Use of Misoprostol for Labor Induction in Patients With Asthma

Peter S. Bernstein, MD, MPH, FACOG; Lev D. Kandinov, MD

Disclosures

November 09, 2004

Question

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.[1]

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.[4]

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]

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