At the time he was a servant of the imperial bedchamber (cubicularius), and although young of age enjoyed the favour of emperor Arcadius (r. 383–408).
This allowed him to influence imperial policy, and gained him the post of tutor (baioulos) to the young heir to the throne, the future Theodosius II (r. 402–450).
[2] The 9th-century chronicle of Theophanes the Confessor reports erroneously that Antiochus came to Constantinople only after Arcadius' death in 408, having been dispatched by the Persian shah Yazdegerd I (r. 399–420) to watch over the young Theodosius.
By c. 421, he had risen to the post of praepositus sacri cubiculi, head of the imperial bedchamber, and the exalted rank of patricius.
His property was confiscated, and he was forced to retire as a monk to the Church of Saint Euphemia at Chalcedon, where he later died.