BBC reports that Nottinghamshire Police have been arrested as part of an ongoing investigation into spiking incidents in Nottingham.
Nottinghamshire Police has received 15 reports of spiking where the victims believe they were injected with a needle on a night out.
The force said there had also been 32 reports of people being spiked by having their drink contaminated since 4 September.
The men, aged 18 and 19, have been released under investigation.
They were arrested on suspicion of conspiracy to administer poison with intent to injure, annoy or aggrieve following information received by police on Wednesday.
A 20-year-old man, arrested earlier this week as part of the investigation, has been released on bail.
Earlier, Lincolnshire Police said it had arrested a 35-year-old man in the early hours of Friday in connection with an attempted drink-spiking at a Lincoln nightclub.
The suspected offence "doesn't involve a needle", the force said.
Several bars in Nottingham have pledged to give female staff the night off to support the boycott and at least six said they planned to close at 22:00 BST.
Ezra Watson, manager of Six Barrel Drafthouse in Hockley, said: "We've swapped shifts so all our female members of staff can stay in and show their support.
"It's just solidarity. You can't and shouldn't ignore it."
Hannah Foxton, a 20-year-old supervisor at The Angel Microbrewery in Hockley - which is also taking part - said: "We have a lot of young female staff who work here and it's hit home for us quite deeply.
"I've gone through being spiked before. It is absolutely terrifying - I can't wrap my head round it.
"It feels like a no-brainer to add our support and our voice to something really important."