Which of the following is NOT a tocolytic agent?

The inhibition of uterine contractions, or tocolysis, has been the mainstay therapy for pre-term labour. Specific tocolytic agents are adrenergic receptor agonists Terbutaline, Ritodrine), MgSO4, Ca2+ channel blockers (Nifedipine), COX inhibitors, oxytocin-receptor antagonists, and nitric oxide donors. Two forms of prostaglandins are commonly used for cervical ripening prior to induction at term a) Misoprostol (PGE1) and Dinoprostone (PGE2) Ref: Schimmer B.P., Parker K.L. (2011). Chapter 66. Contraception and Pharmacotherapy of Obstetrical and Gynecological Disorders. In L.L. Brunton, B.A. Chabner, B.C. Knollmann (Eds), Goodman & Gilman's The Pharmacological Basis of Therapeutics, 12e Archie C.L. (2007). Chapter 10. The Course & Conduct of Normal Labor & Delivery. In A.H. DeCherney, L. Nathan (Eds), CURRENT Diagnosis & Treatment Obstetrics & Gynecology, 10e