Q: A female, 21 years old presented to ER with suspicion of ectopic pregnancy. Ob-Gyn service is considering surgical vs medical approach after the 'expectant management' is ruled out. Which is the drug of choice for medical management of an ectopic pregnancy?
Answer: Methotraxate (MTX)
ΜTX is a folic acid antagonist. It is clinically used in other medical conditions as well, such as neoplasia, severe psoriasis, and rheumatoid arthritis (RA). It inhibits deoxynucleic acid (DNA) synthesis and cell reproduction, primarily in actively proliferating cells such as malignant cells, trophoblast cells which are rapidly proliferating fetal cells (cytotrophoblast and syncytiotrophoblast). One of the advantages of MTX is its rapid renal clearance.
Paradoxically, to its mechanism of action, reduced folates (leucovorin, also called folinic acid, N5-formyl-tetrahydrofolate, citrovorum factor) are given in combination with МΤX. This bypasses the metabolic block induced by МΤX and rescues normal cells from toxicity.
ΜТX is usually given intramuscularly (IM) but can be given intravenously, orally, and in some cases directly into the ectopic рrеgոanϲy sac either transvaginally or transabdominal through a laparoscope which is the preferred method mostly implied.
A pharmacy service should be consulted for dosage.
#ob-gyn
References:
1. Bleyer WA. The clinical pharmacology of methotrexate: new applications of an old drug. Cancer 1978; 41:36.
2. Hajenius PJ, Mol F, Mol BW, et al. Interventions for tubal ectopic pregnancy. Cochrane Database Syst Rev 2007; :CD000324.
3. Barnhart KT, Gosman G, Ashby R, Sammel M. The medical management of ectopic pregnancy: a meta-analysis comparing "single dose" and "multidose" regimens. Obstet Gynecol 2003; 101:778.
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