With a time of 1:43.99, Prologaieva also beat Rung’s previous world record in the SB4 class.
The 22-year-old Norwegian trailed the Ukrainian swimmer by 1.49 seconds, while Spain’s Teresa Perales took bronze.
”I’m pleased. She’s fantastic; it was absolutely well-deserved,” said Rung of the gold medallist.
”Of course it’s a bit disappointing, but I’m also very pleased with myself,” she told broadcaster NRK.
Rung won a gold medal in the 200m freestyle earlier in the Games, as well as taking silver in the 200m medley, a race also won by Prologaieva.
A wheelchair user since a failed back operation in 2008, Rung said she was ready to take on the Ukrainian again in Friday’s 50m butterfly.
“She’s not rid of me yet; there’s one race to go,” said Rung.
Norway’s only other medal at the Games so far came at the weekend, when Tommy Urhaug took gold in table tennis.