"What happens is the medication balances the chemicals out, and when something happens, he reacts properly and doesn't lose his temper."

Rowlands' fight is off

Bright said Tyson's handlers have also been working with Tyson to control himself and remain calm in the ring.

The British board's chief medical officer, Adrian Whiteson, wants information about the drug but insists it must come from doctors, not Tyson's managers, trainers or promoters.

The BBC's boxing correspondent, John Rawling, said the board was likely to demand that the drug was ceased before the bout.

Tyson, who has been training in Phoenix, flies to London on Wednesday before heading to Glasgow a few days before the fight. All 60,000 tickets are expected to be sold.

It will be Tyson's second fight in Britain in five months. He knocked out Julius Francis in the second round in January in Manchester, England.

Meanwhile, the main undercard fight on the night of Tyson's bout at Hampden is off.

Jason Rowlands has had to pull out of his fight with American Zad Judah because of an injured knee.