Meta-analyses indicate that calcium-channel blockers and an oxytocin antagonist can delay delivery by 2–7 days, and β2-agonist drugs delay by 48 hours but carry more side effects.
Alpha-adrenergic agonist, drugs that selectively stimulate alpha adrenergic receptors
Alpha-adrenergic agonists work by decreasing production of fluid and increasing drainage.
Terbutaline (trade names Brethine, Bricanyl, Brethaire, or Terbulin) is a asthma symptoms and as a tocolytic (anti-contraction medication) to delay preterm labor for up to 48 hours.
Vilanterol (USAN), or triphenylacetic acid, is a long-acting beta-2 agonist drug, which in May 2013 was approved in combination with fluticasone furoate for sale as Breo Ellipta by GlaxoSmithKline for the treatment of chronic obstructive pulmonary disease (COPD).