(ShareCast News) - The chief executive of Devro raised his stake in the collagen product manufacturer one day after the company posted a raise in profits thanks to a strong hike in demand.Peter Page holds now a stake of 0.4% in the group with 672,440 shares after purchasing 10,000 new shares at 318.5p each. The purchase cost him £31,850.On Wednesday, the London-listed company said its pre-tax profit surged from £1.6m to £9.6m in the six months to 30 June, as exceptional costs were slashed 62.9% year-on-year to £4m.Revenue rose 2.7% to £112.7m on the back of strong market demand in China, Japan and South East Asia and steady growth in North America.Also on Thursday, Sepura announced its new chairman bought his first shares in the radio maker.Russell King purchased 20,000 shares for an individual price of 158p, spending a total of £31,600 in the transaction.King, who was already a non-executive director of the firm and became chairman on Wednesday, holds now 0.01% of the company's issued share capital.The director replaced John Hughes who stood down after five years as chairman but remains as a strategic advisor.Top Director BuysDevro (DVO) Director name: Mr Peter PageAmount purchased: 10,000 @ 318.50p Value: £31,850Sepura (SEPU) Director name: Mr Russell J KingAmount purchased: 20,000 @ 158.00p Value: £31,600Norcros (NXR) Director name: Mr Martin TowersAmount purchased: 125,000 @ 19.93p Value: £24,912Fidessa Group (FDSA) Director name: Mr John HamerAmount purchased: 1,000 @ 1,989.00p Value: £19,890Top Director SellThere were no sells today