Can we use misoprostol (Cytotec) for labor induction in asthma patients?
Response from Peter S. Bernstein, MD, MPH, FACOG and Lev D. Kandinov, MD
Prostaglandins (PGs) are short-lived, hormone-like, biochemically active lipids that regulate numerous physiologic and pathologic processes. PGs are broken down into 3 groups. For the purposes of our discussion, groups 1 and 3 will be grouped together. These PGs have the following effects: dilation of the airways, decrease in inflammation, vasodilation, increased oxygen flow, and decrease in cellular proliferation. PGs from group 2 induce opposite effects, eg, constriction of the airways, increase in inflammation, and vasoconstriction.
Asthma is a pulmonary disease characterized by airway constriction and inflammation. Multiple factors play a role in this pathologic reaction of the airways. On the cellular level, mast cells, neutrophils, eosinophils, macrophages, and lymphocytes cause local release of histamines, bradykinin, leukotrienes, and PGs, specifically PG-E2 and PG-F2alpha. Release of these substances produces an intense reaction, inflammation, and vasoconstriction.[2,3]
One of the first studies to look into the role of PGs in the pathogenesis of bronchial asthma was published over 20 years ago. Levels of PG-E and PG-F2alpha were measured in 84 patients with asthma and compared against the levels of these PGs in nonasthmatics. A significant decrease of PG-E and an increase of PG-F2alpha were observed in asthmatics.
Misoprostol (Cytotec) is a synthetic prostaglandin E1 analog widely used for labor induction. It falls into the group 1 family of PGs, and therefore could be safely used in patients with asthma.
Several studies have looked into the influence of Cytotec (PG-E1) on patients with acetylsalicylic acid (aspirin)-induced asthma. Aspirin is a cyclooxygenase (COX) inhibitor. Blocking COX in the arachidonic acid pathways leads to diminished levels of PG-E1 and subsequent bronchoconstriction and inflammation. Administering Cytotec (PG-E1) was found to have a protective effect on aspirin-induced bronchoconstriction.
Of note, PG-F2alpha analogs are also commonly used in obstetrics (Prostin and Hemabate). These are group 2 PGs and should be avoided if possible or used with caution in patients with asthma.[5,6]
Medscape Ob/Gyn. 2004;9(2) © 2004 Medscape
Cite this: Peter S Bernstein, Lev D Kandinov. Use of Misoprostol for Labor Induction in Patients With Asthma - Medscape - Nov 09, 2004.