Oxytocin
3-(19-amino-13-sec-butyl-7-(carboxymethyl)-4-(2-(1-(carboxymethylamino)-5- guanidino-1-oxopentan-2-ylcarbamoyl) pyrrolidine-1-carbonyl)-16-(4-hydroxybenzyl)- 6,9,12,15,18-pentaoxo-1,2-dithia-5,8,11,14,17- pentaazacycloicosan-10-yl)propanoic acid

Distribution
Distributed throughout the extracellular fluid. Small amounts may reach fetal circulation.

Elimination
Small amounts are unchanged in the urine. The t ½ of plasma is 1 to 6 min.

Onset
Onset of uterine contraction occurs almost immediately in the IV form. In the IM form, it occurs between 3 to 5 min.

Duration
IM is 2 to 3 h. IV is 1 h.