surgical facilities are available. It should be used cautiously in patients with asthma, abnormal blood pressure, cardiovascular, renal or hepatic disease, anemia, jaundice, diabetes, epilepsy, or in those with compromised uterine condition. In some cases, patients with chorioamnionitis may show reduced response to the drug. Careful examination of the cervix is recommended immediately after abortion.

Drugs acting on the Uterus

Store at 2–8°C. Do not freeze. Protect from light. Once opened, the ampoule should be used immediately.