Carboprost is a synthetic prostaglandin analogue of PGF2α that acts to increase the contractions of the uterus (womb) and can trigger abortion in early pregnancy. This also helps to control excessive bleeding after delivery.

Carboprost tromethamine administered intramuscularly stimulates in the gravid uterus myometrial contractions similar to labor contractions at the end of a full term pregnancy. Whether or not these contractions result from a direct effect of carboprost on the myometrium has not been determined. Nonetheless, they evacuate the products of conception from the uterus in most cases.

Postpartum, the resultant myometrial contractions provide hemostasis at the site of placentation.

Carboprost tromethamine also stimulates the smooth muscle of the human gastrointestinal tract. This activity may produce the vomiting or diarrhea or both that is common when carboprost tromethamine is used to terminate pregnancy and for use postpartum. In laboratory animals and also in humans carboprost tromethamine can elevate body temperature. With the clinical doses of carboprost tromethamine used for the termination of pregnancy, and for use postpartum, some patients do experience transient temperature increases.

In laboratory animals and in humans large doses of carboprost tromethamine can raise blood pressure, probably by contracting the vascular smooth muscle. With the doses of carboprost tromethamine used for terminating pregnancy, this effect has not been clinically significant. In laboratory animals and also in humans carboprost tromethamine can elevate body temperature. With the clinical doses of carboprost tromethamine used for the termination of pregnancy, some patients do experience temperature increases. In some patients, carboprost tromethamine may cause transient bronchoconstriction.

Carboprost Sterile Solution is indicated for aborting pregnancy between the 13th and 20th weeks of gestation as calculated from the first day of the last normal menstrual period and in the following conditions related to second trimester abortion:

• Failure of expulsion of the fetus during the course of treatment by another method;
• Premature rupture of membranes in intrauterine methods with loss of drug and insufficient or absent uterine activity;
• Requirement of a repeat intrauterine instillation of drug for expulsion of the fetus;
• Inadvertent or spontaneous rupture of membranes in the presence of a previable fetus and absence of adequate activity for expulsion.

Carboprost is indicated for the treatment of postpartum hemorrhage due to uterine atony which has not responded to conventional methods of management. Prior treatment should include the use of intravenously administered oxytocin, manipulative techniques such as uterine massage and, unless contraindicated, intramuscular ergot preparations. Studies have shown that in such cases, the use of Carboprost has resulted in satisfactory control of hemorrhage, although it is unclear whether or not ongoing or delayed effects of previously administered ecbolic agents have contributed to the outcome. In a high proportion of cases, Carboprost used in this manner has resulted in the cessation of life threatening bleeding and the avoidance of emergency surgical intervention.

Abortion and Indications 1-4: An initial dose of 1 mL of Carboprost Sterile Solution (containing the equivalent of 250 micrograms of carboprost) is to be administered deep in the muscle with a tuberculin syringe. Subsequent doses of 250 micrograms should be administered at 1½ to 3½ hour intervals depending on uterine response.

An optional test dose of 100 micrograms (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 micrograms (1 mL).

The total dose administered of carboprost tromethamine should not exceed 12 milligrams and continuous administration of the drug for more than two days is not recommended.

For Refractory Postpartum Uterine Bleeding: An initial dose of 250 micrograms of Carboprost Sterile Solution (1 mL of Carboprost) is to be given deep, intramuscularly. In clinical trials it was found that the majority of successful cases (73%) responded to single injections. In some selected cases, however, multiple dosing at intervals of 15 to 90 minutes was carried out with successful outcome. The need for additional injections and the interval at which these should be given can be determined only by the attending physicians as dictated by the course of clinical events. The total dose of Carboprost should not exceed 2 milligrams (8 doses).

• Hypersensitivity (including anaphylaxis and angioedema) to Carboprost Sterile Solution
• Acute pelvic inflammatory disease
• Patients with active cardiac, pulmonary, renal or hepatic disease

The most frequent adverse reactions observed are related to its contractile effect on smooth muscle, especially gastrointestinal effects like vomiting, nausea, diarrhea and pyrexia. Endometritis, retained placental fragments, and excessive uterine bleeding occurred as the most common complications after abortion with Carboprost.

• Use Carboprost by medically trained personnel in a hospital which can provide immediate intensive care and acute surgical facilities.
• Use Carboprost cautiously in patients with a history of asthma, hypo- or hypertension, cardiovascular, renal or hepatic disease, anemia, jaundice, diabetes or epilepsy and compromised (scarred) uteri.
• In few patients with chorioamnionitis, uterus may not respond to Carboprost.
• Cervix should always be carefully examined immediately post-abortion.

Pregnancy & Lactation

Pregnancy category C. Animal studies do not indicate that Carboprost is teratogenic, however, it has been shown to be embryotoxic in rats and rabbits and any dose which produces increased uterine tone could put the embryo or fetus at risk.