Maternal use of cyclobenzaprine (Flexeril) may induce ductal closure and persistent pulmonary hypertension in neonates

J Matern Fetal Neonatal Med. 2014 Jul;27(11):1177-9. doi: 10.3109/14767058.2013.850663. Epub 2013 Nov 5.


A full-term male infant presented shortly after birth with respiratory distress. An echocardiogram done within the first hour of life showed an elevated pulmonary artery pressure, an associated right ventricular hypertrophy without a patent ductus arteriosus. The patient was treated for persistent pulmonary hypertension with favorable response. Maternal history was unremarkable except for chronic low back pain treated with cyclobenzaprine (Flexeril®). A proposed mechanism for cyclobenzaprine includes inhibition of norepinephrine and serotonin reuptake, factors known to inhibit prostaglandin and nitric oxide. These two factors are the leading causes of in-utero ductal closure. This report is the first to indicate that cyclobenzaprine use during late pregnancy should be considered a potential cause of early ductal closure.

Keywords: Cyclobenzaprine; ductus arteriosus; neonate; persistent pulmonary hypertension.

Publication types

  • Case Reports

MeSH terms

  • Abnormalities, Drug-Induced / diagnostic imaging
  • Amitriptyline / adverse effects
  • Amitriptyline / analogs & derivatives*
  • Antidepressive Agents, Tricyclic / adverse effects*
  • Ductus Arteriosus / drug effects
  • Ductus Arteriosus / pathology*
  • Female
  • Heart Septal Defects, Atrial / chemically induced
  • Heart Septal Defects, Atrial / diagnostic imaging
  • Heart Septal Defects, Ventricular / chemically induced
  • Heart Septal Defects, Ventricular / diagnostic imaging
  • Humans
  • Infant, Newborn
  • Male
  • Maternal Exposure / adverse effects*
  • Persistent Fetal Circulation Syndrome / chemically induced*
  • Persistent Fetal Circulation Syndrome / diagnostic imaging
  • Pregnancy
  • Ultrasonography


  • Antidepressive Agents, Tricyclic
  • Amitriptyline
  • cyclobenzaprine