While studying wild chimpanzees, it was noted that after a chimpanzee shared food with a non-kin related chimpanzee,  the subjects levels of oxytocin increased, as measured through their urine. In comparison to other cooperative activities between chimpanzees that were monitored including grooming, food sharing generated higher levels of oxytocin. This comparatively higher level of oxytocin after food sharing parallels the increased level of oxytocin in nursing mothers, sharing nutrients with their kin. Trust is increased by oxytocin. Study found that with the oxytocin nasal spray, people place more trust to strangers in handling their money. Disclosure of emotional events is a sign of trust in humans. When recounting a negative event, humans who receive intranasal oxytocin share more emotional details and stories with more emotional significance. Humans also find faces more trustworthy after receiving intranasal oxytocin. In a study, participants who received intranasal oxytocin viewed photographs of human faces with neutral expressions and found them to be more trustworthy than those who did not receive oxytocin. This may be because oxytocin reduces the fear of social betrayal in humans. Even after experiencing social alienation by being excluded from a conversation, humans who received oxytocin scored higher in trust on the Revised NEO Personality Inventory. Moreover, in a risky investment game, experimental subjects given nasally administered oxytocin displayed "the highest level of trust" twice as often as the control group. Subjects who were told they were interacting with a computer showed no such reaction, leading to the conclusion that oxytocin was not merely affecting risk aversion.
When using to treat hyponatremia, it may cause too rapid correction of hyponatremia resulting in fatal osmotic demyelination syndrome. Pharmacology
Tolvaptan is a selective vasopressin V2 receptor antagonist. Chemistry
Tolvaptan is a racemate, a 1:1 mixture of the following two enantiomers:

References
Further reading
Gheorghiade M, Niazi I, Ouyang J,  et al. (2003). "Vasopressin V2-receptor blockade with tolvaptan in patients with chronic heart failure: results from a double-blind, randomized trial". Circulation. 107 (21): 2690–6. doi:10.1161/01.CIR.0000070422.41439.04. PMID 12742979. External links
"Tolvaptan". Drug Information Portal. U.S. National Library of Medicine.